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  • 1990-1994  (3,705)
  • 1965-1969  (4,232)
  • 1900-1904  (4,371)
  • Inorganic Chemistry  (12,181)
  • Bone
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  • 1
    Electronic Resource
    Electronic Resource
    Dietary variation in arctic foxes (Alopex lagopus)-an analysis of stable carbon isotopes (1994)
    Springer
    Oecologia 99 (1994), S. 226-232 
    Details
    ISSN: 1432-1939
    Keywords: Carbon isotopes ; Arctic fox ; Diet ; Bone ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used stable carbon isotopes to analyse individual variation in arctic fox diet. We extracted collagen from bones (the lower jaw), and measured stable carbon isotopes. The foxes came from three different localities: Iceland, where both microtines and reindeer are rare; west Greenland, where microtines are absent; and Sweden, where scat analyses showed the primary food to be microtine rodents and reindeer. The Icelandic samples included foxes from both coastal and inland habitats, the Swedish sample came from an inland area, and the Greenland sample from coastal sites. The spatial variation in the isotopic pattern followed a basic division between marine and terrestrial sources of protein. Arctic foxes from inland sites had δ13C values of −21.4 (Iceland) and −20.4‰ (Sweden), showing typical terrestrial values. Coastal foxes from Greenland had typical marine values of −14.9‰, whereas coastal foxes from Iceland had intermediate values of −17.7‰. However, there was individual variation within each sample, probably caused by habitat heterogeneity and territoriality among foxes. The variation on a larger scale was related to the availability of different food items. These results were in accordance with other dietary analyses based on scat analyses. This is the first time that stable isotopes have been used to reveal individual dietary patterns. Our study also indicated that isotopic values can be used on a global scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627734
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  • 2
    Electronic Resource
    Electronic Resource
    The time course of renal function and bone turnover in parathyroid crisis due to intratumoral hemorrhage (1994)
    Springer
    Journal of molecular medicine 72 (1994), S. 448-450 
    Details
    ISSN: 1432-1440
    Keywords: Parathyroid ; Crisis ; Kidney ; Bone ; Turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Parathyroid crisis occurring in primary hyperparathyroidism is characteized by extremely high circulating levels of parathyroid hormone and acute onset of severe hypercalcemia. We describe a 62-year-old woman with parathyroid crisis probably due to an intraturnoral hemorrhage. Renal dysfunction reduced the effectiveness of preoperative management and continued to deteriorate for 5 days after parathyroidectomy. The normalization of serum calcium after parathyroidectomy delayed and it took 6 days. Maintenance of renal function is important for pre- and postoperative courses of the present case. The rapid decrease in serum parathyroid hormone after parathyroidectomy was followed by a rapid and transient (about fivefold) increase in serum alkaline phosphatase with peak value on the 10th postoperative day. This indicated that reversal phase from bone resorption (accelerated by parathyroid hormone) to bone formation lasted about 10 days under the conditions of the present case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180519
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  • 3
    Electronic Resource
    Electronic Resource
    Magnesium distribution in human bone (1994)
    Springer
    Calcified tissue international 54 (1994), S. 34-37 
    Details
    ISSN: 1432-0827
    Keywords: Magnesium ; Bone ; Aging ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The present study was undertaken to reveal the magnesium distribution in human bone. Sixty human ribs, obtained from subjects aged 10–80 years of age, were used. Transverse sections were prepared from the middle region of the human ribs. Adjacent sections were ground to a thickness of about 1000 μm. One section was used for magnesium determination by atomic absorption spectrophotometry, and the other was used for analysis with X-ray microanalysis. Thirty micron thick samples were abraded continuously from the periosteal and the endosteal surfaces by abrasive microsampling, as previously described by Weatherell et al. [3]. Results showed that magnesium concentrations were higher in both the periosteal and endosteal surfaces and did not change with age in general, although it tended to be higher among teenagers and lower over 80 years old.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316287
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  • 4
    Electronic Resource
    Electronic Resource
    Age-dependence of bone material quality shown by the measurement of frequency of resonance in the ulna (1994)
    Springer
    Calcified tissue international 54 (1994), S. 96-100 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Material quality ; Sound transmission ; Frequency of resonance ; Age ; Bone width
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract In women before and after the age of peak bone mass, identical values of bone mineral density (BMD) can be obtained. However, there is a much higher incidence of osteoporotic fractures in older women. We investigated whether a deterioration of bone material quality with increasing age might contribute to this phenomenon. Material properties of bone tissue can be characterized by the modulus of elasticity, which is correlated to the square of sound transmission velocity. In this study, sound transmission velocity was determined in cortical bone by measuring the frequency of resonance in the ulna in the direction of the bone's longitudinal axis and correcting the values by multiplying by ulna length. Validation of this method indicated acceptable reproducibility: interobserver variability determined as the mean coefficient of variation was 1.82%. In a clinical study, 21 young women (22.5±1.2 years old) were compared with 21 middle-aged women (52.9±2.7 years old). Pairs were matched that had identical values of BMD in the nondominant forearm at a location representing mainly cortical bone (SPA). The product of ulna length and frequency of resonance in the ulna in the younger women was found to be 61.4±5.8 m/second, and in the middle-aged women 55.7±4.5 m/second. The difference was highly significant with P〈0.005. Our results confirm recent findings indicating a deterioration of bone material quality independent of BMD with increasing age. As shown by comparing ulna width at the site of measurement of bone mineral density between both groups of women, the deterioration of bone material quality in ulnar cortical bone with increasing age might at least in part be functionally compensated by an increase of the moment of inertia due to greater bone width [8, 10].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296058
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  • 5
    Electronic Resource
    Electronic Resource
    Intact serum parathyroid hormone levels increase during running exercise in well-trained men (1994)
    Springer
    Calcified tissue international 54 (1994), S. 256-261 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Lactate ; Acidosis ; Treadmill ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The purpose of this study was to examine the influence of exercise on the serum concentrations of intact parathyroid hormone (PTH). Serum PTH and plasma lactate were measured in 15 well-trained men, 9 long-distance runners and 6 fire-fighters, during two running exercises. Test one consisted of 40-minute treadmill running with a stepwise increased load and test two consisted of 50-minute treadmill running with a constant velocity. When the load was step-wise increased, the PTH concentrations increased moderately at the slower running paces but reached a final value that was about 50% higher than the starting value. This rise occurred despite a concomitant increase of total serum calcium from 2.38±0.06 to 2.49±0.05 mmol/liter (P〈0.01). During the constant running exercise, the long-distance runners, but not the fire-fighters, displayed a significant increase in PTH concentrations although the rise in total serum calcium was similar in both groups. There was a weak correlation between the changes in PTH and lactate in both exercises. The findings demonstrate that both high and low intensity exercise enhance release of PTH in long-distance runners through a mechanism that does not involve serum calcium. This relationship might be of importance for bone mass in men performing long-distance training.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295947
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  • 6
    Electronic Resource
    Electronic Resource
    Selective extractability of noncollagenous proteins from chicken bone (1994)
    Springer
    Calcified tissue international 55 (1994), S. 230-235 
    Details
    ISSN: 1432-0827
    Keywords: Noncollagenous ; Proteins ; Bone ; Sialo-protein ; Osteopontin ; Osteocalcin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Quantitative analyses of a wide variety of different solvents used for the extraction of several of the noncollagenous proteins of fully mineralized chicken bone powder were carried out to compare both the effectiveness of various procedures and the distribution of specific proteins which were solubilized. Extraction procedures included solutions of 6 M guanidine-HCl, pH 7.0, 0.5 M EDTA, pH 7.4, 0.3 N citric acid, 0.3 N HCl, 0.3 N formic acid, and 0.3 N acetic acid. Chelation of calcium ions by EDTA and dissolution of the mineral phase by acid extraction released 95% or more of the total calcium content of the bone powder by 48 hours, guanidine-HCl released less than 20% or less of the total calcium content even when extraction was carried out by 168 hours. Moreover, although guanidine-HCl solubilized a significant amount of collagen as gelatin, essentially none of the phosphoproteins, osteocalcin, or the proteoglycan decorin were solubilized, as detected by immunological techniques. In contrast, extraction of the mineralized bone powder by HCl and formic acid was very efficient in selectively solubilizing osteocalcin and osteopontin, while bone sialoprotein was selectively released by EDTA, and solubilized to a lesser extent by formic acid. Similarly, EDTA selectively removed decorin compared with HCl, formic, acetic, or citric acids. Only small amounts of osteopontin and osteocalcin were detected in the acetic acid extracts. These results provide methods for the selective solubilization of several different major, noncollagenous proteins from mineralized bone which should significantly aid in maximizing the amount of the specific protein recovered, and the ease with which the various proteins can be purified. The data also provide some insight into the intrinsic solubility characteristics of collaten, the specific noncollagenous proteins, and their potential association with each other and the mineral phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425880
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  • 7
    Electronic Resource
    Electronic Resource
    Combined magnetic fields increased net calcium flux in bone cells (1994)
    Springer
    Calcified tissue international 55 (1994), S. 376-380 
    Details
    ISSN: 1432-0827
    Keywords: Electromagnetic ; Bone ; Calcium ; Osteoblast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Low energy electromagnetic fields (EMF) exhibit a large number of biological effects. A major issue to be determined is “What is the lowest threshold of detection in which cells can respond to an EMF?” In these studies we demonstrate that a low-amplitude combined magnetic field (CMF) which induces a maximum potential gradient of 10-5 V/m is capable of increasing net calcium flux in human osteoblast-like cells. The increase in net calcium flux was frequency dependent, with a peak in the 15.3–16.3 Hz range with an apparent bandwidth of approximately 1 Hz. A model that characterizes the thermal noise limit indicates that nonspherical cell shape, resonant type dynamics, and signal averaging may all play a role in the transduction of lowamplitude EMF effects in biological systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299318
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  • 8
    Electronic Resource
    Electronic Resource
    Contribution of collagen and mineral to the elastic anisotropy of bone (1994)
    Springer
    Calcified tissue international 55 (1994), S. 381-386 
    Details
    ISSN: 1432-0827
    Keywords: Acoustic microscopy ; Bone ; Collagen fiber ; Elastic anisotropy ; Mineral crystal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract It has long been thought that collagen fibers within the bone matrix are deposited in an aligned pattern that channels mineral growth. If this model of bone structure is correct, both organic and inorganic phases of bone should have similar elastic anisotropy. Using an acoustic microscope, we measured longitudinal and transverse acoustic velocities of cortical specimens taken from 10 dog femurs before and after removal of either the mineral (using 10% EDTA) or collagen phases (using 7% sodium hypochlorite) and calculated longitudinal (CL) and transverse (CT) elastic coefficients. The anisotropy ratio (CL/CT) decreased significantly after demineralization (1.61 before versus 1.06 after, P〈0.0001, paired t-test). However, there was no significant change after decollagenization (1.51 before versus 1.48 after, P=0.617, paired t-test). We conclude that the orientation of mineral crystals is the primary determinant of bone anisotropy, and the collagen matrix within osteonal bone has little directional orientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299319
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of magnesium deficiency on strength, mass, and composition of rat femur (1994)
    Springer
    Calcified tissue international 54 (1994), S. 44-49 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Stress ; Elasticity ; Mechanical properties ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Magnesium (Mg) participates in the normal formation and remodeling of bone. However, little is known about effects of Mg status on the biomechanical function of bone. We examined gross morphometry and composition as well as biomechanical properties of the femurs of male rats fed diets adequate or deficient in Mg. Comparison of deficient animals and controls yielded a number of differences (all significant at P〈0.05). Mg-depleted animals exhibited slow growth, inefficient food utilization, and greatly reduced concentrations of Mg in both serum and femur ash. Compared with controls, femurs from depleted animals were shorter, but wet weights, diameters, and midfemoral cross-sectional areas showed no differences. Bone length was reduced to a greater degree than could be accounted for by differences in body weights between the groups. Bones of Mg-deficient rats contained less dry matter and less ash (which contained more Ca/g) than those of controls, along with a higher percentage of moisture. Significantly reduced bone strength in depleted animals was evident from the lighter loads supported at the elastic limit (yield point) and at fracture and from decreased stresses accompanying those loads. Modulus of elasticity, however, was not affected by Mg depletion. Different yield and breaking loads were related to different body weights of groups, but stresses were reduced for deficient bones even after adjusting for body size. Our data establish abnormal biomechanical behavior of cortical bone in Mg-deficient animals and emphasize the importance of measuring such functional properties of bone in the assessment of responses to altered metabolic conditions under experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316289
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  • 10
    Electronic Resource
    Electronic Resource
    Broadband ultrasonic attenuation imaging: A new imaging technique of the os calcis (1994)
    Springer
    Calcified tissue international 54 (1994), S. 83-86 
    Details
    ISSN: 1432-0827
    Keywords: Ultrasound attenuation ; Bone ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Ultrasound transmission measurement through the os calcis is an emerging technique and a promising clinical tool for early assessment of osteoporosis. However, several previous studies showed that broadband ultrasonic attenuation (BUA) is sensitive to small variations in bone mass or structure. The os calcis is an inhomogeneous bone and therefore, the attenuation depends on the location in the os calcis. BUA distribution within the os calcis can be measured by rectilinear scanning over the entire bone. We used a mechanical scanning device with both unfocused and focused transducers. The spatial resolution of these was about 25 mm and 4 mm, respectively. There was good agreement (r=0.97) between the results with unfocused and focused transducers. In addition, imaging the variations of BUA is possible with the focused transducers, and high quality images are obtained. These images permit the selection of optimal regions of interest for ultrasound attenuation measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296055
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  • 11
    Electronic Resource
    Electronic Resource
    Helodermin, helospectin, and PACAP stimulate cyclic AMP formation in intact bone, isolated osteoblasts, and osteoblastic cell lines (1994)
    Springer
    Calcified tissue international 54 (1994), S. 284-289 
    Details
    ISSN: 1432-0827
    Keywords: Helodermin ; Bone ; Cyclic AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Helodermin and helospectin are peptides structurally similar to vasoactive intestinal polypeptide (VIP) which were recently isolated from the salivary gland venom of the lizard Heloderma suspectum. Pituitary adenylate cyclaseactivating polypeptide (PACAP) has been isolated from ovine hypothalamus and also shows sequence homology to VIP. A helodermin-like peptide has been detected by combined immunohistochemical and immunochemical techniques in the thyroid C-cells. In the present study, lizard helodermin was found to cause a time- and dose-dependent stimulation of cyclic AMP (cAMP) formation in neonatal mouse calvarial bones. Also, helospectin I, PACAP 27, and the C-terminally extended PACAP 38 stimulated cAMP accumulation in the mouse calvariae. The cAMP rise in response to helodermin was comparable to that induced by VIP, both in terms of potency and magnitude of the response. Helodermin, helospectin I, PACAP 27, and PACAP 38, at concentrations of 1 μmol/liter, stimulated cAMP accumulation in enzymatically isolated mouse calvarial bone cells. A significant response to all peptides was observed in both early and late released bone cells isolated from the calvariae, with low and high alkaline phosphatase activity, respectively. Helodermin and VIP stimulated cAMP accumulation in the cloned mouse calvarial osteoblastic cell line MC3T3-E1, in rat (UMR 106-01), and human (Saos-2) osteoblastic osteosarcoma cell lines, but not in the rat osteosarcoma cell line ROS 17/2.8. The effect of helodermin was synergistically and dose-dependently enhanced by forskolin (0.1 and 1 μmol/liter). These data show that bone cells, including osteoblasts, respond to several peptides of the VIP family, including helodermin, helospectin I, PACAP 27, and PACAP 38. Whether the responses are mediated via one or several receptor populations remains to be established. The finding that VIP and helodermin, at maximally effective concentrations, did not cause additive effect on cAMP formation in intact mouse calvariae suggests that these two agonists may use a common receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295952
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  • 12
    Electronic Resource
    Electronic Resource
    Antiresorptive drugs and trabecular bone turnover: Validation and testing of a computer model (1994)
    Springer
    Calcified tissue international 54 (1994), S. 179-185 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Drugs ; Trabecular ; Turnover ; Computer ; Model ; Sensitivity ; Activation frequency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A computer model of trabecular bone turnover has been developed, based on concepts of Jonathan Reeve [1]. This model predicts changes in bone volume by summing bone resorption and formation over a large number of remodeling sites. Clinical data [histomorphometry and bone mineral content (BMC)] from two clinical studies using an antiresorptive drug (etidronate disodium, EHDP) in post-menopausal osteoporosis were used to test the model. The results for BMC obtained from the EHDP and placebo groups in each study at 60 and 120 weeks were correctly predicted by the model from the histomorphometric data obtained from baseline and week 60 biopsies. The parameter in this model having the greatest influence on predicted changes in bone volume was found by sensitivity analysis to be activation frequency. These results suggest that the contribution of bone turnover to BMC can be predicted solely by considering the cell kinetics of the basic multicellular unit (BMU), and that, in the case of antiresorptive drugs, maximal effects on bone volume may be achieved by pharmacological reduction of activation frequency. The results also suggest that the present model may be useful in predicting in clinical studies the effects of EHDP and similar drugs on bone turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301675
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  • 13
    Electronic Resource
    Electronic Resource
    Lower extremity stress fractures during intermittent cyclical etidronate treatment for osteoporosis (1994)
    Springer
    Calcified tissue international 54 (1994), S. 431-434 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Diphosphonate ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract During intermittent cyclical etidronate treatment, a lower extremity pain syndrome associated with stress fractures was observed in three osteoporotic patients. This report describes the development of stress fractures during initial cycles of treatment, with recurrence of symptoms in two patients when etidronate therapy was resumed. Further studies are needed to confirm whether stress fractures are associated with cyclic etidronate treatment and if so, the incidence and pathophysiology need to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305532
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  • 14
    Electronic Resource
    Electronic Resource
    The modulatory effect of endogenous parathyroid hormone on the action of hydrochlorothiazide in pseudohypoparathyroidism type I (1994)
    Springer
    Calcified tissue international 54 (1994), S. 473-476 
    Details
    ISSN: 1432-0827
    Keywords: Pseudohypoparathyroidism ; Thiazide ; Kidney ; Bone ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract We compared the effect of orally administered 100 mg of hydrochlorothiazide (HCTZ) among eight patients with pseudohypoparathyroidism (PHP) type I, 11 patients with idiopathic hypoparathyroidism (IHP), and 12 patients with primary hyperparathyroidism (1oHPT). Patients with PHP type I or with IHP were studied during the treatment with 1α-hydroxylated metabolites of vitamin D3. HCTZ raised serum levels of calcium (Ca) in 1oHPT (P〈0.001) and PHP type I (P〈0.01) but did not increase urinary excretion of Ca. Serum parathyroid hormone (PTH) in PHP type I decreased (P〈0.02) after HCTZ administration in response to the increase in serum Ca. HCTZ did not raise serum levels of Ca in IHP but increased urinary excretion of Ca in this group (P〈0.01). HCTZ suppressed tubular reabsorption of phosphate (P) in IHP (P〈0.01) and 1oHPT (P〈0.05) but not in PHP type I. Urinary excretion of cAMP did not change after HCTZ administration in PHP type I, IHP, or 1oHPT. Endogenous PTH modulated the effects of HCTZ on Ca mobilization from bone and renal reabsorption of Ca in PHP type I with normal or high serum levels of PTH and in 1oHPT with high serum levels of PTH. The inhibitory effect of HCTZ on renal tubular reabsorption of P (probably from proximal tubules) was independent of PTH. The resistance to this inhibitory effect of HCTZ on P reabsorption in PHP type I suggested a proximal tubular dysfunction in this disorder.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334326
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  • 15
    Electronic Resource
    Electronic Resource
    Human recombinant interleukin-1 receptor antagonist blocks bone resorption induced by interleukin-1β but not interleukin-1α (1994)
    Springer
    Calcified tissue international 55 (1994), S. 12-15 
    Details
    ISSN: 1432-0827
    Keywords: IL-1α ; IL-1β ; IL-1 receptor antagonist ; Bone ; Calcium ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Both interleukin-1α (IL-1α) and interleukin-1β (IL-1β) are powerful stimulators of bone resorption in vivo and in vitro. Interleukin-1 receptor antagonist (IL-1ra) binds to many interleukin-1 receptors. It does not activate the receptor and effectively blocks the action of IL-1α and IL-1β. In this study, human recombinant IL-1ra, at 100-fold excess, was found to block bone resorption in cultured mouse calvaria due to IL-1β but not IL-1α. These observations may be explained by differential affinities of receptors for IL-1α, IL-1β and rhIL-1ra on target bone cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310162
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  • 16
    Electronic Resource
    Electronic Resource
    Effects of infusion of parathyroid hormone and primary hyperparathyroidism on formation and breakdown of type I collagen (1994)
    Springer
    Calcified tissue international 55 (1994), S. 412-416 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Biochemical markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The influence of chronic and acute exposure to parathyroid hormone (PTH) on formation and breakdown of type I collagen, using two recently developed radioimmunoassays for serum PICP (the carboxyterminal propeptide of type I procollagen) and serum ICTP (the carboxyterminal telopeptide of type I collagen), have been evaluated. Fasting morning values were obtained from 18 women with primary hyperparathyroidism (HPT) and an equal number of age-matched, healthy controls. A 24-hour infusion of synthetic human parathyroid hormone (PTH 1-38) was performed in 14 healthy females. The patients with HPT had higher values for serum ICTP than the controls (6.0±3.0 and 4.1±2.1 μg/liter; P〈0.05), whereas the serum PICP concentrations were not different (170±72 and 151±65 μg/liter; n.s.). During infusion of PTH in healthy subjects, there was an increase of the serum ICTP concentrations (from 3.6±1.3 to 4.4±1.8 μg/liter; P〈0.001) whereas those of serum PICP decreased (from 185±78 to 118±42 μg/liter; P≤0.0001). The increase of serum ICTP during infusion of PTH was positively related to the increase of serum calcium and other indices of bone resorption, i.e., fasting urinary excretions of hydroxyproline and calcium. The decrease of serum PICP was also related to the changes of serum ICTP and hydroxyproline in urine, serum calcium, and alkaline phosphatase but not to osteocalcin, an established marker of osteoblastic activity. The findings support the fact that serum ICTP is a valuable method for evaluating bone resorption and is also easy to perform. Furthermore, the discordant results for the different markers of osteoblastic activity indicat that they reflect different functions of the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298553
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  • 17
    Electronic Resource
    Electronic Resource
    The biochemistry of ancient DNA in bone (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 530-535 
    Details
    ISSN: 1420-9071
    Keywords: Bone ; collagen ; fulvic acids ; DNA ; ancient DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The amount of DNA in ancient bone was determined by ethidium bromide staining after the removal of the potent Taq inhibitor, fulvic acid. A complete decalcification and a perfusion protocol were used to recover DNA from bone. A variety of purification techniques including molecular sieve, hydroxyapatite binding and ‘Magic’ preparations yielded DNA that spanned from 3.4μg/g of bone to below detectable limits. Fulvic acid was shown to interfere with the quantification of DNA derived from ancient human skeletal material one hundred to over seven thousand years old. Scanning UV in the 300 to 230 nm range is a simple and sensitive technique for documenting fulvic acid contamination in ancient bone extracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01921721
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  • 18
    Electronic Resource
    Electronic Resource
    Three-dimensional photographic study of cancellous bone in human fourth lumbar vertebral bodies (1994)
    Springer
    Anatomy and embryology 189 (1994), S. 259-274 
    Details
    ISSN: 1432-0568
    Keywords: Bone ; Cancellous ; Trabecular ; Age ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In an analysis of the 3D architecture of cancellous bone, two-dimensional techniques are of limited value. A simple technique employing stereophotographs of whole sections of lumbar vertebrate made possible a detailed description of the 3D structure of the normal fourth lumbar vertebral body and its changes with ageing and osteoporosis. Parallax measurements were used to calculate the real lengths of horizontal trabeculae. The bone presented a continuous spectrum of microstructure, from a honeycomb of tubes, to plates and braces and, finally, fragile rods. A distinct pattern was produced in osteoporotic samples by the removal of horizontal and selected vertical trabeculae followed by a thickening of the remaining vertical trabeculae in the peripheral regions. Very long, thin horizontal trabeculae were formed in all three zones (superior, middle and inferior) during this process. The observation of porotic architecture in intact specimens points to the inadequacy of the clinical criterion of the occurrence of a fracture in judging the osteoporotic state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239013
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  • 19
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    Electronic Resource
    Ectopic ossicles associated with metacercariae of Apophallus brevis (Trematoda) in yellow perch, Perca ftavescens (Teleostei): development and identification of hone and chondroid bone (1994)
    Springer
    Anatomy and embryology 190 (1994), S. 29-46 
    Details
    ISSN: 1432-0568
    Keywords: Ectopic ossification ; Ossicles ; parasite infection ; Chondroid bone ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper describes the development and tissues in mineralized ossicles in the musculature of Perca flavescens infected with metacercariae of the trematode Apophallus brevis. Analysis involved light microscopy, transmission and scanning electron microscopy, X-ray scanning electron microprobe analysis, and tetracycline labelling. Two to 14 days post-infection, fibroblast-like host cells stream towards the parasite cyst forming a fusiform cellular capsule. By 14 days post-infection the capsule differentiates into an inner hypertrophied layer, an extensive middle layer of fibroblast-like cells, and a thin outer layer of flattened fibroblast-like cells forming a fibrous sheath at the capsule/muscle interface. From 21–35 days post-infection, a bony tissue is deposited periosteally in an equatorial ring around the cyst. With time, additional tissue is secreted over the ring increasing its thickness and advancing the matrix front towards the poles of the ossicle. Plump osteoblast-like cells cover the developing ossicle and may become trapped within the matrix in lacunae encapsulated by collagen. By 63 days post-infection, medium-sized ossicles are morphologically similar to large cysts from perch captured in the wild; ovoid with two polarized canals, but lacking acellular or lamellar bone-like tissue. Mineralized ossicles contain calcium, phosphorus and oxygen. Large ossicles retrieved from perch given multiple doses of tetracycline revealed discrete fluorescent bands, indicative of incremental growth. Fully developed ossicles are composed of two skeletal tissues, an inner region of chondroid bone and an outer region of acellular, lamellar bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185844
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  • 20
    Electronic Resource
    Electronic Resource
    Simulation of bone resorption-repair coupling in vitro (1994)
    Springer
    Anatomy and embryology 190 (1994), S. 339-349 
    Details
    ISSN: 1432-0568
    Keywords: Osteoclasts ; Osteoblasts ; Resorption ; Remodelling ; Dentine ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the normal adult human skeleton, new bone formation by osteoblasts restores the contours of bone surfaces following osteoclastic bone resorption, but the evidence for resorption-repair coupling remains circumstantial. To investigate whether sites of prior resorption, more than the surrounding unresorbed surface, attract osteoblasts or stimulate them to proliferate or make new matrix, we developed a simple in vitro system in which resorption-repair coupling occurs. Resorption pits were produced in mammalian dentine or bone slabs by culturing chick bone-derived cells on them for 2–3 days. The chick cells were swept off and the substrata reseeded with rat calvarial osteoblastic cells, which make bone nodules in vitro, for periods of up to 8 weeks. Cell positions and new bone formation were investigated by ordinary light microscopy, fluorescence and reflection confocal laser microscopy, and SEM, in stained and unstained samples. There was no evidence that the osteoblasts were especially attracted to, or influenced by, the sites of resorption in dentine or bone before cell confluence was reached. Bone formation was identified by light microscopy by the accumulation of matrix, staining with alizarin and calcein and by von Kossa's method, and confirmed by scanning electron microscopy (SEM) by using backscattered electron (BSE) and transmitted electron imaging of unembedded samples and BSE imaging of micro-milled embedded material. These new bone patches were located initially in the resorption pits. The model in vitro system may throw new light on the factors that control resorption-repair coupling in the mineralised tissues in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187292
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  • 21
    Electronic Resource
    Electronic Resource
    Métastases osseuses d'origine thyroïdienne (1994)
    Springer
    European journal of orthopaedic surgery & traumatology 4 (1994), S. 13-15 
    Details
    ISSN: 1432-1068
    Keywords: Thyroid ; Bone ; Metastases ; Métastases osseuses ; Thyroïde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé En 25 ans, 1061 cancers de la thyroïde ont été pris en charge. 42 patients étaient atteints de métastases osseuses, unique ou multiples. La forme histologique la moins métastasiante est le cancer papillaire qui de plus, survient chez les sujets jeunes. Deux stades doivent être différentiés dans la maladie métastasiante. La métastase osseuse, unique, est découverte à la scintigraphie, les radiographies sont normales, l'irradiation à l'iode éventuellement associée au cobalt peut la stériliser. La métastase osseuse est visible sur les radiographies, elle n'est pas unique, la scintigraphie objectivera d'autres foyers hyperfixants, le traitement chirurgical, palliatif, aura pour effet de réduire la taille tumorale pour que l'irradiation puisse la stériliser ainsi que les autres foyers fixants.
    Notes: Abstract Over 25 years, 1601 thyroid cancers were treated. 42 patients had solitary or multiple bony metastases. The least metastatic histological form is papillary cancer, which in addition occurs in young subjects. There are two stages of the metastatic disease. The solitary bony metastasis, discovered on scintigraphy with normal Xrays, may be effectively treated by irradiation with iodine with the possible addition of cobalt. Multiple metastases, visible on plain X-ray with other hyperfixation areas on scintigraphy, is best treated by palliative surgery to reduce size so that it can be sterilised by irradiation at the same time as other hyperfixation sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806721
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  • 22
    Electronic Resource
    Electronic Resource
    Aspects actuels de la prise en charge des métastases osseuses en milieu oncologique (1994)
    Springer
    European journal of orthopaedic surgery & traumatology 4 (1994), S. 9-10 
    Details
    ISSN: 1432-1068
    Keywords: Metastases ; Bone ; Métastases osseuses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'histo-pronostic, comme l'utilisation de marqueurs, sont des notions relativement nouvelles qui facilitent la prise en charge de certains cancers. Hormonothérapie et chimiothérapie doivent être discutées en fonction de leurs avantages et de leurs inconvénients. Toutes les ressources modernes contre la douleur doivent être utilisées.
    Notes: Abstract The histological prognosis and use of markers are new concepts, which are of value in managing some cancers. Hormonal therapy and chemotherapy should be considered, along with their advantages and disadvantages. All contemporary modalities of treatment against pain should be used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806719
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  • 23
    Electronic Resource
    Electronic Resource
    Présentation de la série du GECO de métastases osseuses des membres : 90 cas (1994)
    Springer
    European journal of orthopaedic surgery & traumatology 4 (1994), S. 21-21 
    Details
    ISSN: 1432-1068
    Keywords: Metastases ; Bone ; Métastases osseuses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Dans cette série de cas, vus par des chirurgiens, une métastase sur deux est traitée au stade de fracture. Une fracture sur deux est survenue en l'absence de toute symptomatologie évocatrice.
    Notes: Abstract This series of surgical patients shows that 50% of bony metastases are complicated by a fracture. Of these, 50% occurred without any preceding symptoms or signs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806724
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  • 24
    Electronic Resource
    Electronic Resource
    Evolution du traitement des métastases osseuses (1994)
    Springer
    European journal of orthopaedic surgery & traumatology 4 (1994), S. 3-4 
    Details
    ISSN: 1432-1068
    Keywords: Metastases ; Bone ; Métastases osseuses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le traitement des métastases osseuses a vu ses modalités évoluer en fonction d'améliorations obtenues dans la prise en charge du cancer primitif et en raison d'une meilleure compréhension des phénomènes biologiques constatés au niveau de l'os métastatique. Du simple traitement palliatif des douleurs osseuses, la thérapeutique s'est orientée vers la prévention des complications dégradantes que sont les fractures et les paraplégies. Des résultats intéressants sont obtenus actuellement par l'utilisation de traitements chimiques luttant contre l'ostéolyse métastatique.
    Notes: Abstract The treatment of bony metastases has developed due to improvements in the care of the primary cancer and due to a better understanding of the biological phenomenon in the metastasis. From simple palliative treatment of bone pain, treatment is now being directed towards the prevention of the complications of metastasis, such as fractures and paraplegia. Interesting results are currently being obtained by using chemotherapy for treatment of metastatic osteolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806717
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  • 25
    Electronic Resource
    Electronic Resource
    Ostéolyse tumorale maligne métastatique Données actuelles sur la physiopathologie et le traitement (1994)
    Springer
    European journal of orthopaedic surgery & traumatology 4 (1994), S. 5-8 
    Details
    ISSN: 1432-1068
    Keywords: Bone ; Metastases ; Osteoclast ; Cytokines ; Métastases osseuses ; Ostéoclaste ; Cytokines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les métastases ostéolytiques des cancers sont à l'origine de douleurs et de fractures pathologiques responsables d'une importante invalidité altérant la qualité de survie des patients. Ces destructions osseuses sont dues à une augmentation de la résorption osseuse, liée à la stimulation des ostéoclastes par des médiateurs sécrétés localement par les cellules tumorales et médullaires. Les bisphosphonates, puissants agents anti-ostéoclastiques, ont une bonne efficacité sur les douleurs osseuses, la prévention des fractures et des épisodes hypercalcémiques.
    Notes: Abstract Osteolytic metastases are the cause of pain and pathological fractures with marked disability affecting the patient's quality of life. The bone destruction is due to an increase of bone resorption, linked to stimulation of osteoclasts by mediators secreted locally by tumour and medullary cells. Bisphosphonates, strong anti-osteoclastic agents, are effective for bone pain, prevention of fractures and the treatment of hypercalcaemic episodes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806718
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  • 26
    Electronic Resource
    Electronic Resource
    Evolution des conceptions en matière de radiothérapie des métastases osseuses (1994)
    Springer
    European journal of orthopaedic surgery & traumatology 4 (1994), S. 11-12 
    Details
    ISSN: 1432-1068
    Keywords: Radiotherapy ; Metastases ; Bone ; Radiothérapie ; Métastases osseuses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les techniques d'irradiation antalgique sont différentes s'il s'agit de métastases uniques (champs séparés) ou multiples (irradiation hémicorporelle antalgique). Un procédé original d'irradiation hémicorporelle précoce est décrit.
    Notes: Abstract Irradiation for bone pain depends on whether the metastasis is solitary (separate field) or disseminated (antalgic half body irradiation). A new original procedure of early halfbody irradiation is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01806720
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  • 27
    Electronic Resource
    Electronic Resource
    A study of the nutrient foramina of lower limb long bones (1994)
    Springer
    Surgical and radiologic anatomy 16 (1994), S. 409-412 
    Details
    ISSN: 1279-8517
    Keywords: Nutrient foramina ; Bone ; Lower limb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les foramens nourriciers de 269 os longs de membres inférieurs d'adultes ont été étudiés afin d'en préciser le nombre et le siège. L'index foraminal moyen était de 48,82 pour le fémur, 33,17 pour le tibia, 47,82 pour la fibula. Sur le fémur, les foramens sont le plus souvent doubles, situés au tiers moyen de la ligne âpre. Sur le tibia, le foramen est le plus souvent au tiers supérieur de la face postérieure. Enfin sur la fibula, il se situe en général au tiers moyen de face postérieure.
    Notes: Summary In this study a total of 269 adult lower limb long bones were examined to determine the number and location of the nutrient foramina in the shafts of bones. The mean of foraminal index was 48.82 for femur, 33.17 for tibia, and 47.82 for fibula. The number of foramina noted were: two on the linea aspera in the middle third of the femur, one on the posterior surface of the upper third of the tibia, and one on the posterior surface of the middle third of the fibula.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01627662
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  • 28
    Electronic Resource
    Electronic Resource
    Cystic angiomatosis of bone with sclerotic changes mimicking osteoblastic metastases (1994)
    Springer
    Skeletal radiology 23 (1994), S. 247-252 
    Details
    ISSN: 1432-2161
    Keywords: Cystic angiomatosis ; Hemangiomatosis ; Lymphangiomatosis ; Osteosclerosis ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Five unusual cases of cystic angiomatosis of bone which presented with the radiologic appearance of osteoblastic lesions are reported. Three patients were female (ages 37, 41, and 65 years) and two were male (ages 24 and 66 years). Although cystic angiomatosis of bone usually produces widespread osteolytic lesions with a honeycombed appearance in the skeletal system, multiple osteoblastic lesions mimicking metastatic osteoblastic carcinoma are sometimes seen. This radiological presentation has not been well emphasized in previous reports. Histologically, in addition to the angiomatous lesions, both mature thickened lamellar bone trabeculae and immature trabeculae of woven bone were found. In one of our patients, increasing density of the osteoblastic lesions was noted over time. One previous study has suggested that the age of the lesions of cystic angiomatosis is related to radiographic density. It is important to recognize this uncommon variant of cystic angiomatosis and to include this entity among the radiologic differential diagnoses when multiple osteoblastic lesions are encountered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02412356
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  • 29
    Electronic Resource
    Electronic Resource
    The effect of homocysteine thiolactone and its alpha methylated derivative on bone matrix in the mouse (1994)
    Springer
    Amino acids 6 (1994), S. 199-203 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Homocysteine thiolactone ; Alpha-homocysteine thiolactone ; Bone ; Glycosaminoglycans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Homocysteine (HC) is a radiation protector but toxic to bone. Its derivative homocysteine thiolactone (HCTL) and the alpha-alkylated analogue (A-methyl-HCTL) was fed to mice for a period of six weeks in a daily dose of 50 mg/kg body weight. Parameters for bone matrix as collagen content, acid solubility of bone collagen, urinary bone collagen cross links (pyridinolines) and urinary acid glycosaminoglycans were determined. Urinary acid glycosaminoglycans were significantly reduced in the HCTL treated group but not in the alpha-methyl-homocysteine thiolactone (A-methyl-HCTL) group (controls: 45 ± 7 mg/mmol creatinine, homocysteine thiolactone 38 ± 5 mg/mmol creatinine, A-methyl HCTL 45 ± 6 mg/mmol creatinine). No differences were found for the parameters of bone collagen between the groups. The potent radiation protecting methylated derivative therefore did not change bone matrix and should be a candidate for further toxicological studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805847
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  • 30
    Electronic Resource
    Electronic Resource
    Statistical model of the habit and arrangement of mineral crystals in the collagen of bone (1994)
    Springer
    Journal of statistical physics 77 (1994), S. 125-143 
    Details
    ISSN: 1572-9613
    Keywords: Bone ; collagen ; Voronoi tesselations ; small-angle scattering ; structure function ; calcified tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Randomly colored space tesselations are considered as models for the mineral/organic structure of bone. First, it is shown that the structure function for such models is always proportional to the average form factor of the individual tiles and hence independent of the mineral density in the sample. Then the structure function is calculated for three such models: for model I, based on a hexagonal, and model 2, on a Poisson-Voronoi tesselation of the plane and for model 3, based on a random tesselation of the line. These results are compared to experimental structure functions measured by small-angle scattering and excellent agreement is obtained between model 2 and the bone from mice and rats, as well as between model 3 and calcified turkey leg tendon. Divergent conclusions following recent experiments by small-angle x-ray scattering and by electron microscopy are discussed in the light of these structural models and an explanation is proposed which might remove the discrepancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186835
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  • 31
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    Electronic Resource
    The effect of blood flow on the material properties of bone (1994)
    Springer
    Annals of biomedical engineering 22 (1994), S. 194-201 
    Details
    ISSN: 1573-9686
    Keywords: Blood/Fluid flow ; Bone ; Laser ; Material properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract This project was undertaken to establish if the integral circulation had any effects upon the mechanical behavior of bone. The influence of blood flow in the rabbit tibia on the strain induced at the bone surface when under load was assessed. Recordings were taken from three adult and three immature New Zealand White rabbits which had previously had both their tibiae pinned with modified orthopedic pins. Strain readings were obtained from the exposed mid-shaft of the tibia of both hind legs before, during and after blood flow changes. The loading was static and used to maintain a strain of 250 μstrain in adult animals and 180 μstrain in immature animals prior to variation in blood flow. The blood flow was altered by means of a tourniquet inflated to 80 mm Hg and placed medial to the pinned tibia; it was inflated for a specific time (≈40 minutes) during the experimental loading. Reducing the blood flow appeared to alter the strain recorded at the bone surface while the applied load across the pins remained constant. An initial effect when there was reduced perfusion was that the strain increased following a reduction in blood flow. The strain then began to decrease in magnitude on the compressive aspect coincident with release of the cuff to a level below the value of the initial normally perfused bone. Upon return of the blood supply to normal levels following the initial hyperaemic phase, the strain value increased to a value comparable with that of normally perfused bone. During the hyperemic phase, found on the compressive aspect of the tibia, the measured strain decreased to a value below the initial loaded strain despite the load remaining constant. This demonstrates that the presence of a normal cardiovascular perfusion actually stiffens the bone while a reduction in perfusion allows the bone to deform more readily for the same external loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02390377
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  • 32
    Electronic Resource
    Electronic Resource
    Purification of mineralized tissue-associated osteopontin (1994)
    Springer
    Methods in cell science 16 (1994), S. 211-215 
    Details
    ISSN: 1573-0603
    Keywords: Bone ; Bone sialoprotein ; Osteopontin ; Protein purification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A protocol to extract and purify osteopontin, a protein with cell adhesion and mineral-crystal binding properties, from mineral-associated tissues is described. This procedure provides for the complete separation of osteopontin from bone sialoprotein, a mineralized tissue-specific protein with similar properties to that of osteopontin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01540653
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  • 33
    Electronic Resource
    Electronic Resource
    FGFs and their receptors, in vitro and in vivo studies: New FGF receptor in the brain, FGF-1 in muscle, and the use of functional analogues of low-affinity heparin-binding growth factor receptors in tissue repair (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 49-55 
    Details
    ISSN: 1040-452X
    Keywords: FGF ; Receptor ; Brain ; Muscle ; Wound healing ; Skin ; Bone ; Biopolymer ; Heparan-like ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Several heparin-binding growth factors (HBGFs) are thought to play a key role in the natural processes of tissue homeostasis, regeneration or repair. The HBGFs are active upon release from neighbouring inflammatory or circulating cells, as well as upon release from heparan sulfate proteoglycosaminoglycans that are associated with the extracellular matrix (ECM). To better understand the physiological role of these HBGFs, we have focused our effort on studying a subset of HBGFs, namely FGF-1 and FGF-2 and their receptors. We present the purification and characterisation of a new form of heparinbinding FGF receptor from adult bovine brain (Perderiset et al., 1992). This receptor has now been purified to homogeneity. Ligand blot and cross-linking experiments performed with labeled FGF-1 or FGF-2 revealed 80-kd and 130-kd bands. Preliminary sequence information indicates that receptor is different from the receptors, FGFR-1 to -4, but it may be related the cysteine-rich-FGF receptor (CFR).We have previously shown that FGF-1, but not FGF-2, is specifically expressed in myoblastic satellite cells during the proliferating phase preceding myoblast alignment and fusion. We have now transfected primary cultures of rat myoblastic satellite cells with FGF-1 cDNA and expressed this growth factor constitutively. The transfected cells were no longer able to form myotubes. Transfection with antisense FGF-1 induced myotube formation suggesting that endogenous expression of FGF-1 is associated with myoblastic cell differentiation.Numerous studies have concluded that the ECM represents a natural reservoir for various HBGFs. The HBGFs are stored through their interaction with matrix-associated heparan sulfates and can become available for stimulating cell migration, multiplication, and differentiation during tissue repair. In order to better understand how the control of the bioavailability of HBGFs plays a role in wound healing, we have studied the healing effect of various chemically substituted dextrans (CMDBS) selected for their affinity for HBGFs, alone and in association with HBGFs. The CMDBS were obtained by substitution of methyl carboxylic (CM), benzylamide (B), and benzylamine sulfonate (S) groups. We expected that the CMDBS could act in the following ways: (1) to potentiate the biological activity of FGF-1 and FGF-2; (2) to protect FGF-1 and FGF-2 against thermal or pH inactivation; or (3) to protect FGF-1 and FGF-2 against proteolytic degradation (Tardieu et al., 1992). Selected CMDBSs were tested alone in cutaneous and flat bone wound-healing models. Rats were skin punched and skin regeneration was studied by morphometric and histological analysis. The wounds (6-mm diameter) were filled with collagen plaster alone or soaked with CMDBS. The CMDBS in collagen plaster was able to induce a remarkable effect both on the kinetics and on the quality of the restored skin.We have also looked at the effect of CMDBS in the healing of calvarian bone defects. Adult rats were trephined (5-mm diameter) and the healing of their defects was determined after 35 days. Only those treated with CMDBS show appreciable new bone formation. The filling of defects was almost complete, and the response was dose-dependent. Optimal doses were at 50-100 m̈g CMDBS, while at 400 m̈g CMDBS, less bone was formed. Interestingly, when the defect included bone suture, the suture was restored after CMDBS treatment. We have measured by biochemical, immunological, and histological methods the content and distribution of several HBGFs in the granulation tissue formed during healing, in the presence or absence of CMDBS. Our results suggest that the endogenous HBGFs naturally released during the regeneration process could be trapped, protected, and released by CMDBS. In conclusion, biopolymers can be designed to mimic some of the mechanisms regulating the availability of growth factors and so could be used as wound-healing agents. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080390109
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  • 34
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    Electronic Resource
    Immunologicalization of complement C1s and matrix metalloproteinase 9 (92kDa gelatinase/type IV collagenase) in the primary ossification center of the human femur (1994)
    Springer
    Cell & tissue research 277 (1994), S. 239-245 
    Details
    ISSN: 1432-0878
    Keywords: Bone ; Ossification ; Cartilage ; Matrix ; Chondrocytes ; Complement ; Matrix metalloproteinase ; Immunocytochemistry ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The first component of complement $$C\bar 1s$$ has been shown to degrade type I and type II collagens (Yamaguchi et al. 1990), the latter of which is a major constituent of the cartilage matrix. In order to understand the physiological roles of $$C\bar 1s$$ in cartilage resorption, the expression of C1s was examined by immunohistochemistry in the primary ossification center where the matrix is removed and replaced by bone marrow. Hypertrophic chondrocytes, endothelium and hematogenous elements in the capillary buds were intensely stained by a monoclonal antibody against C1s. Matrix metalloproteinase 9 (MMP-9, 92kDa gelatinase/type IV collagenase) was also immunolocalized in hypertrophic chondrocytes, mesenchymal cells in the primitive bone marrow and the cartilage matrix adjacent to the marrow. In addition, $$C\bar 1s$$ was found to activate the zymogen of MMP-9. These observations suggest that $$C\bar 1s$$ and MMP-9 coordinately participate in matrix degradation in cartilage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327771
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  • 35
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    Electronic Resource
    Comparison of DNA extraction and amplification from ancient human bone and mummified soft tissue (1994)
    Springer
    International journal of legal medicine 107 (1994), S. 152-155 
    Details
    ISSN: 1437-1596
    Keywords: Ancient DNA ; Bone ; Soft tissue ; Automated DNA extraction ; PCR ; Sex determination ; alte DNA ; Knochen ; Weichgewebe automatisierte ; DNA-Extraktion ; PCR Geschlechtsbestimmung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Zusammenfassung Für eine vergleichende Untersuchung von Knochen und Weichgewebe als Quellenmaterial für DNA-Analysen wurden südamerikanische, präkolumbische, männliche Mumien verwendet. Die Eignung der DNA-Extrakte beider Quellen wurde über ihre Effektivität als Ziel-DNA in PCR-Amplifikationen bewertet. Die Ergebnisse zeigen, daß bei Verwendung stark degradierten Materials Knochen den Weichgeweben für PCR-Analysen vorzuziehen sind. Dies scheint unabhängig von der spezifischen anatomischen Herkunft der Proben zu sein.
    Notes: Abstract South american precolumbian male mummies were employed as source material for a comparative investigation of bone and soft tissues by DNA analysis. The suitability of the DNA extracts from both sources was tested and evaluated by their effectiveness as target DNA in PCR amplifications. The results suggest that skeletal material should be given preference over soft tissues for PCR analysis if the material is severely degraded. This seems to be independent of the specific anatomical origin of the samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01225603
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  • 36
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    Perspectives: A vital biomechanical model of synovial joint design (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 240 (1994), S. 1-18 
    Details
    ISSN: 0003-276X
    Keywords: Joint ; Bone ; Cartilage ; Mechanical influences ; Growth ; Osteoarthritis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Making a durable joint requires adapting the one present at birth to its subsequent mechanical usage and then maintaining it. The total loads on a joint's momentarily loaded area plus the size of that area determine the unit loads on its articular cartilage and subchondral bone. Given those facts, this model suggests the following.For adaptaion: As is true for bone, a threshold range of unit loads that could turn cartilage modeling ON would lie below this tissue's microdamage threshold. When a joint's unit loads rose to that modeling threshold, chondral modeling would begin enlarging the momentarily loaded area to reduce and keep the unit loads on it below the microdamage thresholds of the bone and cartilage supporting that area.For maintenance: Maintenance activities would control the stiffness of cartilage and bone, which would also affect a joint's momentarily loaded area. These activities would usually repair whatever microdamage normally arises in those tissues, and could modify their microdamage thresholds too.In children, modeling and maintenance in bone and cartilage would function effectively. In adults chondral modeling becomes ineffective, but maintenance activities in bone and cartilage would remain effective, and likewise for modeling in the subchondral bone.This model assigns special importance in joint design to the stiffness of bone, cartilage, and ligament (as distinguished from their strength), to the typical largest unit: loads applied to them by a subject's usual weekly physical activities, and to their microdamage. © 1994 Wiley-Liss, Inc.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/ar.1092400102
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    Comparison of osteopenic changes in cancellous bone induced by ovariectomy and/or immobilization in adult rats (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 239 (1994), S. 243-254 
    Details
    ISSN: 0003-276X
    Keywords: Bone ; Ovariectomy ; Immobilization ; Bone resorption ; Bone formation ; Rats ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Ovariectomy (OVX) and immobilization (IMM) in rats are useful models of osteopenia, replicating some aspects of osteoporosis in humans. The purpose of this study was to compare changes in cancellous bone after OVX and/or IMM.Methods: Differences in cancellous bone were determined at 6 and 12 weeks after OVX or IMM. Comparisons were also made when rats were ovariectomized or immobilized for 6 weeks and then immobilized (OVX/IMM) and ovariectomized (IMM/OVX), respectively, for 6 more weeks. The femurs were used to determine bone mineral content (BMC) using single photon absorptiometry (SPA) and for scanning electron microscopy (SEM). Tibias were collected for microradiography, image analysis, and histomorphometry of metaphyseal cancellous bone.Results: Six and 12 weeks after OVX, there was less cancellous bone mass, compared with controls, as indicated by SPA, SEM, microradiography, image analyses, and histomorphometry. Bone was lost primarily from the central metaphyseal regions in the OVX animals, whereas the loss occurred throughout the metaphyses in the IMM animals. There were more rodlike bone spicules and fewer platelike trabecule in the OVX and IMM groups compared with controls. Differences in the structural aspects of the cancellous bone, including differences in the types of bone struts and marrow star volumes, indicated less trabecular connectivity and greater trabecular separation in the OVX and IMM animals, compared with controls. Endochondral growth indices in the IMM groups tended to be less, whereas the OVX groups tended to be greater than controls. Cancellous bone formation rates were generally greater in the OVX groups but less in the IMM groups compared with controls. Osteoclastic resorption surfaces were substantially elevated in the IMM and OVX groups, particularly the IMM groups. Changes reflecting OVX and IMM, independently, were apparent in the OVX/IMM and IMM/OVX groups and indices of osteopenia were different from controls, including less bone mass, trabecular connectivity, and greater trabecular separation, bone turnover rates, and osteoclastic surface.Conclusions: These results demonstrate differences in the osteopenic changes that occur in cancellous bone following OVX or IMM. The changes were generally more dramatic in the IMM than in the OVX animals. When OVX and IMM were applied in combination, the osteopenic changes are particularly severe, emphasizing the importance of mechanical usage even with a deficiency of gonadal hormones. © 1994 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/ar.1092390303
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    The effect ofin vitro fluoride ion treatment on the ultrasonic properties of cortical bone (1994)
    Springer
    Annals of biomedical engineering 22 (1994), S. 404-415 
    Details
    ISSN: 1573-9686
    Keywords: Bone ; Ultrasound ; Interfacial bonding ; Anisotropy ; Fluoride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The mechanical properties of composites are influenced, in part, by the volume fraction, orientation, constituent mechanical properties, and interfacial bonding. Cortical bone tissue represents a short-fibered biological composite where the hydroxyapatite phase is embedded in an organic matrix composed of type I collagen and other noncollagenous proteins. Destructive mechanical testing has revealed that fluoride ion treatment significantly lowers theZ-axis tensile and compressive properties of cortical bone through a constituent interfacial debonding mechanism. The present ultrasonic data indicates that fluoride ion treatment significantly alters the longitudinal velocity in theZ-axis as well as the circumferential and radial axes of cortical bone. This suggests that the distribution of constituents and interfacial bonding amongst them may contribute to the anisotropic nature of bone tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368247
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    Synthese von ( - )-(Acetoxymethyl)(hydroxymethyl)methyl(phenyl)german [( - )-MePhGe(CH2OAc)(CH2OH)] durch eine Esterase-katalysierte Umesterung: Die erste enzymatische Synthese eines optisch aktiven Germans (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 639-642 
    Details
    ISSN: 0009-2940
    Keywords: Germane, optically active ; Biotransformation, stereoselective ; Transesterification, enzymatic ; Porcine liver esterase ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ( - )-(Acetoxymethyl)(hydroxymethyl)methyl(phenyl)germane [( - )-MePhGe(CH2OAc)(CH2OH)] by an Esterase-Catalyzed Transesterification: the First Enzymatic Synthesis of an Optically Active GermaneThe prochiral germane MePhGe(CH2OH)2 (1) was synthesized by a six-step synthesis starting from GeCl4 (3) [3 → Cl2Ge(CH2Cl)2 (4) → Ph2Ge(CH2Cl)2 (5) → (CF3S(O)2O)PhGe(CH2Cl)2 (6) → MePhGe(CH2Cl)2 (7) → MePhGe(CH2OAc)2 (8) → 1]. Reaction of 1 with Ac2O/NEt3 (molar ratio 1: Ac2O = 1:1) gave the racemic germane rac-MePhGe(CH2OAc)(CH2OH) (rac-2). Stereoselective transesterification of 1 with vinyl acetate (acetate source and solvent), catalyzed by immobilized porcine liver esterase (PLE; E.C.-3.1.1.1), yielded the optically active germane ( - )-MePhGe(CH2OAc)(CH2OH) [( - )-2] (yield 57%, enantiomeric purity 50% ee).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270409
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    Zur Bildung eines Fe2(CO)6-Komplexes mit (Boryloxy)allyl-Brücke (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 91-92 
    Details
    ISSN: 0009-2940
    Keywords: Boranes, amino(imino) ; Iron, tricarbonyl(butanone) ; Diiron, [(boryloxy)allyl]hexacarbonyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Formation of a Fe2(CO)6 Complex with a (Boryloxy)allyl BridgeThe amino(imino)borane Me3Si(tBu)N=B=NtBu (1) reacts with (benzylideneacetone)tricarbonyliron (2) in 1:2 molar ratio to give a 50% yield of the hexacarbonyldiiron complex 3 with a fly-over (boryloxy)allyl bridge, which crystallizes in the space group P21/c. The structure of 3 can be described as a pyramid with Fe(CO)3 at the apex and a non-planar pentagon [-Fe(CO)3-O(BXX′)-C(Me)-CH-C(Ph)-] [X = NHtBu, X′ = N(SiMe3)tBu] as the basis, but there is no bond between the apex and the O atom.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270114
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    Bis(pentamethylcyclopentadienyl)methanol: Synthese, Struktur und Derivatisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 107-112 
    Details
    ISSN: 0009-2940
    Keywords: Bis(pentamethylcyclopentadienyl)methanol ; Diels-Alder reaction, intramolecular ; Chloroformate, bis(pentamethylcyclopentadienyl)methanol ; Tosylate, bis(pentamethylcyclopentadienyl)methanol ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(pentamethylcyclopentadienyl)methanol: Synthesis, Structure, and DerivatizationBis(pentamethylcyclopentadienyl) ketone (1) reacts at low temperatures with LiAlH4 to form in good yields (pentamethylcyclopentadienyl)methanol (2) and its corresponding intramolecular Diels-Alder product 3 in a ca. 2:1 ratio. The alcohol 2 is separated from the tetracyclic compound 3 by crystallisation at -70°C from hexane/pyridine as pyridine adduct. The pyridine-free alcohol 2 is available by repeated dissolving of the adduct in hexane and removal of the volatile components in vacuo. The alcohol tends to intramolecular [4 + 2] cycloaddition even at room temperature with formation of 3. A derivatization of 2 is possible by deprotonation with alkyllithium compounds, which leads to the alcoholate 4, and subsequent treatment with phosgen and tosyl chloride, thus affording the chloroformate 6 and the tosylate 7, respectively, in good yields. The thermolabile tosylate 7 decomposes to pentamethylbenzene or, under basic conditions, to the pentacyclic compound 7.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270118
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    Darstellung geeigneter Vorstufen zur Synthese von 16,16,16,17,17,17-Hexafluorretinalen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 145-149 
    Details
    ISSN: 0009-2940
    Keywords: Bis(trifluormethyl)butenal ; Retinoids ; β-Ionol ; Fluoro compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Suitable Precursors for the Synthesis of 16,16,16,17,17,17-HexafluororetinalsCycloaddition reactions of (CF3)2C = CHCHO with butadiene or 1,3-pentadiene provide the corresponding cyclohexane derivatives 2, 3 and 4. Condensation of 3 with (C2H5O)2P-(O)CH2C(O)CH3 or of 2 with acetone in the presence of bases yields 5 and 7. While 5 reacts with CH2 = CHMgBr to give 6, treatment of 7 with diluted HCI provides 8. Compounds 7 and 8 proved to be not suitable as starting materials for the preparation of 16,16,16,17,17,17-hexafluororetinals. A better synthon is the diene 11. This is obtained in a threestep reaction starting from hexafluoroacetone and (C6H5)3P=CHC(O)CH3 to give 9 which on treatment with CH3MgI provides 10. Dehydration of 10 with 50% H2SO4 forms 11. In this reaction sequence byproduct 12 is formed presumably by addition of CF3C(O)CF3 to 9. At elevated temperatures under pressure 11 adds ethylene to form 13. Functionalization of 13 in 2-position is achieved by hydroboration/oxidation yielding 14 which is oxidized with pyridinium dichromate to 15. Oxidation and bromination reaction of 13 are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270123
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    Zur Kenntnis der carbonylmethylenierenden Molybdän-Aluminium- und Wolfram-Aluminium-μ-methylen-Komplexe (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 127-135 
    Details
    ISSN: 0009-2940
    Keywords: Carbonyl olefination ; Molbydenum aluminium complexes, organo ; Tungsten aluminium complexes, organo ; Tebbe reagent ; Aluminium, molybdenum and tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organomolybdenum and Organotungsten Reagents, VI[1]. On the Carbonyl-Methylenating Molybdenum-Aluminium and Tungsten-Aluminium μ-Methylene ComplexesMoCl5, MoOCl3(THF)2, MoO2Cl2, (MeO)2MoCl3, (MeO)4MoCl, WOCl3(THF)2, and WOCl4 form carbonyl-methylenating complexes and 1-2 equiv. of CH4 by reacting with 2 equiv. of Me3Al. These thermolabile complexes are prepared in solution and differ in their properties (e.g. ability to transfer mostly more than 1 CH2 unit per Mo or W atom in carbonyl-olefinating processes; high sensitivity to water, no hydroxy ketone affinity) from the carbonyl-olefinating 1,3-dimetallacyclobutanes (M = Mo, W) and are believed to be mono- and bicyclic analogs (e.g. hypothic structures 3, 6-8) of the Tebbe reagent (1), containing Mo-μCH2 Al or W -μCH2 Al groups, respectively. Analogous complexes seem to be produced by treating MoOCl3(THF)2 with 2 Me2Zn or (MeO)2MoCl3 and (MeO)4MoCl with 2 MeMgBr in each case. Unlike the dimeric and, due to a Mo—Mo bond, diamagnetic Mo derivatives (Me—O)2MoCl3 and (MeO)4MoCl (according to 1H—NMR structure 9 or 10 and 11 or 12, respectively) the complexes obtained by the reactions (MeO)2MoCl3 + 2 Me3Al and (MeO)4MoCl + 2 Me3Al are paramagnetic, indicating the expected absence of a Mo—Mo bond. The 1H—NMR spectrum of the reaction mixture obtained by treating the MoVI derivative MoO2Cl2 with 2 Me3Al in THF shows various signals for μ—CH2 groups, whereas signals of t-CH2 ligands are missing (t = terminal). In analogy to 1 the carbonyl-olefinating activity of the Mo—Al and W—Al reagents is activated by the addition of 2 equiv. of HMPA. Treatment of PhCOCH2NEt2 (19) with {MoO2Cl2 + 2 Me3Al} leads to carbonyl olefination with formation of 20 and also to α-methylation with formation of PhCOCH(Me)-NEt2 (21), pointing to the intermediate formation of a t-CH2—Mo ligand. {MoO2Cl2 + 2 Me3Al + 2 HMPA} has found to be the best reagent for the carbonyl olefination of aldehydes, whereas {WOCl3(THF)2 + 2 Me3Al + 2 HMPA} was optimal for ketones. In 1:1 reactions both reagents normally give better yields than the Tebbe reagent. By applying (WOCl3(THF)2 + 2 Me3Al} and {MoO2Cl2 + 2 Me3Al} on ketones 16-18 an interesting neighbour group effect of electron donor atoms in the δ position to the keto group was observed.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270121
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    Kleine Ringe, 79. Synthese und Eigenschaften neuer Silyl-substituierter Cyclobutadiene und Tetrahedrane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 191-200 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Valence isomerization ; „Corset effect“ ; limits of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 79[1].  -  Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and TetrahedranesThe cyclobutadienes 2b, d as well as the corresponding tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13C—NMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butyltetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of tetrahedrane 3d with LiAlH4 in boiling THF leads to tetrahedrane 3e, which is much less stable than all previously known tetrahedrane derivatives.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270127
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    Relative Reactivities of Acetals and Ethers under Friedel-Crafts Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 213-217 
    Details
    ISSN: 0009-2940
    Keywords: Alkylation ; Alkoxyalkylation ; Carboxonium ions ; Acetals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Competition experiments have been performed to determine the relative reactivities of acetals and ethers toward allyltrimethylsilane in the presence of catalytic amounts of BF3 OEt2. It is found that acetals R-CH(OMe)2 and their phenylogous p-anisyl ethers R-CH(p-MeOC6H4)(OMe) show very little differences in reactivity. The reactivity scales are employed to rationalize the results of Lewis acid-catalyzed additions of acetals and ethers to CC double bonds.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270130
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  • 46
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    Gas-Phase Kinetics of the Pyrolysis of Some 3,3-Dimethyl-1-(trimethylsilyl)-cyclopropenes  -  Unexpected Product Distribution in the Cyclopropene Rearrangement (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 237-245 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopropenes, 3,3-dimethyl-1-trimethylsilyl-substituted ; Cyclopropene, isomerisation ; Gas-phase kinetics ; Ring opening ; Diradical intermediates ; Cyclopropylidene intermediates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase pyrolyses of 1,3,3-trimethyl-2-(trimethylsilyl)-cyclopropene (9), 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropeneTextReactantlog (A/s-1)Ea/kj mol-1(kcal mol-1)913.41 ± 0.22192.1 ± 2.5(45.9 ± 0.6)1013.54 ± 0.19184.4 ± 2.1(44.1 ± 0.5)1112.17 ± 0.38124.6 ± 3.1(29.8 ± 0.7)(10), and 3,3-dimethyl-1-(methylthio)-2-(trimethylsilyl)cyclopropene (11) have been studied, and the pressure-independent Arrhenius parameters listed in the table were obtained. All three rearrangements are homogeneous, first-order and unimolecular reactions. Rather surprisingly all reactions give the corresponding isomeric allenes as the main products. Amongst possible mechanisms discussed, 10 is proposed to react via a cyclopropylidene intermediate, whilst the results for 9 and 11 throw light on the relative importance of the diradical- and vinylcarbene-type intermediates produced by cyclopropene ring opening.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270134
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    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A5 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270139
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    Charge-Transfer-Komplexe von Metalldithiolenen, XIII. cis-trans-Photoisomerisierbare Viologene als redoxaktive Akzeptoren  - Synthese und elektrische LeitfähigkeitHerrn Prof. Dr. C. Krüger zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 287-294 
    Details
    ISSN: 0009-2940
    Keywords: Metal dithiolenes ; Dipyridinioethylene dihalides ; Charge-Transfer complexes ; Electrical conductivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Charge-Transfer Complexes of Metal Dithiolenes, XIII[1]. - cis-trans-Photoisomerisable Viologens as Redoxactive Acceptors  -  Synthesis and Electrical ConductivityIon Pair Charge-Transfer (IPCT) complexes of the type [A2+[ML2]2-} (1a-f to 4a-f) are synthesized from dianionic metal dithiolenes [M = Ni, Zn, L = cis-1,2-dicyano-1,2-ethene-dithiolate (mnt2-), 2-thioxo-1,3-dithiol-4,5-dithiolate (dmit2-)] and dicationic viologens [A2+ = 4,4′-(1,2-ethenediyl)bis(1-alkylpyridinium)]. The acceptors can exist as cis/trans isomers and may have coordinating properties in the case of 1-cyanoalkyl groups. The IPCT bands are in the range of 500 to 1200 nm and their energy follows the Hush-Marcus relation. For the nickel complexes the reorganization energy amounts to 73, for the zinc compounds to 115 kJ/mol. As shown by X-ray analysis of {A2+[Ni(mnt)2]2-} (2d), A2+ = trans-4,4′-(1,2-ethenediyl)-bis[1-(3-cyanopropyl)pyridinium], the structure consists of stacks of alternating donors and acceptors with a typical plane-to-plane distance of 350 pm. There is no interaction between the cyano group of the acceptor and the nickel atom of the donor. The electrical conductivities of the nickel compounds are in the range of 5 · 10-6 to 3 · 10-11 Ω-1 cm-1, and the corresponding activation energies vary from 0.24 to 0.61 eV. For the dmit complexes these values agree well with the free activation enthalpy of the electron transfer reaction A2+ + [ML2]2- → A+ + [ML2]- calculated from the Hush-Marcus model. This suggests that charge carrier generation occurs by electron transfer. When a trans acceptor is replaced by its cis isomer in [A2+[NiL2]2-}, conductivity changes from 5 · 10-7 to 5 · 10-6 Ω-1 cm-1 and the activation energy from 0.43 to 0.24 eV, when L - dmit2- but stays at about 1 · 10-8 Ω-1 cm-1 for L = mnt2-.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270203
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270101
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    Nb4Te17I4, a New Pseudo One-Dimensional Solid-State Polytelluride (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 11-14 
    Details
    ISSN: 0009-2940
    Keywords: Niobium iodide telluride ; Polytellurides ; Chain compounds, one-dimensional ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new ternary compound Nb4Te17I4 has been prepared and structurally characterized. It crystallizes in the monoclinic system, space group C2/c with unit-cell parameters a = 16.199(4), b = 8.128(2), c = 27.355(6) Å, β = 110.84(2)°, Z = 4. The structure consists of infinite one-dimensional niobium/tellurium chains running parallel to the crystallographic c direction. The chains are separated by iodine atoms. Short and long metal-metal distances alternate in the sequence of three consecutive short bonds ([d ≈ 3.1 - 3.2 Å) and one long (d = 4.268 Å) metal-metal separation. Each Nb atom is eight-coordinate. The composition of the chain is ∞11[(Nb5+)2(Nb4+)2(Te22-)4(Te32-)3(I-)4].
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270103
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    Synthese, Struktur und elektronische Eigenschaften von Cu0.69NbTe2 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 15-21 
    Details
    ISSN: 0009-2940
    Keywords: Copper niobium telluride ; Layer compounds ; Low-dimensional compounds ; Electrical properties ; Band structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structure and Electronic Properties of Cu0.69NbTe2Cu0.69NbTe2 is obtained from the elements in a sealed quartz ampoule at 850°C. The structure of Cu0.69NbTe2 is related to the CdI2 type. The Cu atoms are disordered and situated in tetrahedral sites between the NbTe2 layers. The Nb atoms form zig-zag chains extending in one direction within the layers. This deformation of the Nb sublattice from trigonal symmetry is typical for CdI2 derivatives with formal electron counts close to d2 on the early transition metal. The magnetic susceptibility is temperature-independent between 4 K and 300 K (Pauli paramagnetism). Resistivity measurements confirm the metallic behavior of the compound. The crystal structure and the physical properties are in agreement with the results of tight-binding band-structure calculations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270104
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    Darstellung und Eigenschaften von S-(Trifluormethyl)polysulfanmonosulfonaten CF3SxSO2M [x = 1, M = OH, NH40O, 1/2 HgO2, (CH3)3SiO, (CH3)2N, NH2; x = 2, M = NH4O]Herrn Professor Reinhard Schmutzler zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 457-463 
    Details
    ISSN: 0009-2940
    Keywords: (Trifluoromethyl)sulfane- and -disulfanesulfonic acids ; Mercury compounds ; (Trifluoromethyl)sulfanyl-disulfanyl-, and -sulfinylimine ; Arsenic compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of S-(Trifluoromethyl)polysulfanemonosulfonates CF3SxSO2M [x=1, M = OH, NH4O, 1/2 HgO2, (CH3)2N, NH2; x=2, M = NH4O]*Hydrolysis of CF3SNSO with 2 equiv. of H2O provides [NH4][CF3SSO3] (1), which on treatment with chlorine gives CF3SCl and [NH4][ClSO3]. Trifluoromethyl thiosulfates are synthesized from Hg(SCF3)2 and ClSO2M [M = NH4O, (CH3)3SiO (2), (CH3)2N (3), NH2 (4)]. Insertion of SO3 into Hg(SCF3)2 provides Hg[CF3SSO2O]2 (6). Similarly, S-(trifluoromethyl)thiosulfuric acid (5) is obtained from CF3SH and SO3. New preparations for CF3SXNSO (x=1, 2) are described. These compounds are formed either from Hg(NSO)2 or (CH3)3SiNSO and CF3SxCl in good yields. CF3SSNSO (8) reacts with water to give [NH4][CF3SSSO3] (9). A 1:1 adduct (10) is obtained from CF3SNSO and AsF5. A preliminary X-ray structure investigation proved that AsF5 is coordinated to the oxygen atom. Some reactions of [NH4][CF3SSO3] and CF3SSO2OSi(CH3)3 are mentioned.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270303
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  • 53
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    Funktionalisierte Tripod-Liganden: Synthese und Koordination von Tris[(diphenylphosphanyl)methyl]methan (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 501-506 
    Details
    ISSN: 0009-2940
    Keywords: Tripod ligand synthesis ; Tripod iron trisacetonitrile complexes ; Tripod cobalt acetate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalized Tripod Ligands: Synthesis and Coordination of 1,1,1-Tris[(diphenylphosphanyl)methyl]methaneThe tripod ligand HC(CH2PPh2)3 (4) is easily available from the reaction of 1,3-dichloro-2-(chloromethyl)propane (3) with lithium diphenylphosphide. The ligand 4 itself and two of its coordination compounds, [(HC(CH2PPh2)3)Co(OOCMe)]+-[BPh4]- (5 · BPh4) and [(HC(CH2PPH2)3)Co(OOCMe)]2+ · 2[BF4]- [7 · (BF4)2] have been characterized by X-ray analyses. Coordination of 4 leads to an opening of the CH2—CH—CH2 bond angles (114° in 7 · (BF4)2 and 5 · BPh4 versus 111° in 4). This change in structure is reflected by the unusual low field shift of the methine hydrogen of 7 · (BF4)2 (δ = 3.90) in comparison with the corresponding signal of the free ligand 4 (δ = 1.53).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270308
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  • 54
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    Comparison of the Nucleophilicities of Alkynes and Alkenes. Quantitative Determination of the Nucleophilicities of Alkynes toward Carbenium Ions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 525-531 
    Details
    ISSN: 0009-2940
    Keywords: Alkynes ; Alkenes ; Nucleophilicity ; Carbenium ions ; Vinyl cations ; Kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative reactivities of alkenes and alkynes toward diarylmethyl cations have been determined by direct rate measurements and by competition experiments in dichloromethane. At -70°C alkynes are found to be one to two orders of magnitude less reactive than analogously substituted alkenes (e.g. phenylacetylene/styrene), but the reactivity difference reduces strongly as the temperature is raised. The stereochemistry of the vinyl chlorides produced by addition of benzhydryl chlorides to alkynes is characterized.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270311
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  • 55
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    Relative Reactivities of Alkyl Chlorides under Friedel-Crafts Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 205-212 
    Details
    ISSN: 0009-2940
    Keywords: Alkylation ; Allylation ; Carbenium ions ; Friedel-Crafts reactions ; Linear free energy relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Competition experiments have been performed to determine the relative reactivities of 23 alkyl chlorides toward allyltrimethylsilane in the presence of catalytic amounts of ZnCl2.The krel scale spans over 11 orders of magnitude from 1-adamantyl chloride (least reactive) to bis(p-methoxyphenyl)methyl chloride (most reactive compound). A fair correlation between the alkylating ability and the SN1 reactivity in solvolysis reactions is found, thus providing a quantitative basis for our long-standing working hypothesis that Lewis acid-catalyzed additions of alkyl halides to CC multiple bonds only yield 1:1 products if the reactants ionize faster than the products. Trityl chlorides do not follow this correlation and are 105 times less reactive than predicted from their SN1 reactivities.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270129
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  • 56
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    Zinc Complexes of Porphyrin-Quinone Cyclophanes: Syntheses, Structures and Electron-Transfer-Related Properties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 231-236 
    Details
    ISSN: 0009-2940
    Keywords: Zinc porphyrin complexes ; Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Electron-transfer mechanism in metalloporphyrin-quinone cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to increase the driving force for photoinduced electron-transfer reactions of porphyrin-quinone cyclophanes, the zinc complexes 3a-e and 4a-e were prepared from the corresponding cyclophanes of the 1 and 2 series. Electron-transfer-related properties like redox potentials and fluorescence spectra were determined for 3a-e and 4a-e. The X-ray structure analysis of 4a indicates that for the very fast and solvent-independent electron transfer in these systems a specific mechanism involving an interaction of a quinone carbonyl group with the zinc might be considered as an alternative to through-space electron-transfer.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270133
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  • 57
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    Die Dipol-Route zu Furo-/Thieno-Pyrrolen und α-Pyridonen, sowie deren Benzo-Derivaten (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 247-259 
    Details
    ISSN: 0009-2940
    Keywords: Pyrroles, heteroannulated ; α-Pyridones, heteroannulated ; Pentalenes, dihetero- ; Nitrones ; Heterocyclizations, 1,7-dipolar ; Diels-Alder reactions ; Singlet oxygen ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Route to Isoannulated Heteroaroamtic Compounds, 2[1].  -  The Dipole Route to Furo/Thieno Pyrroles and α-Pyridones, and Their Benzo DerivativesA new methodology involving 1,7-dipolar cyclizations of conjugated dipoles followed by a multistep rearrangement affording ring-contracted products has been employed for the synthesis of various examples of the title compounds. Under different thermolysis conditions the annulated alkynyl nitrones 15-19, 45, and 46 are converted into isoannulated pyrroles and α-pyridones, respectively, with yields up to 90% (general reaction A → B + C). The product distribution is strongly influenced by the nature of the terminal substituent R, hence supporting a mechanism with oxo carbenes as central intermediates which undergo either 6-π cyclization to the pyrrole systems or Wolff rearrangement leading to conjugated ketenes, the precursors of the observed α-pyridones (see Scheme 1). Diels-Alder reactions were performed with benzofuropyridone 40a, napthopyridone 62 as well as with the corresponding dihydronaphtho compounds 64a, b. Whereas the tert-butyl derivatives 22b, 23b and 41b are rather unreactive against dienophiles, they are easily transformed into the cyclic imides 31, 32 and 52, respectively, under the influence of oxygen and light suggesting the formation and subsequent [4 + 2] cycloaddition of 1O2 as important steps.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270135
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    Dinuclear Paramagnetic Metallocenes Bridged by Silyl Groups  -  Synthesis and Intramolecular Interactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 277-286 
    Details
    ISSN: 0009-2940
    Keywords: Metallocenes, dinuclear, silyl-bridged ; Antiferromagnetism ; Cyclic voltammetry ; Paramagnetic NMR spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dilithium salt of the 3a,4,7a,8-tetrahydro-4,4,8,8-tetra-methyl-4,8-disila-s-indacenediyl dianion (L2-, 2) was allowed to react with the solvated metal halides MX2 (M = Ni, Co, Cr) in the presence of the cyclopentadienyl (Cp) anion to give trans-CpMLMCp (3NiNi, 3CoCo, and 3CrCr) in yields up to 80%. The only cis isomers which could be detected were 4NiNi and 4CoCo. Similarly, the reaction of 2 with [CpVCl(PEt3)]2 gave the trans-vanadium analogue 3VV while the successive reaction of 2 with CrCl3 (THF)3 and PEt3 yielded the bridged half-sandwich (Et3P)Cl2CrLCrCl2(PEt3) (5CrCr). The mixed-metal dinuclear metallocene CpFel—NiCp (3FeNi) was synthesized from CpFel-, Cp- and solvated NiBr2. The molecules were characterized by mass spectrometry, elemental analyses, cyclic voltammetry, 1H—, 13C—, and 29Si—NMR spectroscopy and solid-state magnetic measurements. Cyclic voltammetry showed up to six electron transfers per molecule. A metal-dependent splitting of the half-wave potentials of up to 355 mV indicated rather strong electrostatic interaction between the metallocene units. The NMR results established unpaired spin on the ligands. Its distribution within the bridging ligand was correlated with the molecular orbital splitting and the magnetic interaction. Antiferromagnetic interaction was found for 3NiNi, 3CrCr, and 3VV with J = -11.6, -2.56, and -1.34 cm-1, respectively (H = -J · SA · SB). A temperature-dependent folding of the bridging ligand was deduced from the temperature behavior of the 1H—NMR signal shifts.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270202
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    Untersuchungen am System Phosphirenimin/Iminophosphan  -  Insertionsreaktionen und Isomerisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 313-319 
    Details
    ISSN: 0009-2940
    Keywords: Phosphirene imines ; 1,2-Diphosphete diimines ; Isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations of the System Phosphirene Imine/Iminophosphane - Insertion and Isomerization ReactionsTreatment of the iminophosphanes R1P=NR2 1 [R2 = tBu, R1 = Et3C (a); R2 = Aryl, R1 = Et (b), Me (c)] with 1,4-diphenyl-butadiyne (2) leads to the phosphirene imines R1-(R2N=)P̌(Ph)=CCCPh 3a-c and [R1(R2N=)P̌(Ph)=CC]2 4a-c. Further reaction with 1a, c gives the 1,2-diphosphetes R1(R2N=)PP(R1)(=NR2)C(Ph)=CCCPh 5a, b, which isomerize in the case of R1 = Me into the triphosphabicyclo[3.2.0]-hepta-1,6-diene 7. In the reaction of the phosphirene imines R1(ArylN=)P̌(R2)=C(R2) 3 [R1 = Me, R2 = Ph (d); R1 = Et, R2 = COOMe (e)] with the iminophosphanes 1b, d the initially formed diphosphetes 9a, b isomerize to the 1,2-diazaphosphole Cl(Mes*N=)PN(Mes*)P(Me)C(Ph)=C(Ph) 10 or the dioxadiphosphabicyclooctadiene C=C(OMe)OP(=N-Mes*)(Et)C=C(OMe)OP(=NMes*)(Et) 12 depending on the substituents. A reaction of the phosphirene imine 3d with dimethylamino-borane furnishes the vinylphosphane. Ph(H)C=C(Ph)P(Et)N(H)Mes* (14) by ring opening. The compounds 7, 10, 12 have been characterized by X-ray structure analyses.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270206
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    Stereoelektronische Effekte und chirale Erkennung, I. Diastereoselektive Etherbildungen aus Alkylarylcarbinolen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 359-365 
    Details
    ISSN: 0009-2940
    Keywords: Diastereoselectivity ; Effect, kinetic ; Effect, stereoelectronic ; Etherification ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoelectronic Effects and Chiral Recognition, I.  -  Diastereoselective Formation of Ethers from AlkylarylcarbinolsAcid-catalysed etherification of various alkylarylcarbinols 1 leads to a mixture of diastereomeric products 2 and 3. As found in the closely related formation of diastereomeric acetals, the ratio 2/3 is shown to be time-dependent. Preferred formation of the meso-diastereomer 3 under kinetic condition and preferred formation of the racemic diastereomer 2 under thermodynamic conditions is observed. A reaction path based on π-π interactions and stereoelectronic effects is presented to explain experimental results.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270213
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    Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“Herrn Professor Wilhelm Pritzkow zum 65. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 401-408 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Dithiines ; Thioindigo ; Thioketones ; Disulfides, cyclic, molecular structure and reactions ; Valence isomerization, electrocyclic ; Thiophenes, derivatives of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“3-Mercaptobenzo[b]thiophene (1) is transformed with assistance of bases, especially of amines, into the benzo[b]-thieno-annellated 1,2-dithiine 6 and not into the originally claimed “Dithioxo-thioindigo” trans-3. Primarily, the formation of 6 from 1 involves oxidation to the disulfide 4 which may also be used separately. Conceivable rationalizations are discussed. The same compound is accessible (in lower yield)by thionation of thioindigo with the aid of the Lawesson reagent. X-ray elucidation of 6 reveals a non-planar structure of the cyclic disulfide with a dihedral C—S—S—C-angle of 53°. Despite of the absence of any established chromonphoric moiety, 6 is deeply red in the crystal and in solution, as it is representative for the “undisturbed” 1,2-dithiine system. Contrary to the usual behaviour of the non-annellated 1,2-dithiines, 6 displays no spontaneous sulfur extrusion under mild conditions, but only at high temperatures and in the presence of sulfur-binding agents, leading to the benzo[b]thieno-annellated thiophene 22. Moreover, 6 may be reduced to the dithiol 14 (or 13, respectively) and regenerated exclusively from this by oxidation. Further characteristic reactions of 6 are described (e.g. to the sulfoxide 18, to the pyridazine 19, and to the thiphosphoric ester 21).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270217
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    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 445-445 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270222
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    Tris(perfluororganochalkogenyl)methyl-Verbindungen: Synthesen, Strukturen und Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 449-455 
    Details
    ISSN: 0009-2940
    Keywords: Trifluoromethylsulfanyl compounds ; Pentafluorophenylsulfanyl compounds ; Trifluoromethylselenanyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(perfluoroorganochalkogenyl)methyl Compounds: Synthesis, Structures, and PropertiesReaction of (CF3S)2CHC(OC2H5)3 with CF3SCl or CF3SeCl in the presence of NaH in ether provides X(CF3S)2CC(O)OC2H5 (1a, b: X = CF3S, CF3Se). These compounds react with NH3 to form (CF3S)2CHC(O)NH2 (2b) which is also obtained from (CF3S)2CHC(O)OC2H5 and NH3. Dehydration of the amide 2b yields (CF3S)2CHCN (3b), which reacts with NaH and then with CF3SX (X = Cl, SCF3) or with RfCl (Rf = CF3Se, C6F5S) to give Rf (CF3S)2CCN [Rf = CF3S (3c), CF3Se (3d), C6F5S (3e)]. 3c is also obtained from (CF3S)3CBr and AgCN. Hydrolysis of 3c with conc. H2SO4 leads almost quantitatively to (CF3S)3CC(O)NH2 (2c), which on treatment with COCl2 gives only 3c and not the corresponding isocyanate. If phosgene is replaced by oxalyl chloride and treated with 2c in a 1:1 molar ratio, (CF3S)3CC(O)NCO (4a) is formed. The urea derivative (CF3S)3CC(O)NHC(O)NHC(O)C(SCF3)3 (4b) is obtained either by using a 2:1 molar ratio of 2c and [C(O)Cl]2 or from 2c and 4a. Attempts to substitute (CF3S)2CHCO2H - after treatment with NaH in ether - with CF3SCl provides low yields of 2,4-bis[bis(trifluoromethylsulfanyl)methylene]-1,3-dithietane (5). X-ray structure analyses are performed for (CF3S)3CCN (3c) and the 1,3-dithietane 5.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270302
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    Synthese und Koordinationschemie hemilabiler P,N-Hybridliganden mit terminalen 2-Pyridyl-DonorgruppierungenHerrn Professor Dr. O. J. Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 481-488 
    Details
    ISSN: 0009-2940
    Keywords: 2-Pyridylalkylphosphanes ; Hemilabile ligands ; Nickel complexes ; Palladium complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Coordination Chemistry of Hemilabile P,N-Hybride Ligands with Terminal 2-Pyridyl Donor Groups*P,N-hybride ligands 1-7 containing terminal 2-pyridyl donor groups have been obtained by base-catalyzed addition of diphenylvinylphosphane or 2-vinylpyridine to primary or secondary phosphanes [2-Py-(CH2)2-PR′H (R′ = H, Ph), HMeP-(CH2)3-PMeH] or by alkylation of organolithium phosphides, R2P-(CH2)3-PMeLi or 2-Py-(CH2)2-PR′Li (R = Ph, iPr; R′ = H, Ph), with 2-(2-chloroethyl)pyridine or di-tert-butylphosphetanium bromide. Upon reaction with NiBr2 3 H2O or K2MCl4 (M = Pd, Pt) the phosphanes (L) of type 2-Py-(CH2)2-P(R′)-(CH2)m-PR2 (1, 3, 6) form square planar Ni(II), Pd(II), and Pt(II) complexes of composition MX2(L) (10-14). With NiBr2 and K2MX4 the tripod type phosphane 2 forms square pyramidal complexes [MX(2)]X (M = Ni, Pd; X = Cl, Br; 15, 16). An X-ray structural analysis of [NiBr(2)]+Br- (15) reveals a distorted square pyramidal coordination geometry at Ni(II), the 2-Py donor being in apical position with a long Ni—N bond [2.270(15) Å]. The tetradentate ligand 7 forms Ni(II), Pd(II), and Pt(II) complexes MX2(7) which for M = Pd, Pt show dynamic behaviour by exchange of the terminal Py donor groups. With [RhCl(COD)]2 the tridentate ligands L (1 and 3) yield complexes of composition RhCl(L) (20, 21). The structure of 20 has been determinated by X-ray diffraction. The ligand 3, acting in a tridentate manner, is coordinated to Rh(I) in a distorted square-planar arrangement with a normal Rh—N distance [2.145(3) Å].
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270306
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    Study of Calixarenes, V. Friedel-Crafts Reaction of Calixarenes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 519-523 
    Details
    ISSN: 0009-2940
    Keywords: Calixarenes ; Friedel-Crafts reaction ; selective ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The para-acylation of calix[4]arene (2), calix[6]arene (3), and calix[8]arene (4) by Friedel-Crafts reaction with a wide variety of acyl chlorides leads to 5-7 in moderate to good yields. Friedel-Crafts reaction of 26,28-dimethoxycalix[4]arene (8) gave products 9 selectively disubstituted in the para-positions of phenol rings.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270310
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    Komplexe mit makrocyclischen Liganden, I. Zweikernige Kupfer(II)-Komplexe mit vollständig π-konjugiertem Makrocyclus vom Schiff-Basen-Typ: Synthesen, Strukturen, elektro- und magnetochemische Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 465-476 
    Details
    ISSN: 0009-2940
    Keywords: Copper(II) complexes, dinuclear ; Schiff bases, macrocyclic ; Redox properties ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes with Macrocyclic Ligands, I. - Dinuclear Copper(II) Complexes with a Totally π-Conjugated Macrocycle of Schiff Base Type: Syntheses, Structures, Electro-, and Magnetochemical PropertiesThe dinuclear copper(II) complexes 6, 7, and 8 of three novel macrocyclic ligands were synthesized by the Schiff base condensation of 2 equiv. of 1,2-phenylenediamine and 2,6-diformylphenol in the presence of 2 equiv. of copper(II) perchlorate and were characterized by X-ray structure analyses, electrochemical investigations (DCV), and variable-temperature magnetic susceptibility measurements. Complex 6 exists in two different solvated crystalline forms. The Copper(II) ions in all three complexes are octahedrally coordinated with long axial distances to solvent molecules or perchlorate ions. The copper ions in 6 (in solvate a) are only five-coordinate and square-pyramidal. The CuIICuII complexes were reduced in successive, quasi-reversible, one-electron steps. The antiferromagnetic exchange interactions were determined. Upon dissolution in acetonitrile complex 8 decomposed to form [Cu(MeCN)4]+ClO-4 and the benzimidazolium percholorate 9 (X-ray structure determination).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270304
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    {Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2-ethen)nickel(0) und verwandte Verbindungen, Teil II (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 489-500 
    Details
    ISSN: 0009-2940
    Keywords: Alkenes ; Nickel complexes ; Stannenes ; Metal-metal bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: {Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2-ethene)nickel(0) and Related Compounds, Part IIThe coordinatively unsaturated (16e) (ethene)nickel(0) stannylene complex (C2H4)2Ni=Sn{CH(SiMe3)2}2 (1) reacts with 1,6-heptadiene with preservation of the Ni=Sn bond to yield quantitatively the 1,6-diene derivative (η2,η2-C7H12)Ni=Sn-{CH(SiMe3)2}2 (2). The alkene ligands of both 1 and 2 are readily displaceable. Compounds 1 and 2 react with butadiene at -50°C by a 4-e oxidation of the metal-metal pair Ni(0)/Sn(II) to Ni(II)/Sn(IV) and concomitant reduction of two butadiene molecules to butenediyl moieties to afford stereo-selectively the 16-e complex Ni-cis-{η3(Ni),η1(Sn)-anti-C3H4CH2}2Sn{CH(SiMe3)2}2 (3). Similarly, the reaction of 1 or 2 with isoprene yields regio- and stereoselectively the derivative Ni-cis-{η3(Ni,η1(Sn)-anti-C3(3-Me)H3CH2}2Sn{CH-(SiMe3)2}2 (4). These reactions imply the cleavage of one formal Ni—Sn bond and the formation of two new Sn—C bonds. Upon reaction of 3 with PMe3 the configuration of the allyl system changes and, again fully stereoselectively, the 18-e addition compound (Me3P)Ni-cis-{η3(Ni),η1(Sn)-syn-C3H4-CH2}2Sn{CH(SiMe3)2}2 (5) is formed. When 5 is treated with BPh3, the phosphane ligand is trapped and, kinetically controlled, Ni-cis-{η3(Ni),η1(Sn)-syn-C3H4CH2}2Sn{CH(SiMe3)2}2 (6) is obtained as a stereoisomer of 3. At 40°C 6 slowly rearranges into the thermodynamically stable stereoisomer Ni-trans-{η3(Ni),η1(Sn)-syn-C3H4CH2}2Sn{CH(SiMe3)2}2 (7). Mild protolysis of 3 with pyridine hydrochloride or hydrobromide affords region and stereoselectively (Me3Si)2CH}2(X)SnNi-(η3-1-MeC3H4)(NC5H5) (X = C1, 8a; Br, 8b). In the course of this protonation reaction one butadiene molecule is eliminated, accompanied by a 2-e reduction of the metal-metal pair Ni(II)/Sn(IV) to Ni(II)/Sn(II) and, at the expense of two Sn—C bonds, reformation of a Ni—Sn bond. All compounds are isolated in high yield and fully characterized by 1H-, 13C-, and 31P-NMR spectroscopy.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270307
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    Halogen-Kohlenstoff-Schwefel-Verbindungen: Zur Chemie von 1,1,1,4,4,4-Hexafluor-2-buten-2,3-bissulfenylchlorid (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 533-539 
    Details
    ISSN: 0009-2940
    Keywords: Bissulfenyl chlorides ; fluoro substituted ; 1,3-Dithioles ; 1,3,2-Dithiazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halogen-Carbon-Sulfur Compounds: Syntheses with 1,1,1,4,4,4-Hexafluoro-2-butene-2,3-bissulfenyl ChlorideThe bifunctional bissulfenyl chloride 3 is obtained by chlorination of the dithiete 1 or tetrathiocine 2. By excessive chlorination the saturated bissulfenyl chloride 4 is formed. 3 reacts with primary amines to yield the 1,3,2-dithiazoles 5a-e, whereas by reactions with active methylene compounds like ketones or β-dicarbonyls the compounds 7-14 are obtained with HCl elimination. 13 as well as 14 are converted into the carboxylic acid 15 from which the 1,3-dithiole 17 is obtained by decarboxylation. 3 reacts with disulfene to form tetrakis-(trifluoromethyl)tetrathiafulvalene as well as 4,4′,5,5′-tetrakis(trifluoromethyl)-2,2′-spirobi[1,3-dithiole] (18), whose crystal structure has been determined.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270312
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    Thermal Rearrangements, XXII. The Propargyl-Cope Rearrangement of meso- and d,l-3,4-Dimethyl-1,5-hexadiyne-3,4-diol (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 959-963 
    Details
    ISSN: 0009-2940
    Keywords: Rearrangements, thermal ; Propargyl-Cope reaction ; 1,5-Hexadiyne-3,4-diol ; Cyclobutene ; 3,4-diacetyl ; Fragmentations, retro-ene ; Tandem reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal behavior of meso- and d,1-3,4-dimethyl-1,5-hexadiyne-3,4-diol (meso- and d,1-4) has been studied at 400°C in the gas phase. In a tandem reaction the diols isomerize via the bisallenes 5 first to cis- and trans-3,4-diacetylcyclobutene (cis- and trans-8) which have been detected as intermediates by 13C-NMR spectroscopy as well as catalytic hydrogenation to 1,2-diacetylcyclobutane (9). Subsequently, 8 stabilizes itself by ring opening to (E,Z)- and (E,E)-3,5-octa-dien-2,7-dione (E,Z) and [(E,Z)-6]. As a side reaction retroene cleavage of 4 to 2-butynone (10) and methyl vinyl ketone (12) is observed. By pyrolysis of the pure diastereomers 4 it is shown that the retro-ene process is more pronounced in the d,l than in the meso series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270526
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    Substituierte N,N-Chelat-Liganden - Anwendungen in der Molybdän-katalysierten Olefin-EpoxidationHerrn Prof. Dr. H. Schmidbaur zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2373-2379 
    Details
    ISSN: 0009-2940
    Keywords: Chelating ligands ; Molybdenum complexes ; Peroxo complexes ; Catalysis ; Olefine epoxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted N,N-Chelate Ligands - Applications in Molybdenum-Catalyzed Epoxidation of Olefins*Oxodiperoxomolybdenum complexes 4 of substituted 2-[3(5)-pyrazolyl]pyridines (2a-g) were synthesized in order to control the solubility of these complexes in organic solvents. Alkyl side chains (butyl, octyl, octadecyl) increase the solubility of the complexes and enable spectroscopic investigations in solution. Due to the symmetry of the ligands the peroxo complexes 4 appear in two isomeric forms, with the terminal oxo ligand in the trans position either to pyridine or to pyrazole. The latter isomer of (C5H4NC3H2N2CH2COOEt)MoO(O2)2 (4f) was characterized by an X-ray structure analysis. The alkyl-substituted peroxo complexes are active catalysts for the epoxidation of olefins with tert-butyl hydroperoxide.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271206
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    A Comparative Study of the Reactivity of Mn(no)2L2H and Mn(CO)3L2H Complexes (L = Phosphorus Donor)Dedicated to Prof. E. Lindner, Universität Tübingen, on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2403-2415 
    Details
    ISSN: 0009-2940
    Keywords: Manganese complexes ; Insertion processes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mn(NO)2L2H complexes [L = PMe3 1a, PEt3 1b, P(OMe)3 1c, P(OEt)3 1d, P(OiPr)3 1e] have been prepared by the reaction of the corresponding Mn(NO)2L2Br compounds with NaBH4 in ethanol. The reactivity of 1a and 1b is compared to that of Mn(CO)3L2H species (L = PMe3 2a, L = PEt3 2b). Compound 1b reacts with weak acids like PhOH, (CF3)2CHOH and CH3COOH to yield Mn(NO)2(PEt3)2X complexes [X = OPh 3a, OCH(CF3)2 3b, OC(O)CH3 3c] and H2. Compound 2b does not undergo reaction with these acids. At room temperature in toluene 1a, b undergo facile CO2 insertion processes, while 2a, b do not show this reactivity even under more rigorous reaction conditions. From 1a, b and CO2 formato complexes Mn(NO)2L2[OC(O)H] (L = PMe3 4a, L = PEt3 4c) are obtained. The reaction of 1b with salicylaldehyde in toluene proceeds with the formation of a [2-(hydroxymethyl)-phenoxy]dinitrosylbis(triethylphosphane) manganese complex 5b, which exchanges the phenoxy ligand in the presence of excess of salicylaldehyde to give (2-formylphenoxy)-dinitrosylbis(triethylphosphane)manganese (6b) and α,2-dihydroxytoluene. p-Hydroxybenzaldehyde, vanilline, and 4-hydroxy-3,5-dimethoxybenzaldehyde and 1b also afford phenoxy derivatives Mn(NO)2(PEt3)2(OAr) [Ar = p-OC6H4-CHO 7a; OC6H3-2-OCH3-4-CHO 7b; OC6H2-2,6-(OCH3)2-4-CHO 7c] and H2. Compounds 2a, b do not react with any of these hydroxybenzaldehydes. Compounds 1a, b have been converted into Mn(NO)2L2 [(Z)-C(COOR′)≡C(R)H] species (L = PMe3, R = H, R′ = Me 8a; L = PEt3, R = H, R′ = Me 8b; L = PMe3 R, R′ = Me 9a; L = PMe3, R = Ph, R′ = Et 10a; L = PMe3, R = COOMe, R′ = Me 11a; L = PEt3, R = COOMe, R′ = Me 11b) in the presence of alkyl propiolates RC≡CCOOMe (R = H, Me, Ph, COOMe; R′ = Me, Et). Similarly, but under more rigorous conditions, insertion of RC≡CCOOMe (R = H, COOMe) into 2a, b occurs and α metalation products Mn(CO)3(PMe3)2[(Z)-C(COOMe) = CHR] (L = PMe3, R = H 12a; L = PEt3, R = H 12b; L = PMe3, R = COOMe 13a; L = PEt3, R = COOMe 13b) are formed. In the case of the methyl propiolate insertion into 2a, 10% of an additional β-metalation compound Mn(CO)3(PMe3)2[(Z)-CH = CH(COOMe)] (12c) have been detected spectroscopically. Compounds 11b and 13a, b have been transformed into manganacyclic complexes MN[C(COOMe)=CH(COOMe)]-(NO)2(PEt3)2 (14b) and MN[C(COOMe)=CH(COOMe)]-(CO)2L2 (L = PMe3 15a; L = PEt3, CO 15b; L = PEt3 15c). Compound 15c has been identified spectroscopically, and 1a, 8a, and 9a have been characterized by X-ray structure determinations.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271211
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    Synthesis and Complexation of a New 14-Membered N2O2 Macrocycle with vic-Dioxime Moieties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2483-2488 
    Details
    ISSN: 0009-2940
    Keywords: vic-Dioximes ; N2O2 macrocycles ; Trinuclear complexes ; Pentanuclear complexation ; Tribenzo[b.h.l][1,10,4,7]dioxadiazacyclotetradecine derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new vic-dioxime ligand 2 (LH4) carrying a 14-membered N2O2 macrocycle has been prepared. Mononuclear complex (LH3)2Ni, trinuclear complexes (LH)2Cu3, (LH)2Co3, (LH)2-Pd3, and (LH)2Co3(py)3Cl3, dinuclear complex (LH3)2-(UO2)2(OH)2, and pentanuclear complex [L2Cu5(phen)2]-(NO3)2 have been synthesized from LH4. The electrochemical properties of tri- and pentanuclear complexes were investigated by cyclic voltammetry. For (LH)2Cu3 two reduction waves appeared at 0.215 and -0.870 V. [L2Cu5(phen)2](NO3)2 exhibited four reduction waves at 0.200, -0.025, -0.670, and -1.170 V.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271219
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    Novel, Very Strong, Uncharged Auxiliary Bases; Design and Synthesis of Monomeric and Polymer-Bound Triaminoiminophosphorane Bases of Broadly Varied Steric DemandDedicated to Professor Christoph Rüchardt on the occasion of his 65th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2435-2454 
    Details
    ISSN: 0009-2940
    Keywords: Uncharged auxiliary bases ; Triaminoiminophosphorane bases ; Deprotonation ; Hindered bases ; Polymeric bases ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and properties of a number of very strong iminophosphorane bases up to an extremely high level of steric hindrance are described. They cover a range of ca. 4 pK units in basicity and a range of more than 11 orders of magnitude in their rates of methylation with methyl iodide. Most of the systems are readily prepared in up to molar quantities, conveniently recovered from their salts and are of high chemical and thermal stability. Crystal structures were determined in order to parametrize a force field, which is utilized in molecular modeling studies offering a rationalization of the observed differences in steric hindrance and basicity. Depending on the degree of steric protection of the basic center, these novel bases are proposed as unprecedented, versatile auxiliary bases in E2 eliminations and in reactions involving deprotonation in the presence of more or less strong electrophiles.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271215
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    Übergangsmetallsubstituierte Acylphosphane und Phosphaalkene, XXI. Isophosphaalkine als μ3-Liganden in Übergangsmetallkomplexen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1349-1353 
    Details
    ISSN: 0009-2940
    Keywords: Isophosphaalkynes ; Transition metal complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, XXI.  -  Isophosphaalkynes as μ3-Ligands in Transition Metal ComplexesReaction of the μ-isophosphaalkyne complex (η5-C5H5)2 (CO)2(μ-CO)Fe2(μ-CPMes) (Mes = 2,4,6-Me3C6H2) (2a) with [(Z)-Cyclooctene]Cr(CO)5 or Fe2(CO)9 gives rise to the μ3-isophosphaalkyne complexes (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[M(CO)n]Mes} 3a [M(CO)n = Cr(CO)5] and 4a [M(CO)n = Fe(CO)4]. Similarly (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[Cr (CO)5]C6H2(CF3)3-2,4,6} (3d) is obtained. The metal carbonyl fragments are attached to 2 in a η1-fashion by the lone-pair at the phosphorus. In contrast to this the treatment of 2a with (Ph3P)2Pt(η2-C2H4) affords complex 5a in which 2a serves as an η3-3e ligand towards the PtPPh3 moiety. The molecular structures of 3a and 5a are determined by single-crystal X-ray analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270804
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    Transition Metal Chemistry of Main Group Hydrazides, 9. Platinum Complexes of Diphosphanylhydrazides R2PN(Me)N(Me)PR2 · PtCl2 (R = OPh, o-OC6H4CH2CHCH2) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1355-1357 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphanylhydrazides ; Diphosphanes, dinitrogen-bridged ; Cycloplatinaphosphahydrazides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While the transition metal complexes of bis(phosphanyl)amines (PII-N-PIII) have been known for over three decades, the ligating properties of the next homologue PIII-N-N-PIII have been unprecedented so far. The X-ray structures of cycloplatinaphosphanehydrazides, [(OR)2PN(Me)N(Me)P(OR)2-PtCl2], reveal short distances for the P-N [1.639(5) Å] bonds.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270805
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    A Synthetic Pathway to 1,3-Bis(trisilylmethyl)disiloxane [(H3Si)3CSiH2]2O  -  the Octasila Analogue of Dineopentyl Ether [(H3C)3CCH2]2O (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1359-1362 
    Details
    ISSN: 0009-2940
    Keywords: Silanes ; Siloxanes ; Si - C bond, selective cleavage ; Arylsilylmethanes ; Si,C,O single-source CVD precursor ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic route to partly silylated tetra(silyl)methanes (ArH2Si)nC(SiH3)4  -  n′ to their precursors (TfH2Si)nC-(SiH2Ar)4  -  n (Ar = p-tolyl, phenyl; Tf = CF3SO3; n = 3, 2, 1), and to 1,3-bis(trisilylmethyl)disiloxane [(H3Si)3CSiH2]2O (9) is reported. Starting from symmetrical tetrakis(arylsilyl)-methanes (aryl = p-tolyl, phenyl), we have obtained the selectively dearylated (arylsilyl)silylmethanes (ArH2Si)nC(SiH3)4  -  n (Ar = p-tolyl, phenyl; n = 3, 2, 1) by Si - Ar cleavage with equivalent quantities of trifluoromethanesulfonic acid (triflic acid) and hydrogenation of the corresponding silyl triflates (TfH2Si)nC(SiH2Ar)4  -  n (n = 3, 2, 1) with LiAlH4. The synthesis of 9 has been accomplished by treating trisilyl(p-tolylsilyl)methane p-TolH2SiC(SiH3)3 (7) with stoichiometric amounts of triflic acid to give (trisilylmethyl)silyl triflate TfH2SiC(SiH3)3 (8) and hydrolysing the latter with water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270806
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    Ein neuer Zugang zu 1,2- und 1,3-DiborolHerrn Prof. Dr. Joachim Knappe zum 65. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1363-1368 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Diboroles, 2,5-dihydro- ; 1,3-Diboroles, 2,3-dihydro- ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Approach to 1,2- and 1,3-DiboroleHerrn Prof. Dr. Joachim Knappe zum 65. Geburtstag gewidmet.Diaminoborylation of 1,3-dilithiopropenes leads to the (Z)-1,3-bis(diaminoboryl)propenes 4a, b, which are transformed by an amine/chlorine exchange to the (Z)-1,3-bis(aminochloroboryl)propenes 5a, b. These react with sodium to yield the 2,5-dihydro-1H-1,2-diboroles 2c, d, whereas the reaction with potassium leads to the 2,3-dihydro-1H-1,3-diboroles 6a, b by rearrangement of the C3B2 skeleton. The constitutions of the heterocycles 2c, d and 6a, b are established by X-ray structure analyses. Reaction of the 1,2-diboroles 2c, d with (C5H5)Co(C2H4)2 leads to the red (1-borabutadiene)cobalt complexes 3c, d. In 3c a sigmatropic rearrangement is studied by NMR spectroscopy.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270807
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    Kohlenwasserstoffverbrückte Komplexe, XXX. Nucleophile Addition von Carbonylmetallaten an kationische Vinyl-, Dien-, Dienyl- und Trien-Komplexe von Eisen, Ruthenium und Cobalt: Zwei-, drei-, vier- und fünfkernige Komplexe mit σ,σ- und σ,π-KohlenwasserstoffbrückenHerrn Professor Ekkehard Lindner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1369-1377 
    Details
    ISSN: 0009-2940
    Keywords: Tungsten complexes ; Rhenium complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; Cobalt complexes ; Vinyl ; Cyclohexadienyl ; Cycloheptadienyl ; Cyclooctatrienyl ; Hydrocarbon-bridged complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Complexes, XXX.  -  Nucleophilic Addition of Carbonylmetallates to Cationic Vinyl, Diene, Dienyl and Triene Complexes of Iron, Ruthenium and Cobalt: Di-, Tri-, Tetra- and Pentametallic Complexes with σ,σ- and σ,π-Hydrocarbon BridgesHerrn Professor Ekkehard Lindner zum 60. Geburtstag gewidmet.The reactions of [Re(CO)5]-, [Ru(CO)2Cp]-, and [Os(CO)4]2- with [Cp2(OC)2Fe2(μ-CO)(μ-η1:η2-CH=CH2)]+, [Cp*Ru(η2:η4-1,3,7-octatriene)]+, [(OC)Fe(η4-diene)(η5-cycloheptadienyl)]+, and [CpCo(η5-cyclodienyl)]+ give the nucleophilic adducts whereas with [Mn(CO)5]-, [W(CO)3Cp]-, and [Fe(CO)2Cp]- formation of the corresponding C-C coupling products and of the metal-metal-bonded dimers is observed. The structures of Cp*Ru(μ-η1:η2:η3-1,5-octadienyl)Re(CO)5 (4), [Cp* Ru(μ-η1:η2:η3-1,5-octadienyl)]2Os(CO)4 (6), and of (OC)-Fe(η4-1,3-cyclohexadiene) (μ-η1:η4-1,3-cycloheptadiene)Re(CO)5 (9) have been determined by X-ray diffraction.
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    URL: http://dx.doi.org/10.1002/cber.19941270808
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    Binary [Hydrotris(1,2,4-triazolyl)borate]metal Complexes [M{HB(C2H2N3)3}2] with M = Fe, Co, Cu, Zn: Synthesis, Characterization, Magnetochemistry, and X-ray Structure of [Cu{HB(C2H2N3)3}2·4CH3 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1379-1385 
    Details
    ISSN: 0009-2940
    Keywords: Hydrotris(triazolyl)borate ; metal complexes ; Chelate ligands ; Clathrates ; Magnetochemistry ; Spin crossover ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bis[hydrotris(1,2,4-triazolyl)borate]metal complexes [M{HB(C2H2N3)3}2] with M = Fe (5), Co (6), Cu (7), Zn (8) are obtained from MX2 and K[HB(C2H2N3)3] (9). The complexes are characterized by IR, UV/Vis, and MS. Temperature-variable magnetic measurements show a Curie-Weiss behavior for the paramagnetic complexes 6 and 7 with a temperature-dependent magnetic moment for 6. The iron complex 5 exhibits a spin crossover from diamagnetic to paramagnetic, starting at around 270 K. Single-crystal X-ray structures of the solvates 7 · 4 CH3OH and 9 · 2 H2O have been determined. The structure of 7 · 4 CH3OH shows the Jahn-Teller distorted copper complex 7 surrounded by methanol molecules through hydrogen bonding to exocyclic nitrogen atoms of the tris(1,2,4-triazolyl)borate ligand. The crystal system for 7 · 4 CH3OH is monoclinic, space group P21/n. Compound 9 · 2 H2O is a one-dimensional coordination polymer with the potassium atom bridged by the water molecules and the tris(1,2,4-triazolyl)borate ligand and crystallizes in the orthorhombic space group Ccm21.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270809
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  • 80
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    Copper-Catalyzed Conjugate Addition of Trimethylaluminium to α,β-Unsaturated Ketones (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1489-1493 
    Details
    ISSN: 0009-2940
    Keywords: Conjugate alkylation ; Trimethylaluminium ; Copper catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conjugate methylation of α,β-unsaturated ketones with trimethylaluminium occurs smoothly in a very simple procedure under the catalytic effect of Cu1 salts. Scope and limitations of this process as well as the influence of solvent and catalyst on the kinetics were studied. In addition, the effect of chlorotrimethylsilane as an additive was investigated. Attack on the carbonyl group in 1,2-fashion could not be observed under the reaction conditions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270823
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  • 81
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    Synthesis, Structure and Reactivity of Cyclopenta-annulated 1,2,3,4-TetrazinesDedicated to Professor Dr. Donald J. Cram on the occasion of his 75th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1479-1488 
    Details
    ISSN: 0009-2940
    Keywords: 1,2,3,4-Tetrazines ; 2H-Cyclopenta[e]-1,2,3,4-tetrazines ; Azodiazo-tetrazino isomerism ; Ketene imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2-aryl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3a-n are formed by coupling of the diazocyclopentadienes 1a and 1b with arenediazonium salts and subsequent reversible electrocyclization of the primary coupling products 2a-n. From the solutions of the equilibrium mixtures of 2a ⇌ 3a - 2n ⇌ 3n the tetrazines 3a-d, h-k and the arylazo-diazocyclopentadienes 2e-g and 21-n crystallize. The 2-methyl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3o and 3p are obtained by addition of methyllithium to 1a and 1b followed by a diazo transfer reaction and cyclization. In solutions of 3o and 3p the ring-opened isomers 2o and 2p could not be detected. X-ray analyses of 3h and 3p prove their bicyclic planar geometry in the solid state. 15N-NMR and temperature-dependent 1H-NMR spectroscopy have enabled a detailed study of the reversible ring closure reaction in the case of 2d ⇌ 3d. Reaction of 2-phenyl-2H-cyclopenta[e]-1,2,3,4-tetrazine (3b) with tetrafluoroboric acid results in the formation of the protonated monocyclic salt 4. Furthermore 3b undergoes electrophilic substitution reactions preferably at C-7, as demonstrated by bromination, formylation, and trifluoroacetylation. Photolysis of solutions of 2i/3i, 2k/3k, and 21/31 leads to the ketene imines 11a-c. The structure of 11c has been determined by X-ray crystallography.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270822
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  • 82
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    Synthesis, Absorption Spectra, and Photostability of Triarylmethane Dye Ethynylogues Containing Trifluoromethyl Group(s) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1627-1632 
    Details
    ISSN: 0009-2940
    Keywords: Triarylmethane dye ethynylogues ; Trifluoromethyl group ; Triphenylmethane dyes ; Photostability ; Absorption spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triarylmethane dye ethynylogues 7′- 11′ containing trifluoromethyl group(s) are synthesized in moderate to good yields by treating 1,1,3-triaryl-2-propyn-1-ols, prepared from diaryl ketones and lithium arylacetylides bearing trifluoromethyl group(s), with perchloric acid. The first absorption bands of a series of triarylmethane dye ethynylogues containing trifluoromethyl group(s) 11′ are observed around 700 nm. The photostability of the triarylmethane dyes is also examined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270914
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  • 83
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    Synthesis and Thermolysis of a Chiral, Non-Racemic Iminoaziridine11 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1699-1706 
    Details
    ISSN: 0009-2940
    Keywords: Aziridines, 2-imino-, chiral, non-racemic ; Imidoyl halides, 2-halo ; Imidates, 2-chloro ; 1,3,2-Thiazaphos-pholidines ; Amidines, 2-halo ; 1,3-Elimination, inversion of configuration in ; E/Z Diastereomerization ; [2 + 1] Cycloreversion, kinetics of thermal ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2-halo imidoyl chlorides 7 are obtained from the amide 5 and the 2-halo amides 6 by the action of phosphorus pentachloride and thionyl chloride, respectively. Non-racemic (S)-6a is converted into 7a which is racemic, however. The reaction of Lawesson's reagent with 6a furnishes the diaste-reomeric 1,3,2-thiazaphospholidine derivatives 15. Treatment of (S)-6a (98% ee) with methyl triflate affords 2-chloro imidate 8 (95% ee) which reacts with methanamine in the presence of methanammonium chloride to yield the 2-chloro amidine (S)-9a (90% ee). The 2-halo imidoyl halides 7a and b react with methanamine to produce the 2-halo amidines 9a and b.  -  Strong bases, e.g. potassium tert-butoxide or sodium hydride in the presence of catalytic amounts of tert-butyl alcohol, eliminate hydrogen chloride or bromide from the 2-halo amidines 9a and b and (S)-9ato yield mixtures of the 2-iminoaziridines (E)- and (Z)-4, and (E,R)- and (Z,R)-4 (83% ee), respectively. The 1,3-elimination of hydrogen bromide from 9b is diastereoselective at -30 to -40° [(E)-4:(Z)-4 = 〈10:〉90]. The diastereomers equilibrate at 36° with (kEZ + kZE) = (5.92 ± 0.08) . 10-5 s-1 (K = kEZ/kZE = 0.428 ± 0.013). - The thermolysis of (E)- and (Z)-4 in [D6]benzene solution yields the imine 16 and methyl isocyanide (17). The decomposition follows the first-order rate law. The following Arrhenius and Eyring parameters are calculated from five rate constants obtained in the temperature range of 70-110°: Ea = (115.2 ± 0.4) kJmol-1, IgA = (12.06 ± 0.28), δH
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270921
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  • 84
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    Oxidative Cyclisierung von Anilinopyrazolen zu Pyrazolo[1,5-a]benzimidazolenHerrn Professor Christoph Rüchardt zum 65. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1729-1733 
    Details
    ISSN: 0009-2940
    Keywords: Pyrazoles ; Aminyls, heterocyclic ; Pyrazolo[1,5-a]benzimidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free Radical Reactions of N-Heterocyclic Compounds, XIV[1]. - Oxidative Cyclization of Anilinopyrazoles to Pyrazolo[1,5-a]benzimidazolesHerrn Professor Christoph Rüchardt zum 65. Geburtstag gewidmet.Substituted Anilinopyrazoles 1 were oxidized by dibenzoyl peroxide or lead(IV) oxide. Different oxidation products were isolated depending on the substituents in the anilino group of anilinopyrazoles 1. Intermediate pyrazolyl radicals 5, which could be trapped by triphenylmethyl or phenoxyl radicals, undergo cyclization reaction with formation of pyrazolo[1,5-a]benzimidazoles 4. The structures of compounds 4 were proven by 1H- and 13C-NMR spectroscopy, 15N labeling and transformation of 4e to the betain 7e.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270924
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    Triphenanthro-anellierte [18]Annulene mit Alkoxy-Seitenketten  -  Eine neue Klasse discotischer Flüssigkristalle (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1735-1745 
    Details
    ISSN: 0009-2940
    Keywords: [18]Annulenes ; Liquid crystals, discotic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triphenanthro-Anellated [18]Annulenes with Alkoxy Side Chains - A Novel Class of Discotic Liquid CrystalsTwo different types 6 and 16 of [18]annulenes condensed with phenanthrene systems were prepared by cyclocondensation reactions (Schemes 2 and 3). The central 18-membered rings do not show a macrocyclic diamagnetic ring current. Conformational analyses and X-ray analyses in the solid state reveal non-planar structures in which aromatic “islands” are connected by (E)-configurated olefinic bridges. The introduction of long alkoxy side chains yields a new class of discotic liquid crystals; either ND or hexagonal columnar phases are generated, which were characterized by DSC, microscopy with polarized light, and small-angle scanning X-ray.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270925
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  • 86
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    LiClO4-induzierte Dreikomponenten-Aminoalkylierung von Aldehyden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1761-1764 
    Details
    ISSN: 0009-2940
    Keywords: Mannich reaction ; α-Aminoalkylation ; Ketene acetals, O-silylated ; Amino nitriles ; Diastereoselectivity ; Ik Addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: LiClO4 Induced One Pot Three-Component Aminoalkylation of AldehydesLiClO4-mediated one-pot reaction of isobutyraldehyde (1) or benzaldehyde (5) with (trimethylsilyl)dialkylamines 2 and C nucleophiles such as O-silylated ketene acetals 3, 6, allyl Grignard, lithium (trimethylsilyl)acetylide, triinethylsilyl cyanide, and diethylzinc afforded in high yields the corresponding aminoalkylation products 4 and 7-13. The lithium enolate of cyclohexanone adds in 5 M LiClO4 solution in an Ik manner to the corresponding mannich base (19, 20) with good yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270928
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    Synthesis of 9,10-Dihydro-9,10-propanoanthracene-12-ones from Anthracenes and Oxyallyl Cation Intermediates Generated by the the BSA [N,O-Bis(trimethylsilyl)acetamide] Method (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1755-1760 
    Details
    ISSN: 0009-2940
    Keywords: Anthracenes ; Oxyallyl cations ; Ketones, α,α'-oligobromo- ; Dibenzohomobarrelenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sonication of a zinc/copper couple, N,O-bis(trimethylsilyl)-acetamide (BSA) and α,α'-oligobromo ketones in benzene gives rise to oxyallyl intermediates which cycloadd to anthracene. Starting from 1,1,3,3-tetrabromoacetone (2a) and anthracene (1a), we obtained 11,11,13-tribrominated adduct 4 as the major product (42%). The expected 11,13-dibrominated adduct trans-3 was formed as a minor product (5%), but it became the main product when the known oxyallyl methodology was applied. Dibenzohomobarrelenes 9 and 17 were prepared by short routes.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270927
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  • 88
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    Das Thermogramm einer C6H6-Chemie im Temperaturbereich von 450 bis 730°C (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1747-1753 
    Details
    ISSN: 0009-2940
    Keywords: Isomerization, thermal ; Radicals ; D-Labeling ; 1,5-Hexadiyne ; Pentafulvene ; Rearrangement, homoallyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal Rearrangements, XXIII[1].  -  The Thermogram of a C6H6 Chemistry in the Temperature Range from 450 to 730°CThe thermal isomerization of 1,5-hexadiyne (1) and its [1,6-D2]-labeled derivative (1a) was studied in the temperature range 450-730°C and in the presence of different carrier gases (N2, H2, D2, N2/toluene). By detailed analysis (GC, GC MS, NMR) all volatile reaction products were identified and determined quantitatively by using hexafluorobenzene as an internal standard. The experimental data show clearly that the reaction products are formed by two different routes: (i) electrocyclization leading to dimethylene cyclobutene (3) at temperatures up to about 600°C and (ii) radical reaction leading to benzene (4) and pentafulvene (5) at temperatures above 550°C. Cyclopentadienylmethyl radicals are supposed to be the essential radical intermediates.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270926
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  • 89
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    1,3,5-Cyclohexatrien-1,4-diyl und 2,4-Cyclohexadien-1,4-diyl (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1765-1779 
    Details
    ISSN: 0009-2940
    Keywords: Diradicals ; NO and O2 trapping ; Heat of formation ; Energy well ; Rearrangments ; Bergman cyclisation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Energy Well of Diradicals, V[1].  -  1,3,5-Cyclohexatriene-1,4-diyl and 2,4-Cyclohexadiene-1,4-diylThe energy profile of the Bergman rearrangement of (Z)-3-hexene-1,5-diyne (4) has been established from the NO and oxygen dependance of the trapping rate of the intermediate diradical 1 which leads to a heat of formation for 1,4-didehy-drobenzene (1) of δHOf= 138.0 ± 1.0 kcal . morl-1. By the same technique the heat of formation of 1,2,4-cyclohexatriene (2), generated by thermolysis of (Z)-1,3-hexadien-5-yne (10), gives δHOf = 105.1 ± 1.0 kcal . mol-1 which indicates a high diradical character for 2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270929
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  • 90
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    Zur Reaktion von Bis(trimethylphosphan)titanocen mit Ketonen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1797-1798 
    Details
    ISSN: 0009-2940
    Keywords: Titanocenes ; Fulvenes ; Solvent effect ; Ketyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Bis(trimethylphosphane)titanocene with KetonesFulvenes are the products of the reaction of aliphatic and aromatic ketones with bis(trimethylphosphane)titanocene in nonpolar solvents, but no formation of pinacols is observed. The mechanism is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270931
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    Propargyl-Stabilisierungsenergie (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1781-1795 
    Details
    ISSN: 0009-2940
    Keywords: Resonance energy ; Stabilisation energy ; Propargyl resonance ; Force field calculation ; Intrinsic rotational barrier ; Single pulse shock tube ; Gasphase kinetics ; Heats of hydrogenation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propargyl Stabilisation EnergyFor the alkynyl-substituted olefines 1-14 activation parameters for the geometrical isomerisation have been determined in the gasphase by the single-pulse shoke-tube technique. By comparison of these barriers with the corresponding one of the isolated double bonds, each corrected by the steric energy contribution of the ground and transition state, a value of 7.8 ± 1.3 kcal · mol-1 for the propargyl stabilisation energy (PrSE) has been derived.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270930
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  • 92
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    Synthesis of Novel Heteroaromatic Polyfused as-Triazines by Ring Transformation[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1799-1802 
    Details
    ISSN: 0009-2940
    Keywords: as-Triazinium salt, fused ; Ring opening ; Ring transformation Heteroaromaticity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring transformation of the tricyclic furo-fused as-triazinium salt 1 in the presence of nucleophilic reagents (e.g. sodium hydrogensulfide, sodium salts of malonic ester, ethyl cyanoacetate, acetylacetone, dimedone, or malononitrile) leads to the two new heteroaromatic ring systems thieno[2,3-e]pyrido[1,2-b]-as-triazinium salt (5) and differently substituted cyclopenta[e]pyrido[1,2-b]-as-triazine compounds (8, 9, 10, 11, and 13).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270932
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    Wanzlick-Carbene in der [4 + 1]-Cycloaddition mit Bis(methylthio)- und Bis(trifluormethyl)-1,2,4,5-tetrazin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1803-1806 
    Details
    ISSN: 0009-2940
    Keywords: Singlet carbenes ; [4 + 1] Cycloadditions ; 1,2,4,5-Tetrazines ; SEAr reactions, intramolecular ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Wanzlick Carbenes in the [4 + 1] Cycloaddition Reaction with Bis(methylthio)- and Bis(trifluoromethyl)-1,2,4,5-tetrazineThe 3,6-disubstituted 1,2,4,5-tetrazines 3 and 4 have been submitted to a [4 + 1] cycloaddition reaction with the nucleophilic singlet carbenes (Wanzlick carbenes) 2a-d, which are generated from the precursors 1a-d. With 3 as diazadiene the expected spiro compounds 6a-d are formed. In contrast to this presumed two-step reaction sequence of 3, with the tetrazine 4 the cascade cycloaddition/cycloelimination is surprisingly followed by an intramolecular electrophilic aromatic substitution to yield the chiral tetracyclic compounds of type 8 with high diastereoselectivity. The crystal structure of 8d has been determined by X-ray diffraction methods.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270933
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A-105 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270936
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  • 95
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    Palladium-Catalyzed Coupling of Vinylferrocene with Aromatic Halides  -  A Highly Efficient Route to (Ferrocenylvinyl)arenes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1811-1813 
    Details
    ISSN: 0009-2940
    Keywords: Vinylferrocene ; Palladium-catalyzed couplin ; (Ferrocenylvinyl)arenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Ferrocenylvinyl)arenes 3, 5, and 7 are obtained from vinylferrocene (1) and substituted aromatic and heteroaromatic halides by palladium-catalyzed Heck-type reactions. Up to three ferrocene units are introduced in one step by the multi-fold reaction of 1,2-dibromo- (4) or 1,3,5-tribromobenzene (6) with 1. The first crystal structure of a bis(ferrocenylvinyl)benzene chromophore (5) is reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270935
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    Carbon-Carbon Bond Formation Promoted by “Bare” Lanthanide Cations: The Reactions of Ce+ and La+ with Propene in the Gas Phase (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1807-1810 
    Details
    ISSN: 0009-2940
    Keywords: Gas-phase organometallic chemistry ; Bond activation, C-H, C-C ; Coupling reactions, C-C ; Lanthanide cations ; Benzene complexes ; Butadiene complexes ; FT MS ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cationic butadiene and benzene complexes CeC4H6+ and CeC6H6+ are the main products in the reaction of thermalized Ce+ ions with propene in the gas phase, as shown by FT MS. Following the formation of the primary products, i.e. CeCH2+ and CeC3H4+, selective C-C coupling processes at the lanthanide cation occur as secondary reactions with high efficiency. Ligand-exchange reactions and comparative collision-induced dissociation experiments are applied to probe the structures of the final reaction products of this first example of Ce+ gas-phase chemistry. The reaction of Ce+ with cyclopropane yields a product distribution very similar to the propene reaction; however, it reacts significantly slower. Furthermore, La+ reacts in nearly the same manner with propene as Ce+ which indicates that the single f electron in the latter ion is chemically inert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270934
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271001
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  • 98
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    Chirale Tripod-Liganden: Ein neuer Syntheseweg zu chiralen, C1-symmetrischen Neopentyltris(phosphan)-Liganden H3CC[CH2P(Ra)2][CH2P(Rb)][CH2P(Rc)2] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1837-1842 
    Details
    ISSN: 0009-2940
    Keywords: Tripod ligand synthesis ; Oxetane cleavage ; Phosphane-Boranes ; Chiral neopentyl system ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral Tripod Ligands: A New Synthetic Route to Chiral C1-symmetrical Neopentyltris(phosphane) Ligands H3CC[CH2P(Ra)2][CH2P(Rb)2][CH2P(Rc)2]A novel synthesis of chiral tripod ligands H3CC[CH2P-(Ra)2][CH2P(Rb)2][CH2P(Rc)2] (6) containing three different donor groups at their neopentyl backbone is described. The key intermediates H3CC[CH2P(Ra)2][CH2P(Rb)2](CH2OH) (3) are easily obtained starting from pentaglycerine, H3CC-(CH2OH)3, via the oxetanes (2) following published procedures. The compounds 3, after protection of the phosphane functions by BH3 {formation of H3CC[CH2P(Ra)2BH3][CH2P(Rb)2BH3](CH20H) (4)} are transformed into the mesylates H3CC[CH2P(Ra)2BH3][CH2P-(RB)2BH3](CH20Ms) (5), which upon reaction with KP(Rc)2 and deprotection with morpholine gives fair yields of racemic 6. The synthetic route described is thus a valuable and efficient alternative to a recently published procedure, based on H3CC(CH2CI)(CH2Br)(CH20S02CF3) as the key intermediate. The compounds 2-6 are obtained in analytically pure form and are fully characterised by spectroscopic data.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271004
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  • 99
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    Ein- und zweikernige makrocyclische Übergangsmetallkomplexe mit Liganden vom Schiff-Basen-Typ: Synthesen, Strukturen, elektro- und magnetochemische Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1817-1826 
    Details
    ISSN: 0009-2940
    Keywords: Metal(II) complexes mono- and dinuclear ; Schiff bases, macrocyclic ; Redox properties ; Superexchange interactions of d9 systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes with Macrocyclic Ligands, III[1]. - Mono- and Dinuclear Macrocyclic Transition Metal Complexes of Ligands of Schiff Base Type: Syntheses, Structures, Electro- and Magnetochemical Properties.Four new mononuclear metal(II) complexes (4a-d) of a macrocyclic ligand derived from the Schiff base condensation of 2 equiv. of 1,2-phenylenediamine (3a) and 5-tert-butyl-2-hydroxy-1,3-benzenedicarbaldehyde (2) were synthesized and the cobalt complex 4b characterized by X-ray structure analysis. Reaction of 1,2-diamino-3,4,5,6-tetrafluorobenzene (3b) with the dicarbaldehyde 2 in the presence of Mn(ClO4)2 or Co(ClO4)2 leads to the novel metal-free macrocyce 6 (X-ray structure determination). The macrocycle 6 and Cu(ClO4)2 yield the new dinuclear copper complex 8, the structure of which was also determined by X-ray diffraction. The copper-(II) ions in 8 have a distorted square-pyramidal coordination by the four donor atoms of the macrocycle and an apical acetonitrile ligand. The Cu…Cu distance is 318.1 pm, and the two Cu(II) ions show only a small antiferromagnetic exchange interaction of J= -41 cm-1. Another new dinuclear Cu(II) complex (10) of a macrocyclic ligand derived from the Schiff base condensation of 2,2′-diaminooctafluorobiphenyl (9) and dicarbaldehyde 2 was synthesized and characterized by X-ray structure analysis, electrochemical investigations (DCV), and variable-temperature magnetic susceptibility measurements. One copper ion in complex 10 is five-coordinate (square-pyramidal), the other one six-coordinate (distorted octahedral). The Cu…Cu distance is 301.5 pm and the antiferromagnetic coupling J= -774 cm-1.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271002
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  • 100
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    Umlagerung und Abbau bicyclischer Amin - Tetraorganodiboroxane[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1843-1849 
    Details
    ISSN: 0009-2940
    Keywords: Amine-Diboroxanes, bicyclic ; 1,2-Deaminoboration, intramolecular ; Deoxyboration ; Allyl-aminoboranes, organosubstituted, rearrangement ; C-Borylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangement and Degradation of Bicyclic Amine-Tetraalkyldiboroxanes[1]The amine-tetraalkyldiboroxanes [1a: R1,4,7,7′ = Et; 1b: R1,4,7 = Et, R7′ = Ph; 1b′: R4,7,7′ = Et,R1 = Ph; 1c: R1,7,7′ = Et, R4 = Ph] react on heating by EtBO elimination and allylborane rearrangement to yield the allyl-aminoboranes Me2NB(Et)CH2C(R4)=C(R7,7′) [2a: R4,7,7′ = Et; 2b/2b′: R4 = Et, R7,7′ = Et, Ph; 2c: R4 = Ph, R7,7′ = Et]: On heating above 60°C the diastereomeric syn/anti-Id/1d′(Id: R1,7 = C8H14, R4,7′ = Et; 1d′: R1,7′ = C8H14, R4,7 = Et) give the unsaturated rac-amino-trialkyldiboroxane (rac-3) (X-ray structure analysis) by intramolecular 1,2-deaminoboration. rac-3 is characterized by reaction with (Et2BH)2 and (Et2BD)2 with formation of the 1,2,6-oxadiborinane 5 by evolution of H2 or HD respectively. The intramolecular CH-borylation of rac-3 is compared with those of the thujopsen hydrocarbons I-III.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271005
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