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  • 1985-1989  (2,455)
  • 1965-1969
  • 1920-1924
  • 1915-1919  (295)
  • 1890-1899  (293)
  • 1987  (2,455)
  • 1918  (295)
  • 1893  (293)
  • Life and Medical Sciences  (1,790)
  • Organic Chemistry  (1,126)
  • pharmacokinetics  (127)
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  • 1985-1989  (2,455)
  • 1965-1969
  • 1920-1924
  • 1915-1919  (295)
  • 1890-1899  (293)
Year
Keywords
  • 101
    Electronic Resource
    Electronic Resource
    Phase I clinical trial and pharmacokinetics of weekly ICRF-187 (NSC 169780) infusion in patients with solid tumors (1987)
    Springer
    Investigational new drugs 5 (1987), S. 187-198 
    Details
    ISSN: 1573-0646
    Keywords: ICRF-187 ; phase I ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract ICRF-187 was given to 62 evaluable patients with advanced solid tumors in a Phase I clinical trial. Weekly infusions were given in dosages ranging from 0,85 g/m2 to 7.42 g/m2 for a total of four weeks with a two week rest period between courses. Dose-limiting hematological toxicity was seen in heavily pretreated patients at a dose of 3.8 g/m2/week. All patients also developed reversible SGOT elevations. In patients with less prior therapy hematologic toxicity was not dose-limiting but hepatotoxicity, manifest by transient SGOT levels greater than 5 times baseline was seen at 7.42 g/m2/week even though only 3/6 patients could receive 4 consecutive weekly doses. At virtually all dose levels tested some patients developed anemia. Other toxicities, including alopecia, nausea, vomiting and reversible serum amylase elevations, were mild. Cumulative monthly doses achieved on this weekly schedule are significantly higher than a 48-hour infusion or daily times 3 or 5 schedule in adults and a daily times 3 schedule in children. Pharmacokinetic studies in eight patients indicate that the drug disappears from the plasma biphasically with a terminal t1/2 of 3.2 +0.9 hr. The total clearance was 288.7 + 85.0 ml/hr/kg and the volume of distribution (Vda) was 1.3 ± 0.4 1/kg. Pharmacokinetics were not dose-dependent from 3.8–7.4 g/m2 and no difference in pharmacokinetics was found in patients studied during the first and second treatments of a course. If Phase II trials of ICRF-187 are to be pursued on this schedule, appropriate doses would be 3.8 g/m2/week × 4 for heavily pretreated and 7.42 g/m2/week for “good risk” patients. Because of erratic hematologic toxicity in heavily pretreated patients, some might only tolerate three weekly doses. In good risk patients transaminitis was significant but reversible, thus, Phase II protocols should include dose escalation schemata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203545
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  • 102
    Electronic Resource
    Electronic Resource
    Phase I study and pharmacokinetics of caracemide (NSC-253272) administered as a short infusion (1987)
    Springer
    Investigational new drugs 5 (1987), S. 365-371 
    Details
    ISSN: 1573-0646
    Keywords: caracemide ; phase I ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A Phase I study of caracemide evaluating a short intravenous infusion repeated every 21 days is presented. Patients were entered at 85 mg/m2 with subsequent escalation levels of 170, 425, 595, and 795 mg/m2. Mild to moderate nausea and vomiting occurred at all dose levels. An apparent allergic reaction was observed at the 425 mg/m2 level. A “burning pain” originating in the mucosal areas of the head and neck, progressing to the chest and abdomen, was noted at the 425 mg/m2 level. Because of this observation, the infusion time was extended to 4 h. At the 795 mg/m2, this toxicity precluded completion of the 4 h infusion. Pharmacokinetic evaluation disclosed blood levels of 0.74–2.31 μg/ml at the 425 mg/m2 during the 0.5 h infusion. At the same dose for a 4 h infusion time, blood levels were 0.15–0.18 μg/ml. At 595 mg/m2 administered as a 4 h infusion, blood levels increased to 0.33 ± 0.14 μg/ml. The drug was cleared rapidly from the blood compartment with a half-life of 2.5 min and a total body clearance of 11.5 1/min/m2. No partial or complete response was observed. However, an advanced colon carcinoma patient experienced subjective pain relief with a decrease in carcinoembryonic antigen. The dose-limiting toxicity of caracemide using the 4 h infusion was an intolerable “burning pain” with a maximum tolerated dose of 795 mg/m2. Further characterization of this dose-limiting toxicity is required prior to further clinical evaluation of caracemide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169976
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  • 103
    Electronic Resource
    Electronic Resource
    Delayed elimination of a prazosin metabolite compared with kinetics of prazosin injected intravenously into rabbits (1987)
    Springer
    Bulletin of experimental biology and medicine 103 (1987), S. 85-87 
    Details
    ISSN: 1573-8221
    Keywords: prazosin ; prazosin metabolite ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00840147
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  • 104
    Electronic Resource
    Electronic Resource
    Correlation between the rate of ethanol elimination and psychophysiological differences in rats (1987)
    Springer
    Bulletin of experimental biology and medicine 103 (1987), S. 658-660 
    Details
    ISSN: 1573-8221
    Keywords: ethanol ; rats ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00841830
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  • 105
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of ethanol when injected intraperitoneally and intravenously into rats differing in initial alcohol motivation (1987)
    Springer
    Bulletin of experimental biology and medicine 104 (1987), S. 941-944 
    Details
    ISSN: 1573-8221
    Keywords: ethanol ; predisposition ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00841902
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  • 106
    Electronic Resource
    Electronic Resource
    Multicompartment models of cancer chemotherapy incorporating resistant cell populations (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 145-177 
    Details
    ISSN: 1573-8744
    Keywords: Chemotherapy ; mutation ; resistance ; compartmental analysis ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of antineoplastic drugs based on compartmental models are combined with deterministic exponential growth models of tumors containing drug-resistant and sensitive cells. Model predictions for single-drug therapy are compared with in vivodata obtained by other investigators for L1210 t-cell leukemia in mice treated with BCNU and AraC and for in vitrotreatment of L1210 with Ara-C. The model and data compare favorably in terms of rate of tumor growth and duration of drug action for both constant infusion and bolus delivery of the drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062341
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  • 107
    Electronic Resource
    Electronic Resource
    Protein binding of glycopeptide antibiotics with diverse physical-chemical properties in mouse, rat, and human serum (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 5-13 
    Details
    ISSN: 1573-8744
    Keywords: Structure-activity relationships ; pharmacokinetics ; protein binding ; glycopeptide antibiotics ; charge ; lipophilicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In previous studies of the pharmacokinetics and urinary excretion of nine glycopeptides with diverse isoelectric points (pI),as pIdecreases, the total systemic and renal clearance, urinary recovery, and volume of distribution decrease, whereas the half-life increases. With glycopeptides of similar pI,clearance decreases and half-life increases with increasing lipophilicity. The present study examines the serum protein binding of these glycopeptide antibiotics in mouse, rat, and human serum and calculates the previously reported pharmacokinetic parameters for these drugs based on unbound concentration. Increased negative charge and lipophilicity increase serum protein binding (90-fold, fu 83% to 0.96%), which decreases the renal clearance and total systemic clearance (90-fold, 16.4 to 0.18 ml/min/kg) of these drugs. Increased serum protein binding also decreases the volume of distribution of these compounds, but this change is relatively small (sixfold, 755 to 131 ml/kg) compared with the change in total systemic clearance causing an increase in elimination half-life (25-fold, 20 to 492 min). The results demonstrate that the large differences in the total systemic clearance and half-life of these glycopeptide antibiotics are primarily due to dramatic differences in serum protein binding and notto differences in the intrinsic elimination processes (enzymes or transport proteins). It appears that the same physical-chemical properties that govern the protein binding and pharmacokinetics of small organic molecules govern the disposition of these high-molecular weight glycopeptide antibiotics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062935
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  • 108
    Electronic Resource
    Electronic Resource
    A minimax approach to the single-point method of drug dosing (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 255-269 
    Details
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; singie-point dose prediction ; dosage ; minimax estimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The single-point dose prediction method is based on the observation that for drugs obeying single compartment elimination kinetics there is a nearly constant reciprocal relation between the plasma level at a fixed time following a single loading dose and the dose that is required to maintain the desired steady state plasma level of the drug. This paper describes an improved method for choosing a plasma sampling time and a proportionality constant. It applies to either drugs administered intravenously or to drugs whose rates of absorption from the site of administration are very rapid compared to their rates of elimination from the body. The sampling time and proportionality constant chosen are those that minimize the maximum relative deviation of the maintenance dose estimated by the single-point method from the dose that would be estimated if the individual's true elimination rate constant were known. The paper also supplies a method to determine the maximum error that may be introduced into the estimation of the maintenance dose by using the single-point method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066321
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  • 109
    Electronic Resource
    Electronic Resource
    Constant-rate infusion of nicotine and cotinine. I. A physiological pharmacokinetic analysis of the cotinine disposition, and effects on clearance and distribution in the rat (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 583-599 
    Details
    ISSN: 1573-8744
    Keywords: cotinine ; nicotine ; rat ; tissue distribution ; pharmacokinetics ; constant-rate infusion ; physiological model ; iv bolus ; osmotic minipump
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The tissue partition of cotinine was measured by a GC-MS method following a 6-day constant-rate input of nicotine and cotinine to male rats by means of an osmotic minipump. The tissue-to-blood partition coefficients of cotinine were calculated for adipose (0.08), brain (0.48), heart muscle (0.55), intestinal (0.53), hepatic (0.64), pulmonary (0.50), renal (0.99), and skeletal muscle tissue (0.51), following the cotinine infusion. When nicotine was infused the tissue partitioning of cotinine increased by a factor of 2.3–4.9, depending on the tissue sampled. Another group of animals were killed at timed intervals from 10 min to 30 hr, after having received a single intravenous bolus dose of 0.5 mg cotinine, and the washout of cotinine was traced in blood and tissues. A physiological model was used to simulate the disposition of cotinine. Generally, the model-predicted concentrations were consistent with those found experimentally. The fractional uptake of cotinine into various tissues was simulated. Blood, intestinal, and skeletal muscle tissues embodied more than 70% of the total body load of the drug. Clearance (Cl),volume of distribution (Vd),and the biological half-life (t1/2)were calculated both from the infusion study and by fitting a monoexponential model to the iv blood data of the rat. Significant differences were found in the apparent clearance calculated from the single iv bolus dose compared to the constant rate infusion. The volume of distribution was, however, consistent from both studies. The impact of a change in clearance was also simulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01068414
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  • 110
    Electronic Resource
    Electronic Resource
    A double-peak phenomenon in the pharmacokinetics of veralipride after oral administration: A double-site model for drug absorption (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 225-239 
    Details
    ISSN: 1573-8744
    Keywords: veralipride ; pharmacokinetics ; enterohepatic recycling ; double site of drug absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Equal doses of veralipride have been given to 12 healthy volunteers by three different administrations-intravenous infusion, oral solution, and oral capsule-in a randomized cross-over design. After the intake of the solution, but not after infusion or capsules, two maximum plasma concentrations have been observed and interpreted, according to a double-site model for drug absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066319
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  • 111
    Electronic Resource
    Electronic Resource
    Kinetics of ajmaline disposition and pharrnacologic response in beagle dogs (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 39-55 
    Details
    ISSN: 1573-8744
    Keywords: Ajmaline ; antiarrhythmic drug ; pharmacokinetics ; pharmacodynamics ; plasma protein binding ; combined pharmacokinetic-pharmacodynamic model ; ECG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pharmacokinetics and pharmacodynamics of ajmaline were studied in four healthy dogs after intravenous administration of the drug at the infusion rate of 1.0 mg/min for 45 min. Ajmaline exhibited a saturable binding to plasma protein. One kind of binding site was found in the range of observed drug concentrations and its binding capacity showed nearly threefold interindividual difference. The time course of ajmaline concentration in whole blood Cbcould be described by the two-compartment open model and the unbound concentration of ajmaline in plasma Pf wasestimated from Cbby using the hematocrit value and the parameters of plasma protein binding and erythrocyte partitioning. The pharmacologic responses to ajmaline were assessed by recording ECG, and the changes in PQ and QRS interval were studied in relation to ajmaline disposition. When ECG changes were related to the ajmaline concentration, a significant degree of hysteresis was observed. The relationship between the unbound drug concentration and the pharmacologic effect was analyzed by a combined pharmacokinetic-pharmacodynamic model, where the hypothetical effect compartment is connected to the Pfin the central compartment by a first-order process. This model allows estimation of the changes in PQ and QRS intervals after intravenous administration of ajmaline. By comparing the drug effect on PQ and QRS intervals, it was suggested that ajmaline distributes to the atrial and the ventricular tissue in a similar degree and causes a reduction in the conduction rate in both sites with similar activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062938
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  • 112
    Electronic Resource
    Electronic Resource
    The pharmacokinetics and pharmacodynamics of lignocaine and MEGX in healthy subjects (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 101-115 
    Details
    ISSN: 1573-8744
    Keywords: Lignocaine ; MEGX ; pharmacokinetics ; pharmacodynamics ; active metabolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Lignocaine clearance declines during continuous intravenous infustion in man and in vitrostudies suggest that this may partly be due to inhibition by MEGX, a metabolite of lignocaine, MEGX is pharmacologically active in animals, but this is not yet proven in man. This study examined the pharmacokinetics and pharmacodynamics of lignocaine and MEGX in eight healthy male volunteers given lignocaine HCl 120mg, MEGX HCl 120 mg, lignocaine HCl 120 mg+MEGX HCl 120 mg, and placebo, administered according to a randomized double-blind protocol. One-, two-, or three-compartment models were fitted to drug and metabolite blood concentration-time profiles and clearance, volume (V ss ), andhalf-life values were calculated and compared by paired t-test. Systolic time intervals and QTinterval were recorded and compared by repeated measures ANOVA. When administered in combination with MEGX, lignocaine clearance was significantly reduced from 58±18 to 48±13 L hr(su−1) (p 〈0.02). The V(inss) was unchanged and there was a trend toward an increase in terminal half-life. Lignocaine, MEGX, and the combination significantly reduced QTinterval up to 30 min after injection and this was maintained to 2 hr with the lignocaine and the combination. Transient side effects were experienced with all active treatments, but were most pronounced with the combination. Thus, lignocaine clearance was inhibited by MEGX, which was pharmacologically active in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062338
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  • 113
    Electronic Resource
    Electronic Resource
    Etintidine-propranolol interaction study in humans (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 557-568 
    Details
    ISSN: 1573-8744
    Keywords: etintidine ; propranolol ; 4-hydroxypropranolol ; interaction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Etintidine HCl is a potent H2 -blocker. The effect of clinical doses of etintidine on the disposition of a single oral dose of propranolol was investigated in 12 normal subjects. This was a double-blind, two-way crossover study. Each subject received etintidine (400 mg) or placebo twice a day with meals for 4 days on two occasions (separated by 4 days). On each occasion, the subjects were fasted overnight on Day 3 and were given an oral dose of Inderal® (40 mg propranolol hydrochloride) 30 min following the administration of the morning dose of etintidine or placebo on Day 4. Blood samples were collected prior to and up to 24 hr following the administration of propranolol. The plasma samples were analyzed for propranolol and 4-hydroxypropranolol by HPLC. Comparison of the pharmacokinetic parameters of propranolol between etintidine and the placebo groups indicates that etintidine significantly increased the AUC0−∞,values (573.5 vs. 146.4 ng·hr/ml, p=0.0001)and prolonged the elimination half-life (4.61 vs. 2.33 hr) of propranolol. Statistical evaluation of the pharmacokinetic parameters of 4-hydroxypropanolol indicates that etintidine also increased the AUC0−24 values (43.8 vs. 16.4 ng·hr/ml, p=0.0028) and prolonged the elimination half-life (4.87 vs. 1.97 hr) of 4-hydroxypropranolol. The data suggest that etintidine, like cimetidine, impaired the elimination of propranolol. Etintidine also protracted the elimination of 4-hydroxypropranolol, an active metabolite of propranolol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01068412
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  • 114
    Electronic Resource
    Electronic Resource
    Dose-Proportional Absorption of Etretinate After Doses of 25, 50, 75, and 100 mg (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 420-424 
    Details
    ISSN: 1573-904X
    Keywords: etretinate ; pharmacokinetics ; dose proportionality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Twelve healthy male subjects received single oral doses of etretinate, ranging from 25 to 100 mg (1 to 4 × 25-mg capsules) in an open-label, four-way randomized crossover design. Plasma concentrations of etretinate and two active metabolites were determined by a specific high-performance liquid chromatographic (HPLC) method. Analysis of variance and orthogonal contrasts were used to assess dose proportionality. Mean (± %CV) maximum concentrations after 25- to 100-mg doses were 133 (50), 195 (33), 261 (53), and 446 (65) ng/ml, whereas AUC0−12 values were 581 (46), 1090 (39), 1500 (52), and 2440 (63) ng · hr/ml, respectively. The test for proportionality indicated that C max and AUC0−12 increased proportionally with an increase in dose (P 〉 0.05).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016494531044
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  • 115
    Electronic Resource
    Electronic Resource
    Dose-Dependent Pharmacokinetics of a New Oral Cephalosporin, Cefixime, in the Dog (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 33-37 
    Details
    ISSN: 1573-904X
    Keywords: oral cephalosporin ; cefixime ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cefixime (CL 284,635; FK 027) is a new third-generation oral cephalosporin. To study dose-dependent pharmacokinetics of cefixime in dogs, two balanced four-way crossover studies were conducted. In the first study, oral doses of 50, 100, and 200 mg/kg and an intravenous dose of 50 mg/kg cefixime were administered. In the second study, oral doses of 6.25, 12.5, and 25 mg/kg and an intravenous dose of 12.5 mg/kg cefixime were administered to the same dogs. A period of 1 month separated the two studies. When the two intravenous doses were compared (i.e., 12.5 and 50 mg/kg), a twofold increase in clearance and volume of distribution was observed after the higher dose. The oral systemic bioavailability in the dose range 6.25–50 mg/kg was 55%. It decreased to 44% at 100 mg/kg and 27% at 200 mg/kg. The average peak serum concentrations ranged from 15.8 µg/ml at 6.25 mg/kg to 119 µg/ml at 200 mg/kg. Within this concentration range, the fraction of free drug in serum (unbound to proteins) increased from 7 to 25%. This concentration-dependent protein binding was primarily responsible for changes in total clearance, volume of distribution, and bioavailability of the drug in dogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016473709720
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  • 116
    Electronic Resource
    Electronic Resource
    An Equation for the Systemic Availability of Drugs Undergoing Simultaneous Enterohepatic Cycling, First-Pass Metabolism, and Intestinal Elimination (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 195-199 
    Details
    ISSN: 1573-904X
    Keywords: enterohepatic recirculation ; pharmacokinetics ; bioavailability ; area under the curve ; bile ; hepatic extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A relationship between systemic availability and its determinants has been derived for a physiologically realistic model of drug disposition that includes enterohepatic cycling (EHC), gallbladder emptying (with an arbitrary time course), first-pass metabolism to noncycling metabolites, and fecal excretion. Systemic availability (F) has been shown to be determined by the fraction of the dose initially absorbed (f a*), the fraction of the drug excreted into the GI tract that is reabsorbed with each cycle (f a), the hepatic extraction ratio (E), and the fraction of extracted drug that is transported to the gallbladder for EHC (f g) according to the relationship F = f a*(1 −E/(1 − f a f g E) The implications of the above relationship are that (1) systemic availability is dependent on EHC, (2) values of F calculated to be greater than unity cannot be explained simply by the presence of EHC, (3) calculations of E based on the usual expression F = f a* (1 − E) are erroneous for drugs subject to EHC, and (4) a compound that has a high systemic availability and is subject to EHC is not necessarily inefficiently metabolized. The quantitative interrelationship of systemic availability and its determinants is illustrated using a contour plot. Slices through the surface are used to demonstrate that the presence of EHC changes the sensitivity of F to changes in E.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016447826075
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  • 117
    Electronic Resource
    Electronic Resource
    Application of Moment Analysis to Nonlinear Drug Disposition Described by the Michaelis–Menten Equation (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 59-61 
    Details
    ISSN: 1573-904X
    Keywords: mean residence time ; pharmacokinetics ; Michaelis–Menten elimination ; one-compartment model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An equation for the mean residence time (MRT) of drug in the body is derived for the system where drug is injected intravenously into a one-compartment model and eliminated by a single, capacity-limited process. This MRT is a complex function of dose, volume, V m, and K m but degenerates into the classical volume/clearance expression under limiting low-dose conditions (K m ≫ C 0). The equation was validated by comparison of the MRT obtained by direct calculation versus numerical area estimation for simulated data. The equation may be useful analytically in the estimation of the fundamental Michaelis–Menten parameters, V m and K m, from experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016486012446
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  • 118
    Electronic Resource
    Electronic Resource
    Effect of Amiodarone and Desethylamiodarone on the Pharmacokinetics of Antipyrine in the Rat (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 251-254 
    Details
    ISSN: 1573-904X
    Keywords: amiodarone ; antipyrine ; desethylamiodarone ; drug metabolism ; drug interactions ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of amiodarone on hepatic drug metabolism in vivo was examined in the rat using antipyrine as a model substrate. Pretreatment with oral amiodarone hydrochloride, 100 mg/kg/day, for 5 days resulted in a 19% reduction in antipyrine clearance and a 22% increase in half-life. The administration of single oral doses of amiodarone hydrochloride, 100 mg/kg, 1 or 5 hr prior to antipyrine administration had no significant effect on antipyrine pharmacokinetics. The administration of a single intravenous dose of amiodarone hydrochloride, 50 mg/kg, reduced antipyrine clearance by 32% and increased the half-life by 46%. The desethyl metabolite of amiodarone was also found to reduce antipyrine clearance (21%) after a single oral dose of 100 mg/kg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016468430618
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  • 119
    Electronic Resource
    Electronic Resource
    Computer-Aided Dosage Form Design. I. Methods for Defining a Long-Acting First-Order Delivery System of Maximum Formulating Flexibility (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 311-316 
    Details
    ISSN: 1573-904X
    Keywords: computer-designed formulation ; prolonged-action dosage forms ; drug delivery systems ; long-acting formulations ; theophylline delivery systems ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The method provides an a priori assessment of the maximum allowable flexibility in the rate of release from a prolonged-release formulation. The clinical pharmacokinetic parameters describing the drug candidate are employed to calculate the ranges of rate constants and doses required for the formulation to provide a selected therapeutic duration. For a given patient, there may be an infinite number of combinations of release rate constants and dose sizes which will maintain steady-state plasma drug concentrations within a desired range when the formulation is administered at the selected dosing interval. Computer simulations of steady-state plasma concentrations are employed to establish the ranges for all of the acceptable rate constants and doses for each member of a group. The entire group is then examined to define the range of release rate constants and doses which would provide a useful formulation for every member in the group. Literature values for theophylline clinical pharmacokinetics in children and adults have been employed to illustrate the application of this method. The method is unique in that it provides an entire range of release rates on which to gauge the feasibility for success.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016445220140
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    Pharmacokinetics of Gold Sodium Thiomalate in Rabbits (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 332-336 
    Details
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; gold ; rabbits ; intramuscular ; intravenous ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Male, New Zealand white rabbits (3.5–4.3 kg) received a single 2-mg/kg dose of gold sodium thiomalate (Myochrysine) via intramuscular (N = 4) and intravenous (N = 3) routes. Blood samples were drawn from the marginal ear vein for a period of 5–10 days. The concentration of gold in whole blood was determined using graphite furnace atomic absorption spectrophotometry. The blood concentration–time profiles obtained following both routes of administration were best described by a two-compartment open model with first-order absorption for the intramuscular route. Gold was absorbed rapidly with a mean (harmonic) absorption half-life of 9.0 min, with a peak concentration of 6.0 ± 1.0 µg/ml (N = 4). Blood concentrations declined in a biphasic manner; the mean α half-lives were 0.738 and 1.78 hr for the iv and im routes, respectively. The corresponding terminal (β) half-lives were 54.1 and 63.0 hr. The estimated volume of the central compartment (70 to 93 ml/kg) agreed closely with the rabbit blood volume. The mean ( ±SD) extent of the dose absorbed following intramuscular injection was 68.9 ± 12.4%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016453421958
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    Computer-Aided Dosage Form Design. II. Methods for Defining a Zero-Order Sustained-Release Delivery System of Maximum Formulating Flexibility (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 385-391 
    Details
    ISSN: 1573-904X
    Keywords: zero-order delivery ; drug delivery system ; sustained release ; computer simulation ; dosage form design ; theophylline ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Classical methods employing pharmacokinetic data to calculate zero-order release rates for sustained release products require that a constant-rate drug delivery system must have a duration which is exactly equal to the desired dosage interval. This traditional approach fails to establish the minimum acceptable duration and also fails to provide any flexibility in the formulation goal. While it does calculate one pair of duration and dose values, there are infinite pairs of values capable of maintaining the desired plasma concentrations using the selected dosing interval. In the current method, computer simulations are used to establish the boundary conditions within which any pair of duration and dose values will maintain the desired levels when administered on the chosen dosing interval. By comparing the boundary conditions for every subject in a group, a single set of conditions which would work for the entire group can be selected. These final limits represent the broadest specifications for zero-order drug delivery system design for that particular drug combined with the plasma concentration goals and the desired dosing interval. The method is illustrated using theophylline pharmacokinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016478127409
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  • 122
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    Pharmacokinetic drug interactions between digoxin and antiarrhythmic agents and calcium channel blocking agents: An appraisal of study methodology (1987)
    Springer
    Cardiovascular drugs and therapy 1 (1987), S. 183-189 
    Details
    ISSN: 1573-7241
    Keywords: drug interactions ; digoxin ; pharmacokinetics ; antiarrhythmic drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary While preliminary screening for interactions between new cardiovascular pharmacotherapeutic agents and digoxin can be efficiently and safely conducted in normal healthy volunteers, it is particularly important to detect and quantify drug interactions in patients with varying degrees of cardiac, hepatic and/or renal dysfunction. Much of the previously published literature provides only minimal data to guide clinical practice because of limitations of study design including sample size and measurement techniques. Important factors that determine the ability of a particular study design to detect a drug interaction with digoxin include the accuracy and precision of the assay method for serum digoxin concentrations, intrasubject and intersubject variability in serum digoxin concentration, and sample size. The format of the trial (chronic versus single digoxin dosing in cardiac patients; chronic verus single digoxin dosing in normal subjects) and the method of assessment of alterations in digoxin handling (formal determination of digoxin clearance, comparison of multiple or single digoxin measurements during various phases of trial) also impact greatly on the clinical relevance of such investigations. Guidelines for future studies of drug interactions with digoxin in cardiac patients are proposed with particular emphasis on laboratory methods; measurement techniques during baseline, placebo, and active drug phases; calculation of the statistical power of the study; time course of the trial; and assessment of the clinical significance of the findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02125472
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  • 123
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    Complexes of 2,2′,2″-Nitrilotriphenol. Part 1. A Study of Bimolecular Nucleophilic Substitution at the Boron Atom (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 499-510 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetradentate ligand 2,2′,2″-nitrilotriphenol forms a boron complex III with an intramolecular, transannular N→B dative bond of 1.68 Å in a strained tricyclo[3.3.3.0]undecane chelating system. The complex reacts with nitrogen bases L, such as pyridine, quinuclidine and others, to form complexes III-L, in which the intramolecular B-N bond is replaced by one between B and the external nucleophile. In solution, this displacement reaction is reversible. It was studied by temperature-dependent NMR spectroscopy. The resulting reaction and activation parameters suggest that the reaction is a bimolecular nucleophilic substitution (SN2).
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700303
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  • 124
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    Complexes of 2,2′,2″-Nitrilotriphenol. Part 3. Crystal and Molecular Structures of Three Aluminium Complexes (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 520-533 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal and molecular structures of three Al(III) complexes of the tripod ligand 2,2′,2″-nitrilotriphenolate (I) are presented. They all show 5-coordinate Al in approximately trigonal bipyramidal geometry, with an external nucleophile X occupying the second axial position. X is OH- in[Al(I)(OH)]-[Hquin]+ (quin = quinuclidine), N in [Al(I)(py)] (py = pyridine), and one of the O-atoms of a second molecule in the dimeric [(Al(I))2]. Correlated variations in the axial bond lengths of the trigonal bipyramid are observed: [(Al(I))2]: Al-Nint. = 2.094 Å, Al-Oext. = 1.850 Å; [Al(I)(py)]: Al-Nint. = 2.153 Å, Al-Next., = 1.992 Å; [Al(I)(OH)]-: Al-Nint. = 2.278 Å, Al-Oext. = 1.765 Å. They are interpreted in terms of a dissociative reaction path at the Al(III) centre.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700305
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  • 125
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    Molluscicidal Saponins from Swartzia madagascariensis DESVAUX (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 570-576 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phytochemical investigation of the dried fruits of Swartzia madagascariensis (Leguminosae) afforded the five triterpenoid saponins 1-5. They were shown to be glucuronides of oleanolic acid and of gypsogenin by chemical and spectral means (FAB-MS, 13C-NMR, GC/MS). One of the isolated compounds, identified as 3-O-[O-α-L-rhamnopyranosyl-(1→3)-(β-D-glucopyranosyluronic acid)]oleanolic acid, was responsible for the high molluscicidal activity of Swartzia madagascariensis fruits against the schistosomiasis-transmitting snails Biomphalaria glabrata and Bulinus globosus.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700309
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  • 126
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    The Hydrolysis of Ethyl 1-Methyl-2,4-cyclopentadiene-1-carboxylate by Nonenzymatic and Enzymatic Methods. Carbon-Carbon vs. Carbon-Oxygen Bond Cleavage (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 587-592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title ester 5 is shown to undergo C-C bond cleavage under the conditions of basic ester hydrolysis (KOH/EtOH) with formation of potassium ethyl carbonate (6) and the tautomeric methylcyclopentadienes 7 and 8. In contrast, porcine liver esterase (PLE, EC 3.1.1.1) cleanly hydrolyses 5 to give the isolable 1-methyl-2,4-cyclopentadiene-1-carboxylic acid (13). The latter undergoes thermal dimerization with conservation of the geminal-substitution pattern. The configuration of the Diels-Alder adduct 17 is ascertained by it photochemical transformation into bishomocubane dicarboxylic acid 12, easily distinguished by its C2 symmetry. Under the conditions of acid-catalyzed hydrolysis, dimerization of ester 5 and polymerization prevail, unless low acid concentration is used. The dimer 9 of 5 has one ester function that is reluctant to undergo basic hydrolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700311
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  • 127
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    Potassium Carboxylates by Direct Carbonylation of Potassium Alkoxides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 593-599 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the K+ alkoxide of linalool (1) in benzene with CO at 425-440 bar and 120-130° for 12-30 h gave the K+ salt of 2,6-dimethyl-2-vinyl-5-heptenoic acid (4a) in a ca. 25% yield based on ca. 65% converted alkoxide. Reaction of the [K+ ⊂ 18-crown-6] alkoxide of 1 with CO at 50-55 bar and 40° for 90-140 h gave a mixture containing mainly the [K+ ⊂ 18-c-6] salts of 4a (ca. 62%) and of the homogeranic acids 3a and 6a (together ca. 27% of the mixture) in a ca. 35% combined yield based on 50-60% converted alkoxide. The uncomplexed or complexed K+ alkoxide of (S)-1 gave, with ca. 85% net retention, the K+ salt of (S)-4a. Reaction of the [K+ ⊂ 18-c-6] alkoxide of geraniol (2) with CO at 50 bar and 40° for 65-70 h gave myrcene (10) and geranyl formate (11) in a ca. 40-50% yield each based on ca. 85% converted alkoxide. Reaction of the [K+ ⊂ 18-c-6] alkoxide of 3-pentyl-1,4-pentadien-3-ol (14) at 50 bar and r.t. for 70 h gave a mixture of the [K+ ⊂ 18-c-6] salts of 2-pentyl-2-vinyl-3-butenoic acid (15a) (67%) and the 4-pentyl-2,4-hexadienoic acids 18a and 19a (together 23% of the mixture) in a ca. 90% combined yield based on ca. 65% converted alkoxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700312
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    Synthesis and Copper(I) Complexes of a Series of 9- to 13-Membered N3 Macrocycles (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 680-689 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight cyclic triamines with ring sizes between 9 and 13 were synthesized by the p-toluenesulfonate method. The open-chain triamines bis(2-aminoethyl)amine (dien) and bis(3-aminopropyl)amine (diprop) were used as starting materials. In some cases, the corresponding dimeric cyclic hexaamines have been isolated and characterized as major by-products. The complexation of Cu(I) by the triamines has been studied potentiometrically in CH3CN/H2O. All ligands L form ternary complexes [Cu(CH3CN)L]+. The corresponding association constants vary between 1011 and 107, decreasing with increasing ring size. In addition, complexes [Cu(CH3CN)yLH]2+, y = 1 or 2, are found as less important species with maximum concentrations of 7 to 50%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700318
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    The Microstructure of Selective Palladium Hydrogenation Catalysts Supported on Calcium Carbonate and Modified by Lead (Lindlar Catalysts), Studied by Photoelectron Spectroscopy, Thermogravimetry, X-Ray Diffraction, and Electron MicroscopyThe following abbreviations and acronyms are used in the text: B. e. : Binding energy [eV], BET: Brunauer-Emmett-Teller (method of surface-area determination by physisorption of N2), AES: Auger electron spectroscopy, XPES: X-ray photoelectron spectroscopy, UPES: Ultraviolet photoelectron spectroscopy, ISS: Ionscattering spectroscopy, UHV: Ultrahigh vacuum (10-5 Pa), FTIR: Fourier-transform IR spectroscopy, TGA: Thermal gravimetric analysis, XRD: X-ray diffraction, XDA: Energy dispersive microanalysis, SEM: Scanning electron microscopy, TEM: Transmission electron microscopy, FWHM: Full width at half maximum. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 627-679 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed analysis of the system Pd + Pb on CaCO3 is presented. This system known as Lindlar catalyst is used for selective hydrogenations of C≡C bonds to C=C bonds. It was found to consist of seven distinct chemical phases. Essential ingredients are solid solutions of hydrogen and oxygen in Pd. The latter phase enables the metal particles to be attached to the support via an orientational relationship calcite (113)∥Pd + O (111). The addition of Pb neither changes the micromorphology of the disk-shaped Pd particles nor does it modify the electronic structure of Pd as studied by chemisorption experiments. The addition of Pb seems to block certain active sites and, thus, to enhance the selectivity. The support was found to be a multi-domain mixture of calcite and aragonite with domain sites of several hundred Å. The free surface of the pore-free solid is covered by a calcium-hydroxide carbonate. This phase as well as several other Pb phases seem to represent only spectator materials. Verification of this as well as finding the correlation between structure and function of the various components requires a kinetic analysis which is outside the scope of this paper. It is demonstrated that a variety of analytical techniques is required to unravel the complex nature of such a ‘simple' catalyst’ as it is Pd on CaCO3.
    Additional Material: 36 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700317
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    Verapliquinones: Novel Diprenylquinones from an Aplidium sp. (Ascidiacea) of Ile-Verte Waters, Brittany (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 621-626 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Aplidium sp. (Ascidiacea), collected in French Atlantic waters near the Ile Verte, is shown to contain verapliquinone B (2) and verapliquinone D (6) as the first examples of linear diprenylquinones of the neryl type, besides their respective isomers 1 and 5 of the geranyl type.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700316
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  • 131
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    Fe(II)-Induced Fragmentation Reaction of γ-Hydroperoxy-α,β-enones. Part 1. Synthesis of 13(14→8)-abeo-Steroids (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 701-716 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some steroidal analogues embodying the hitherto unknown 13(14→8)-abeo skeleton have been synthesized by Fe(II)-induced rearrangement (tandem β-fission/reductive alkylation) of 14α-hydroperoxy-7-en-6-ones. The configurational assignment was made by thorough analysis of NMR spectra; the structure of one of the products was unambiguously assessed by X-ray single-crystal analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700320
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    Light-Induced, Thermal, and Acid-Catalyzed π-Skeletal Rearrangements of Five-Ring-Annelated HeptalenesPresented in part by H.-J.H. in a lecture at the ETH in Zürich, 1985. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 742-759 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that, upon irradiation in CDCl3 solution, 5,6,8,10-tetramethylheptalene-1,2-dicarboxylic anhydride (6) rearranges to its double-bond-shift (DBS) isomer 7 in an equilibrium reaction (Scheme 2). The isomer 7 is DBS stable at -50°. At ca. 30°, a thermal equilibrium with 97.8% of 6 and 2.2% of 7 is rapidly established. Similarly, the ‘ortho’-anhydrides 9 and 11 (Schemes 4 and 5) can be rearranged to their corresponding DBS isomers 12 and 13, respectively. Whereas 12 is DBS stable at 30° (at 100° in tetralin, 94.0% of 9 are in equilibrium with 6.0% of 12), the i-Pr-substituted isomer 13 is already at 30° in thermal equilibrium with 11 leading to 98.7% of 11 and 1.3% of 13. It is shown by rearrangement of diasteroisomeric ‘ortho’-anhydrides of known relative and absolute configuration (Scheme 6) that the DBS in such five-ring-annelated heptalenes occurs with retention of the configuration of the heptalene skeleton as already established for other heptalene compounds. It is found that the DBS process may also take place under acid catalysis (e.g. HCl/CH3OH), thus yielding 9 from 12 (Scheme 9). The ‘ortho’-anhydrides 21 and 23 (Scheme 10) which are isomeric with 9 and 11 (Scheme 3) undergo rapid DBS' already at room temperature. The thermal equilibrium 21⇄22 consists of 18% of 21 and 82% of 22 at 30° and that of 23⇄24 of 17% of 23 and 83% of 24 at -30°. From these equilibrium mixtures, the pure DBS isomer 22 can be obtained by crystallization. Again, these rapid DBS' occur with retention of configuration of the heptalene skeleton (Fig. 4).
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700323
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    Synthese und NMR-Spektren von Nonafulven sowie Vergleich mit 10-PhenylnonafulvenHerrn Prof. Dr. Hans Nitschmann zum 80. Geburtstag gewidmet52. Mitt. über Fulvene, Fulvalene; 51. Mitt. [1]; Kurzmitt. [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 862-880 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-PhenylnonafulveneExperimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT-; see 4) with bromomethyl acetate (1a, R = H, X = Br) to give (cyclononatetraenyl)methyl acetate (5a; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A⇄6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of 5b) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700327
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    Field-Desorption Mass Spectra of Fern Phloroglucinols Containing Three to Six Ring ConstituentsDedicated to the late Prof. Peter Brown (12.IX.1938-15.III.1981), Dept. of Chemistry, Arizona State University, Tempe, Arizona 08521, U.S.A., Whose premature death was a great loss to his friends and collegues. The last letter which we received from him (November 15, 1980) contained the first FD mass spectra of five relatively large fern phloroglucinols which he had successfully analyzed. Two of these spectra, in which no thermal rearrangement and /or fragmentation was observed, are reproduced in this article (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 881-893 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been previously shown that the structural analysis of the title compounds by electron-impact ionization (EI)mass spectrometry is complicated by extensive, if not complete, thermal rottlerone-type rearrangement and/or fragmentation reactions. The use of a ‘softer’ ionization technique such as field desorption (FD) is, therefore, required in order that these compounds may be characterized in terms of their molecular size and composition. In this report, the FD mass spectra of typical representatives of this class of compounds are described along with the attempted suppression of undesirable thermal reactions by the optimization of the emitter temperatures.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700402
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    Structures and Electrical Properties of Some New Organic Conductors Derived from the Donor Molecule TMET (S,S,S,S,-Bis(dimethylethylenedithio) tetrathiafulvalene) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 942-953 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf-6, AsF-6, SbF-6, I-3 (incommensurate), and 3:2 with tetrahedral anions BF-4, CIO-4, ReO-4 are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)3(CIO4)2 is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700405
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    Bildung tricyclischer Thietan-Derivate durch intramolekulare(2+2)-Cycloaddition (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 992-994 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Thietane Derivatives via Intramolecular (2+2) CycloadditionOn irradiation, the two 4-vinyl-1,3-thiazole-5(4H)-thiones 1a, b, synthesized from thiobenzoic acid and the corresponding 3-amino-2H-azirines 2a,b, undergo an intramolecular (2+2)-cycloaddition reaction of the C=S and C=C bonds to give the tricyclic thietane derivatives 3a,b.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700409
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    Photochemical Synthesis of 2-Alkylidene-1,3-cyclocalkanediones. Preliminary Communication (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 995-996 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photolysis (λ = 254 nm) of 4-(tert-butyl)-4,6,7,8-tetrahydro-7,7-dimethy-2H-1-benzopyran-2,5(3H)-dione (3a) in t-BuOH affords 2-(2,2-dimethylpropylidene)-5,5-dimethyl-1,3-cyclohexanedione (1a) in 80% yield via homolysis of the lactone O—CO bond and subsequent ketene elimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700410
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    Some Cyclic Oligopeptide with S2n Symmetry (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1012-1016 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some cyclic oligopeptides formed by an equal number of alternating D- and L-amino-acid residues have been synthesized by using the hydrochloride of the open-chain peptide acid as precursor and the mixed-anhydride condensation method. The cyclic oligopeptides (tetra-, hexa-, and octavaline, hexaleucine, and hexaphenylalanine) form very stable H-bonded structures (IR-amide band at 3270-3290 cm-1) which are insoluble in common organic solvents. In CF3COOH/CDCI3 (25°), they yield 1H-NMR spectra snowing the expected equivalency of the various amino-acid residues.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700413
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  • 139
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    Strukturaufklärung ungewöhnlicher Umlagerungsprodukte von S-(1-Alkenyl)sulfoximiden mit Hilfe der Stossaktivierungsmassenspektrometrie (CAD-MS) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1041-1049 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure Determination of Unusual Rearrangement Products of S-(1-Alkenyl)sulfoximides by Collisionally Activated Dissoication Mass Spectrometry (CAD-MS)The Molecular ions of s-(l-alkenyl)--N-(p-tolyl)sulfoximides 1 are transformed into the N(phenylsufenyl)sulfonamides 3+ by a 1,2-migration of the alkenyle group to the O-atom of the sulfoximide function followed by a 2,3-sigmatropic rearrangement. The structure of the production e has been unambiguouslydetermined by the CAD method, showing the identity of the ion e (m/z368) obtained from 1a and from 4a.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700416
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  • 140
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    Reaktionen von 1,2-Bis(trimethylsilyl)iminen mit Selen-und Tellur-halogeniden (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1076-1078 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 1,2-Bis(trimethylsilyl)imines with Selenium and Tellurium HalogenidesThe reactions of benzil-bis(trimethylsily)imine and phenanthrene-9,10-bis(trimethylsilyl)imine with SeOCl2, SeCl4 and TeCl4 are described.
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    URL: http://dx.doi.org/10.1002/hlca.19870700420
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  • 141
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    Remote Tricarbonyl(diene)iron Substituent Effect on Ester Heterolysis. The Solvolyses of 5,6,7,8-Tetramethylidenebicyclo[2.2.2]oct-2-yl Methanesulfonate and of its Tricarbonyliron Mono- and Dinuclear ComplexesPart of Ph.D. thesis of J.-C. Zwick, Ecole Polytechnique Fédérale de Lausanne, 1987. Part of this work has been presented at the Fall Meeting of the Swiss Chemical Society in Bern, Oct. 10, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1079-1094 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Buffered acetolyses and hydrolyses of 5,6,7,8-tetramethylidenbicyclo[2.2.2]oct-2-yl methanesulfonate (17), of its ‘syn-endo’ (18), ‘syn-exo’ (19), ‘anti-endo’ (20), ‘anti-exo’ (21) tricarbonyliron complexes and of its ‘anti-exo,syn-endo’ (22) and ‘anti-endo,syn-exo’ (23) bis(tricarbonyliron) dinuclear complexes have been investigated (product analysis and kinetics). In contract with the solvolyses of the uncomplexed mesylate 17, the solvolyses of the complexed esters can be highly chemo- and stereoselective. The nature of the products (non-rearranged bicyclo[2.2.2]oct-2yl vs. rearranged bicyclo[3.2.1]oct-2-yl derivatives) depends on the relative configuration of the tricarbonyl(diene)iron moieties and on the medium. The rates of solvolyses of 17 are only slightly affected by complexation of one or both s-cis-butadiene units with Fe(CO)3 groups, except in the cases where the diene moiety ‘anti’ with respect to the mesylate is complexed onto its ‘endo’ face (20,23). In these cases, significant rate-retardation effects are observed, consistent with the inductive effect of the Fe(CO)3 substituent. Such retardation effects are overwhelmed by competing accelerating homoallylic participation by uncoordinated ‘anti’ -diene moieties (18,19) or, as in the case of the ‘anti-exo’-Fe(CO)3 complexes 21 and 22, by possible direct metal participation to the ionization process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700421
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  • 142
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    Synthetic Models of the Active Site of Cytochrome P-450. 1st Communication. The Synthesis of a Doubly-Bridged Iron(II)-Porphyrin Carrying a Tightly Bound Thiolate LigandPresented in part at the ‘Gordon Research Conference’ on the ‘Chemistry and Biology of Pyrroles’, New Hampshire, 27.7.-1.8.86 (W.-D.W.), and at the ‘Swiss Chemical Society’ meeting, Bern, 10.10.86 (B.S.). (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1173-1193 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The doubly-bridged iron(II)-tetraphenylporphyrin derivative 6, carrying a sterically fixed S- ligand in the ‘proximal’ position and the substrate at the ‘distal’ site, was synthesised as an enzyme model for cytochrome P-450. Compound 36, the CO complex of 6, displays a split Soret band (403 and 457 nm) similar to the native cytochrome P-450.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700425
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  • 143
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    Stereoselektive Alkylierung an C(α) von Serin, Glycerinsäure, Threonin und Weinsäure über heterocyclische Enolate mit exocyclischer DoppelbindungZughörige Kurzmitteilungen: [1] (Weinsäre) [2] (Threonin) [3] (Serin) [4] (Glycerinsäure).Siehe auch die Diskussionen in den vor kurzem erschienenen Übersichtsartikeln [5][6]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1194-1216 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steroselective Alkylation at C(α) of Serine, Clyceric Acid, Threonine, and Tartaric Acid Involving Heterocyclic Enolates with Evocyelic Double BondsThe chiral, non-racemic title acids are converted to methyl dioxolane-(cf. 13), oxazoline-(4) and oxazolidinecarboxylates (cf. 9). Deprotonation by Li(i-Pr) 2N at dry-ice temperature gives solutions of the lithium enolates A-D With exocyclic enolate double bonds. These are stable crough with respect to β-elimination (Scheme 1) to be alkylated with or without cosolvents such as HMPA or DMPU The products are formed in good to excellent yields and, with the exception of the tartrate-derived acetonlde (see Scheme 2), with diastereoselectivities above 90%. While the tartrate-and threonine-derived enolates (A and B, resp.) are chiral due to the second stereogenic center of the precursors, the serine- and glyceric-acid-derived enolates (Aand B, resp.) are chiral due to the second sterogenic center of the precursors, the serine-nd glyceric-acid-derived enolates are non-racemic due to a tert butyl-substituted (pivalaldehyde-derived) acetal center (C and D, resp.). The products of alkylation can be hydrolyzed to give α-branched tartaric acid (Scheme 2), allothreonine (Scheme 3), serine (Scheme 4), and glyceric-acid derivatives (Scheme 5) with quaternary stereogenic centers. The configurations of the products are determined by NOE-NMR measurements and by chemical correlation. These show that the dioxolane-derived enolates A and D are alkylated preferentially from that face of the ring which is already substituted (‘syn’-attack), while the dihydrooxazol-and oxazolidine-derived enolates B and C are alkylated from the opposite face (‘anti’-attack). The ‘syn’-attack is postulated to arise from strong folding of the heterocyclic ring due to electronic repulsion between the enolate π-system and non-bonding electron pairs on the heteroatoms (see Scheme 6).
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  • 144
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    Novel Synthesis of Agaritine, a 4-Hydrazinobenzyl-Alcohol Derivative Occurring in Agaricaceae (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1261-1267 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 4-hydrazinobenzyl alcohol (3 was prepared (58%)) by diiobutylaluminiumhydride reduction of methyl 4-hydrazinobenzoate (4), whereas LiA1H4 or LiBh4 reduction of4 proceeded further to yield (via intermediate 3) (4-tolyl)hydrazine (5). The alcohol 3 was stable under O2-free conditions and exhibited no tendency to eliminate H2O, neither thermally nor with H+ catalysis. Oxidation of 3 with SeO2 yielded 4-(hydroxymethyl)benzine-diazonium ion (8), identified by its azo coupling product 9 with 2-naphthol. Condensation of 3 with 1-benzyl 5-Hydrogen N-(benzyloxycarbonyl)-L-glutamate (10) in presence of dicyclohexylcarbodiimide afforded 81% of N2-(benzyloxycarbonyl)-L- glutamic acid 1-(benzyl-ester) 5-{2-[4-(hydroxymethyl)phenyl]hydrazide} (11) which upon controlled hydrogenolysis (quinoline-sulfur-poisoned Pd/C catalyst) gave 82% of L-Glutamic acid 5-{2-[4-(hydroxymethyl)phenyl] hydrazide} (1), i. e. agaritine, a metabolite of Agaricus bisporus. Without poisoning of the catalyst, hydrogenolysis of (11) yielded L-glutamic acid 5-[2-(4-tolyl)hydrazide] (12).
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    URL: http://dx.doi.org/10.1002/hlca.19870700505
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  • 145
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    The Solid and Solution Conformations of (±)-Corycavine (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1482-1486 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of corycavine, a protopine-type alkaloid, has been determined by X-ray analysis. A conformational feature observed is the existence of a strong electrostade interaction between the N- and C-atom at a distance of 2.618 Å. Such an interaction stabilizes the 10-membered ring conformation of the structure. Analyses of NMR spectra indicate that corycavine has the same conformation in solution as in the crystal state.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700605
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  • 146
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    Dimethylformamide-Exchange Mechanism on Some First-Row Divalent Transition-Metal IonsPart 33 of the series ‘High-Pressur NMR Study’. Part 32: [1].Taken in part from the diploma work of C. Cossy, Université de Lausanne, 1983.This work was presented in part at the 24th International Conference on Coordination Chemistry, Athens, Greece, August 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1516-1525 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of temperature on the dimethylformamide exchange on Mn(DMF)2+6 and Fe(DMF)2+6 has been studied by 13C- and 17O-NMR, respectively, yielding the following kinetic parameters: k298 equals; (2.2±0.2). 106 S-1, ΔH≠ = 34.6 ± 1.3 kJ mol-1, ΔS≠ = -7.4 ± 4.8 J K-1mol-1 for Mn2+ and K298 = (9.7 ± 0.2).105 S-1, Delta;H≠ = 43.0 ± 0.9 kJ mol-1, ΔS≠ = + 13.8 ± 2.8 J K-1mol-1 for Fe2+. The volumes of activation, ΔV≠ in cm3mol-1, derived from high-pressure NMR on these metal ions, together with the previously published activation volumes for Co2+ and Ni2+ (+2.4 ± 0.2 (Mn2+), +8.5 ± 0.4 (Fe2+) +9.2 ± 0.3 (Co2+), + 9.1 ± 0.3 (Ni2+)) give evidence for a dissociative activation mode for DMF exchange on these high-spin first-row transition-metal divalent ions. The small positive ΔV≠ value observed for DMF exchange on Mn2+ seems to indicate that a mechanistic changeover also occurs along the series, (probably from Id to D), as for the other solvents previously studied (Ia to Id, for H2O, MeOH, MeCN). This changeover is shifted to the earlier elements of the series, due to more pronounced steric crowding for dimethylformamide hexasolvates.
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    URL: http://dx.doi.org/10.1002/hlca.19870700608
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  • 147
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    Two New Antifungal Naphthoxirene Derivatives and their Glucosides from Sesamum angolense WELW (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1551-1557 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two novel naphthoxirene derivatives 1 and 2 their glucosides 3 and 4 have been isolated from the root bark of Sesamum angolense Welw. (Pedaliaceae) by preparative liquid chromatography. The structure of 1 was established by X-ray diffraction analysis. The identities of the other naphthcxirenes were deduced by spectroscopic (IR, UV, 1H-NMR, 13C-NMR, EI-MS, DCI-MS) and chemical methods (oxidation, acid and enzymatic hydrolysis). Compounds 1-3 exhibited antifungal activity. Naphthoxirene 1 was, in addition, cytotoxic to human colon carcinoma cells.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700613
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  • 148
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    On Negative Birefringence in Water-in-Oil Microemulsions (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1531-1536 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The occurrence of a negative birefringence in water-in-oil (W/O) microemulsions has been substantiated and analyzed. The analysis is based on the well-established aqueous nanodroplet model of W/O microemulsions. In the particularly investigated water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/aliphatic oil systems, the AOT monolayer exhibits a negative induced intrinsic birefringence, which is brought about by the pronounced polarizability of the alkyl moiety of the AOT molecule approximately perpendicular to the direction of its permanent dipolement.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700610
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    Erratum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2246-2246 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700829
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  • 150
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2305-2306 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700830
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  • 151
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    Herstellung und Charakterisierung in Membranen von Ionophoren mit Selektivität fü Natrium-Ionen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 153-157 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Neutral Sodium-Selective Ionophores and their Characterization in Membrane ElectrodesDifferent ionopbores based on N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide (1) have been prepared by substitution of the aromatic ring carrying the ether O-atoms. Substituents of widely different electronegativity (CH3, CH3O, CHO, CN NO2, Br) do not relevantly influence the ion selectivity.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700119
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  • 152
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    Complexes of 3,3′-Oxybis[(diphenylphosphino)methylbenzene] with Ni(II), Pd(II), Pt(II), Rh(I), and Ag(I). How Important is Backbone Rigidity in the Formation of trans-Spanning Bidenatate Chelates?? (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 158-170 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bidentate diphosphine ligand, 3,3′-oxybis[(dipenylphosphino)methylbenzene] (1) forms monomeric, trans-square-planar complexes MX2(1) (M = Ni, Pd, Pt; X = Cl-, Br- I-, and, in part, N3-, NCS-, CN-, NO3-) as well as Pt(H)Cl(1), Pt(H)Br(1), and RhCl(CO)(1). Polymeric species have been observed with substitutionally inert metal centres: trans-[PtCl2(1)]2 and cis-[PtCl2(1)]n (mean value of n ≈ 4-5) 31P-NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans-spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans-spanning chelate ligands. The crystal structure of AgCl(1)·0.5 (CH3)2C=O·0.39 C6H12 (space group C2/c,a = 21.02 Å, b = 14.57 Å, c = 24.79 Å, β = 99.77°, V = 7531.4 Å3, Z = 8) confirms the presence of three-coordinate Ag(I), with a coordination intermediate between a trigonal-planar and a T-shaped geometry (P-Ag-P = 145.61(8)°).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700120
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  • 153
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    Aza-2-dienes-1,3. Partie 5. Préparation de N-aminoimidazoles, 3H-pyrroles, triazolo[1,2,4][1,5-a]pyrazines et imidazo[1,2-a]pyrazines (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 187-195 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Aza-1,3-dienes. Access to N-Aminoimidazoles, 3H-Pyrroles, [1,2,4]Triazolo[1,5-a]pyrazines, or Imidazo[1,2-a]pyrazinesNucleophilic attack of 5-(dialkylamino)-2-aza-1,3-diene-1,1-dicarbonitriles (or their 1-methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N-aminoimidazoles, [1,2,4]triazolo-[1,5-a]pyrazines, or α-dihydrazino derivatives. With α-amino esters (or analogous), imidazo[1,2-a]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3H-pyrroles. Structures and rationalisation of this nucleophilic attack are discussed.
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    URL: http://dx.doi.org/10.1002/hlca.19870700123
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    Syntheses of Tetrahydrolipstatin and Absolute Configuration of Tetrahydrolipstatin and Lipstatin (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 196-202 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipstatin (1), a natural product, and tetrahydrolipstatin (2) are pancreatic lipase inhibitors. Non-stereoselective and partially stereoselective syntheses of 2 are used to establish the absolute configuration of tetrahydrolipstatin and lipstatin.
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    URL: http://dx.doi.org/10.1002/hlca.19870700124
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  • 155
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    Ring-Open Analogues of Adenine Nucleoside. Aminoacyl Derivatives of Cyclo- and Acyclo-Nucleosides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 219-231 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of acyclic analogues of ribo- and deoxyribonucleosides is described. These compounds (Table 3) are both poor substrates and poor inhibitors of adenosine deaminase. The synthesis of dinucleotides from these analogues is also described, and the activity along with the inhibitory properties of some of them are studied against deaminase enzyme. These nucleotides are resistant to degradation by phosphodiesterases. HCl impregnated on silica gel is an excellent reagent for the preparation of the chloromethyl ether precursors of acyclo-nucleosides. A general and rapid procedure is developed for the preparation and isolation of the 5′-aminoacyl derivatives of robo- and arabinonucleosides. Quinoline has a marked effect on aminoacylations without racemization. Compounds 35a, b possess remarkable antiviral effects in vitro. A procedure is also developed for the conversion of acyclo-ribonucliosides 13e, f to acyclo-deoxyribonucleosides 11e, f.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700127
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    Functionalisation of saturated hydrocarbons. Part 9Part 8:[1].. Oxidation of patchouli alcohol by the ‘gif system’: Isolation and organoleptic properties of three new ketonic derivativesDedicated to Prof. Vlado Prelog on the occasion of his 80th birthday (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 273-280 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of patchouli alcohol (1) using the ‘Gif system’ afforded as major isolated products three new ketonic derivatives 16-18. The structures of these compounds were established by spectral techniques including 2D-NMR. Ketones 16-18 display interesting organoleptic properties.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700202
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  • 157
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    Synthese von ω-(5-Oxo-1-cyclopentenyl)alkansäure-methylestern aus 2-Nitrocycloalkanonen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 315-320 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Methyl ω-(5-Oxo-1-cyclopentenyl)alkanoates Starting from 2-NitrocycloalkanonesA convenient synthesis of methyl ω-(5-oxo-1-cyclopentenyl)alkanoates 1 is described. 2-Nitrocycloalkanones 2 are converted to 2-(3,3-dimethoxypropy1)-2-nitrocycloalkanones 4. Treatment of 4 with MeOH/MeONa led to the ring-opened nitronates 5 which underwent a Nef reaction to form the corresponding oxo derivatives 6. Partial hydrolysis of followed by base-catalyzed aldol reaction gave the desired products in high yields.
    Additional Material: 2 Tab.
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    Cyclobut-2-enones from Alkynes via Dichlorocyclobut-2-enonesIn part taken from the Ph.D. thesis of A.A.A., University of Zürich, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 321-328 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [2 + 2]-cycloaddition of dichloroketene (prepared in situ from CCl3COCl and Zn(Cu)) with three alkynes 1a-c to form 2,3-dimethyl-(2a), 2,3-diethyl-(2b) and 3-butyl-4,4-dichlorocyclobut-2-enone (2c) proceeds rapidly in the absence of POCl3. The primary products 2a-c rearrange in situ to the 2,4-dichlorocyclobut-2-enones 3a-c under the influence of ZnCL2 produced during the reaction. ZnCl2 converts both 2a and 3a into a 4:6 equilibrium mixture of the two; this isomerization does not occur with LiCl. The Cl-atoms of both 2a, b and 3a, band of 2c may reductively be removed with Zn(Cu) in AcOH/pyridine to afford the alkylcyclobutenones 4a-c. Without pyridine, this reduction gives ca. 1:1 mixtures of the double-bond isomers 4 and 5 in low yields. The cyclobutenones 2c and 4c may be deuterated by CD3COOD in the presence of pyridine. D-Atom is introduced into 2c at C(4) and at C(γ), and into 4c at C(2) and C(4). A mechanism for this deuteration is considered, which does not involve a cyclobutadienolate 7, but rather a cyclobutenolate of type 8. The reductions of 2 and 3 to 4 might also pass through the same type of intermediate 8.
    Additional Material: 1 Tab.
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  • 159
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    3-(Dimethylamino)-2,2-dimethyl-2H-azirin als α-Aminoisobuttersäure(Aib)-Äquivalent: Cyclische Depsipeptide durch direkte Amid-CyclisierungVorläufige Mitteilung s. [1]; vgl. auch [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 329-338 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-(Dimethylamino)-2,2-dimethyl-2H,-azirine as an α-Aminoisobutyric-Acid (Aib) Equivalent: Cyclic Depsipeptides via Direct Amid CyclizationIn MeCN at room temperature, 3-(dimethylamino)-2,2-dimethyl-2H-azirine (1) and α-hydroxycarboxylic acids react to give diamides of type 8 (Scheme 3). Selective cleavage of the terminal N,N-dimethylcarboxamide group in MeCN/H2O leads to the corresponding carboxylic acids 13 (Scheme 4). In toluene/PhSH, phenyl thioesters of type 11 are formed (see also Scheme 5). Starting with diamides 8, the formation of morpholin-2,5- diones 10 has been achieved either by direct amide cyclization via intermediate 1,3-oxazol-5(4H)-ones 9 or via base-catalyzed cyclization of the phenyl thioesters 11 (Scheme 3). Reaction of carboxylic acids with 1, followed by selective amide hydrolysis, has been used for the construction of peptides from α-hydroxy carboxylic acids and repetitive α-aminoisobutyric-acid (Aib) units (Scheme 4). Cyclization of 14a, 17a, and 20a with HCI in toluene at 100° gave the 9-, 12-, and 15-membered cyclic depsipeptides 15, 18, and 21, respectively.
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  • 160
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    Synthese von 2-Hydeoxy-3-methyl-2-hexen-4-olid (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 369-374 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 2-Hydroxy-3-methyl-2-hexen-4-olidThe title compound 13a, a substance used in food-flavoring, was synthesized in 89% overall yield, starting from methyl 2-hydeoxy-3-butenoate (3a). The key step in this transformation is the isomerization of the C=C bond in 3a which yielded methyl 2-oxobutanoate as an intermediate. The latter underwent a self-condensation yielding 2-hydroxy-4-(methoxycarbonyl)-3-methyl-2-hexen-4-olid (11a), which, after hydrolysis and decarboxylation, gave 13a. In addition, the syntheses of five other compounds related to 13a are reported.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700214
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  • 161
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    Triaziridine 7. Mitteilung6. Mitteilung: [1].. Stabile pyramidale Konfigurationen an den Stickstoff-Atomen von Dialkyl-und Trialkyl-triaziridinen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 381-389 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stable Pyramidal configurations at the Nitrogen Atoms of Dialkyl-and Trialkyl-triaziridinesStereochemical features of the recently synthesized nine samples of di- and trialkyl-triaziridines, namely the 1,3-cyclopentylen-(series a) and the two stereoisomers of the diisopropyl derivatives (series b and c), containing as the third substituent an H-atom (2), a CH3 group (3)or a CH2OH group (4), were elaborated on the basis of the 1H-, 13C-, and 15N-NMR spectra. The three N-atoms of the saturated N3-homocycle were found to be stable to pyramidal inversion in all cases. According to their NMR spectra, 2-4 of the series a and b possess twofold symmetry (Cs), while 2-4 of series c are asymmetric. Thus, series c has the trans-configuration at N(2)/N(3) and, consequently, the cis-configuration at N(1)/N(2), while series a and b have the cis-configuration at N(2)/N(3) and -since the all-cis-arrangement is excluded-the trans-configuration at N(1)/N(2). The asymmetry of the trans-configurated 2c turned into twofold symmetry (C2), when a little CF3COOH was added. The 1H- and 13C-NMR data of series b and c of our alkyl-triaziridines exhibit a shielding effect, according to which there are two types of i-Pr groups, i-Pr(a) and i-Pr(b). They differ in the NMR signals of the H- and the C-atoms of their CH groups: the H-atoms of i-Pr(a) are more deshielded by 0.75-1.111 ppm and its C-atoms are more shielded by 10.0-160.0 ppm as compared to the corresponding atoms of i-Pr(b). i-Pr(a) is cis (on the N3-homocycle) to a large substituent (such as i-Pr, Me, CH2OH) and to a lone pair, while i-Pr(b)is cis only to a small (H) or to no substituent and to one or two lone pairs. An analogous effect appears in the NMR signals of the CH3 and CH2OH groups at N(1) of 3 and 4 in the series b and c.
    Additional Material: 2 Tab.
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  • 162
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    Synthese eines Nickel(II)-B,C,D-hexadehydrocorrinats durch (A→D)-CyclisierungKurzmitteilung: [1].Professor Dr. Gerhard Quinkert zum 60. Geburtstag gewidmet (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 402-411 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Nickel(II) B,C,D-Hexadehydrocorrinate by (A→D)-Ring ClosureThe B,C,D-hexadehydrocorrin of type 10 fills a gap in the corrin family whose members can occur at different oxidation levels. We report here on the synthesis of a correspondingly protected secocorrin 23 and its convenient cyclization to 10
    Additional Material: 3 Tab.
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  • 163
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    Studies on the Biosynthesis of Tabtoxin (Wildfire Toxin). Origin of the Carbonyl C-Atom of the β-Lactam Moiety from the C1-Pool (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 412-422 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Re-isolation of Pseudomonas tabaci strain NCPPB 2730 from its host, the tobacco plant, led to an activation of the bacteria in order to produce the β-lactam dipeptide tabtoxin (Wildfire toxin, 1). Incorporation of several 14C-labelled amino acids as well as L-[methyl-13C]methionine, L-[1,2-13C2]- and L-[3,4-13C2]aspartate, rac -[1,2-13C2]glycerol, and [1,2-13C2]acetate into isotabtoxion (2) demonstrated that the building blocks of tabtoxin (1) are L-threonine, L-aspartate, the Me group of L-methionine and a C2-unit derived from the C3-pool (Fig. 3). The Me group of L-methionine provides the carbonyl C-atom of the β-lactam moiety. These findings represent a novel pathway in β-lactam biosynthesis. Mechanistic aspects with respect to the β-lactam ring formation are discussed. A biradical 16 is proposed as an intermediate during the cyclization of a N-formyl-α-amino ketone 15.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700220
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 488-491 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700229
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  • 165
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    On the Purported Structure of Cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 480-487 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the bis(sulfonium salt)7 in a solution of Na2CO3 in H2O/EtOH yielded three main products 8-10. The spectroscopic data of 8 were identical to those which led Mithcell and Sondheimer to assign them to cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (3). Our investigations show, however, that the correct structural assignment leads to the structure of 7,7a-dihydrodibenzo[de,mn]naphthacene (8).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700228
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  • 166
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    Masthead (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700101
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  • 167
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    Mehrstufige Redoxsysteme. XLIX. MitteilungXLVIII. Mitteilung:[1]. Mit π-Systemen substituierte 1,3-Dimethylidencyclobutane: Synthese und Eigenschaften (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 929-941 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multistep Redox Systems. 1,3-Dimethylidenecyclobutanes Substituted by π-Syntheses and PropertiesAs potential redox systems 1,3-dimethylidenecyclobutanes are synthesized in which the ‘exo’-methylidene group participates in a cyclopentadienyl (typeC4)or cycloheptatrienyl (type A5) system. Benzo-annellated systems are also described. The formation of the C=C bond by the reaction of thioketones (3 and 31) with diazo compounds is extended to extended to 1,6,7,21, and 24, which so far had not been employed. In some cases, intermediate thiiranes can be isolated (e.g.4) which are smoothly transformed into the target compounds of types C4 and A5 by extrusion of sulfur. The new C=C bonds may be introduced stepwise, thereby allowing the synthesis of unsymmetrically substituted 1,3-dimethylidenecyclobutanes (e.g. 20 and 35). Reduction of by Na does not produce bicyclobutanes but compounds 43 and 44 with one dihydrofulvene unit.
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    URL: http://dx.doi.org/10.1002/hlca.19870700404
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  • 168
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    Verecynarmin A, a Novel Briarane Diterpenoid Isolated from Both the Mediterranean Nudibranch Molluse Armina maculata and its Prey, the Pennatulacean Octocoral Veretillum cynomorium (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 984-991 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The briarane diterpenoid verecynarmin A (=(-)).(8R,9S,11R,12aR,4Z,6Z)-11,12-epoxy-8,8a,9,10,12,12a,13-octahydro-1,5,8a,12-tetramethylbenzo[4,5]cyclodeca[1,2-b]furan-9-yl acetate; ((-)-1) is shown to be contained in both the Mediterranean nudibranch mollusc Armina maculata(RAFINESQUE) and its prey, the pennatulacean octocoral Veretillum cynomorium(PALLAS). The structure is mainly solved by 1D-NMR, 2D-NMR, and NOE studies of (-)-1. However, the relative configurations at the epoxide and angular methyl centres, as well as the preferred conformation, are established by shift-reagent and NOE studies of diol(-)-4 obtained by epoxide-ring opening of (-)-1 with LiA1H4. The absolute configuration is established via deacetylation of (-)01 followed by Horeau's esterification.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700408
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  • 169
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    Oxidationsreaktionen methyl-substituierter 2,1,3-Benzothiadiazole und 2,1,3-Benzoselenadiazole mit Selen-dioxid (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 997-1000 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation Reactions of Methyl Substituted 2,1,3-Benzothiadiazoles and 2,1,3-Benzoselenadiazoles with Selenium DioxideThe synthesis 5-8 by oxidation of 4-methyl-(1),5-methyl(2), 5,6-dimethyl-2,1,3-benzoselenadiazole (3), and 5,6-dimethyl-2,1,3-benzothiadiazole (4), respectively, with selenium dioxide as well as their spectroscopic properties are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700411
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    Steric Effects on Reaction Rates. Part IX. Force-Field Parameters for Bridgehead and Rigid Tertiary Carbenium Ions (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1017-1024 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular-mechanics calculations for strain of carbenium ions are tested using Bentley's unified reactivity scale for bridgehead solvolysis as reference. Excellent correlations are obtained for solvolytic bridgehead reactivity with the calculated steric-energy difference (ΔEst) between substrate (R—H or R—OH) and cation (R+). After adjustment of appropriate force-field parameters, the approach is successfully extended to the rigid, but planar cations derived from structures 15-20; however, the general set of parameters cannot be applied to highly strained systems such as the cation formed from 17. With all of the 18 sets of parameters tested, the 2-endo-norbornyl derivative 16, is adequately correlated, while the exo isomer 15 exhibits enhanced reactivity by a factor of ca. 102 to 103.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700414
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  • 171
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    Complexes of 2,2′,2″-Nirtilotriphenol. Part IV. Cage Compounds with Phosphorus(III) and Phosphorus(V) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1063-1069 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand 2,2′,2″-nitrilotriphenol reacts with P(III) and P(V) compounds to form corresponding phosphorus complexes. Syntheses and NMR data of 2,2′,2″-nitrilotriphenyl phosphite (II), 2,2′,2″-nitrilotriphenyl phosphate (III) and of a hydrolysis product of II, 2,2′-[N-(2-hydroxyphenyl)imino]diphenly phosphonate (IV), are reported, as well as crystal structures of II and IV. Phosphite II shows a bicycloundecane framework; no NċPinteraction is present. The phosphonate IV shows two coordinated and one dangling phenol group; the N-atom does not interact with the P-atom. Strong acids protonate II as well as III to form cations: in these, NMR evidence indicates coordination of the N-atom to the P-atom.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700418
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  • 172
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    Octacarbonyldicoblat-Inauced (1,3) H Shits in 1-Methylallenecarboxylates and Allenic LactonesDedicated to Professor Dr. André S. Dreiding (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1070-1075 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The allenecarboxylates 1a,b and allenic lactones 4a,b undergo thermally induced (1,3) H Shifts in the presence of Co2(CO)8. The non-isolated 1,3-dienes 2a,b react further affording the Diels-Alder Adducts 3a,b Scheme 1 in high yields. These adducts were not formed in the case of the 2-vinybutenolides 5a,b. On irradiationin the presence of Co2(CO)8 or Mn2(Co)10, the studied allenes reacted in a different manner, yielding either cyclization products 7 and 8 (Scheme 3) or products 9 and 10, formed via H abstracton and solvent addition (Schemes 4 and 5).
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    URL: http://dx.doi.org/10.1002/hlca.19870700419
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  • 173
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    Brominations of Cyclic Acetals from α-Amino Acids and α- or β-Hydroxy Acids with N-Bromosucinimide (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1104-1114 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of novel electrophilic building blocks for the synthesis of enantiomerically pure compounds (EPC) is described. Thus, the 2-(tert-butyl)dioxolanones, -oxazolidinones, -imidazolidinones, and -dioxanones obtained by acetalization of pivalaldehyde with 2-hydroxy-, 3-hydroxy-, or 2-amino-carboxylic acids are treated with N-bromosuccinimide under typical radical-chain reaction conditions (azoisobuytyronitril/CCl4/reflux). Products of bromination in the α-position of the carbonyl group of the five-membered-ring acetals are isolated or identified (2, 5, and 8; Scheme 1). The dioxanones are converted to 2H, 4H-dioxinones under these conditions (12, 14, 15, 21, and 22; Schemes 2 and 3). The products can be converted to chiral derivatives of pyruvic acid (methylidene derivatives 3 and 6) or of 3-oxo-butanoic and -pentanoic acid (16 and 23). The mechanism of the brominations is interpreted. The conversion of serine to enactiomcrically pure dioxanones 26-28 (Scheme 4) is also discussed.
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    URL: http://dx.doi.org/10.1002/hlca.19870700423
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    Addendum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1229-1229 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700428
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  • 175
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1230-1231 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700429
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  • 176
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    Enzyme-Catalyzed Hydrolysis of Some Functionalized Dimethyl MalonatesPresented at the meeting of the Swiss Chemical Society, Berne, October 10, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1250-1254 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the preparation of (+)-(R)-methyl hydrogen 2-(tert-butoxymethyl)-2-methyl-malonate (5e) in synthetically useful amounts from readily available starting material.
    Additional Material: 1 Tab.
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    Diels-Alder-Reaktionen von 2,4-Bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien mit HeterodienophilenTeil der geplanten Dissertation von U. R. [1]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1255-1260 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diels-Alder Reactions of 2,4-Bis{[(tert-Butyl)dimethylsilyl]oxy}-3-aza--1,3-pentadien with HeterodienophilesThe 2,4-bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien(2) reacts via the Diels-Alder adducts 3, 6a-c, and 8a, b, which cannot be isolated, giving the triazines 4, 7a-c, and the oxadiazines 9a, b. The hydrolysis of 4 in MeOH affords the N-acetyl-acetamid derivative 5. The formula of 9a is proven by an X-ray-structure analysis.
    Notes: No. Abstract.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700504
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  • 178
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    Zwei weitere Iridoid-glycoside und ein Monoterpen-glycosid aus Sambucus ebulus L. (Caprifloiaceae). 3. Mitteilung über die Inhaltsstoffe der Zwergholunderwurzel (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 91-101 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Iridoid Glycosides and a Monoterpene Glycoside from Sambucus ebulus L. (Caprifloiaceae)From the roots of Sambucus ebulus L., two novel valeriana-type ester iridoid glycosides, 6′-O-apiosylebuloside (1) and 7,7-O-dihydroebuloside (3), along with the open-chain monoterpene glycoside 5 were isolated. Their structure elucidation is based mainly on one- and two-dimensional NMR methods. 1H,1H-COSY experiments permitted complete assignment of signals arising from the disaccharide unit in 1. Biogenetically, 3 seems to represent the equivalent of loganin in the valeriana-type series of iridoid glycosides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700111
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  • 179
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    Synthese von ‘D-Isothreonin’ und ‘L-Alloisothreonin’ aus L-Alanin (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 116-120 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ‘D-Isothreonine’ and ‘L-Alloisothreonine’ Starting from L-AlanineStarting from L-alanine, ‘D-isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L-alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700113
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  • 180
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    Oxidative Breaking of Long-Chain Acetylenic Enol Ethers of Glycerol of the Marine Sponges Raspailia pumila and of Model Compounds with Aerial Oxygen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1400-1411 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The raspailynes (novel long-chain enol ethers of glycerol having the enol ethers double bond conjugated in sequence, to an acetylenic and an olefinic bond, isolated from the North-East-Atlantic sponges Raspailia pumila and R. ramosa) are stable under normal hydrolytic conditions for enol ethers. In contrast, when their solutions are evaporated, these lipids such as raspailyne Bl (=(-))-3-[(1Z,5Z)-(tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(--2) rapidly react with aerial O2 under normal laboratory-daylight conditions, with rupture of the C=C enol ether bond to give 1-O-formylglycerol (3) and an aldehyde (such as tridec-4-en-2ynal(4) from (-)-2). This reaction must be caused by triplet O2, since thermally generated singlet O2 has no effect on (-)-2 in solution. That the mere presence of an enol-ether moiety conjugated to an acetylenic group is responsible for such a behaviour is demonstrated with the model compounds 1-methoxypentadec-1-en-3-yn-5-ol (6a) and its 5-O-acetyl or 5-O-tetra-hydropyranyl derivatives 6b and 6c, respectively. Resistance to both hydroytic conditions and singlet O2 of these compounds is thought to arise from electron depletion at the enol-ether C(beta;) atom by the acetylenic group. Plausible reaction pathways for enol-ether bond rupture in these compounds by aerial O2 are outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700521
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  • 181
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    Catalytic Intramolecular Palladium-Ene Reactions. Preliminay CommunicationPresented at the ‘4th IUPAC-Symposium on Organometallic Chemistry Directed towards Organic Synthesis’ (OMCOS IV), July 28, 1987, Vancouver, Canada. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1477-1481 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pd(dba)2[dba = dibenzylideneacetone]/PPh3-or Pd(PPh3)4-catalyzed cyclizations of acetoxy-dienes 2 → 3 and 10 → 11 gave 1-vinyl-2-methylidene-subsituted cyclopentances and cyclohexanes in high yield, consistent with a palladium-ene/β-elimination mechanism (D → E → F, Scheme 2). The efficient and highly stereoselective cyclizations 7 → 7 and 8 → 9 illustrate intramolecular allylpalladium insertions into 1,2-dialkyl-, trialkyl-, trialkyl-, and cyclic alkenes followed by elimination of the exocyclic β-H giving 1,2-divinylcyclopentanes. These new olefin insertions proceed faster in AcOH (compared to THF) and occur preferentially cis relative to the Pd (13 → 14 → 15).
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700604
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  • 182
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    Drug-induced modifications of the immune response part 9Part8: [1]4-(Arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenylcycolopropyl)furan-3-carboxamides as Novel Antiallergic Compounds (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1526-1530 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and antiallergic activity of a series of 4-(arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenyl-cyclopropyl)furan-3-carboxamides 10 are described. Treatment of N-substituted 2-amino-4,5-dihydro-4-oxofuran-3-carboxylic acids 9 with chlorooxobis(2-oxo-1,3-oxazolidin-3-yl)phosphorus (2) and an appropriate aromatic amine in the presence of Et3N, resulted in a novel 3(2H)-furanone-→2(5H)-furanone rearrangement that led to the facile preparation of the new amides 10. The latter exerted a potent antiallergic activity when tested in the dermal vascular permeability and active anaphylaxis assays in rats. The most active compound 10b inhibited the action of serotonin, histamine, and bradykinin by 94, 92, and 100%, respectively, when administered intraperitoneally to rats at doses of 100 mg/kg. The present series of 10 represents a novel class of antiallergic agents.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700609
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  • 183
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    Notiz über die Verwendung von 3-(Arylsulfonyl)-2-cycloalkenonen als 2-Cycloalkinon-Synthese-Equivalente (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1537-1539 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Use of 3-(Arylsulfonyl)-2-cycloalkenones as Synthesis Equivalents of 2-Cycloalkynones3-(Arylsulfonyl)-2-cyclopentenones and 3-phenylsulfonyl-2-cyclohexnone undergo Diels-Alder reactions with cyclopentadiene. Elimination of arylsulfinic acid leads to products, which would have been obtained directly from a Diels-Alder reaction of 2-cyclopentynone or 2-cyclohexynone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700611
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  • 184
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    Inhibition of Electron-Hole Recombination in Substitutionally Doped Colloidal Semiconductor Crystallites (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1596-1604 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The subtitutional doping of 120-Å- sized TiO2 Particles with Fe(III)ions has a profound effect on the charge carrier recombination time in this colloidal semiconductor. In undoped particles, the mean lifetime of an electronhole pair is ca. 30 ± 15 ns. Doping with 0.5% Fe(III) drastically augments the charge-carrier lifetime which is extended to minutes or hours. The slow character of the recombination dynamics in Fe(III)-doped colloids was confirmed by laser photolysis using the characteristic optical of electrons in TiO2 to monitor the time course of the reaction. EPR studies showed the Fe(III) ions to enter the host lattice on Ti(IV) sites, charge compensation taking place through the formation of oxygen vacancies. Valence-band holes produced under band-gap excitation react with these centers it the bulk forming Fe(IV), the conduction band electrons being trapped by Ti(IV) at the particle surface. Presumably, the spatial separation of the trapped electron and hole sites inhibits their recombination.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700617
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  • 185
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    The Radical Anions of 1,2-diphenylcyclohexene and Structurally Related Compounds. Conformational ESR and ENDOR studies (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1558-1568 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ESR, ENDOR, and TRIPLE resonance studies have been performed on the radical anions of 1,2-diphenylcyclohex-1-ene (4), 1,2-di(perdeuteriophenyl)cyclohex-1-ene ((D10)4) the trans-configurated 3,4-diphenyl-8-oxabicyclo[4.3.0]non-3-ene (5) and its 2,2,5,5-tetradeuterio derivative (D4)5, and 2,3-diphenyl-8,9,10-trinorborn-2-ene (6). The spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} exhibit strong temperature dependence along with a specific broadening of ESR hyperfine lines and proton ENDOR signals. The coupling constant, which bears the main responsibility for these features, is that of the β-protons in the quasi-equatorial positions of the cyclohexene ring, and the experimental findings are readily rationlized in terms of relatively modest conformational changes without invoking the inversion of the half-chair form. The hyperfine data for the β-protons in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} closely resemble the corresponding low-temperature values for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document}, However, the ‘unusual’ features observed for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} are absent in the ESR and ENDOR spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document}, because the half-chair conformation of the cyclohexene ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} is deprived of its flexibility. Although the boat form of this ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} is also rigid, the spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} are temperature-dependent, due to an interconversion between two propeller-like conformations of the phenyl groups. The pertinent barrier is 30 ± 5 kJ·mol-1. An analogous interconversion presumably takes place in \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} as well, but, unlike \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document}, it is not amenable to experimental study.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700614
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  • 186
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    Synthesis and Formation of Ironcarbonyl Complexes of 3′,3′-Dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane]. Single-Crystal and Molecular Structure of syn,exo2,3-anti,endo5,6-trans-μ-[(1r,2r,3s,4s,5s,6r)-c,2,3,c-η:c,5,6,c-η-(3′,3′-dimethyl-2,3,5,6,-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane])]bis(tricarbonyliron)Interaction between non-conjugated chromophores, Part 27. Part 26, see [1]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1638-1648 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3′,3′-dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane] (3) was derived from 6,6-dimethylfulvene and maleic anhydride. Its reaction with 1 equiv. of ethylenetetracarbonitrile (TCNE) was not regioselective and gave a 1:1 mixture of the corresponding monoadducts 10 and 11. The rate constants of the Diels-Alder additions of 10 and 11 to TCNE were significantly smaller than that of the reaction 3 + TCNE. Monocomplexation of 3 with Fe2(CO)9 was highly exo-face selective giving a mixture of the corresponding monocomplexes 12(anti-exo) and 13(syn-exo). The latter were complexed with Fe2(CO)9 in a non-stereoselective fashion, giving mixtures of the dicomplexes 14(anti-exo, syn-endo), 15(anti-exo,syn-exo), and 16(anti-endo, syn-exo). Exchange of the CO ligands was a faster process for the endo-Fe(CO)3 moieties than for the exo-Fe(CO)3 moieties. Line-shape analysis of the 13C-NMR spectrum of 15 established that one of the exo-Fe(CO)3 groups in 15 rotates ca. 3 times as fast as the other Fe(CO)3 group at 40°. The structure of the anti-endo, syn-exo dicomplex 16 was determined by single-crystal X-ray diffraction studies.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700621
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  • 187
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    New Antifungal Chromenyl Ketones and their Pentacyclic Dimers from Hypericum revolutum VAHLPresented in part at the 34th Annual Congress on Medicinal Plant Research, Hamburg, FRG, 22-27 September, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1694-1702 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new 2H-1-benzopyranyl ketones 1 and 2 and three new pyrano[3,2-c: 4,5,6-d′ e′]di[1]benzopyrandiyl diketones 3, 4a/4b, and 5 have been isolated from the leaves and twigs of Hypericum revolutum VAHL (Guttiferae). The structure of 3 (hyperevoline) was established by X-ray analysis as 1,1′-[1,13,13a,13b-tetrahydro-5,8,10-trihydroxy-2,2,6,9,13,13-hexamethyl-2H, 7aH-pyrano[3,2-c:4,5,6-d′e′]di[1]benzopyran-4, 11-diyl]bis[2-methyl-1-propanone]. The structures of the isolated compounds were established by spectroscopic (UV, IR, EI-MS, 1H- and 13C-NMR) and chemical (acetylation and acidic dimerization) methods.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700705
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    Mammalian Alkaloids: Configurations of Optically Active Salsoline- and 3′,4′-Dideoxynorlaudanosoline-1-carboxylic AcidsSalsoline and norlaudanosoline are well known alkaloids, and these names will be used in the General Part (for systematic names, see Expert. Part). The systematic name for salsoline is 1-methyl-7-methoxy-1,2,3,4-tetrahydroisoquinolin-6-ol and that for norlaudanosoline, also named tetrahydropapaveroline, is 1-(3′,4′-dihydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1721-1731 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of the optical isomers of (±)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate ((±)-2) was accomplished by reaction of (±)-2 with (+)-(R)-1-phenylethyl isocyanate, separation of the urea diastereoisomers (-)-4A and (+)-4B, and alcoholysis of the ureas in refluxing BuOH. Optically active isoquinoline-carboxylates 2A,B and hydantoins 8A,B isolated were characterized. The absolute configuration of the reaction products was established by X-ray analysis of the optically active hydantoin (+)-8A. Hydrolysis of the methyl isoquinolinecarboxylates 2A,B with 48% HBr soln. at reflux afforded the desired optically active 3′,4′-dideoxynorlaudanosoline-1-carboxylic acids 1A,B required for enzyme-inhibition studies. Details of the X-ray diffraction analysis of (+)-methyl salsoline-1-carboxylate hydrobromide ((+)-11A·HBr) prepared earlier are included. CD spectra of (+)-(S)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate hydrobromide ((+)-2A. HBr) and (-)-(R)-methyl salsoline-1-carboxylate hydrochloride ((-)-11B·HCl) confirmed the assignment of their (S)- and (R)-configurations, respectively.
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    URL: http://dx.doi.org/10.1002/hlca.19870700707
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  • 189
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    Determination of the Quantum Yield of Intersystem Crossing of Rose Bengal (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1760-1773 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum yield of intersystem crossing (Φisc) of a sensitizer is related to the quantum yield of singlet-oxygen production (Φ(1O2)) by the efficiency of the energy transfer (ϕet) and is an important parameter in the evaluation of potential applications of sensitized photo-oxidations. Using two different laser photolysis techniques, the energy-transfer method and the partial saturation method, Φisc of rose bengal has been determined in MeOH and in aqueous solutions. The results confirm that with Φisc(H2O) = 1.05(± 0.06) and Φisc(MeOH)=0.90(±0.08), the generally assumed relation Φisc · ϕet = Φ(1O2), with ϕet = 1, cannot be maintained any longer (Φ(1O2, H2O) = 0.75 and Φ(1O2, MeOH) = 0.76). During these experiments, a second intermediate has been observed which is produced from the triplet state of rose bengal and, stabilized in a anionic micellar solution, has been shown to be the radical cation of the sensitizer. The efficiency of the electron transfer has been evaluated from transient absorption and bleaching recordings, and it seems conclusive to attribute the results to the difference between Φisc and Φ(1O2).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700712
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  • 190
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    ‘Face-to-Face’-Benzo-anellierte homologe Hypostrophene. Synthesen, Röntgenstrukturanalysen und PE-Spektren (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1816-1842 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ‘Face-to-Face’ Benzo-anellated Homologous Hypostrophenes. Syntheses, X-Ray-Structure Analyses and PE Spectra‘Face-to-face’ Benzo-anellated homologous hypostrophenes (series M), of interest as substrates for [6 + 6]-photocycloaddition reactions, have been synthesized. From X-ray structural analyses of 13b and 13c shortest C—C distances of 2.80(2.76)/2.71 Å and interorbital angles (ω) of 129° (128°)/130° between the benzene rings have been determined. The PE spectra are discussed in the context of transannular π,π interactions.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700718
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  • 191
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    Formation and Structure of the Phosphoranyl Radical Derived from 1,2-Phenylene Phosphorochloridate: a Solid-State ESR Study (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1897-1904 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of 1,2- phenylene phosphorochloridate has been determined. X-Ray irradiation of these crystals, at low temperature, leads to the formation of a radical exhibiting hyperfine structure with P and Cl nuclei. The corresponding ESR tensors are obtained, and they show that this radical is a phosphoranyl radical adopting a slightly distorded σ* structure. The same species could be produced in frozen solution, its hyperfine tensors are, then, more in accordance with a trigonal-bipyramid structure. The effects of the host matrix on the stabilization of the structure of phosphoranyl are investigated.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700724
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  • 192
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    Isolierung und Strukturaufklärung von 36 Diterpenoiden aus Trichomen von Plectranthus edulis (VATKE) T.T. AYE (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1911-1929 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation and Structure Elucidation of 36 Diterpenoids from Leaf-Glands of Plectranthus edulis (VATKE) T.T. AYEAnalysis of the polar diterpenoids from the yellow glands of the title plant from Kenya and Abyssinia led to the identification of several novel abietanoids. Main compound is the known edulon A (40), a 5(4→3) abeo-abietane. Minor compounds include 6 different royleanones, 15 spirocoleons, 3 vinylogous quinones, 8 acylhydroquinones (as their 6,7-dioxo compounds or the tautomeric disophenols), 2 naphthaquinones (as the 1,10-seco-abietanoids), and deacetyledulon A. The known coleon-A-lactone (37) now has also been found in Plectranthus edulis. The intermediacy of the γ-enollactol 44, combined with a leaving group on C(3) is postulted to explain the biogenesis of the unusual 4H-5-oxaaceanthrylen skeleton of edulon A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700726
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  • 193
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    Synthesis of trans-10,11-Dihydro-10,11-dihydroxy-5H-dibenz[b,f]azepine-5-carboxamide, a Major Metabolite of Carbamazepine (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1955-1962 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoselectivity of the reduction of 5-carbamoyl-10,11-dihydro-11-oxo-5H-dibenz[b,f]azepine-10-yl acetate (6), prepared in two steps from 10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide (4), has been studied. Among the reagents used, diisobutylaluminum hydride (DIBAH) was found to give the highest trans/cis diol ratio. This allowed the preparation of the important trans-diol metabolite 3 of carbamazepine (1).
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700730
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  • 194
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    Are the known Δ2-cephems inactive as antibiotics because of an unfavourable steric orientation of their 4α-carboxylic group? Synthesis and biology of two Δ2-cephem-4β-carboxylic acids (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1967-1979 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two representatives of the yet unknown type of Δ2-cephem-4β-carboxylic acids were prepared. Contrarily to the prediction based on the activity model of Cohen, both acids proved inactive as antibiotics. Possible reasons for this discrepancy are briefly discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700732
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  • 195
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    Isolierung von 10′-Apo-β-carotin-10′-ol und (3R)-10′-Apo-β-carotin-3,10′-diol (Galloxanthin) aus Rosenblüten. 5. Mitteilung über Rosenfarbstoffe1. bis 4. Mitt., s. [1-4]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1988-1993 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation of 10′-Apo-β-carotene-10′-ol and (3R)-10′-Apo-β-carotene-3,10′-diol (Galloxanthin) from Rose FlowersThe novel (all-E)-10′-apol-β-carotene-10′-ol (2) and (all-E,3R)-10′-apo-β-carotene-3,10′-diol (5) have been isolated from petals of one yellow species and various whitish or yellow blend varieties of rose cultivars. Each (all-E)-compound is accompanied by a (Z)-isomer, probably the (9Z)-isomer. Diol 5 proved to be identical with galloxanthin, an apo-10′-carotenol previously isolated from the retina of chicken.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700803
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  • 196
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    Nucleotides. Part XXVI.Part XXV: [1].. A new synthesis of 9-(′-D-ribofuranosyl)uric acid and its 5′-monophosphateDedicated to Professor Morio Ikehara, Osaka University, Osaka, Japan (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 210-218 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses for 9-(β-D-ribofuranosyl)uric acid (16) and its 5′-monophosphate 14 have been achieved starting from guanosine and applying the 2-(p-nitrophenyl)ethyl group for protection of the aglycon moiety as well as the phosphate function. A more efficient and direct approach to 14 uses O6, O8-dibenzyl protection and phosphorylation by the Yoshikawa procedure. The various protected intermediates have been characterized by spectroscopic means and elemental analysis.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700126
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  • 197
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    Erratum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 271-271 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700131
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  • 198
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    Intramolecular Cyclizations of Allenic Acylureas and -Amides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 262-270 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Allenic acids are found to add to dicyclohexylcarbodiimide affording, in the presence of Et2NH, the 4H-1,3-oxazin-4-ones 5 via 4. Under neutral conditions, they add to diaryl- or pyridyl(cyclohexyl)carbodiimides and triphenylketene imine to give the corresponding tricyclo[5.2.2.01,5]undeca-4,8,10-trien-3-ones 7, 8, 9, and 12. The allenic phenyl ester 13a dimerises, on heating in a [2+2] head-to-head fashion, to 14 but fails to undergo intramolecular Diels-Alder cyclization, to 15.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700130
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  • 199
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    Addition of Chiral Glycine, Methionine, and Vinylglycine Enolate Derivatives to Aldehydes and Ketones in the Preparation of Enantiomerically Pure α-Amino-β-Hydroxy Acids (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 237-261 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral enolates of imidazolidinones and oxazolidinones from the title amino acids react with carbonyl compounds to afford the corresponding alcohols in excellent yields (see Scheme 5). Furthermore, the addition to aldehydes proceeds with high diastereoselectivity to give, after acid hydrolysis, threo-α-amino-β-hydroxy acids of high enantiomeric purity. Some of the threo-α-amino-β-hydroxy acids prepared in this work are the proteinogenic (S)-threonine (26), the naturally occurring (S)-3-phenylserine (28), and (S)-3-hydroxyleucine (27) as well as the unnatural (S)-4,4,4-trifluorothreonine (30) and (S)-3-(4-pyridyl)serine (31). The N-methylamide of (2S,3R,4R,6E)-3-hydroxy-4-methyl-2-(methylamino)-6-octenoic acid (32), the unique amino acid in the immunosuppressive cyclosporine, was prepared by the new method. This report presents also information suggesting that both steric and stereoelectronic effects are responsible for the good stereoselectivities observed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700129
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  • 200
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 272-274 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700132
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