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  • 1985-1989  (620)
  • 1970-1974
  • 1960-1964
  • 1945-1949
  • 1900-1904
  • 1986  (620)
  • Organic Chemistry  (570)
  • Electron microscopy
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Years
  • 1985-1989  (620)
  • 1970-1974
  • 1960-1964
  • 1945-1949
  • 1900-1904
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Histopathology of otitis media with effusion (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 269-273 
    Details
    ISSN: 1434-4726
    Keywords: Otitis media with effusion ; Electron microscopy ; Human temporal bones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultrastructural studies of the middle ear mucosa appear to be of significant value in better understanding the pathology of otitis media with effusion (OME). Our present study was undertaken in order to take advantage of the use of electron microscopy in investigating all areas of the middle ear mucosa. Tissues studied were obtained from the fresh postmortem temporal bones of three patients with OME and terminal head and neck malignancies. In the mucoid type of effusion (cases 1 and 2), goblet cells were seen to proliferate and secretory activity was greatly enhanced. In contrast, there was no evidence of secretory cell proliferation in the serous type of effusion. It was noteworthy that accumulated fluid was not homogeneous in the same ear, as exemplified by case 1, in which both mucoid and serous effusions were present. This occurrence was possibly the result of topographic diversity involving the secretory activity of the middle ear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464444
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  • 2
    Electronic Resource
    Electronic Resource
    Experimental tympanosclerosis following infection with Streptococcus pyogenes and vitamin D3 intoxication (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 296-303 
    Details
    ISSN: 1434-4726
    Keywords: Experimental tympanosclerosis ; Induced calcifications ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A rat animal model was used to study the ultrastructure of submucosal calcifications induced in the middle ear following inoculation with Streptococcus pyogenes and high doses of parenteral vitamin D3. The morphological changes present in affected animals resembled the classical picture of tympanosclerosis. While calcification occurred about bacterial remnants and myelin structures, the most important calcification centers were lysosomal and non-lysosomal matrix vesicles in the extracellular spaces. These formed band-like calcifications close to the basal membrane without affecting the epithelial layer. This animal model offers the possibility of studying the effect of various therapeutic regimens in the treatment of the dynamic tympanosclerotic process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00460205
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  • 3
    Electronic Resource
    Electronic Resource
    Heterogeneity of circular mitochondrial DNA molecules from sugar beet with normal and male sterile cytoplasms (1986)
    Springer
    Current genetics 10 (1986), S. 695-700 
    Details
    ISSN: 1432-0983
    Keywords: Sugar beet ; Cytoplasmic male sterility ; Mitochondrial DNA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) DNAs from normal (N) and male sterile (S) cytoplasms of sugar been have been isolated and investigated by electron microscopy. The results showed that mtDNA was composed of a heterogeneous population of circular molecules. Their contour lengths varied from 0.28 to 51 μm, but unlike in the case of maize, a large difference was not observed in the distribution of molecular classes greater than 1.0 μm between N and S cytoplasms of sugar beet. On the other hand, N and S cytoplasms were shown to contain their own characteristic combinations of small circular mtDNA species with lengths between 0.28 μm and 0.6 μm. Mitochondrial DNAs from various sources of male-sterile cytoplasms were analyzed by agarose gel electrophoresis to determine the extent of cytoplasmic variation. Additional low molecular weight DNA bands appeared in all male-sterile lines examined, and as a result, three distinctive banding patterns were recognized. These data are in general agreement with those based upon restriction endonuclease digestion of mt and chloroplast DNAs and the genetic analysis of fertility restoration in test crosses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410918
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  • 4
    Electronic Resource
    Electronic Resource
    Alpha-subunit-producing pituitary adenomas (1986)
    Springer
    Virchows Archiv 409 (1986), S. 417-431 
    Details
    ISSN: 1432-2307
    Keywords: Pituitary neoplasms ; Pituitary hormones ; Immunocytochemistry ; Electron microscopy ; Alpha-subunit ; Acromegaly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunohistological techniques demonstrate the alpha-subunit of glycoprotein hormones in the majority of endocrine-inactive, undifferentiated pituitary adenomas and pituitary oncocytomas. In about one-fifth of endocrine-active adenomas, the alpha-subunit is produced in combination with either adrenocorticotropic hormone or prolactin, and it is found in combination with growth hormone in about half of those adenomas causing acromegaly. Pure alpha-subunit-producing, endocrine-inactive adenomas characteristically have small secretory granules that are destroyed by direct osmium fixation, but are well preserved after prefixation with glutaraldehyde. As only a few atypical prolactinomas show similar secretory granules, and as they display a positive reaction for the alpha-subunit only exceptionally, this ultrastructural feature can serve as a guide to differentiate such adenomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705414
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  • 5
    Electronic Resource
    Electronic Resource
    Frequency and diagnostic value of the virus-like filamentous intranuclear inclusions in giant cell tumor of bone, not associated with Paget's disease (1986)
    Springer
    Virchows Archiv 410 (1986), S. 65-68 
    Details
    ISSN: 1432-2307
    Keywords: Giant-cell ; Virus-like inclusion ; Intranuclear inclusion ; Giant cell tumour of bone ; Paget's disease of bone ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper deals with the paramyxovirus-like intranuclear inclusions observed in giant cells tumours of bone (GCTB). Twenty-one (49%) of 43 cases of GCTB (1977–1985), either fresh and/ or cultured, show these ultrastructural inclusions. Fifty samples of various bone lesions in which giant cell lesions occurred, including aneurysmal cysts, hyperparathyroidism, osteoblastoma, human and rat osteopetrosis, GCT of tendon sheaths, and non skeletal granuloma were used as controls. These, together with 20 samples of normal bone (osteoclasts) did not contain intranuclear or intracytoplasmic viral inclusions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00710907
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of experimental torsion of the spermatic cord on Leydig cell function in the guinea pig testis: An ultrastructural stereological analysis (1986)
    Springer
    Urological research 14 (1986), S. 253-256 
    Details
    ISSN: 1434-0879
    Keywords: Guinea pig ; Spermatic cord torsion ; Stereology ; Electron microscopy ; Leydig cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ultrastructural stereological analysis of Leydig cells of the guinea pig testis was carried out following surgically induced testicular torsion. Morphometric analyses of the Leydig cells of the experimental group of animals revealed an increase in the nucelar and mitochondrial volume and a decrease in the lipid volume, in comparison to those in the Leydig cells of the control group of animals. We believe that these changes in the Leydig cells of the experimental group of animals are indicative of cellular hypertrophy. The possible mechanisms of the Leydig cell hypertrophy in the guinea pig testis following the induction of spermatic cord torsion are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256568
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructural abnormalities in muscular vessels of hyperthyroid patients (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 64-69 
    Details
    ISSN: 1432-0533
    Keywords: Muscular diseases ; Capillar pathology ; Grave's disease ; Hyperthyroidism ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary an electron microscope study of needle biopsies from the quadriceps muscle was carried out in 11 non=selected patients (ten females and one male), with clinically and laboratory-diagnosed hyperthyroid disease. Alterations of the normal structure of muscle fibres were found in all cases. Changes in capillaries were found in ten patients, and ranged from an increase in basement membrane thickness with reduplication, to total destruction of the capillaries. The importance of the vascular involvement in the muscles of patients with Graves-Basedow disease is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687963
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  • 8
    Electronic Resource
    Electronic Resource
    Proliferating potential of folliculo-stellate cells in human pituitary adenomas (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 233-242 
    Details
    ISSN: 1432-0533
    Keywords: Folliculo-stellate cell ; Pituitary adenoma ; Glial fibrillary acidic protein ; S-100 protein ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Folliculo-stellate cells (FS cells) in 40 pituitary adenomas and portions of anterior pituitary adjacent to the tumor in 26 cases were investigated immunohistochemically, using polyclonal antisera to S-100 protein (S-100) and glial fibrillary acidic protein (GFAP). The objective was to clarify the histological behavior of the FS cells. In most pituitary adenomas there were few or no S-100-or GFAP-positive cell, in comparison with numerous positive cells in the parts of the adenohypophyses compressed by adenomas. However, positive FS cells were observed in some types of pituitary adenomas. Growth hormone and prolactin producing adenomas frequently contained significant amounts of FS cells. In non-functioning adenomas, an unique case of FS cell adenoma was present. The adenoma was composed mainly of FS cells and immature glandular cells. The FS cells were sometimes located around follicles containing Periodic acid Schiff-positive material. Therefore, the FS cell adenoma is characterized by S-100- and GFAP-positive FS cells and PAS-positive follicles. In this type of adenoma, FS cells seemed to be the main proliferating component. In parts of the adenohypophyses adjacent to the adenomas, GFAP0-positive FS cells were numerous. In the pathological conditions FS cells may possess the potential of reactive proliferation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688045
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  • 9
    Electronic Resource
    Electronic Resource
    The distribution of Ia antigen in the lesions of rat acute experimental allergic encephalomyelitis (1986)
    Springer
    Acta neuropathologica 70 (1986), S. 149-160 
    Details
    ISSN: 1432-0533
    Keywords: Ia antigen ; Central nervous system ; Experimental allergic encephalitis ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ia antigen, encoded within the major histocompatibility complex, plays an important role in the activation of T lymphocytes. Since experimental allergic encephalitis is an essentially T cell-mediated disease, Ia antigen in the central nervous system (CNS) may be pathogenetically relevant. The occurrence of Ia antigen in the CNS of normal rats and of rats with experimental allergic encephalitis was studied by light and electron microscope immunocytochemistry using the monoclonal anti-Ia antibodies Ox 4 and Ox 6. In normal, unsensitized animals a distict population of stellate cells in the meninges and some perivascular mononuclear cells in the nervous tissue carried Ia antigen. In rats with experimental allergic encephalitis a dramatic increase of Ia-positive cells was found. In addition to the positive cells found in normal animals, monocytes, macrophages and many lymphocytes in the meningeal perivascular and parenchymal inflammatory infiltrates as well as “activated microglia” stained for Ia antigen. We did not find evidence for Ia expression on endothelial cells, astrocytes or other components of the CNS in either normal or diseased rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691433
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  • 10
    Electronic Resource
    Electronic Resource
    Transplantation of Pacinian corpuscles of the rat into the brain (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 314-321 
    Details
    ISSN: 1432-0533
    Keywords: Pacinian corpuscles ; Transplantation to the brain ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In adult inbred rats of the AVN strain, branches of the crural interosseous nerve were dissected out from donors and transplanted into the brain of recipients, together with a cluster of Pacinian corpuscles, (either into a suction cavity or the cerebral cortex) into a slit 1–2 mm deep. The grafts were fixed and processed for electron microscopy 10 days to 6 months after the operation, and their ultrastructure was examined. Sporadic axons of small diameter grew into the nerve branches of some of the grafts from 11 days onward, and became myelinated during the 2nd month after the operation, but none of the transplanted Pacinian corpuscles became reinnervated. The corpuscles, however, survived denervation and grafting. Most of them retained a well-preserved inner core and an intact capsule, consisting of a normal complement of 29.2±1.0 (mean ±SE) capsular layers (n=8), as did the corpuscles previously examined after denervation in situ. Some of the corpuscles underwent degenerative changes, presumably due to a delayed or restricted revascularization. In this group of corpuscles, the inner core underwent disintegration and was gradually replaced by collagen fibrils, whereas the capsule remained preserved but the number of its layers eventually reduced by 40%. It is assumed that the lack of reinnervation of the grafted Pacinian corpuscles was due to the paucity of regenerating axons, and their failure to form correct projections along those Schwann cell columns connected with the corpuscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688310
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  • 11
    Electronic Resource
    Electronic Resource
    Intercellular deposits of basement membrane material in active human pituitary adenomas detected by immunostaining for laminin and electron microscopy (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 326-331 
    Details
    ISSN: 1432-0533
    Keywords: Pituitary adenoma ; Basement membrane ; Laminin ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thirty-eight human pituitary adenomas (24 endocrine active and 14 endocrine inactive tumors) were studied immunohistochemically for the presence of the basement membrane component, laminin, and ultrastructurally for the presence of basement membrane. Immunoreactivity of laminin delineated staining of epithelial and endothelial basement membranes, the reaction product being confined mostly to the perivascular zones. Moreover, a hitherto undescribed presence of intercellular laminin-positive droplets was observed in ten of the active adenomas (nine patients with hyperprolactinemia and/or acromegalia and one patient with Cushing's syndrome). Concurrently, at the ultrastructural level, bunches of basement membrane-like material intermingled between the adenoma cells were demonstrated in seven of these ten active adenomas. Furthermore, secretory granules were entrapped occasionally in this intercellular matrix, indicating a mutual dependence between excessive hormone extrusion and an increase of “misplaced” deposits of basement membrane components, e.g., laminin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688057
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  • 12
    Electronic Resource
    Electronic Resource
    Astroblastoma revisited: A report of three cases (1986)
    Springer
    Acta neuropathologica 70 (1986), S. 10-16 
    Details
    ISSN: 1432-0533
    Keywords: Astroblastoma ; Immunohistopathology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The very existence of astroblastoma has been a question of considerable controversy, although there appears now to be sufficient documentation to establish it as a tenable entity. Due to the rarity of this tumor, little information exists in the literature as to its natural history, efficacy of therapy and its pathological and radiological appearance. We report three cases of astroblastoma, describing their natural history, the response to therapeutic interventions and their light microscopic, ultrastructural and immunohistochemical characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689508
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  • 13
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of S-100 protein in neurofibroma (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 103-110 
    Details
    ISSN: 1432-0533
    Keywords: Neurofibroma ; von Recklinghausen's disease ; S-100 protein ; Electron microscopy ; Immunoelectron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The nature of the cells in neurofibromas was studied by electron microscopy and immunoelectron-microscopic examination of S-100 protein. Ultrastructurally, all five neurofibromas studied were found to be composed of Schwann cells, perineurial cells, and intermediate cells, which had features of both perineurial cells and fibroblasts. The Schwann cells had complex, branched cytoplasmic processes and a continuous basal lamina. The perineurial cells were distinguishable from Schwann cells by the presence of numerous pinocytotic vesicles, unbranched slender cytoplasmic processes and a discontinuous basal lamina. The intermediate cells had no basal lamina, but were topographically related to Schwann cells and had a similar fine structure to that of perineurial cells. Thus, they seemed to be modified neoplastic perineurial cells. Immunoelectron-microscopic studies showed the presence of cells with and without S-100 protein in the neurofibromas: cells with S-100 protein resembled Schwann cells ultrastructurally, and those without S-100 protein were perineurial and intermediate cells. Some Schwann cells with S-100 protein in one neurofibroma had numerous pinocytotic vesicles characteristic of perineurial cells, suggesting that Schwann cells and perineurial cells, are functional variants of the same cell type. Thus this study showed that neurofibromas were composed of Schwann cells with S-100 protein and perineurial and intermediate cells, including socalled endoneurial fibroblasts, without S-100 protein. Morphological and functional transition seems to occur between Schwann cells and perineurial cells, and between perineurial cells and intermediate cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687045
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  • 14
    Electronic Resource
    Electronic Resource
    Farber's disease in two siblings, sural nerve and subcutaneous biopsies by light and electron microscopy (1986)
    Springer
    Acta neuropathologica 72 (1986), S. 178-188 
    Details
    ISSN: 1432-0533
    Keywords: Farber's disease ; Peripheral nerve ; Subcutaneous nodules ; Electron microscopy ; Ceramidase deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two siblings born from consanguineous tunisian parents are reported. They showed a severe form of Farber's disease with prominent involvement of the central and peripheral nervous system: low conduction velocity was noticed in both children. Macular cherry red spots were observed in one of them. The diagnosis for the girl investigated was confirmed by evidence of ceramidase deficiency in cultured fibroblasts. Here we report the pathological findings in the subcutaneous nodules using light and electron microscopy (one case), and in sural nerves using morphometric studies (both cases). Varying morphological aspects of intracellular inclusions, depending on the tissues involved, are described and discussed. A review of all cases reported since Farber's first paper in 1952 is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685981
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  • 15
    Electronic Resource
    Electronic Resource
    Minisegments of newborn rat optic nerves in vitro: gliogenesis and myelination (1986)
    Springer
    Experimental brain research 65 (1986), S. 189-199 
    Details
    ISSN: 1432-1106
    Keywords: Rat optic nerve ; Gliogenesis ; Myelination ; In vitro ; In vivo ; Electron microscopy ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The question of whether the development of CNS glial cells requires the presence of axons or not can be studied with in vitro systems. In order to compare the differentiation of glial cells during development in vitro with that in situ, we have selected the optic nerve, which is anatomically as well as histotypically a well defined structure. For the in vitro investigations, small explants, called minisegments, of newborn rat optic nerves were cultivated taking four major conditions into account: (1) the regular size of the minisegments should guarantee a permanent exchange of the culture medium in order to avoid cell death, (2) neither mechanical nor enzymatic dissociation of the tissue were applied, (3) the minisegments were explanted into flasks without substrate for cell adhesion and (4) the minisegments were under constant gyratory agitation. The following in situ results were obtained: optic nerves of newborn rats are morphologically characterized by the presence of naked axons, astrocytes, glial precursors, and the absence of both differentiated oligodendrocytes and myelin. At postnatal day 5 myelin sheaths are still absent. Two weeks after birth, differentiated oligodendrocytes and microglial cells are present and numerous axons are surrounded by compact myelin. The in vitro experiments show the following main results, which were obtained after 14 h, 2 d, 5 d and 14 d in culture: during time in culture, the shape of minisegment of newborn rat optic nerves undergoes drastic changes, which indicate high cellular dynamics. After 14 h in vitro, axonal profiles, cells with pyknotic nuclei as well as clusters of astrocytes and glial precursors are present. After 2 days in culture the axonal profiles disappeared and the number of degenerating cells decreased drastically. Many large cells, probably phagocytes containing inclusions and more cells are differentiated. At the stage of 5 d in vitro 4 major types of cells can be distinguished: differentiated oligodendrocytes, which form compact and loose myelin, astrocytes, large and small glioblasts and phagocytes. Immunoprecipitates for myelin basic protein and/or myelin associated glycoprotein were found in oligodendrocytes, in their processes and associated to the myelin. Processes of some astrocytes showed immunoreactive products of glial fibrillary acidic protein. After two weeks in culture, the minisegments were mostly composed of astrocytes, whereas oligodendrocytes became rare and phagocytes disappeared. It can be concluded that CNS glial cells can attain their structural and immunocytochemical characteristics in the total absence of neuronal cell bodies and axons. However, it can be speculated that neurons (or neuronal factors) could regulate the number of astrocytes and oligodendrocytes and keep these glial cells in a physiological equilibrium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00243842
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  • 16
    Electronic Resource
    Electronic Resource
    A paediatric case of sideroblastic anaemia (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 422-427 
    Details
    ISSN: 1432-1076
    Keywords: CFU-E ; BFU-E ; Electron microscopy ; Sideroblastic anaemia ; Dyserythropoiesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined the morphological and functional characteristics of erythroblasts derived from marrow erythroid progenitor cells grown in a methylcellulose microculture, which were taken from a female child with rate atypical sideroblastic anaemia (SA) partially responsive to pyridoxine. Colony formation was within the normal range in three successive cultures (median values: 82.25 CFU-E and 16.4 BFU-E derived colonies/6.6×104 cells) compared to growth by normal cells (65-315 CFU-E and 9-40 BFU-E). We evaluated in vitro differentiation by biochemical microassay of a cytosol enzyme involved in the haeme pathway: uroporphyrinogen I synthase (UROS). The UROS values in the erythroid colonies from SA marrow were at the lower end of the normal range (median values: 6.7±0.3 and 14.4±3.8 pmol uroporphyrinogen/h in CFU-E and BFU-E-derived colonies respectively versus 17.4±7.3 and 25±7.2 pmol/h in CFU-E and BFU-E colonies from normal subjects. Ultrastructural examination of the SA erythroblasts from non-cultured bone marrow or derived from cultured BFU-E revealed the characteristic deposition of iron in mitochondria around the nucleus of most cells (ringed sideroblasts). However, the majority of cultured cells had marked dyserythropoietic featuress, with a large number of bilobulated or trilobulated crythroblasts, multiple cytoplasmic vacuoles, numerous abnormalities of the nucleus, and excessive membrane material beneath the plasma membrane, all features difficult to observe in non-cultured marrows.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00439253
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  • 17
    Electronic Resource
    Electronic Resource
    Cytomorphological changes in liver cells exposed to allyl and benzyl isothiocyanate and their cysteine and glutathione conjugates (1986)
    Springer
    Archives of toxicology 59 (1986), S. 103-110 
    Details
    ISSN: 1432-0738
    Keywords: Cytotoxicity ; Cell morphology ; RL-4 hepatocyte ; Electron microscopy ; In vitro study ; Allyl isothiocyanate ; Benzyl isothiocyanate ; Tert-butylhydroperoxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since allyl isothiocyanate has been reported to be a bladder carcinogen and benzyl isothiocyanate is a known anti-carcinogen, it is important to know the mode of their cytotoxic action. This was investigated in a RL-4 hepatocyte cell line by studying the morphological effects of increasing concentrations of the isothiocyanates and their glutathione and cysteine conjugates. These effects were compared with those induced by tert-butylhydroperoxide which supposedly has its primary effect upon the cytosolic glutathione status and thus upon the integrity of Ca2+-sequestrating mitochondria. The results agree with the previously postulated role of conjugation in the exposure of cells to isothiocyanates: Conjugates show effects similar to those produced by the free parent compounds because conjugates release free isothiocyanates in aqueous solution. The cytomorphological effects increase in a more or less dose-dependent manner with increasing concentrations of isothiocyanate or exposure time. Probably due to increased exposure, suspended RL-4 cells are more sensitive to the toxic action than cells growing on a substrate. No qualitative differences were found between the effects of allyl and benzyl isothiocyanate, indicating that their different effects in vivo are perhaps related to organ-specific differences in equilibrium between the conjugated and unconjugated forms of the test substances. The first cytomorphological effects of isothiocyanates consist of surface blebbing (zeiosis) and swelling of dictyosomal cisternae. At higher concentrations swelling extends to vesicles of endoplasmic reticulum. Mitochondria are not affected until the cells reach the necrotic phase of injury. In contrast, tert-butylhydroperoxide causes mitochondrial damage in an early pase of toxic injury. The cellular symptoms suggest that the primary target of isothiocyanates is in the plasma membrane and the cellular membrane system, affecting the monovalent cation and water balance of the cell organelles rather than the Ca2+ homeostasis as in cells exposed to tert-butylhydroperoxide. Differences in lipophilicity may be at the basis of this differenc in primary action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00286732
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  • 18
    Electronic Resource
    Electronic Resource
    An electron microscopic study of cerebral vasospasm with resultant myonecrosis in cases of subarachnoid haemorrhage, meningitis and trans-sylvian surgery (1986)
    Springer
    Journal of neurology 233 (1986), S. 348-357 
    Details
    ISSN: 1432-1459
    Keywords: Cerebral vasospasm ; Myonecrosis ; Myofilament ; Calcium ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopic data on the development of myonecrosis following cerebral vasospasm associated with subarachnoid haemorrhage, meningitis and trans-sylvian surgery are presented. The basic feature of myonecrosis was dissolution of myofilaments with resultant fine granular or filamentous material. The disintegrating cytoplasm often contained numerous glycogen granules, dense bodies, autophagic vacuoles and myelin-like membranous bodies. A well-developed sarcoplasmic reticulum was preserved despite myofilament dissolution, while mitochondria showed marked sweling. The nuclei showed either dilution of chromatin or pyknotic change. The basal lamina was remarkably thickened and maintained an irregular outline of the necrotic smooth muscle cells. Enlarged intercellular space contained abundant cellular debris, vesicular structures and connective tissue fibres. The pathogenesis of these changes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313921
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  • 19
    Electronic Resource
    Electronic Resource
    A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris (1986)
    Springer
    Archives of microbiology 146 (1986), S. 267-274 
    Details
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Ectothiorhodospira ; Serial thin sectioning ; Three dimensional reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous “bridges”. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403228
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  • 20
    Electronic Resource
    Electronic Resource
    Role of relA mutation in the survival of amino acid-starved Escherichia coli (1986)
    Springer
    Archives of microbiology 143 (1986), S. 400-402 
    Details
    ISSN: 1432-072X
    Keywords: E. coli relA +/relA ; Starvation survival ; Guanosine tetraphosphate ; Electron microscopy ; Glycogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amino acid-starved cells of Escherichia coli relA +, which contain a large number of glycogen particles, are able to survive in phosphate buffer for a longer time period than their relaxed counterparts. With regard to NH 4 + starvation differences in the survival of both strains were not found. NH 4 + starved cells of E. coli relA are able to synthesize glycogen but amino acid-starved cells of the relA strain are not. We suggest that the synthesis of glycogen triggered by guanosine tetraphosphate during amino acid starvation is responsible for the prolonged viability of the E. coli relA + strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00412809
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  • 21
    Electronic Resource
    Electronic Resource
    Bradyrhizobium japonicum mutants defective in root-nodule bacteroid development and nitrogen fixation (1986)
    Springer
    Archives of microbiology 144 (1986), S. 355-366 
    Details
    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409885
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  • 22
    Electronic Resource
    Electronic Resource
    Pathogenesis of pulmonary fibrosis induced by chrysotile asbestos (1986)
    Springer
    Virchows Archiv 408 (1986), S. 329-346 
    Details
    ISSN: 1432-2307
    Keywords: Pulmonary fibrosis ; Asbestosis ; Chrysotile ; Macrophages ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A single instillation of 1 mg chrysotile B with a fiber length between 0.05 and 0.2 µm in 0.1 ml tricaprylin was made via a polyvinyl catheter into the lower lobe of the right lung of 120 six-week-old Wistar rats under anesthesia. The animals were killed at intervals between five minutes and two years. The lower lobes of the right lung were investigated by light and electron microscopy. The process of pulmonary fibrosis induced by asbestos can be subdivided into four phases: these are the phase of phagocytosis (five to 15 min), the phase of granuloma formation (between one and two weeks), the phase of septal fibrosis (between two and six months) and finally the scar stage (after one year). After instillation of small asbestos fibers into the alveoli, a major proportion of these fibers is phagocytosed by alveolar macrophages after five minutes and leaves the lungs via the airways. A proportion of the fibers penetrates through the alveolar wall (mostly conveyed by type I pneumocytes) and reaches the interstitium of the lungs. There, the fibers are taken up by pulmonary tissue macrophages and giant cells. Within the phagolysosomes, the fibers are broken down into fragments less than 0.01 µm in length. Type II pneumocytes produce surfactant in excess. These cells become necrotic, tubular myelin and lamellar bodies pass into the alveoli and into the interstitium. Surfactant is phagocytosed by resident macrophages. These macrophages phages can break down. Besides asbestos and surfactant, mediators of fibrillogenesis are released. Macrophages following up from blood monocytes ingest surfactant and asbestos. This process is perpetuated up to complete scarring. After two years, small asbestos fibers less than 0.01 µm long are present in fibroblasts and pleural mesothelia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707692
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  • 23
    Electronic Resource
    Electronic Resource
    Diversity of Vicia faba circular mtDNA in whole plants and suspension cultures (1986)
    Springer
    Theoretical and applied genetics 72 (1986), S. 541-547 
    Details
    ISSN: 1432-2242
    Keywords: Mitochondrial DNA of plants ; Electron microscopy ; Suspension culture ; Vicia faba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A comparative analysis of the Vicia faba mitochondrial genome in whole plants and in longterm suspension culture has been conducted. Restriction fragment patterns of the mtDNA isolated from these two sources were notably different. Electronmicroscopic analysis also revealed significant differences. Large circular mtDNA patterns shifted from a 37–80 kb subpopulation, which was predominant in whole plants, to 18–34 kb subpopulations although in both classes notable quantities of circular molecules of 80 to 120 kb and more were also found. Both in whole plant and suspension culture cells very large circular DNAs were observed. Some of them had lengths nearly 290 kb and could be considered as evidence of the existence of master chromosomes. The minicircular DNA population was also altered. In the suspension culture we observed a notable increase of percentage of minicircles with sizes near 1 kb. Simultaneously, the percentage of minicircles with sizes near 3.5–10 kb significantly increased in suspension culture cells. In addition, a new peak (10–12 kb) of minicircles appeared. Copy number alterations for some sequences homologous to CCC1A, CCC1B and CCC2 (Negruk et al. 1982, 1985) were shown. Southern hybridization revealed the existence of a family of minicircles having sizes 1.4–2 kb with predominance of CCC1A, CCC1B and CCC2. The copy numbers of CCC1B and some minor minicircles was changed in the suspension culture when compared with the whole plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00289538
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  • 24
    Electronic Resource
    Electronic Resource
    Lipokeratinocytes of the epidermis of a cetacean (Phocena phocena) (1986)
    Springer
    Cell & tissue research 244 (1986), S. 385-394 
    Details
    ISSN: 1432-0878
    Keywords: Cetaceans ; Lamellar bodies ; Epidermal lipids ; Permeability barrier ; Electron microscopy ; Phocena phocena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Biochemical and ultrastructural analysis of epidermis from the porpoise, Phocena phocena, revealed certain similarities and differences between cetaceans and terrestrial mammals. The predominant cell of cetacean epidermis, not found in normal terrestrial mammals, is a lipoker-atinocyte, which elaborates not only keratin filaments, but also two types of lipid organelles: first, lamellar bodies, morphologically identical to those of terrestrial mammals, are elaborated in great abundance in all suprabasal epidermal layers, forming intercellular lipid bilayers in the stratum corneum interstices: and second, non-membrane-bounded droplets appear and persist in all epidermal layers. Although the porpoise lipokeratinocyte morpologically resembles the sebokeratocyte of avians in certain respects, nonmembrane-bounded lipid droplets are not released into the intercorneocyte space as they are in avian stratum corneum. Whereas phospholipid/neutral lipid gradients are similar in porpoise and terrestrial mammals, PAS-positive glycoconjugates, specifically glycosphingolipids, are retained in porpoise stratum corneum, but lost from these layers in terrestrials. The novel, non-polar acylglucosyl-ceramides, which also are lost during cornification in terrestrial mammals, are retained in porpoise stratum corneum. The lipid components of porpoise lipokeratinocytes appear to subserve not only barrier function in a hypertonic milieu, but also underlie the unique buoyancy, streamlining, insulatory, and caloric properties exhibited as adaptations to the cetacean habitat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219214
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  • 25
    Electronic Resource
    Electronic Resource
    Collagen remodeling during decidualization in the mouse (1986)
    Springer
    Cell & tissue research 244 (1986), S. 443-448 
    Details
    ISSN: 1432-0878
    Keywords: Collagen ; Uterus ; Decidua ; Mouse ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural study of the features and distribution of collagen fibrils was performed in the endometrium of virgin and pregnant (2nd to 11th day) mice. Collagen-containing structures were observed in the cytoplasm of fibroblasts on the 2nd day of pregnancy. Treatment of tissues with lanthanum nitrate established that these structures were intracytoplasmic. Their association with lysosome-like bodies suggested the occurrence of intracellular digestion of collagen, probably connected with remodeling of the endometrial stroma prior to decidualization. On the 4th day of pregnancy, very few collagen fibrils were present in the intercellular space. From the 6th day of pregnancy onwards, “thick” collagen fibrils were observed between decidual cells. The diameter of these fibrils measured up to 300 nm whereas the fibrils present in the endometrium of virgin mice measured 40–68 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219220
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  • 26
    Electronic Resource
    Electronic Resource
    Culture of intramural cardiac ganglia of the newborn guinea-pig (1986)
    Springer
    Cell & tissue research 244 (1986), S. 605-612 
    Details
    ISSN: 1432-0878
    Keywords: Heart innervation ; Tissue culture ; Autonomic ganglia ; Non-neuronal cells ; Cell interrelationships ; Electron microscopy ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study describes the ultrastructure of non-neuronal cells and their interrelationships with intracardiac neurones present in cultures dissociated atria and interatrial septum from newborn guinea-pig. When compared with the in situ preparation, most of these features in culture were similar to those observed in situ, but some differences were also apparent. Both mature and immature Schwann cells were observed in culture, and as in situ, the latter were closely associated with intracardiac neurones, whilst the former were more widely separated. The ultrastructure of satellite cells was more variable in culture than in situ: three general types were distinguished on the basis of their 10-nm filament content. This variation could be due to conditions of culture. Interstitial cells were present in culture and closely resembled those described in situ, although there was less space between cultured interstitial cells and their associated cells. Many fibroblasts, some myoblasts and a few mast cells were also found in the culture preparations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212540
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  • 27
    Electronic Resource
    Electronic Resource
    Culture of intramural cardiac ganglia of the newborn guinea-pig (1986)
    Springer
    Cell & tissue research 244 (1986), S. 595-604 
    Details
    ISSN: 1432-0878
    Keywords: Heart innervation ; Tissue culture ; Autonomic ganglia ; Neurones ; Small granule-containing cells ; Electron microscopy ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of cultured intrinsic neurones and SIF (small intensely fluorescent) cells dissociated from the atria and interatrial septum of newborn guinea-pig heart has been studied for the first time and compared with these cells in situ. Mononucleate and binucleate neuronal somata and their processes were observed in the culture preparation; their ultrastructure was similar to that of neurones in intracardiac ganglia observed in situ. The number of neurites associated with neuronal cell bodies increased after the first week in culture. A subpopulation of intracardiac neurones showed abnormalities in culture, comparable to the changes previously described in neurones of the monkey heart after unilateral vagotomy in situ. Small granule-containing cells were observed in culture, corresponding to those described in the heart in situ. One type of large process in the culture preparation containing densely packed mitochondria has not been seen in situ, suggesting that changes in cell ultrastructure due to the conditions of culture cannot be discounted. However, the ultrastructure of the cultured cells was, for the most part, consistent with that of the same cell type in situ, indicating that the culture preparation may be a useful model for investigation of the roles and interactions of intramural neurones in the heart, which are inaccessible for such studies in situ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212539
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  • 28
    Electronic Resource
    Electronic Resource
    Morphological evidence for the existence of a more complex cytoskeleton in Amoeba proteus (1986)
    Springer
    Cell & tissue research 246 (1986), S. 163-168 
    Details
    ISSN: 1432-0878
    Keywords: Cytoskeletal organization ; Filaments ; Triton extraction ; Replica technique ; Electron microscopy ; Amoeba proteus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Various stabilization and extraction procedures were tested to demonstrate the ultrastructural organization of the cytoskeleton in normal, locomoting Amoeba proteus. Most reliable results were obtained after careful fixation in glutaraldehyde/lysine followed by prolonged extraction in a polyethylene glycol/Triton X-100 solution. Before dehydration in a graded series of ethanol and critical-point drying, the amoebae were split by the sandwich-technique, i.e., by mechanical cleavage of cells mounted between two poly-L-lysine-coated glass slides. Platinum-carbon replicas as well as thin sections prepared from such cell fragments revealed a cytoskeleton composed of at least four different types of filaments: (1) 5–7-nm filaments organized as a more or less ordered cortical network at the internal face of the plasma membrane and probably representing F-actin; (2) 10–12-nm filaments running separately or slightly aggregated through the cytoplasm and probably representing intermediate filaments; (3) 24–26-nm filaments forming a loose network and probably representing microtubules; and (4) 2–4-nm filaments as connecting elements between the other cytoskeleton constituents. Whereas microfilaments are responsible for protoplasmic streaming and other motile phenomena, the function of intermediate filaments and cytoplasmic microtubules in amoebae is still obscure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219013
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  • 29
    Electronic Resource
    Electronic Resource
    Structure and development of the surface coat of erythrocytic merozoites of Plasmodium knowlesi (1986)
    Springer
    Cell & tissue research 245 (1986), S. 281-290 
    Details
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Malaria parasites ; Merozoites ; Surface coat ; Maturation ; Plasmodium knowlesi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface of extracellular merozoites of P. knowlesi is covered with a coat 15–20 nm thick, made up of clusters of filaments standing erect on the plasma membrane. Filaments have stems 2 nm thick, the peripheral ends of which are complex, branching or ending in long trailing threads. Coat filaments occur on the surface of the parasite in regular rows at an early schizont stage, and persist until well after merozoite release. They are sensitive to trypsin and papain, and bind ethanolic phosphotungstate, indicating a proteinaceous nature. They are also removed by exposure to phosphate-buffered saline. Filaments bear negative charges, binding cationised ferritin throughout the depth of the coat and staining with ruthenium red. They cover the whole merozoite surface and mediate intercellular adhesion at distances of 15–150 nm, membrane to membrane. It is suggested that these filaments correspond to a major merozoite surface protein, and are important in the initial capture of red cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213933
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  • 30
    Electronic Resource
    Electronic Resource
    Nephridial innervation in the leech Hirudo medicinalis L. (1986)
    Springer
    Cell & tissue research 245 (1986), S. 397-404 
    Details
    ISSN: 1432-0878
    Keywords: Leech ; Nephridium ; Innervation ; Electron microscopy ; Cobalt filling ; Hirudo medicinalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The main organs for salt and water homeostasis in the medicinal leech, the nephridia, were found to be densely innervated by a single branch of the corresponding median anterior segmental nerve. The projections of two different neurons into the nephridia are described: 1. Dendritic projections of the previously identified, afferent ‘nephridial nerve cell’, a possible salt receptor, lie between the urine forming cells and the blood vessels supplying the nephridium without making any contact. 2. Projections of an unidentified neuron which contains dense-core vesicles (85 nm) as well as smaller clear vesicles (45 nm) contact the primary urine forming canaliculus cells. The neurosecretory role of these neurons is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213947
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  • 31
    Electronic Resource
    Electronic Resource
    The coxo-trochanteral muscle receptor organ of locusts (1986)
    Springer
    Cell & tissue research 243 (1986), S. 517-524 
    Details
    ISSN: 1432-0878
    Keywords: Muscle receptor organ ; Electron microscopy ; Tubular body ; Mechanosensory transduction ; Locust, Locusta migratoria migratorioides (R.&F.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The coxo-trochanteral muscle receptor organ of the hind leg of the locust Locusta migratoria migratorioides (R.&F.) has been investigated by use of scanning and transmission electron microscopy with special emphasis on its distal attachment site. The overall morphology of the receptor muscle, the sensory neuron and its dendrites was found to share many common features with other arthropod sense organs of that type with two important differences: (1) the connective tissue segment (= intercalated tendon) is extremely short compared to that of other muscle receptor organs; (2) the naked dendritic terminals of the non-ciliated, multipolar sensory neuron of the organ contain clusters of microtubules, interconnected by an amorphous matrix, that resemble the tubular bodies of ciliated, epithelial receptor cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218058
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  • 32
    Electronic Resource
    Electronic Resource
    The hypothalamo-hypophysial system of the frog Rana temporaria (1986)
    Springer
    Cell & tissue research 243 (1986), S. 649-654 
    Details
    ISSN: 1432-0878
    Keywords: Median eminence ; Peptidergic projections ; Aminergic projections ; Electron microscopy ; Autoradiography ; Frog (Rana temporaria)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The median eminence (ME) of the adult frog, Rana temporaria, was studied by means of electron microscopy including quantitative electron-microscopic autoradiography. In frogs captured in May and June numerous peptidergic neurosecretory fibres extending via the internal zone to the pars nervosa display large swellings containing few granules, mitochondria, neurotubules and cisternae of the smooth endoplasmic reticulum. In addition, few secretory globules up to 1.5 μm in diameter occur in these varicosities. In animals collected during the autumn period many of these neurosecretory swellings filled with neurosecretory granules and polymorphic inclusions resemble Herring bodies. Three types of granule-containing neurosecretory fibres were observed in the external zone (EZ) of the ME of adult R. temporaria. Peptidergic A1- and A2-type fibres are characterized by granules 150–220 nm and 100–160 nm in diameter, respectively. Monoaminergic fibres of type B with granules approximately 100 nm in diameter represent ∼ 50% of all neurosecretory elements in the EZ of the frog ME; ∼12% of the total number of granule-bearing axons in the EZ actively taking up radiolabelled 5-hydroxytryptophan are thought to be serotoninergic terminals. Neurosecretory terminals of all types and glial vascular endfeet establish direct contacts with the perivascular space of the primary portal capillaries. Some neurosecretory terminals are separated from the lumen of the third ventricle by a thin cytoplasmic lamella of tanycytes. The possible physiological significance of this structural pattern is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218074
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  • 33
    Electronic Resource
    Electronic Resource
    An ultrastructural study of embryonic chick retinal neurons in culture (1986)
    Springer
    Cell & tissue research 245 (1986), S. 563-577 
    Details
    ISSN: 1432-0878
    Keywords: Chick retina ; Tissue culture ; Electron microscopy ; Development, ontogenetic ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The differentiation of cells and synapses in explants of 9-day-old chick embryo retina has been studied by light and electron microscopy over a period of 35 days in vitro, and samples of retina from the 9-day chick foetus were directly fixed and prepared for study. At the time of explantation the retinae were poorly differentiated and no lamination was apparent. From day 14 onwards, (i) outer and inner nuclear layers (ONL, INL) separated by a layer of neuropil corresponding to the outer plexiform layer (OPL) and (ii) a layer of scattered large ganglion cells separated from the INL by a zone of neuropil resembling the inner plexiform layer (IPL) were apparent, and (iii) a well-differentiated outer limiting membrane was established close to the surface of the explants. In the oldest cultures some development of photoreceptor outer segments occurred but a distinct optic nerve fibre layer did not form. Although cell identification presented problems even in the oldest cultures, the major retinal cell types described in vivo could be identified. Photoreceptor cells developed pedicles in the OPL which became filled with synaptic vesicles and synaptic ribbons and established ribbon synapses (including triads) with and were commonly invaginated by processes from horizontal and bipolar cells. Processes of bipolar cells in the IPL formed simple and dyad synapses. At least two types of presynaptic amacrine cells were also identified in the INL, one of which contained large numbers of dense-core vesicles. The ganglion cells, though sparse, were large and well differentiated. These findings show that all the major neuronal types of the retina are capable of developing and differentiating in vitro, lagging behind the time-table of development and differentiation in vivo by approximately 7 days, but resulting in a histotypically organised retina with synaptic neuropil showing many similarities to the corresponding neuropil in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218558
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  • 34
    Electronic Resource
    Electronic Resource
    Embryonic cholinesterase activity during morphogenesis of the mouse genital tract (1986)
    Springer
    Cell & tissue research 244 (1986), S. 153-164 
    Details
    ISSN: 1432-0878
    Keywords: Cholinesterase ; Genital tract ; Mesenchyme ; Histochemistry ; Electron microscopy ; Mouse embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the genital tract of male and female mouse embryos cholinesterase activity is described that is independent from innervation. The enzyme activity is localized in the mesenchyme at the junction of Wolffian and Müllerian ducts with the urogenital sinus. During male development prostate buds and vesicular glands grow out into the cholinesterase-active mesenchyme. During female development the active mesenchyme participates in the downgrowth of the vaginal anlage. Ultrastructurally the cholinesterase activity is localized in the perinuclear cisterna and in smooth endoplasmic reticulum of the mesenchymal cells. The enzyme activity disappears with definitive differentiation of the tissue. The embryonic cholinesterase is a component of a primitive muscarinic system. Its relation to the morphogenetic action of testosterone and its possible general functions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218393
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  • 35
    Electronic Resource
    Electronic Resource
    Cytoplasmic virus-like particles associated with the nucleolus in wheat, similar to “S bodies” and retroposon particles (1986)
    Springer
    Protoplasma 133 (1986), S. 160-164 
    Details
    ISSN: 1615-6102
    Keywords: Cytoplasm ; Electron microscopy ; Nucleolus ; Virus-like particles ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Wheat roots from germinating seedlings of Chinese spring wheatTriticum aestivum grown for 36 hours at 20°C were examined by conventional thin-section electron microscopy. Virus-like particles were seen inside a large cytoplasmic intrusion into the nucleus having the appearence of a nucleolar vacuole. The particles were isometric and about 50 nm in diameter with a membrane-like coat and a small core. The cytoplasmic intrusion was bounded by nuclear envelope with pores apparent where it abutted nucleoplasm. The particles are similar to previously reported solitary particles “S bodies” from a range of plants but are also similar in size and morphology to the retroposon particles associated with copia like elements in other organisms. The position of the virus-like particles in the young wheat roots is discussed in relation to interactions with components of the cell skeleton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304631
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  • 36
    Electronic Resource
    Electronic Resource
    Influence of culture medium pH on charasome development and chloride transport inChara corallina (1986)
    Springer
    Protoplasma 130 (1986), S. 5-11 
    Details
    ISSN: 1615-6102
    Keywords: Chara corallina ; Charasome development ; Chloride transport ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Internodal cells ofChara, grown in culture either at pH 5.7, 6.5 or 7.5, were studied to determine their chloride influx capability, the quantitative aspects of charasome morphology and the degree to which these two parameters could be correlated. In cells grown at pH 5.7 the charasomes were relatively small, were widely spaced on the plasma membrane, and contributed only a 0.6% increase to the surface area of the plasma membrane in the acid region of the cell. In contrast, the charasome membrane surface area of cells grown at pH 7.5 had increased × 19, the density of charasomes on the cell surface increased × 42, thus producing a × 3.57 increase in the acid region plasma membrane surface area. Chloride influx in cells grown at pH 7.5 was × 8.7–12.7 greater than in cells grown at pH 5.7. Cells that had been starved of chloride exhibited a × 2.4 average increase in the rate of chloride influx. Our observations establish the existence of a positive correlation between the rate of chloride influx and the increase in membrane surface area due to charasomes, although other factors, such as the effect of pH on transport-related enzymes, and the effect of charasome structure on chemical equilibria, may also be of importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283326
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  • 37
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    Electronic Resource
    The effects of raised phosphate level on the energy metabolism, contractile function, and fine structure of oxygenated and oxygen-deficient myocardium (1986)
    Springer
    Heart and vessels 2 (1986), S. 6-14 
    Details
    ISSN: 1615-2573
    Keywords: Inorganic phosphate ; Normoxia/anoxia ; ATP ; Glycogen ; Cardiac function ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The possible role of inorganic phosphate (Pi) in depressing the contractility of oxygen-deficient myocardium was investigated by examining the effects of 30 mM Pi on the cardiac function and myocardial biochemistry and fine structure in normoxic and anoxic Langendorff-perfused isolated rat hearts. In normoxia, the intracellular Pi level increased three-fold, the ATP content remained normal, and there was moderate loss of glycogen only. Contractile performance (as assessed from systolic pressure recordings) was significantly depressed, as was the heart rate for the first 10 min. The myocardial fine structure showed persistent glycogen, marked relaxation of myofibrils, and a higher incidence of vacuolation than in hearts with normal Pi. In anoxia, the intracellular Pi level was comparable with that of the perfusate and both ATP and glycogen were severely depleted. Contractile performance and heart beat ceased completely at 15 min, although in anoxic controls both persisted at low levels for at least 25 min. In anoxia, Pi also depressed coronary flow rate. In the inner half of the ventricular wall of oxygen-depleted hearts, where flow became reduced after 15 or more min, Pi markedly reduced the formation of intramitochondrial densities and augmented mitochondrial swelling and ischaemic contracture, which extended out through the mid-myocardium. In the outer half of the wall, where flow remained high, it promoted severe dilatation of the sarcoplasmic reticulum vesicles and undifferentiated regions of the intercalated discs. The observed effects in normoxia are probably attributable at least in part to the lowering of the free Ca2+ concentration of the perfusate by the increased Pi level. The effects in anoxia may be related chiefly to the critical reduction of available intracellular Ca2+ and the more rapid and extensive development of ischaemic contracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02060238
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  • 38
    Electronic Resource
    Electronic Resource
    In vivo homologous recombination intermediates of yeast mitochondrial DNA analyzed by electron microscopy (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 421-428 
    Details
    ISSN: 1617-4623
    Keywords: Recombination intermediates ; Mitochondrial DNA ; Electron microscopy ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To study the structure of in vivo mitochondrial DNA recombination intermediates in Saccharomyces cerevisiae, we used a deletion mutant of the wild type mitochondrial genome. The mtDNA of this petite is composed of a direct tandem repetition of an ∼4,600 pb monomer repeat unit with a unique HhaI restriction enzyme site per repeat. The structure of native mtDNA isolated from log phase cells, and mtDNA crosslinked in vivo with trioxsalen plus UVA irradiation, was studied by electron microscopy. Both populations contained crossed strand “Holliday” type recombination intermediates. Digestion of both non-crosslinked and crosslinked and mtDNA with the enzyme HhaI released X and H shaped structures composed of two monomers. Electron microscopic analysis revealed that these structures had pairs of equal length arms as required for homologous recombination intermediates and that junctions could occur at points along the entire monomer length. The percentage of recombining monomers in both non-crosslinked and trioxsalen crosslinked mtDNA was calculated by quantitative analysis of all the structures present in an HhaI digest. The relationship between these values and the apparent dispersive replication of mtDNA in density-shift experiments and mtDNA fragility during isolation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333272
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  • 39
    Electronic Resource
    Electronic Resource
    Electron microscopic localization of hydrogenase genes on the megaplasmid pHG 1 in Alcaligenes eutrophus (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 476-480 
    Details
    ISSN: 1617-4623
    Keywords: Hydrogen bacterium ; Hydrogenase genes ; Megaplasmid pHG1 ; Localization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plasmids carrying hydrogenase genes in Alcaligenes eutrophus wild type H 16 and in two transposon Tn5 —induced mutants have been investigated by electron microscopy. Besides the pHG1 megaplasmid (458±27 kb) carrying genes coding for structural and regulatory properties of hydrogenases, small plasmids of unknown significance have been detected. The sizes of EcoRI fragments obtained from pHG1 were measured from electron micrographs. They were significantly different from sizes determined previously by agarose gel electrophoresis. Plasmid pHG1 isolated from the wild type H 16 was shown to contain two inverted repeats (IR 16-1 and IR 16-2) with sizes similar to known transposons. From electron microscopic hybridization studies, it was deduced that the sites of insertion of Tn5 into a regulation gene on pHG1 for both soluble and membrane-bound hydrogenase, and of Tn5-Mob into the gene coding for structural properties of the soluble hydrogenase, are about 67.2 kb apart. One of the inverted repeats (IR 16-1) was localized in between these sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333280
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  • 40
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    Abnormal mucociliary function in a mucocoele of the maxillary antrum (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 207-210 
    Details
    ISSN: 1434-4726
    Keywords: Maxillary sinus mucocoele ; Mucociliary system ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have examined the mucociliary function present in a mucocoele of the maxillary antrum and have found certain abnormalities in the tissues studied. Our findings also indicate that the mucocoele's intrinsic pathology is too complex to be improved by any conservative treatment and justifies its surgical removal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00470623
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  • 41
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    An experimental study of auditory dysfunction associated with hyperlipoproteinemia (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 242-245 
    Details
    ISSN: 1434-4726
    Keywords: Hyperlipoproteinemia ; Auditory dysfunction ; Cochlea ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We sought to clarify whether or not hyperlipoproteinemia induces auditory dysfunction. In so doing, we studied the general states and cochlear pathologies of guinea pigs after the administration of a hyperlipid diet for 3 months. Serum biochemistries indicated marked elevations of cholesterol, high density lipoprotein (HDL)-cholesterol and low density lipoprotein (LDL) levels. An increased auditory threshold varying from 10 to 20 dB was observed in 40% of the guinea pigs using auditory brainstem responses. Histochemical study of the inner ear revealed variations in lipid metabolism and partial disorders of the outer hair cells. Electron microscopic observations showed vacuolar and parenchymal protrusions on the surfaces of the stria vascularis and Corti's organ, and vacuolar degeneration was seen around the capillary vessels of the vascular stria. Our data has shown that the auditory dysfunction present in the inner ear was less marked than were the morphological changes seen. Our findings suggest that other factors besides hyperlipoproteinemia are involved in the development of severe auditory damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464438
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  • 42
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    Preparation of Optically Active Secondary Amines by Thermal Decomposition of (Methylbenzyl)urea Analogs: Absolute Configuration of (+)- and (-)-Mecamylamine. Preliminary CommunicationThe full paper will be published elsewhere.Patent application has been filed. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 283-287 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermolysis of the (α-methylbenzyl)urea diastereoisomers 4 and 5 of (±)-mecamylamine ((±)-1) and 6 and 7 of (±)-1-noreseroline O-methyl ether ((±)-3) in refluxing alcohol afforded optically pure amines in high yield, besides optically pure carbamates of (α-methylbenzyl)amine which can be recycled. The absolute configuration of (-)-mecamylamine hydrochloride ((-)-1 · HCl) was determined by X-ray diffraction analysis.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690205
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  • 43
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    2,5-Chinonmethide des 1,6-Methano[10]annulens mit S,N- und N,N-Acylketenacetal StrukturMeinem hochverehrten Lehrer, Prof. Dr. Siegfried Hünig, Würzburg, zum 65. Geburtstag gewidmet (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 315-328 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,5-Quinonemethides of 1,6-Methano[10]annulene with the Structures of S,N- and N,N-Acylketene AcetalsInvestigation on the chemical reactivities of 2-(tert -butoxy)-1,6-methano[10]annulene and the syntheses of the compounds 2, 4, 6-8, 11, 13-22 are described; the results of 1H- and 13C-NMR-spectroscopic measurements are reported.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690209
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  • 44
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    1,2-Epoxycarotinoide. 6. Mitteilung. Isolierung von 1′,2′-Epoxy-1′,2′-dihydro-ε,ψ-carotin aus der ‘Delta-Mutanten’-Tomate (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 340-344 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids Isolation of 1′,2′-Epoxy-1′,2′-dihydro-ε,ψ-carotene from a ‘Delta Mutant’ TomatoFrom ‘Delta Mutant’ tomatoes, optically active 1′,2′-epoxy-1′,2′-dihydro-ε,ψ-carotene (7) was isolated. According to the CD data, the configuration is 6R and presumably 2′S.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690212
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  • 45
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    (Cholestanyloxycarbonyl)benzyl esters as peptide substituents: Conformational properties of fully protected oligo-L-lysines with C-terminal (cholestanyloxycarbonyl)benzyl and benzyl ester moieties (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 350-358 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study involves L-lysine oligo peptides, protected at the N-terminus by the Nps and at the ε-amino functions by Boc groups. Two series were prepared from dimer to octamer, one containing the p-[(cholestan-3β-yloxy)carbonyl]benzyl, the other one the benzyl ester group at the C-terminus. Conformational analyses were performed by IR absorption. The occurrence of the intermolecular β-structure in the solid state and in CH2Cl2 solution was demonstrated for the highest oligomers. The relative stabilities of the self-associated species were determined by adding a variety of polar solvents to the CH2Cl2 solutions. The cholestanyl-containing peptides have a lower propensity to self-aggregate than the benzyl-ester analogues. Self-aggregation and decreasing solubility run in parallel. It was also directly shown that soluble urea derivatives may disrupt intermolecular H-bonds in CH2Cl2, a point of practical interest, particularly in solid-phase peptide synthesis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690214
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  • 46
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    Electronic Resource
    Die toxischen und sedierend wirkenden Bufadienolide von Kalanchoedaigremontiana HAMETet PERR (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 359-367 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Toxic and Sedative Bufadienolides of Kalanchoe daigremontiana HAMET et PERR.From the toxic Crassulacee Kalanchoe daigremontiana five biosynthetically related bufadienolides have been isolated and structurally elucidated by X-ray and 1H- and 13C-NMR spectroscopy. The compounds were identified as bersaldegenin 1,3,5-orthoacetate (2), bersaldegenin 1-acetate (4), bersaldegenin 3-acetate (3), 1β,3β,5,11α,14-pentahydroxy-12,19-dioxo-5β,14β-bufa-20,22-dienolide 1,3,5-orthoacetate ( = daigremontianin; 1), and 3β-acetoxy-1β,5,14-trihydroxy-5β,14β-bufa-20,22-dienolide ( = daigredorigenin-3-acetate, 5). According to the pharmacological investigations, the two orthoacetates 1 and 2 comprise the positive inotropic, sedative, and toxic activity of the plant.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690215
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  • 47
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    Electronic Resource
    Enantioselective Synthesis of D-erythro-Sphingosine and of Ceramide (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 368-373 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enynol 2 was transformed into D-erythro-sphingosine 11 (7 steps, 46%) and into ceramide 1 (8 steps, 41% overall yield). The key steps were the mono-epoxidation of the enynol 5 (Ti(t-BuO)4, (-)-D-diethyl tartrate, t-BuOOH) to 6 (86%, ≥ 98% ee), the regioselective intramolecular opening of the oxirane 6 via the benzylurethane 7, and the reductive tranformation of the acetylene 9 into the oxazolidinone 10 (Li, EtNH2, 88%).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690216
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  • 48
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    An ESR Study of the Radical Cations of Tetrathiafulvalene (TTF) and Electron Donors Containing the TTF Moiety (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 141-151 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hyperfine data and g factors are reported for the radical cations of tetrathiafulvalene (TTF; 1) and of its derivatives 2-13. From the intense satellite spectra of 1+-13+ not only the coupling constants of the 33S isotopes in the TTF moiety could be determined, but also, in favourable cases, those of the 13C isotopes in the central double bond. The former values range from 0.370 (8+) to 0.470 mT (4+) and the latter from 0.255 (8+) to 0.360 mT (4+) in the radical cations of bis(ethylenedithio)-TTF (8+) and tetracyano-TTF (4+). The radical cation of TTF (1+) exhibits intermediate values, 0.425 for the 33S and 0.285 mT for the 13C isotopes. The spin population in 1+-13+ resides, to a large extent, in the central S2C = CS2 part of the π-system. It tends to increase (decrease) by substitution with electron-accepting (donating) groups in the 2,3,6,7-positions of TTF.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690117
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  • 49
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    Conformation-Odor Relationships in Norlabdane Oxides (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 163-173 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational factors have been found responsible for the dramatic change in odor between (-)-deoxyambreinolide (12) and its (+)-epi derivative 13. The presumably molecular event during the receptor interaction has been simulated by the diastereoisomeric 11-methyl-ambrox derivatives 3 and 5 as model compounds.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690120
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  • 50
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    Crystal Structures of Chiral Ionophores: Bis(9,9′-spirobifluorene)-26-crown-4 and -32-crown-6 (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 626-631 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray crystal structures of bis(9,9′-spirobifluorene)-26-crown-4βbenzene solvate (monoclinic, a = 15.47 Å, b 11.265 Å, c = 15.220 Å, β = 91.54°, space group C2) and bis(9,9′-spirobifluorene)-32-crown-6·dichloromethane solvate (tetragonal, a = 20.958 Å, c = 11.779 Å, space group P41212) are described. Both compounds act as enantioselective ionophores for α-aminoalcohols.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690312
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  • 51
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    Steric Effects on Reaction Rates. Part VIII. The Significance of Front Strain Release in Solvolysis of Bridgehead Derivatives (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 635-645 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The steric requirements of leaving groups for 14 bridgehead derivatives have been examined using MM2 calculations. The strain varies almost monotonously throughout the series upon variation of the leaving group from H to C1, OH, CH3, CH3CH2O, (CH3)3CO, (CH3)3C and no significant trends for differential F-strain effects are detected expect for the perhydrophenalene derivative 13. The experimental rates of solvolysis of bridgehead derivatives correlate well with the calculated steric energy differences between substrate R-X and the corresponding carbenium ion R⊕. However, the strain calculations using the more recent force-fields (MM2) disagree, in part, with those reported in the literature: chloride and p-toluenesulfonate leaving groups correlate with identical slopes, and the perhydrotriquinacene derivative 10 shows no anomalous behavior. The calculations suggest that F-strain and C,C-hyperconjugation should not play any dominant role in bridgehead solvolysis.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690314
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    Die Synthese und der thermische Zerfall des 1,2-Diazabenzo[e]-semibullvalens und dessen Beziehung zur Thermolyse des Benzobenzvalens (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 670-675 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Synthesis and the Thermal Decay of 1,2-Diazabenzo[e]semibullvalene and its Relation to the Thermolysis of BenzobenzvaleneThe [4 + 2]-photoadduct of naphthalene and 4-phenyl-4H-1,2,4-triazol-3,5-dione (PTAD) was subjected to a triplet-sensitized di-π-methane rearrangement. Hydrolysis of the resulting urazol 15 gave a stable semicarbazide 16 which by nickel-peroxide oxidation gave 1,2-diazabenzo[e]semibullvalene (10). At 40 °C, the latter decays in CHCl3 solution to produce benzofulvene (2) as the principal product, accompanied by benzobenzvalene (1) and small amounts of naphthalene. This decay reaction is rationalized in terms of a 1,3-dipolar cycloreversion which is followed by denitrogenation to give indenyl carbene (19). The thermolysis of 1 in solution is believed to proceed via the same carbene. At present, these findings provide only a partial answer to the benzobenzvalene enigma (i.e., in solution at 150°, 1 gives 2, but in the gas-phase at 300°, 1 yields naphthalene). MeOH is shown to add readily to 10 in a homologous Michael addition.
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    URL: http://dx.doi.org/10.1002/hlca.19860690317
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    Formale Totalsynthese von (±)-Isocomen durch Anwendung der α-Alkinon-Cyclisierung (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 659-669 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formal Total Synthesis of (±)-Isocomen by Application of the α-Alkinon CyclizationA total synthesis of the racemic form of the sesquiterpene isocomene (A) was accomplished by application of the cyclopentenone anellation B→D (Scheme 1) which includes the α-alkynone cyclization C→D, a gas-phase flow thermolytic process. Starting with the known product 2 (Scheme 3) of the anellation B→D, the elaboration of ring C of A proceeded in 9 steps to the α-alkynone 16 (Scheme 5) which was cyclized at 540° selectively to give the angularly fused triquinane 4 (77%). A two-step procedure then led to 5 (Scheme 6), a last but one intermediate in a known total synthesis of (±)-A. The conversion of 16 to 4 also demonstrated the compatibility of an acetoxy function with the anellation sequence B→D.
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    URL: http://dx.doi.org/10.1002/hlca.19860690316
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    Photochemical Rearrangements of 5,6-Epimino-5,6-dihydro-β-ionone and Derivatives (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 692-697 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On irradiation at -20°, 5,6-epimino-5,6-dihydro-β-ionone (E)-3 rearranges to the products 6 and 7. The N-methyl derivative (E)-4 does not lead to any photoproduct upon brief irradiation; on prolonged irradiation, only unspecific photodecomposition is observed. The N-acylated derivative (E)-5 undergoes rapid (E)/(Z)-isomerization and slow rearrangement to 12 and 13.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690320
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    Pteridine. Teil LXXX.Teil LXXIX: [1]. Synthese, Reaktionen und Photochemie von Pteridinthionen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 708-717 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Reactions, and Photochemistry of PteridinethionesThe pteridine-6(5H)-thione 1 and various pteridine-7(8H)-thiones (13, 22, 26) have been synthesized, and their photochemical reactivity has been investigated under aerobic conditions. The formation of different photooxidation products is pH-dependent. In acidic to neutral media, disulfides (2, 15, 23, 29) are formed, whereas neutral to alkaline solutions favour the formation of pteridinesulfinic (3, 17) and -sulfonic acids (6, 16, 24, 30). Prolonged irradiation of the disulfides 2 and 15 led to the intensively yellow fluorescing bis(thio)dilumazines 19 and 20, respectively.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690323
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    Cacospongione A, cacospongienone A, and cacospongienone B, new C21 difuran terpenoids from the marine sponge Cacospongiascalaris SCHMIDT of the Côte d' Azur (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 726-733 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sponge Cacospongia scalaris (family Thorectidae), collected at the Cap de Nice (Cǒte d'Azur), is shown to contain a series of truncated, linear C21 difuran terpenoids comprising the known sponge products furospongin-1 ((+)-1), furospongin-2 (2), and dihydrofurospongin-2 ((-)-(E)-3), besides the new products cacospongione A ((-)-4), cacospongienone A ((-)-(Z)-6), and cacospongienone B ((-)-(E)-6), whose absolute configurations have been assigned by chemical correlations with (+)-1. Possibly, one of the two cacospongienones is an artifact, as these two terpenoids interconvert on standing. This is the first finding of linear C21 difuran terpenoids, which are typical of the Spongiidae, in a member of the family Thorectidae.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19860690325
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    Mitteilungen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 749-750 
    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.19860690327
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    Deoxy-nitrosugars 12th communication11th Communication: [1]. Synthesis of isosteric mono-phosphonate analogues of β-and α-D-fructose 2,6-bisphosphate (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 751-760 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthesis of the isosteric mono-phosphonate analogues 2a and 19 of the β-and α-D-fructose 2,6-bisphosphate, respectively, is described. Chain elongation of the 1-deoxy-1-nitro-D-arabinose 3 (Scheme 1) by a Henry reaction with paraformaldehyde followed by protection of the resulting alcohol (methoxymethyl ether) and a radical-chain substitution by nitromethane anion gave the key intermediates, the gluco-anhydroalditol 6 and the manno-anhydroalditol 7. These products equilibrated under basic conditions. Conversion of 7 to the aldehyde 9, Abramov reaction of 9 with diphenyl phosphite followed by deoxygenation according to Barton gave the phosphonate 11 (Scheme 2). Selective hydrogenolysis of 11, phosphorylation and deprotection gave 2 which was converted to the tetrasodium salt 2a. Similarly, 6 was transformed into the isosteric phosphonate analogue 19 of the α-D-fructose 2,6-bisphosphate (Scheme 3).
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    Sequence dependence of secondary-structure formation part IVPart III: [1]. Helix-forming potential of amphiphilic oligopeptides containing aib residues (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 786-792 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational properties of Aib-containing oligopeptides having the propensity to adopt amphiphilic helical conformations were investigated by CD spectroscopy in solution. The peptides CF3COOH.H-Pro-Glu-[Ala-Aib-Glu-Aib-]4Gly-OH (I), HCl.H-Pro-Ala-Aib-[Gul-Ala-Ala-Aib-]2Glu-Ala-Aib-Gly-PEGM (II), and CF3COOH.H-Ala-Aib-[Glu-Glu-Ala-Aib-]3PEGM (III) were synthesized according to the general principles of the liquid-phase method for peptide synthesis. Peptides I-III exhibit helical conformations in CF3CH2OH, MeOH, and in H2O at acidic pH; however, at pH 7, only II forms a stable helix, whereas I and III are predominantly in an unordered conformation. Some general features for the construction of amphiphilic helices are discussed in the light of the experimental data.
    Additional Material: 5 Ill.
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    Conformational Analysis of Endoperoxides Grafted onto Bicyclo[2.2.n]alkanes as a Test of the Rigidity of the Bicyclic Skeleton. Photo-oxidation of [2.2.2] Hericene and 2,3,5,6-Tetramethylidenebicyclo[2.2.n]alkanesInteraction between non-conjugated chromophores, Part 24. Part 23, see [1a]. For a preliminary report, see communication No. ONII-10, Autumn Meeting of the Swiss Chemical Society, Bern, Oct. 18, 1985. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 761-772 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photo-oxidation of [2.2.2]hericene (6) gave successively the endoperoxides 11 (9,10,11,12-tetramethylidene-4,5-dioxatricyclo[6.2.2.02,7]dodec-2(7)-ene), the bis-endoperoxide 16 (15,16-dimethylidene-4,5,11,12-tetraoxatetracyclo[6.6.2.02,7.o9,14]hexadeca-2(7),9(14)-diene), and the tris-endoperoxide 19 (4,5,11,12,17,18-hexaoxapentacyclo[6.6.6.02,7.09,14.015,20]icosa-2(7),9(14),15(20)-triene). The endoperoxides 11, 16, and 19 were formed in the presence or in the absence of a dye sensitizer. The sensitized photo-oxidations of 2,3,5,6-tetramethylidenebicyclo[2.2.2]octane (4), 5,6,7,8-tetramethylidenebicyclo[2.2.2]oct-2-ene (5), 2,3,5,6-tetramethylidenebicyclo[2.2.1]-heptane (7), and 2,3,5,6-tetramethylidene-7-oxabicyclo[2.2.1]heptane (8) gave successively the corresponding mono-endoperoxides 9, 10, 12, and 13 and the bis-endoperoxides 14, 15, 17, and 18, respectively. Low-temperature NMR spectra of the bis-endoperoxides 14 and 16 indicated that their C2 and Cs conformers have the same stability. Similarly, there was no difference in the enthalpy of the D3 and C2 conformers of the tris-endoperoxide 19. The following reactivity sequence was observed for the sensitized photo-oxidations of 6-8 and 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene (23): 6 + 1O2→11 〉 7 + 1O2→12〉8 + 1O2→13〉23 + 1O2→24, a trend parallel with that reported for the ethylenetetracarbonitrile (TCNE) cycloadditions to the same polyenes. The rate-constant ratios k1/k2 and k2/k3 for the three successive photo-oxidations of [2.2.2]hericene (6) did not differ significantly from unity, in contrast with the Diels-Alder additions of 6. Similarly, the rate-constant ratios k1/k2 for the two successive photo-oxidations of tetraenes 7 and 8 were significantly smaller than those reported for the successive TCNE cycloadditions to 7 to 8. The endoperoxide formations are not sensitive to the change in the exothermicity of the reactions but they are sensitive to the electronic properties (IP's) of the polyenes.
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    Ion-Molecule reaction in the gas phase part VIFor Part V, see [1]. Regioselective SN2 reaction from terpenoid diastereoisomeric diols using CI/NH4+Dedicated to Prof. Tino Gäumann on the occasion of his 60th birthday (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 806-815 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A stereospecific and regioselective SN2 mechanism (Walden inversion) is observed during studies involving modified terpenoid epimeric diols in a high-pressure ion source using ammonia as a reagent gas.
    Additional Material: 4 Tab.
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    Three Novel Spin-Labeled Substrates for Enzymatic Incorporation into Nucleic Acid Lattices (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 345-349 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of one C(4)-spin-labeled uridine-5′-diphosphate (C(4)-UDP) and two nitroxide-containing 2′-deoxyuridine-5′-triphosphate (dUTP) analogs are reported. The C(4)-UDP derivative was incorporated into copolymers by polynucleotide phosphoxylase (PNPase); one of the two dUTP analogs, substituted at position C(4), was a good substrate for TdT, whereas the other one, substituted at position C(5), served as substrate for E. coli DNA polymerase (Pol I).
    Additional Material: 1 Tab.
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    Reaktionen von 3-substituiertem 5-Trifluormethyl-1,3,4-oxadiazol-2(3H)-on mit NucleophilenIX. Mitt. über Synthese von Heterocyclen. VIII. Mitt. s. [1].Vorgetragen an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft am 18. Oktober 1985 in Bern. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 333-339 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 3-Substituted 5-Trifluoromethyl-1,3,4-oxadiazol-2(3H)-one with NucleophilesThe 3-substituted 5-trifluoromethyl-1,3,4-oxadiazolones 3, 4, 13, and 15 are attacked by N- and S-nucleophiles either at the ring C-atom C(2) or C(5). Depending on the nature of the substituent and the nucleophile, the ring-opening products 7, 10, 12, and 14 or the ring-enlargement products 16 are formed. The reaction of 4 with thiols is a novel variant of the Grob-type fragmentation. The reactivity of the 1,3,4-oxadiazolones is compared with that of the analogous 1,3,4-thiadiazolones. The structures of the new compounds were elucidated by 1H- and 13C-NMR spectroscopy.
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    URL: http://dx.doi.org/10.1002/hlca.19860690211
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    Synthese von 4,4-disubstituierten 1,3-Thiazol-5(4H)-thionen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 374-388 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 4,4-Disubstituted 1,3-Thiazol-5(4H)-thionesAn easy synthesis for the 1,3-thiazol-5(4H)-thiones 5, a class of heterocycles which have hitherto only been available with difficulty, is described. Reaction of 3-amino-2H-azirines 25 with thiocarboxylic acids at 0° yields monothiodiamides of type 20 (Scheme 6) which, on treatment with Lawesson reagent at 100°, undergo thiation and cyclization to give 5 in good yield.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19860690217
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    Herstellung von disubstituierten Maleinsäure-anhydriden mit Hilfe von reaktiven 2-Oxo-3H-imidazo[1,2-a]pyridinium-Verbindungen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 396-403 
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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 Disubstituted Maleic Anhydrides from Reactive 2-Oxo-3H-imidazo[1,2-a]pyridinium CompoundsA new useful method for the preparation of disubstituted maleic anhydrides, most of them bearing additional functional groups in the side chain, is described. The key step of the synthesis consists of the addition of 2-oxo-3H-imidazo[1,2-a]pyridinium compounds to a variety of different Michael acceptors.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19860690219
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    Konfigurationsbestimmung von geometrischen Isomeren mittels selektiver 13C{1H}-NOE-Differenzspektroskopie (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 898-904 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Application of Selective 13C{1H}-NOE Difference Spectroscopy in Determination of the Configuration of (Z)/(E)-IsomersHeteronuclear 13C{1H}-NOE studies have been performed to elucidate the configuration at the imino double bond in N,N′-Dicyanoquinonediimines. Selective low-power irradiation of the neighbouring ring protons in compounds 1-5 increases the signal intensities of CN as well as of the imino-C-atoms in the 13C-NMR spectra. The increase of signal intensity can easily be detected by the difference spectroscopy. The results of this investigation are in good agreement with a recently published study on the stereochemistry of N,N′-Dicyanoquinonediimines, based on the interpretation of 13C-chemical shifts.
    Additional Material: 4 Ill.
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    Synthese und Strukturaufklärung von Merucathin und Pseudomerucathin. Zwei Inhaltstoffe von Catha edulis FORSK (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 918-926 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure Elucidation of Merucathine and Pseudomerucathine. Two Constituents of Catha edulis FORSK.Starting from L-alanine, two constituents of Catha edulis FORSK. (3R,4S)-4-amino-1-phenyl-1-penten-3-ol ((3R,4S)-4, merucathine) and (3S,4S)-4-amino-1-phenyl-1-penten-3-ol ((3S,4S)-4, pseudomerucathine) were synthesized.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690420
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    Mitteilungen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 955-956 
    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.19860690424
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    1,4-Dithiafulvene aus der Umsetzung von 4,4-disubstituierten 1,3-Thiazol-5(4H)-thionen mit AcetylenderivatenVorläufige Mitteilung s. [1]. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 419-429 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,4-Dithiafulvenes, Products of the Reaction of 4,4-Disubstituted 1,3-Thiazol-5(4H)-thiones and Acetylenic CompoundsOn heating in toluene, 4,4-disubstituted 1,3-thiazol-5(4H)-thiones 1 and acetylenecarboxylates or acetylenecarbonitriles 2 undergo a cyclosubstitution reaction to yield 2-methylidene-1,3-dithiol derivatives 3 (1,4-dithiafulvenes) and a nitrile. Further heating of 3a and 3b in the presence of excess 2a leads to the isomeric 2,3-dihydrothiophene-2-thiones 4a and 4b, respectively. The benzodithiafulvene 14 has been formed in a similar reaction from 1a and in situ generate benzyne.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19860690223
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    Perimeter-Type Structures in Charged [4n + 2] Annuleno [4n + 2] annulenes. The Importance of the Frontier-Orbitals (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 949-954 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetra(tert-butyl)[14]annuleno[14]annulene 1 is transformed, via alkali metal reduction, into its radical monoanion, dianion, radical trianion, and tetraanion. The paramagnetic species are characterized by ESR and ENDOR spectroscopy and the diamagnetic species by 1H- and 13C-NMR spectroscopy. Well-resolved ESR and NMR spectra can only be obtained, if the reduction is carefully monitored. For the interpretation of the data, the ions derived from the structurally related [14]- and [22]annulenes 3 and 5 as well from the tetra(tert-butyl)[14]annuleno[18]annulene 2 serve as suitable model compounds. While the behavior of the neutral annulenoannulene 1 is governed by that of the [14]annulene-subunit, the corresponding ionic systems can best be described as macrocyclic perimeters. This outcome can be rationalized by the nodal properties of the frontier MO's.
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    URL: http://dx.doi.org/10.1002/hlca.19860690423
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    Stereoselective Reduction of δ-Hydroxy-β-ketoesters (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 803-805 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reduction of δ-hydroxy-β-ketoesters 1 was investigated with three different reducing agents. In several instances, high selectivity in favor of syn-1,3-diols was observed.
    Additional Material: 2 Tab.
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    Anion Selectivity of Metalloporphyrins in Membranes (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 849-854 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipophilic Co(III) and Mn(III) complexes of 5,10,15,20-tetrakis[4-(hexyloxycarbonyl)phenyl]porphyrin act as positively charged carriers for anions and induce anion selectivities in membranes clearly deviating from the sequence of classical anion exchangers. Different anion selectivities are observed for the Co(III) and Mn(III) porphyrins.
    Additional Material: 1 Ill.
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    Approaches to 1H-Cyclopropa[l]phenanthrenes. Eliminations with 1a,9b-Dihydro-1H-cyclopropa[l]phenanthrene Derivatives (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 855-864 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Base-induced elimination of the sulfonium salt 2i in the presence of furan affords the addition products 7 and 8, derived from 1H-cyclopropa[l]phenanthrene (1) and the isomeric cyclopropene 5a (Scheme 3). Upon oxidation, the selenide 2c yields phenanthrene-9-methanol (9), presumably via 1. No evidence for the intermediate 1 is obtained from sulfoxide pyrolysis with 2e, which leads to products formed by radical pathways (Scheme 5). Reductive elimination of the disulfone 3b gives half-reduction to monosulfone 2g and complete reduction to cyclopropane 2 as well as 9-methylphenanthrene (15), but no evidence for the intermediate 1.
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    Fluorine-Containing Organozinc Reagents Part 1 A Simple Synthesis of 2,2-Dichloro-3,3,3-trifluoropropanol (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 881-886 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 1, which can be regarded as a synthetic equivalent of substituted 1,1,1-trifluoroacetone 2, is prepared by Zn-induced reductive addition of 1,1,1-trichloro-2,2,2-trifluoroethane (3) to formaldehyde (4). A brief survey of the scope of this C—C-bond formation leading to a variety of new CF3-containing synthetic building blocks is also given.
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    Intramolekulare 1,3-dipolare Cycloadditionen mit alkenyl-substituierten 3,4-DiarylsydnonenTeilweise in vorläufigen Mitteilungen veröffentlicht [1] [2].Als Sydnone werden mesoionische 1,2,3-Oxadiazol-5-one (1,2,3-Oxadiazolium-5-olate, Anhydro-5-hydroxy-1,2,3-oxadiazolium-hydroxide) bezeichnet [3]. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 927-940 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecular 1,3-Dipolar Cycloaddition Reactions of Alkenyl-substituted 3,4-DiarylsydnonesThe 3,4-diarylsydnones 1 and 12a-e with an allyl or alkenyloxy substituent on the N(3)-phenyl group have been synthesized by classical methods starting from 2-allylaniline and the corresponding alkenyloxyanilines, respectively (Schemes 2 and 3). Whereas the allyl-substituted sydnone 1 undergoes an intramolecular 1,3-dipolar cycloaddition at room temperature in solution to yield 13 (Scheme 4), the alkenyloxy-substituted sydnones 12a-e are thermally stable. On irradiation of 1 and 12a-d, formation of the fused dihydropyrazoles 2 and 14a-d (Schemes 1 and 5) is observed. In the case of 12d, the yield of 14d is very low, and the symmetric 1,2,3-triazole 15a has been isolated as the main product. A very likely reaction mechanism for the formation of the photoproducts involves decarboxylation of the sydnones to give a nitrile-imine which undergoes an intramolecular 1,3-dipolar cycloaddition onto the C=C bond.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19860690421
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    Intramolecular Oxygen Transfer on the Ozonolysis of a Diphenylcyclopentene Derivative (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 941-948 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ozonolysis of cis-3,4a,7,7a-tetrahydro-3,3-dimethyl-6,7a-diphenylcyclopenta[1,2,4]trioxine (1) in CH2Cl2 at -78° gave the secondary endo ozonide 2 (43% yield) and an acetal 3 (27% yield) derived from O-insertion at the ortho position of the C(7a) phenyl substituent. Both structures were elucidated by X-ray. Repetition of the ozonolysis in MeOH/CH2Cl220:3 at -78° also gave the same two products in 12 and 15% yields, repectively, together with the hemiperacetal 4 (54% yield) formally derived from the secondary ozonide by addition of MeOH.
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    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986) 
    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.19860690501
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    Isoswerosid, ein neues Secoiridoidglycosid aus den Wurzeln des Zwergholunders Sambucus ebulus L. (Caprifoliaceae). 2. Mitteilung über die Inhaltsstoffe der Zwergholunderwurzel (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1113-1119 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isosweroside, a New Secoiridoid Glycoside from the Roots of Sambucus ebulus L. (Caprifoliaceae)The paper describes the isolation and structure elucidation of isosweroside (6-(β-D- glucopyranosyloxy)-methyl-9-vinyl-2,8-dioxabicyclo[3.3.1]non-6-en-3-one), the first Valeriana-type secoiridoid glycoside from the roots of Sambucus ebulus L. along with the two known glycosides ebuloside and morroniside.
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    URL: http://dx.doi.org/10.1002/hlca.19860690519
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    Synthèse d'acétals de désoxy-3-hydroxyamino-3-furannoses. Note de laboratoire (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1132-1136 
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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 3-Deoxy-3-(hydroxyamino)furanose AcetalsReduction of sugar ketoximes with NaBH3CN under acidic conditions constitutes a good synthetic pathway to deoxy(hydroxyamino)sugar derivatives. These compounds which are useful building blocks for the preparation of analogs of various classes of biologically important carbohydrates are reasonably stable.
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    URL: http://dx.doi.org/10.1002/hlca.19860690521
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  • 80
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    1,3-Dioxanone Derivatives from β-Hydroxy-carboxylic Acids and Pivalaldehyde. Versatile Building Blocks for Syntheses of Enantiomerically Pure Compounds. A Chiral Acetoacetic Acid Derivative Preliminary Communication (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1147-1152 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R)-3-Hydroxybutyric acid (from the biopolymer PHB) and pivalaldehyde give the crystalline cis - or (R,R)-2-(tert-butyl)-6-methyl-1,3-dioxan-4-one (1a), the enolate of which is stable at low temperature in THF solution and can be alkylated diastereoselectively (→3, 4, 5, and 7). Phenylselenation and subsequent elimination give an enantiomerically pure enol acetal 10 of aceto-acetic acid. Some reactions of 10 have been carried out, such as Michael addition (→11), alkylation on the CH3 substituent (→13), hydrogenation of the C=C bond (→1a) and photochemical cycloaddition (→16). The overall reactions are substitutions on the one stereogenic center of the starting β-hydroxy acid without racemization and without using a chiral auxiliary.
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    URL: http://dx.doi.org/10.1002/hlca.19860690523
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    Diastereoselectivity and Reactivity in the Diels-Alder Reactions of α-Chloronitroso Ethers (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1137-1146 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the α-chloronitroso ether 1, obtained from the hydroximolactone 2 and tert-butyl hypochlorite (89%), was established by X-ray crystallographic analysis. The [4 + 2] cycloadditions of 1 with the dienes 3 and 8-11 led to the N-unsubstituted 3,6-dihydro-2H-1,2-oxazines 6 and 12-16 in high enantiomeric excess (Table 1). Due to the additional α-alkoxy group, the reactivity of 2 is much superior to the one of known α-chloronitrosoalkanes. The reactive conformation of 1 was deduced from the X-ray analysis as well as the high diastereoselectivity of the cycloadditions. The importance of the α-alkoxy group was evidenced from the similar reactivity of the racemic α-chloronitroso ethers 25-27 which were prepared from the hydroximo ethers 28-30 and tert-butyl hypochlorite.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19860690522
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  • 82
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    Desoxy-nitrozucker 14. Mitteilung13. Mitteilung: [1]. 1-C-Nitroglycale. Herstellung und Umsetzung mit einigen Stickstoff-Nucleophilen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1191-1204 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-C-Nitroglycals. Preparation and Reaction with Some Nitrogen NucleophilesAcetylation of the 1-deoxy-1-nitromannopyranoses 2 and 6 was accompagnied by spontanous β-elimination to give the 1-C-nitroglucals 3 and 7, respectively, while acetylation of the gluco- and galacto-configurated 1-deoxy-1-nitropyranoses 8 and 14 gave the acetates 9 and 15, respectively (Scheme 1). The acetylation of the ribo- and arabino-configurated 1-deoxy-1-nitrofuranoses 19 and 21 also occurred without β-elimination to give the acetates 20 and 22, respectively (Scheme 2). Mild base treatment of the previously described O-acetylnitro-β-D-glucose 4, the O-acetylnitro-β-D-pyranoses 9 and 15, and the O-acetylnitro-β-D-furanoses 17, 20, and 22 gave the 1-C-nitroglycals 3, 10, 16, 18 and 23, respectively (Scheme 1 and 2). The previously obtained 1-C-nitroglucal 3 was deacetylated by treatment with MeOH in the presence of KCN or sodium m-nitrophenolate to give the free nitroglucal 5. Deacetylation of the benzylidene protected 1-C-nitroglucal 10 (MeOH, NaOMe) gave the 4,6-O-benzylidene-1-C-nitroglucal 11 and traces of the 2-O-methyl-1-C-nitromannoses 12 and 13. The UV, IR, 1H-NMR and 13C-NMR spectra of the 1-C-nitroglycals are discussed. In solution, the 1-C-nitroglycals 1, 5, 7, 10, 11, and 16 adopt approximately a 4H5- and 3 a flattened 4H5 conformation. The structure of 5 was established by X-ray analysis. In the solid state, 5 adopts a sofa conformation, which is stabilized by an intramolecular H-bond. The β-addition of NH3 to the 1-C-nitroglucals 7 and 10 was followed by an O→ N acetyl migration to give exclusively anomeric pairs of the N-acetyl-1-nitromannosamine derivatives 24/25 and 26/27, respectively (Scheme 3). The β-addition of methylamine, octadecylamine, and tryptamine to the 1-C-nitroglucal 11 also stereoelectronically controlled and gave the crystalline N-alkyl-1-nitromannosamines 28, 29, and 30, respectively. The stereoelectronically controlled β-addition of NH3 to the 1-C-nitrogalactal 16, followed by acetylation, yielded exclusively the talosamine derivative 31, while the reversible β-addition of azide ions to 16 gave the anomeric 2-azido-1-nitrogalactoses 32 and 33. The β-addition of azide ions to the 1-C-nitroglucal 1 led to the 2-azido-1-nitromannose 34. In the presence of excess formaldehyde, this addition was followed by a Henry reaction. Chromatography of the crude product was accompagnied by solvolytic removal of the NO2 group to give the 3-azidomannoheptulose 35 in high yields (Scheme 4).
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    Comparison of the Complexation of Open-Chain and Cyclic N2S2 Ligands with Cu+ and Cu2+ (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1216-1223 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexation properties of the open-chain N2S2 ligands 1-4 are described and compared to those of analogous N2S2 macrocycles 5-7. With Cu2+, the open-chain ligands give complexes with the stoichiometry CuL2+ and CuLOH+, the stabilities and absorption spectra of which have been determined. The ligand field exerted by these ligands is relatively constant and independent of the length of the chain. With Cu+, the species CuLH23+, CuLH2+, and CuL+ were identified and their stabilities measured. The redox potentials calculated from the equilibrium constants and measured by cyclic voltammetry agree and lie between 250 and 280 mV against SHE. The comparison between open-chain and cyclic ligands shows that (1) a macrocyclic effect is found for Cu2+ but not for Cu+, (2) the ligand-field strength is very different for the two types of ligands, and (3) the redox potentials span a larger interval for the macrocyclic than for the open-chain complexes.
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    Nucleotides. Part XXVPart XXIV: [1].. Chemical synthesis of the hexaribonucleotide C-A-A-C-C-A (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1768-1777 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chemical synthesis of the ribo-hexamer C-A-A-C-C-A has been achieved by two different routes applying the phosphotriester approach and using the (p-nitrophenyl)ethyl group for phosphate protection. The 2′-hydroxy groups as well as the terminal 2′,3′-diol function have been blocked by the (tert-butyl) dimethylsilyl group as permanent protection throughout all the synthetic steps with great success. Final deblocking of all protective groups could be performed with 80% yield to give the hexamer 23. The various protected intermediates have been characterized by elemental analysis and UV spectra.
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    Errata (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1787-1787 
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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.19860690736
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    The Formation of Bridged Bicyclic 1,2,4-Trioxanes by Intramolecular Capture of β-Hydroperoxy Cations (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1778-1786 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1,4-endoperoxide, prepared from 3-(4-methylnaphth-1-yl)propanal by photo-oxygenation in CH2Cl2, gave on treatment with Amberlyst-15®, 3,10b-epidioxy-2,3,4a,10b-tetrahydro-6-methyl-1H-naphtho[2,1-b] pyran in 85% yield. Its structure was determined by X-ray crystal structure analysis. The 1,2,4-trioxane moiety is locked in a twist-boat conformation with trans fusion to the parent six-membered ring. The 1,4-endoperoxides of the methyl, butyl, and phenyl ketone analogues of the aforementioned aldehyde underwent similar acid-catalyzed rearrangement to the corresponding bridged bicyclic trioxanes in 94, 47, and 48% yields, respectively.
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    URL: http://dx.doi.org/10.1002/hlca.19860690735
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    New Synthetic Routes to β-Olefinic Trialkoxyphosphonium Salts and Phosphonates: Organometallic Variants of the Michaelis-Arbuzov ReactionReactions with Metal-Coordinated Olefins, Part V. Part IV: see [1]. Presented in part at the XIIth International Conference on Organometallic Chemistry, Vienna, September 1985. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1757-1767 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The low-temperature addition of tertiary phosphites to [(allyl)Fe (CO)4]+X- complexes proceeds regio- and stereospecifically and produces metal-coordinated β-olefinic trialkoxyphosphonium ions. These can be converted by various routes into the uncomplexed phosphonium salts or phosphonates. Similar reactions of acyclic [(dienyl)Fe(CO)3]+X- compounds give metal-coordinated (2,4-dien-1-yl)trialkoxyphosphonium salts or dialkyl (2,4-dien-1-yl)phosphonates. The mechanisms and their relationship to the classical Michaelis-Arbuzov reaction are discussed. The new compounds are characterized, if possible, by 1H-, 13C-, and 31P-NMR spectra. The new phosphonium salts and phosphonates, potentially useful for Wittig-Horner reactions, are difficult to obtain by conventional routes.
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    URL: http://dx.doi.org/10.1002/hlca.19860690733
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    Mitteilungen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1788-1789 
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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.19860690737
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    Masthead (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986) 
    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.19860690801
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    Membrane Structure of Substance P. I. Prediction of Preferred Conformation, Orientation, and Accumulation of Substance P on Lipid MembranesPeptide nomenclature and abbreviations, see IUPAC-IUB JBCN Recommendations 1983 on ‘Nomenclature and Symbolism for Amino Acids and Peptides’ [1a]. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1789-1797 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preferred conformation, orientation, and accumulation of substance P on a neutral hydrophilic-hydrophobic interface was estimated and extrapolated to interactions with neutral and anionic lipid bilayer membranes according to our general procedure. Nine residues at the C-terminus were predicted to be transferred to the hydrophobic phase as an α-helical domain, oriented quite perpendicularly on the membrane surface. The N-terminal residues remained in the aqueous phase with their charges exposed to H2O. The molecular amphiphilic moment vector was strong (338 arbitrary units) and pointed its hydrophilic end towards the N-terminus, only 15° away from the helix axis. The molecular electric dipole moment vector was also strong (124 debye) and pointed its positive end towards the N-terminus, only 9° away from the helix axis. Thus, it reinforced the effect of the amphiphilic moment of a peptide intruding into the membrane dipole layer. The estimated dissociation constant for the equilibrium between membrane-bound and free substance P was Kd ≍ 46 mM for neutral membranes, and Kd ≍0.43 mM for anionic membranes with a Gouy-Chapman surface potential of -40 mV. Thus, substance P behaved similarly to dynorphin A and adrenocorticotropin peptides which insert their N-terminal message segments as perpendicularly oriented helical domains into membranes, whereas their C-terminal address segments remain in the aqueous phase as random coils. Substance P is the first instance of a neuropeptide which is expected to insert a C-terminal message into lipid membranes.
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    Membrane Structure of Substance P. II. Secondary Structure of Substance P, [9-Leucine]substance P, and Shorter Segments in 2,2,2-Trifluoroethanol, Methanol, and on Liposomes Studied by Circular DichroismPeptide nomenclature and abbreviations, see IUPAC-IUB JBCN Recommendations 1983 on ‘Nomenclature and Symbolism for Amino Acids and Peptides’ [1a] and Table 1. Amino-acid residues are in their L-configuration unless explicitly stated otherwise. Random coil means nonregular, nonrepeating sequences of backbone dihedral angles with or without equilibria between various random coil conformers. PC = phosphatidyl-choline; DOPC = dioleoyl-sn-glycero-3-phosphocholine; PS = phosphatidylserine (brain). (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1798-1806 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Comparative CD studies with substance P (1), [Leu9]substance P ([Leu9]-1), and their shorter peptide segments supported the membrane structures predicted for substance P and [Leu9]substance P. They indicated that the C-terminal segments (from residue 3 or 4 onward) can adopt α-helical conformations in hydrophobic environments and on lipid membranes. The N-terminal segment, (residues 1-4) had a poly(proline)-like conformation in aqueous and hydrophobic surroundings. Residues 3 and 4 (Lys-Pro) appeared to belong to both domains and bring about the transition between the two. The estimated free energies of transfer for 1 and [Leu9]-1 from their random conformations in H2O to their partially helical conformations on an aqueous-hydrophobic interface are too small to allow detectable interaction with neutral lipid membranes at low concentrations. The two peptides should, however, interact detectably with anionic membranes because of favourable Boltzmann distribution factors. This prediction was shown to be correct for liposomes prepared from 1,2-dioleoyl-sn-glycero-3-phosphocholine (neutral) and phosphatidylserine (anionic).
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    Membrane Structure of Substance P. III. Secondary Structure of Substance P in 2,2,2-Trifluoroethanol, Methanol, and on Flat Lipid Membranes Studied by Infrared SpectroscopyPeptide nomenclature and abbreviations, see IUPAC-IUB JBCN Recommendations 1983 on ‘Nomenclature and Symbolism for Amino Acids and Peptides’ [la] and Table 1. Amino-acid residues are in their L-configuration unless explicitly stated otherwise. Random coil means nonregular, nonrepeating sequences of backbone dihedral angles with or without equilibria between various random-coil conformers. IR-ATR = infrared attenuated total reflection spectroscopy. POPC = 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1807-1816 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: IR data of the neuropeptide substance P (1) and its synthetic segments des-(Arg1-Gln6)-substance P (6), des-(Arg1-Pro4)-substance P (4), des-(Arg1-Lys3)-substance P (3), and des-Arg1-substance P (2) indicate predominant β-structures in the solid state and α-helical structures in CF3CH2OH (amide I band shape analysis). In MeOH, the spectra of 1 suggest a partly helical structure. On membranes prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, a C-terminal α-helix consisting of 8 or 9 peptide bonds appears to be induced (IR attenuated total reflection studies). Its perpendicular orientation on the membrane is suggested by the dichroic ratios of the amide-I and -II bands. This study is consistent with our CD experiments and lends support to the membrane structure of 1 predicted from the estimated amphiphilic moment, hydrophobic-association constant, and helix length.
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    Enantioselective Synthesis of β-Necrodol and of 1-Epi-β-necrodol via Asymmetric 1,4-Addition and Magnesium-Ene Cyclization. Preliminary Communication (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1817-1820 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomerically pure β-necrodol (1) and its 1-epimer 16 have been synthesized starting from aldehyde 5. The two key steps are an asymmetric conjugate addtion/Mannich reaction tandem (10→12) and a type-II-magnesiumene cyclization/oxidation sequence (14→1 + 16).
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    3,7-Dioxaazelaamides as Ionophores for Lithium Ion Selective Liquid Membrane Electrodes (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1821-1828 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipophilic neutral carriers were synthesized which show Li+/Na+ selectivities of up to ca. 80 in highly lipophilic liquid membranes. The sensor membranes exhibit improved response times and increased lifetimes as compared to systems described earlier. They allow reliable measurements of Li+ in blood serum within the clinical concentration range. A 1:1 Li+/ionophore complex of one representative (N,N,N′,N′-tetracyclohexyl-5,5-dimethyl-3,7-dioxaazelaamide) has been prepared, and its structure was elucidated by X-ray analysis.
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    URL: http://dx.doi.org/10.1002/hlca.19860690806
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    Stoffwechselprodukte von Mikroorganismen. 237. Mitteilung236. Mitt.: [1]. (2S, 3R, 4R, 6R)-2,3,4-Trihydroxy-6-methylcyclohexanon aus zwei Actinomyceten-Stämmen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1829-1832 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (2S, 3R, 4R, 6R)-2,3,4-Trihydroxy-6-methylcyclohexanone from Two Strains of ActinomycetesA tetrazolium-blue positive compound was isolated from two strains of acinomycetes. Its constitution and relative configuration 1 were determined by spectroscopic methods, and the absolute configuration by degradation to (+)-(R)-methylsuccinic acid.
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    Stoffwechselprodukte von mikroorganismen. 238. Mitteilung237. Mitt.: [1].. Isolierung und Strukturaufklärung von Differolid (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1833-1836 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation and Structure Elucidation of DifferolideFrom cultures of a new actinomycete, Streptomyces aurantiogriseus (PREOBRAZHENSKAYA 1975), strain Tü 3149, a compound C12H12O4 was isolated, which enhances the formation of aerial mycelium and spores of Streptomyces glaucescens. The structure determined by X-ray diffraction studies was that of racemic dilactone 1 ((±)-differolide).
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    Carbophile Additionen von Organocupraten mit 1,3-Thiazol-5(4H)-thionen (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1837-1843 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbophilic Additions of Organocuprates and 1,3-Thiazole-5(4H)-thionesOrganocuprates and 1,3-thiazole-5(4H)-thiones 1 react in THF at 0° via carbophilic addition onto the C—S bond to give 4,5-dihydro-1,3-thiazole-5-thiols 3 (Scheme 3). This observation is in marked contrast to the previously described reaction of organolithium compounds and 1, which undergo a thiophilic addition onto the exocyclic S-atom. As an exception, treatment of the 1,3-thiazole-5(4H)-thione 1a with tert-butyl cuprate leads to 7a (Scheme 3).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690809
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  • 98
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    Synthesis of 3β-Hydroxy[21-14C]-5β-pregn-8(14)-en-20-one from Chenodeoxycholic Acid (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1844-1850 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3β-Hydroxy[21-14C]5β-pregn-8(14)-en-20-one (17) was prepared from chenodeoxycholic acid (1a). The synthetic sequence involved: (i) degradation of the bile-acid side chain to an etianic acid; (ii) formation of the 8(14)-double bond; (iii) inversion of the configuration at C(3); (iv) construction of the acetyl side chain at C(17) with the required isotopic label at C(21). Structures of all described products were confirmed by chemical and spectroscopic (IR, 1H-NMR, 13C-NMR, MS) methods.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690810
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  • 99
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    Neue 1,6-Methano[10]annulen-Derivate durch Umlagerungsreaktionen der Trimethylsilyl-Gruppe (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1851-1854 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Derivatives of 1,6-Methano[10]annulene by Rearrangement of Trimethylsilyl GroupsOxidation of derivatives of trimethylsilyl-substituted bicyclo[4.4.1]undeca-1,3,5,7-tetraenes 1-3 leads to 1,6-methano[10]annulenes. In the case of 2 and 3a, rearrangement of the trimethylsilyl group takes place. This rearrangement can be used to prepare 2,9-disubstituted 1,6-methano[10]annulenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690811
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  • 100
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    Highly Stereoselective Photochemical Oxidative Addition Reactions. Preliminary Communication (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1855-1857 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclometallated complexes of the type cis-bis(2-phenylpyridine)platinum(II) (C22H16N2Pt) and cis-bis(2-(2′-thienyl)pyridine)platinum(II) (C18H12N2S2Pt) undergo thermal or photochemical oxidative addition (TOA or POA) reactions with a number of substrates. TOA (with CH3I, CH3CH2I etc.) yield mixtures of several isomers which rearrange slowly (within ca. one week at room temperature) to one of the possible cis-isomers. CH2Cl2, CHCl3, or (E)—ClCH=CHCl, e.g., do not react thermally. POA yield directly complexes of Pt(IV) with the halide and a σ-bonded C-atom in cis-position. The configuration, as assigned by extensive use of 1H-NMR data, can be characterized for the two chelating ligands C … N and C′ … N′ by C,C′-cis; N,N′-cis and C(chelate), Cl-trans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690812
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