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  • Cerebellum
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  • 1980-1984  (1,071)
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  • 1
    Electronic Resource
    Electronic Resource
    The perineuronal net in the fastigial nucleus of the rat cerebellum (1984)
    Springer
    Anatomy and embryology 170 (1984), S. 79-85 
    Details
    ISSN: 1432-0568
    Keywords: Perineuronal net ; Astrocytes ; Fastigial nucleus ; Cerebellum ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphological study of the rat fastigial nucleus with the Golgi-Rio Hortega method showed the presence of glial perineuronal nets surrounding the large neurons, but not the small ones. This perineuronal net appeared as a mesh of tenuous glial processes which covers the neuronal perikarya and proximal dendrites. The small alveolate compartments in this mesh seem to correspond to the holes for the synaptic boutons. Our results also indicate that the perineuronal net is derived from interneuronal protoplasmic and velate astrocytes. Using camera lucida drawings of this perineuronal net we have made a quantitative estimation of the size and density of synaptic boutons on these large neurons. The average numerical density of synaptic boutons was about 19 per 100 μm2 of the neuronal surface, the mean area of the synaptic holes being 2.5 μm2. Furthermore, the quantitative data evidence that about 52.5% of the neuronal surface is presumably occupied by synaptic boutons whereas the remaining 47.5% is covered by the glial processes of the perineuronal net. Semithin sections prepared from thick Golgi sections were used for the cytological study of the neurons surrounded by this glial pericellular network. The possible functional significance of the perineuronal net in the regulation of synaptic transmission in the fastigial cerebellar nucleus is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319461
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  • 2
    Electronic Resource
    Electronic Resource
    Cerebellar histogenesis and synaptic maturation following pre- and postnatal alcohol administration (1984)
    Springer
    Acta neuropathologica 63 (1984), S. 57-65 
    Details
    ISSN: 1432-0533
    Keywords: Fetal alcohol syndrome ; Rat ; Cerebellum ; Purkinje cells ; Synaptic maturation ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fetal alcohol syndrome was produced in rats by feeding an ethanol-enriched, vitamine-supplemented liquid diet over a period of 4 weeks before mating and throughout pregnancy. The amount of ethanol was equivalent to 38–40% of the daily calories; control animals were fed an isocaloric amount of sucrose. The offspring of experimental animals displayed a diminished birth weight. In contrast to previous experiments, the ethanol diet was also administered during the lactating period. On postnatal day 7, experimental animals and controls were killed by perfusion and the cerebella prepared for electron microscopy. Morphometric analysis showed a reduced number of Purkinje cells. On day 12, Purkinje cells of experimental animals displayed ultrastructurally fewer organelles. Furthermore, a delayed synaptogenesis in the molecular layer was demonstrated with osmiumzinc iodide and ethanolic phosphotungstic acid showing an immature appearance of the presynaptic grid and weaker stained synaptic cleft material. The following discussion deals with possible mechanisms underlying these alcohol-induced alterations of cerebellar synaptogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688471
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  • 3
    Electronic Resource
    Electronic Resource
    Cerebellar connections in Xenopus laevis (1984)
    Springer
    Anatomy and embryology 169 (1984), S. 167-176 
    Details
    ISSN: 1432-0568
    Keywords: Cerebellum ; Cerebellar afferents ; Cerebellar efferents ; Inferior olive ; Xenopus laevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the present study the cerebellar afferents in the clawed toad Xenopus laevis have been analysed with the horseradish peroxidase (HRP) technique. In addition, data on the efferent connections of the cerebellum could be gathered, based on the phenomenon of anterograde transport of HRP. Cerebellar afferents in Xenopus laevis appear to arise mainly in the vestibular nuclear complex, in a primordial inferior olive and in the spinal cord. Both primary (arising in the ipsilateral vestibular ganglion) and secondary vestibulocerebellar projections were found. A distinct crossed olivocerebellar projection to the molecular layer of the cerebellum was found. Two spinocerebellar pathways are present in Xenopus laevis, as in other anurans, viz. an ipsilateral dorsal spinocerebellar tract, presumably arising in dorsal root ganglion cells, and a larger ventral pathway, bilaterally arising in the spinal gray matter. The latter tract mainly originates in the ventrolateral and ventromedial spinal fields. Furthermore, a secondary trigeminocerebellar projection arising in the descending trigeminal nucleus, a cerebellar projection arising in the dorsal column nucleus, a small projection arising in a possible primordium of the mammalian nucleus prepositus hypoglossi, a raphecerebellar projection, and a small cerebellar projection originating in the ipsilateral mesencephalic tegmentum were demonstrated. Cerebellar efferents in Xenopus laevis are mainly aimed at the vestibular nuclear complex. A distinct ipsilateral cerebellovestibular projection present throughout the vestibular nuclear complex presumably arises in Purkyně cells, a smaller contralateral projection in the cerebellar nucleus. In addition, a small primordial brachium conjunctivum, projecting to the red nucleus, was noted. The basic pattern of cerebellar connections as suggested for terrestrial vertebrates (ten Donkelaar and Bangma 1984) is also found in the permanently aquatic anuran Xenopus laevis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303146
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  • 4
    Electronic Resource
    Electronic Resource
    Organic lead and histological parameters of brain development (1984)
    Springer
    Acta neuropathologica 63 (1984), S. 306-312 
    Details
    ISSN: 1432-0533
    Keywords: Cerebellum ; Hippocampus ; Lead ; Brain development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Relatively little work has been done on the structural effects of organic lead in the central nervous system (CNS), although this form of lead may be a significant fraction of total brain lead. We tested a number of easily measured light-histological parameters of neuronal development in rats for sensitivity to (a) normal growth between 18 and 28 days of life and (b) the effect of weekly injections of tetramethyl lead (TML), administered from 1 week after conception until post-natal day 6. Several of the histological parameters were found to be sensitive to normal growth, but none showed any effect of organic lead treatment. This was despite a small but significant decrease in brain weight, and a significant increase in body/brain weight ratio, with tetramethyl lead treatment. The body/brain weight ratio was the parameter most sensitive to tetramethyl lead treatment. Possible reasons for the disparity between weight and histological parameters are discussed, with reference to previous workers' findings concerning the effects of organic lead on the development of myelin in the CNS and the availability of organic lead to brain tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687338
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  • 5
    Electronic Resource
    Electronic Resource
    Mutual inhibition between olivary cell groups projecting to different cerebellar microzones in the cat (1984)
    Springer
    Experimental brain research 54 (1984), S. 293-303 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Inferior olive ; Climbing fibre microzones ; Mutual inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was carried out predominantly on the b zone in the lateral vermis of the cerebellar anterior lobe. This zone is divided into sagittally oriented microzones which receive a somatotopically organized climbing fibre input. 1. It was shown that the climbing fibre input to one microzone is inhibited by stimulation of a nerve that projects to an adjacent microzone. 2. The degree of inhibition was related to the proximity of the microzones involved. 3. The latency of the inhibition was short and the duration 70–110 ms. 4. The inhibition of climbing fibre responses occurred in the inferior olive and was presumably due to post-synaptic inhibition of the olivo-cerebellar neurones. 5. The mutual inhibition could be produced by antidromic activation of olivo-cerebellar neurones. 6. An inhibition with similar properties as in the b zone, but weaker, was observed between forelimb and hindlimb inputs to the c1 and c3 zones in the pars intermedia. In the c3 zone, an inhibition between adjacent forelimb microzones also occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236230
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  • 6
    Electronic Resource
    Electronic Resource
    Harmaline induced tremor III. A combined simple units, horseradish peroxidase, and 2-deoxyglucose study of the olivocerebellar system in the rat (1984)
    Springer
    Experimental brain research 57 (1984), S. 128-137 
    Details
    ISSN: 1432-1106
    Keywords: Harmaline tremor ; Cerebellum ; Inferior olive ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Purkinje cells were recorded extracellularly and mapped in the cerebellar cortex of the rat under tremogenic doses of harmaline. Four différent types of responses were encountered, of which two were considered as being responsible for the harmaline tremor. The latter had a regular firing pattern of complex spikes at 5 to 10 Hz and were mostly found in the vermis. Their number decreased in the more lateral region of the cerebellar cortex until they eventually disappeared. Horseradish peroxidase was injected into all the areas of the cerebellar cortex containing Purkinje cells with harmaline-induced activity. Labeled neurons were in all cases traced to the medial accessory olive. The metabolic activity of the inferior olive under harmaline was measured with 2-deoxyglucose. Increased labeling was only found in the medial accessory olive. Such an increase was demonstrated as being due to a direct effect of the drug on the inferior olivary neurons, indicating that the medial accessory olive is responsible for the harmaline tremor in the rat. Our results point out that, in the rat, there is an inverse relationship between serotoninergic innervation of a region in the inferior olivary nucleus and that with harmaline sensitivity, therefore a serotoninergic mechanism hypothesis for the harmaline tremor needs further investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231139
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  • 7
    Electronic Resource
    Electronic Resource
    Regional cerebellar choline acetyltransferase activity following peduncular lesions (1984)
    Springer
    Experimental brain research 53 (1984), S. 370-373 
    Details
    ISSN: 1432-1106
    Keywords: Choline acetyltransferase ; Cerebellum ; Cerebellar peduncle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The activity of choline acetyltransferase (ChAT) in the cerebellar lobules of the rat was determined after bilateral destruction of either the superior, middle, or inferior cerebellar peduncles. A significant, 40–60% decrease in ChAT activity occurred in all subdivisions of the cerebellum (anterior lobe, posterior lobe hemisphere, posterior lobe vermis/nodulus and flocculus/paraflocculus) following bilateral inferior peduncle lesions. In contrast, bilateral lesions of the superior or middle peduncles did not result in significant reductions of enzyme activity. These findings indicate that the cholinergic afferents to the cerebellum are contained predominantly in the inferior peduncle, from which they emerge to innervate all of the gross subdivisions of the cerebellum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238167
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  • 8
    Electronic Resource
    Electronic Resource
    A physiological study of identification, axonal course and cerebellar projection of spinocerebellar tract cells in the central cervical nucleus of the cat (1984)
    Springer
    Experimental brain research 55 (1984), S. 272-285 
    Details
    ISSN: 1432-1106
    Keywords: Central cervical nucleus ; Spinocerebellar tract ; Cerebellum ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Spinocerebellar tract (SCT) neurones in and around the central cervical nucleus (CCN) were physiologically identified by antidromic activation of these cells on stimulation of the cerebellum. Among the Spinocerebellar tract cells thus identified, those ascending the contralateral spinal funiculi were found in the CCN and ventralwards, whereas those ascending the ipsilateral funiculi existed mostly dorsal to the CCN partly overlapping with crossed cells in the nucleus. Mapping sites from which CCN cells were antidromically activated showed that axons of the CCN-SCT cross at the same segment, ascend the ventral funiculus initially, the lateral funiculus at rostral C1 and the lateral border of the medulla to reach the cerebellar peduncle, enter the cerebellum mainly via the restiform body but possibly also via the superior peduncle. Systematic mapping of stimulation within the cerebellum indicated that the CCNSCT projects to the medial part of the anterior lobe and the posterior lobe bilaterally. Projection to lobules I–II was found in almost all CCN-SCT cells examined. Three fourths of CCN-SCT cells projected to the posterior lobe, as revealed by less extensive mapping. Mapping of axonal regions of the same single CCN-SCT cells showed that they project multifocally in the cerebellum, where projection to lobules I–II was common and that to other areas varied with individual cells. Conduction velocites decreased within the cerebellum probably as the result of repeated branching. Mossy fibre responses evoked on stimulation of the C2 dorsal root in cats with the transected dorsal funiculi were shown to be mediated mostly via the CCN-SCT. Mapping the field potential showed that the response was by far the largest in lobules I–II. This suggested that the terminals provided by the CCN-SCT are the densest in these lobules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237278
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  • 9
    Electronic Resource
    Electronic Resource
    Intracranial cerebellar grafts: Intermediate filament immunohistochemistry and electrophysiology (1984)
    Springer
    Experimental brain research 55 (1984), S. 372-385 
    Details
    ISSN: 1432-1106
    Keywords: Intracranial transplants ; Cerebellum ; Glial fibrillary acidic protein ; Vimentin ; Electrophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pieces of the developing cerebellar anlage were prepared from 13–15 day old rat embryos and transplanted to the cerebellar region of 5–7 and 13–14 day old rat pups. Approximately two months later, sections showed most grafts to consist of both cerebellar cortex, with a typical trilaminar organization, and white matter areas containing large neuronal perikarya. The astrocytic populations were studied using immunohistochemistry with antisera raised against the intermediate filaments, glial fibrillary acidic protein (GFA), and vimentin. The GFA-antiserum revealed a glial interface along most of the border between host brain and graft. Both antisera stained long, slender, although slightly distorted Bergmann fibers spanning the molecular layer. Using GF-Aantiserum, star-shaped fluorescent astrocytes were seen in the granular layer and in the white matter. Only in the white matter did the amount of GFA-like immunoreactivity suggest an astrocytic gliosis. With vimentin antiserum fluorescent astrocytes in the white matter were seen. There were no signs of increased amounts of vimentin-like immunoreactivity. Taken together, the amount and distribution of GFA-and vimentin-like immunoreactivity suggests a rather normal astrocytic development in the cerebellar grafts. Using an antiserum against the neurofilament (NF) triplet, delicate immunoreactive fibres were seen in both the molecular and the granular layer. No positive cell bodies could be visualized in the cortical areas. Although the Purkinje cells themselves were negative, fibre baskets around them were intensely stained. In the white matter a high density of NF-positive fibres and some positive perikarya were visualized. Thus the distribution of NF-like immunoreactivity in the grafts corresponded well to the normal NF distribution. The functional maturation of the cerebellar grafts was studied electrophysiologically. A spontaneous mean discharge rate of 19.3 + 1.7 Hz was recorded from the Purkinje cells. This compares with a discharge rate of 26.8 + 1.0 Hz for Purkinje neurons in situ. The difference was at least partly ascribable to the absence of climbing fibre bursts in the grafts. Local stimulation of the graft surface caused both decreased and increased Purkinje cell discharge. In conclusion, these experiments suggest that grafts of fetal cerebellar buds to the young cerebellum develop into cerebellar tissue having both morphological and electrophysiological characteristics quite similar to the normal cerebellum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237288
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  • 10
    Electronic Resource
    Electronic Resource
    Topographic features of climbing fiber input in the rostral vermal cortex of the cat cerebellum (1984)
    Springer
    Experimental brain research 55 (1984), S. 445-454 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Climbing fiber responses ; Olivocerebellar projection ; Somatotopic organization ; Mechanoreceptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The topographic organization of the climbing fiber (CF) responses was mapped in the rostral vermal cortex (lobules III, IV, and Va) of the cerebellum. Extracellular, single-unit recordings were obtained from 699 Purkinje cells in cats anesthetized with sodium pentobarbitol. Approximately 72% of the CF responses were elicited by low-threshold or deep tactile stimulation, whereas the remaining units were unresponsive to any peripheral stimulation. On the basis of response characteristics, the vermal cortex was separated into an approximately 1-mm-wide medial zone and a 1 to 1.5-mm-wide lateral zone. The medial zone contained many unresponsive cells, except along the midline, where about 35% of the CF responses were elicited by deep stimulation at the base of the tail. The majority (78%) of the CF responses within the lateral vermal cortex represented various areas of the hindpaw, although representations of the forepaw (8%), tail (4%), and chin (0.6%), as well as unresponsive units (10%), were evident. The lateral vermal cortex contained a mediolateral topography of different receptive fields, although the topography was not sharply defined or equally displayed in all animals. The medial part of the lateral zone contained a representation of the ipsilateral forelimb in lobules IV and Va; the middle part had a representation of the medial or the lateral half of the hindpaw; and the lateral portion of the zone had an extensive representation of the distal hindpaw. The CF responses with similar receptive fields were often found in patches, which in some areas were arranged in layers from the inner to the outer areas of the sublobules. A particular body surface may be represented in multiple patches and in different lobules. Activation of the majority of CF responses within a sublobule may occur only during selected behaviors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235275
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  • 11
    Electronic Resource
    Electronic Resource
    Regulation of cerebello-cortical transmission in the rat ventromedial thalamic nucleus (1984)
    Springer
    Experimental brain research 55 (1984), S. 535-552 
    Details
    ISSN: 1432-1106
    Keywords: Thalamus ; Cerebellum ; Basal ganglia ; Electrophysiology ; Rat ; Firing patterns ; Transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary On the basis of antidromic stimulation we have identified two distinct neuronal populations in the rat ventromedial thalamic nucleus. The largest population (96%) are thalamo-cortical relay cells which project via the internal capsule to the cerebral cortex. The smaller population of cells (4%) project caudally to the reticular formation and superior colliculus. These two cell types could be distinguished further on the basis of their patterns of spontaneous discharge. Relay cells fluctuate between two activity patterns (i) a rhythmic pattern characterized by periods of high-frequency bursting, and (ii) a more tonic discharge pattern of single spikes. The caudally projecting cells had a characteristic fast, regular type of spontaneous firing. Brachium conjunctivum stimulation evokes two distinct responses in thalamic relay cells, (i) a short-latency single spike, (ii) a longer latency, rhythmic response of 2–3 spikes. Both excitatory responses are followed by a period of cell quiescence. The type of response is dependent upon the cell's firing pattern. The short-latency response occurs during tonic, single-spike activity whilst the longer latency response occurs during highfrequency bursting activity. The short-latency response can be altered to the long latency response by increasing the level of anaesthesia or by applying a conditioning shock to known inhibitory pathways. Conversely the long latency response can be altered to the short-latency response by decreasing anaesthesia or by stimulation of the reticular formation. It is argued that both response types are evoked monosynaptically by activation of the same cerebello-thalamic fibres but that different ionic conductances which are active at different levels of membrane polarization are responsible for the two response patterns. Efficient time-locked cerebellothalamo-cortical transmission occurs only during tonic single-spike activity, when cerebellar stimulation evokes a short-latency response. Such transmission is allowed or disallowed by the fine balance between converging excitatory and inhibitory afferents. In addition to a monosynaptic excitatory input from the cerebellar nuclei, relay cells received converging synaptic inputs from the substantia nigra, cerebral cortex, reticular formation and superior colliculus. Due to the anatomical arrangement in the rat it proved impossible to assess the role of the pallidum. The population of caudally projecting cells also received several converging synaptic inputs, but unlike those influencing relay cells, these inputs were all excitatory. We have obtained no clear physiological evidence for the occurrence of local interneurones within the ventromedial nucleus. However, a powerful recurrent inhibitory circuit is activated following antidromic activation of relay cells. The interneurones responsible for this inhibition appear to lie in the thalamic nucleus reticularis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235285
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  • 12
    Electronic Resource
    Electronic Resource
    Effects of serotonin on cerebellar Purkinje cells are dependent on the baseline firing rate (1984)
    Springer
    Experimental brain research 56 (1984), S. 50-58 
    Details
    ISSN: 1432-1106
    Keywords: Serotonin ; Cerebellum ; Purkinje cell ; Microiontophoresis ; Rate dependency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Serotonin applied iontophoretically to cerebellar Purkinje cells elicited one of three effects: inhibition (62% of the cells), biphasic response (27%), and excitation (11%). This study describes a correlation between the spontaneous discharge rate of Purkinje cells and the action of serotonin. Purkinje neurons that responded to serotonin with an increase in firing rate had a significantly slower predrug firing frequency (40 Hz) than those cells that were suppressed by serotonin (51 Hz). Furthermore, it was shown that with increasing firing rates the proportion of excitations decreased, and the proportion of depressions increased. A quantitative comparison revealed a statistically significant correlation between the spontaneous discharge rate of cells displaying excitation and the magnitude of the excitatory response. On several occasions, the direction of the Purkinje cell response to serotonin reversed following a decrease or increase in the baseline spontaneous rate. Glutamate- or asparate-induced excitations elicited an augmentation of serotonin-mediated inhibition and in some cases a reversal of excitation to inhibition. Likewise, the lowering of neuronal activity by the continuous application of glycine augmented excitation and reduced and reversed serotonin inhibitions. Preliminary results from experiments in which various receptor antagonists were tested against serotonin actions suggest that the effects of serotonin occur, at least in part, at postsynaptic sites on Purkinje cells. These results strongly suggest that the overall qualitative effects of serotonin is to set Purkinje cells at a preferred firing rate. In this sense, the term biaser or modulator may best describe the role of serotonin in the cerebellum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237441
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  • 13
    Electronic Resource
    Electronic Resource
    Origin of signals conveyed by the ventral spino-cerebellar tract and spino-reticulo-cerebellar pathway (1984)
    Springer
    Experimental brain research 54 (1984), S. 426-431 
    Details
    ISSN: 1432-1106
    Keywords: Spinal cord ; Scratch reflex ; Ventral spino-cerebellar tract ; Spino-reticulo-cerebellar pathway ; Cerebellum ; Cooling the nervous tissue ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary (1) The “fictitious” scratch reflex was evoked in decerebrate curarized cats by pinna stimulation. Activity of neurons of the ventral spinocerebellar tract (VSCT) from the L4 and L5 segments of the spinal cord as well as of neurons of the spinoreticulo-cerebellar pathway (SRCP) from the lateral reticular nucleus of the medulla oblongata was recorded. Cooling and destruction of different parts of the lumbo-sacral enlargement of the spinal cord were performed. (2) Cooling of the L5 or L6 segment abolished the rhythmic activity in the greater part of the spinal hindlimb centre but did not affect the generation of rhythmic oscillations in the remaining (rostral) segments of the lumbo-sacral enlargement. Under these conditions, neither the rhythmic activity of VSCT neurons located rostral to the thermode nor that of SRCP neurons changed. (3) A normal rhythmic activity of SRCP neurons also persisted after destruction of grey matter in the L3 and L4 segments. It can be concluded that activity of these neurons is independent of whichever part of the enlargement generates rhythmic oscillations. (4) From these observations a hypothesis is advanced that the main content of signals conveyed by the VSCT and SRCP to the cerebellum is the information regarding activity of the generator of rhythmic oscillations that is located in the L3-L5 spinal segments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235467
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  • 14
    Electronic Resource
    Electronic Resource
    Cerebellar feedback signals of a passive hand movement in the awake monkey (1984)
    Springer
    Pflügers Archiv 402 (1984), S. 292-299 
    Details
    ISSN: 1432-2013
    Keywords: Cerebellum ; Climbing fibre ; Purkinje cell ; Awake monkey ; Passive movement ; Sensory feedback
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract From three intact and awake monkeys, 149 Purkinje cells and 44 presumed mossy fibres were recorded in the intermediate part of the cerebellar anterior lobe, and this activity was analyzed with regard to different parameters of a passive hand movement. The tonic discharge rate of the simple spikes (SS) varied according to different joint positions only in a single Purkinje cell, whereas such a position relation was found in nine out of 44 presumed mossy fibres. A phasic increase of the complex spike (CS) discharge rate of Purkinje cells in response to passive wrist movements usually occurred within 100 ms after movement onset. However, in some units a phase of increased CS rate was observed which lasted for the whole movement duration. The amount of this phasic increase in the CS rate depended on the acceleration of movement, but the SS response to movements of different velocity remained unchanged.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585512
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  • 15
    Electronic Resource
    Electronic Resource
    Release of labelled taurine from the rat dorsal medulla and cerebellum in vivo (1984)
    Springer
    Pflügers Archiv 401 (1984), S. 193-197 
    Details
    ISSN: 1432-2013
    Keywords: Cerebellum ; Dorsal medulla ; Taurine ; Neuromodulator ; Amino acid ; Neurotransmitter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stimulus-induced release of labelled taurine has been studied in the superfused rat cerebellar cortex and dorsal medulla in vivo. In the cerebellum both elevated potassium and electrically induced depolarization consistently produced marked increases in the efflux of exogenously applied taurine in a calcium-dependent fashion. Veratridine-stimulation evoked a large Ca2+-independent taurine efflux which was, however, prevented by tetrodotoxin. In the dorsal medulla, both high K+ and veratridine induced a clear Ca2+-independent increase in taurine efflux. Electrical stimulation was always ineffective in changing taurine efflux from the dorsal medulla. These data strongly support a possible neurohumoral role for taurine in the cerebellum but not in the dorsal medulla.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583881
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  • 16
    Electronic Resource
    Electronic Resource
    Cerebellar afferents in the frogs, Rana esculenta and Rana temporaria (1984)
    Springer
    Cell & tissue research 237 (1984), S. 259-267 
    Details
    ISSN: 1432-0878
    Keywords: Cerebellum ; Cerebellar afferents ; Transport, retrograde ; Horseradish peroxidase (HRP) technique ; Brainstem ; Anurans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Afferents to the cerebellum in frogs (Rana esculenta, Rana temporaria) were studied by use of retrograde transport of horseradish peroxidase. Following injections restricted to the molecular layer of the cerebellum cell labelling was found in the contralateral inferior olive and the ventral portion of the caudal medullary raphe. Injections involving the granular layer resulted in labelling in the ventral horn of the cervical spinal cord, the caudal spinal trigeminal nucleus, the nucleus caudalis and the medial portion of the nucleus ventralis of the vestibular nerve, the inferior reticular nucleus and the nucleus of the fasciculus longitudinalis medialis. Following larger injections, which may have spread significantly into the cerebellar, secondary gustatory, trigeminal or vestibular nuclei, labelled cell bodies were also found in the nucleus ruber, nucleus solitarius, the rostral spinal trigeminal nucleus and the rostral rhombencephalic reticular formation. It is unclear whether the fibers from these latter areas innervate the cerebellum of the frog, as they do in mammals, or only reach the underlying areas. This situation emphasizes a limitation of the HRP technique when applied to small structures as is often the case in lower vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217144
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  • 17
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    Regional differences in the ultrastructure of Purkinje cells of the rat (1984)
    Springer
    Cell & tissue research 235 (1984), S. 91-98 
    Details
    ISSN: 1432-0878
    Keywords: Cerebellum ; Purkinje cells ; Cytoarchitectonics ; Quantitative neuroanatomy ; Albino rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the albino rat, perikaryal diameter, volume density of the granular endoplasmic reticulum and Golgi apparatus, and lumenal diameter of cisternae of the granular endoplasmic reticulum are larger in Purkinje cells of lobule Via (neocerebellum) than in those of lobule X (archicerebellum). In contrast, only the surface density of cisternae of the granular endoplasmic reticulum is larger in Purkinje cells of lobule X. The cisternae of granular endoplasmic reticulum are arranged into conspicuous Nissl bodies parallel to the nuclear membrane, but the content of ribosomes and polysemes is markedly less in lobule-X cells than in cells from lobule VI a. These results indicate qualitative and quantitative differences between the metabolically important organelles in Purkinje cells of the neo- and archicerebellum (cf. Larsell 1952).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213728
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  • 18
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    The He(Iα) Photoelectron Spectra of the Perfluoroderivatives of Trisannelated Benzenes and Tetrakisannelated Cyclooctatetraenes (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 47-53 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(Iα) photoelectron (PE) spectra of tris(perfluorocyclobuta)benzene 4(F)3,3,4,4,7,7,8,8,11,11,12,12-Dodecafluorotetracyclo[8.2.0.02,5.06,9]dodeca-1,5,9-triene, tris(perfluorocyclopenta)benzene 5(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-Octadecafluoro-2,3,4,5,6,7,8,9-octahydro-1H-trindene., tetrakis(perfluorocyclobuta)cyclooctatetraene 6(F)3,3,4,4,7,7,8,8,11,1l,l2,l2,l5,15,16,16-Hexadecafluoropentacyclo[12.2.0.02,5.06,9.010,13]hexadeca-1,5,9,13-tetraene., and of tetrakis(perfluorocyclopenta)cyclooctatetraene 7(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Tetracosafluoro-1,2,3,4,5,6,7,8,9,10,11,12-dodeca-hydrotetracyclopenta[a,c,e,g]cyclooctene. are reported. A tentative assignment of the PE spectra is derived by empirical correlation with those of relevant reference compounds. The results suggest that 6(F) retains the D4h-conformation in the gas phase, i.e. A conformation with a planar cyclooctatetraene ring, as observed in the crystal. All four compounds exhibit a sharp increase of their first ionization energies, relative to the corresponding parent hydrocarbons, due to the perfluoro effect.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670107
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  • 19
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    Transition metal complexes with bidentate ligands spanning trans-positions. Part XIVPart XIII: see [1].. Some complexes of 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene with platinum (0) and their reactivities (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 65-72 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) has been used to prepare complexes of the type [PtL(1)] (L = C2H4, CH2=CH—CO2Me, PhC≡CPh, MeC≡CMe, MeO2CC≡CCO2Me, (i-Pr)O2CC≡CCO2(i-Pr), Ph3P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph3P)2]. The preparation of complexes trans-[PtX(R)(1)] by oxidative addition of RX (RX = PhCH2Br and Mel) to [Pt(C2H4)(1)] is described. The isolation of [PtO2(CH3)2CO(1)] is also reported.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670109
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  • 20
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    Intermolecular Electron Spin Transfer between Naphthalene π-Systems Separated by a Variable Number of Spirobonded Cyclobutane Rings, An. ESR and ENDOR Study (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 416-424 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical anions of the compounds N1N, N3N and N5N, in which two naphthalen π-systems are separated by 1, 3 and 5 spirobonded cyclobutane rings, respectively, and tha tof the reference compound N1, containing one naphthalene π-system and one cyclobutane ring, have been studied by ESR and ENDOR spectroscopy under a variety of experimental conditions. The intramolecular electrons spin transfer between the two π-moieties in N3N.⊖ and N5N.⊖ is slow on the hyperfine time-scale, irrespective of the applied conditions. It is also slow in N1N.⊖, except for media of high solvating power. In such media, with a slight reduction of N1N to its radical anion, a paramagnetic species is observed, the hyperfine data for which are consistent with N1N to its radical anion, a paramagnetic species is observed, the hyperfine data of which are consistent with N1N.⊖, undergoing a fast intramolecular electron spin tansfer. The ESR and ENDOR spectra of this species are superimposed on those characteristic of a slow transfer. It is suggested that the fast and slow transfer involve the syn- and anti-conformations, respectively, since the distance, r, between the two naphthalene π-systems of N1N.⊖ is considerably shorter in the former than in the latter (r = 740 vs. 880 Pm for the distance between the centres of the π-systems). Glassy solutions of exhaustively reduced N1N display signals of the dianion triplet state, whereas no such signals are found for N3N and N5N. The zero-field splitting parameter, D, is 4.7 mT, corresponding to r ≈ 480 pm.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670210
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  • 21
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    The mass spectra of organic compounds. 7th Communication6th Communication, see [1].. 4,4-Dimethyl-1-pentene (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 425-433 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Loss of CH3., CH4, C2H4, C3H5., C3H6 and C3H7 from the molecular ions of a number of 13C-labeled analogs of 4,4-dimethyl-1-pentene was studied both in normal (source) 70-eV electron impact (EI) spectra dn in metastable spectra. For loss of CH3. in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C-1 (16%) and C-3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C-1 or C-3 are lost with any other C-atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C-1 and C-3 being 6%. If C-1 seems to these two positions become completely equivalent in the metastable time range. The T-values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C3H5 (allylic cleavage) is 100% C-1, C-2 and C-3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C3C6 (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C3H7. appears to be the the result of consecutive loss of CH3. and C3H4, rather than a one-step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C6H11+ and C5H10+ secondary ions occurs in an essentially random fashion.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670211
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  • 22
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    Synthese von para-substituierten phenyl-terpyridin liganden (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 450-454 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Up to now the synthesis of para-substituted phenyl-terpyridine ligands was difficult with respect to the purification of the reaction products. We have found that these compounds can easily be isolated as hydrobromides from acetic acid. Starting from the hydrobromides the purification turned out to be easy. Synthesis of para-substituted Cl-, Br-, H3C-, H2BrC-, HO- 2,6-Bis(2-pyridyl)-4-phenylphyridine is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670214
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  • 23
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    Complexation de l'argent(I) par des teramines cycliques (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 441-449 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of Silver(I) by Cyclic TetraminesThe nature of Ag(I)-complexes with 1,4,8,11-tetraazacyclotetradecane (1), 1,5,9,13-tetraazacyclohexadecane (2) 1,5,10,14-tetraazacyclooctadencane (3) and 1,6,11,16-tetraazacycloeicosane (4) is studied. The effect of ring size on disproportionation of the Ag() cation in the presence of ligand is reported. The stability of Ag(I)-complexes with 3 and 4 in aqueous solution is determined by means of potentiometric titration.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670213
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  • 24
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    Mitteilungen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 625-627 
    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.19840670231
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  • 25
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    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.19840670301
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  • 26
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    Radikalionen von überbrückten [14] Annulenen. Untersuchungen zum Frontorbitaleinfluss auf Reaktivität und Bindungszustand (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 625-639 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical Ions of Bridged [14] Annulenes. Investigations on the Influence of Frontier Orbitals on Reactivity and BondingThe radical anions and the radical cations derived from trans-15, 16-dimethyl-1, 4:8,11-ethandiyliden[14]annulene (6), trans-15-methyl-1,4:8,11-ethandiyliden[14]annulene (7) and cis-15, 16-propano-1,4:8,11-ethandiyliden[14]annulene (8) are described. The hyperfine data of the radical anions 6, 7 and 8 resemble those of the structurally related radical anions of trans-10b, 10c-dimethyldihydropyrene (4) and trans-10b, 10c-dihydropyrene (5). This finding leads to the conclusion, that the change in the relative arragement of the saturated bridge within the fourteen-membered π-perimeter by passing from 4 (5) to 6 (7, 8) does not in fluence the energetic sequence of the lowest unoccupied molecular orbitals. The behavior of 6 and 7 towards oxidation parallels the photochemical reactivity of 4. The hyperfine coupling constants of the radical cations derived from 6 and 7 indicate that the removal of an electron is accompanied by an isomerization of the molecular framework. The investigation of the electron transfer process gby cyclic voltammetry supports these findings. The radical cations prefer the cyclophane-like structures 6a and 7a, in which the central σ-bond (C(15)-C(16) bond) is broken.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670302
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  • 27
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    Photochemistry of 2-(Trifluoromethyl) cyclohexanone (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 664-668 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photochemical behaviour of the title compound 1a is compared to that of the non-fluorinated parent ketone 2-methylcyclohexanone (1b). Substitution of the CH3- group on C(2) by a trifluoromethyl group strongly enhances 2H- and RH- reduction product formation in cyclohexane or 2-propanol and oxetane formation in the presence of 2-methylpropene as olefinic component. Under all these conditions 1b exclusively undergoes a-cleavage, a process observed for 1a only in non-reducing solvents as benzene or tert-butyl alcohol.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670305
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  • 28
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    Synthesis of Optically Pure Compounds by Enantiotopically Differentiating Monoacetalization of Prochiral Diketones. Part II. Fragmentation of β-Keto-AcetalsPart I: [1]. These results, which have been presented in part at the ‘Herbstversammlung der Schweizerischen Chemischen Gesellschaft’, October 16, 1981, in Bern, are comprised in the Ph. D. thesis of P. M. [2]. The nomenclature and classification of stereodifferentiating reactions proposed by Izumi & Tai [3] are used in this communication (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 832-844 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of β-keto-acetals, derived from non-enolisable β-diketones, with sulfonic acids in boiling benzene resuots in a smooth retro-Claisen-type fragmentation. The acetal-C-atom is thereby transformed into a carboxylic ester via a dialkoxycarbenium ion, which is dealkylated by the sulfonate counter-ion. Application of this reaction to the diastereomeric monoacetals 3 and 4, derived from cis-9-methyl-decalin-1,8-dione (1), followed by transesterification with CH3OH, yields optically pure 4-(2′-methyl-3′-oxocyclohexyl)butyrate 9 ((+)-9 from 3, (-)-9 from 4) and the monosulfonate of Meso-2,3-butanediol (-)-13 (Scheme 2). Unexpectedly, this cleavage proceeds as well with monoacetal 26, obtained by acetalization of trans-9-methyl-decalin-1,8-dione (27) with 2,2-dimethyl-1,3-propanediol (Scheme 7). Some attempts, aiming at an isomerization of the cis- and trans-decalin derivatives 3 and 24, or 25 and 26, via the postulated carboxonium intermediate, were not successful.
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    URL: http://dx.doi.org/10.1002/hlca.19840670324
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  • 29
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    Preparation of Bicyclo[3.3.0]octane-2,8-dione- and Declain-1,8-dione-DerivativesThese results are comprised in the Ph. D. thesis of P. M. [1] (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 856-865 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of bicyclo[3.3.0]octane-2,8-dione (1), which is prepared by a modification of the procedure described in the literature, gives the methyl- and propynyl-derivatives 6 and 7 (Scheme 1). In addition to the method described previously (Scheme 2), 9-methyl-cis-decalin-1,8-dione 9 is obtainable stereoselectively either by cyclization of keto-acid 16, or by aldol cyclization of keto-aldehyde 26 and oxydation of the resulting alcohols 24 and 25 (Scheme 4). The β-keto-alcohols 24 and 25 undergo a base-catalyzed isomerization; the trans-decalin isomers 27 and 28 are not detected in this equilibrium mixture (Schemes 4 and 5)l. Monoreduction of cis-dione 9 gives the endo-alcohol 25, while 27 is the favored product of the reductin of trans-dione 10 (Scheme 4). Optically pure (+)-25 can be prepared from (9S,10R)-monoacetal 29 (Scheme 5).
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    URL: http://dx.doi.org/10.1002/hlca.19840670326
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  • 30
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    Synthesis of a S-(Carboxymethyl)cysteine Analog of (L-2-Amino-6-adipyl)-L-cysteinyl-D-valine and its Cell Free Biosynthetic Conversion into 6-[2-(D-2-Amino-2-carboxyethyl)thio) acetamido]penicillanic Acid (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 870-875 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new tripeptide (dimer), bis[(L-cysteine-S-acetyl)-L-hemicystinyl(S2 → S2)-D-valine] (6) was synthesized by coupling N-(tert-butoxycarbonyl)-S-carboxymethyl-L-cysteine benzyl ester (1) with S-trityl-L-cysteinyl-D-valine benzyl ester and subsequent removal of the protecting groups. After reduction of the disulfide, the free tripeptide Cys (CH2CO-Cys-D-Val) (Ib) was used as a substrate of isopenicillin-N synthetase in a cell-free conversion to 6-[2-((D-2-amino-2-carboxyethyl)thio)acetamido]penicillanic acid (IIa).
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    URL: http://dx.doi.org/10.1002/hlca.19840670328
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  • 31
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    The Synthesis of cis- and trans- 7-Phenylkacetamido-O-2-isocephemO-2-Isocephems are alternatively called isooxacephems (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 902-905 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the title compounds is described.
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    URL: http://dx.doi.org/10.1002/hlca.19840670331
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    Erratum (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 927-927 
    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.19840670334
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    Absolute Conformation and Configuration of (2S, 3S)-3-Acetoxy-5-(dimethylaminoethyl)-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one Chloride (Dilthiazem Hydrochloride) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 916-926 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resolution of racemic cis-3-(2-aminophenylthio)-2-hydroxy-3-(4-methoxyphenyl) propionic acid (2) via the cinchonidine salt 3, and brucine salt 4, isolation of the calcium salts (+)- and (-)-5, as well as their cyclization to enantiomeric 1,5-benzothiazepines (+)- and (-)-1, are described. X-Ray single-crystal analysis reveals (2S, 3S) absolute configuration of (+)-1 on the basis of tentative comparison of CD data with those for the 1,4-benzodiazepine derivative (+)-8 of known absolute configuration.
    Additional Material: 4 Ill.
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    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.19840670401
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  • 35
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    Synthese und Struktur von Zink-Komplexen von 2-Amino-1-azetinen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 927-933 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis ad Structure of Zinc Complexes of 2-Amino-1-azetinesThe 2-dimethylamino-3,3-dimethyl-1-azetines 7a and 7b have been synthesized in analogy to the procedure reported by Ghosez et al. [1] (Scheme). The crystal structure of 1-benzhydryl-azetidindimethyliminium chloride 5a, a precursor of azetine 7a, has been established by X-ray diffraction analysis. Treatment of azetines 7a and 7b with ZnBr2 in CH2Cl2/MeCN yielded tetrahedral bis (azetine)dibromozinc complexes 8a and 8b, respectively (Scheme 2). The molecular structure of 8a has been determined by X-ray diffraction analysis too.
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  • 36
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    Enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathiane and their olfactive properties (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 947-952 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathine 8 and 9 form (E)-2-hezen-1-ol (1) as common starting material is described. The two enantiomeric forms exhibit different organoleptic properties.
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    Aliphatic Liquid Crystals with Positive Dielectric Anisotropy (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 959-963 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanothyl-subsituted cylohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthisized. Their mesmorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohenxanoates show mesmorphic properties in contrast to the corresponding cyano derivative. Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of the mesophase. In aromatic compound, the cyanoethyl group leads to lower clearing points. These phenomena are attributed to teh influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670407
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  • 38
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    Monohaptenic Nα-Benzoyl-L-lysine Derivatives as Anaphylactogens: the Importance of the Unsubstituted Carboxyl Group (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1000-1002 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nα-L-Iysine with a 2-carboxy-4, 6-dinitrophenyl (Dncp) haptenic group on the ε-amino function is a potent anaphylactogen in the guinea pig. We prepared Nε -Dncp- Nα-benzoly-L-Iysinamide and Nε-Dncp-Nα-benzoyl-L-lysyl-1-aminopropane where the carboxyl group of Iysine is blocked. Both compounds were non-elections of anaphylaxis.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670411
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  • 39
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    C45- und C50-Carotinoide. 2. Mitteilung. Synthese von optisch aktiven acyclischen C15-Endgruppen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 21-28 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C45- and C50-Carotenoids. Synthesis of Optically Active Acyclic C15-End GroupsThe optically active C15-end groups (S)-12, (S)-13 and (R)-14 were prepared from the C12-synthon (S)-11 in good chemical and optical yield. These C15-end groups are suitable compounds for the synthesis of optically active C45- and C50-carotenoids.
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  • 40
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    Interactions between Functional Groups. Part I. Crystal Structure of 2-Phenylethynyl-N,N-dimthlaniline at 98 K: A Remarkably Short C—H … C Distance (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 39-46 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one N—CH3 bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other N—CH3 bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H- and an acetylenic C-atom. The Taft σI parameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond-angle deformation at the ipso-C-atom.
    Additional Material: 5 Ill.
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  • 41
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    Die Herzglykoside des Pfeilgiftes von Lophopetalum toxicum LOHER. 13. Mitteilung über Celastraceen-InhaltsstoffeAus der Dissertation von Helmut Habermeier, München, 1981. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 54-64 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHERFrom the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and 1- and 13C-NMR spectroscopy. Besides the known k-Strophanthidin (1), Antiarigenin (6) and β-Antiarin (Antiarigenin-3-β-O-α-L-rhamnoside, 10) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D-allopyranoside (strophalloside, 2), strophanthidin-3-β-O-β-6-desoxy-D-glucopyranoside (= Strophanthidin chinovoside, 3), strophanthidin-3-β-O[-4Oβ-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (4), strophanthidin-3-β-O-[3-O-β-D-glucopyranosyl-β-6-desoxy-D-talopyranoside] (5), antiarigenin-3-β-O-[3-O-β-D-gulopyranosyl-β-6-desoxy-D-talopyranoside] (7), antiarigenin-3-β-O-[4O-β-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (8), and antiarigenin-3-β-O-β-6-desoxy-D-allopyranoside (antiallosid) (9). The structure of strophanthidinchinovoside (3) could be confirmed by synthesis.
    Additional Material: 3 Ill.
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    On the Structure of Oxirane Molecular Cation. Preliminary CommunicationDedicated to Prof. Christoph Tamm on the occasion of his 60th birthday (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 86-90 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A recent controversy on the interpretation of the ESR spectrum of ionized oxirane is clarified on the basis of the electronic absorption spectra of ionized tetramethyloxirane and 9,10-octalineoxide. The results favour a ring-opened structure for oxirane molecular cation, resulting from C—C bond cleavage and being iso-π-electronic to allyl radical.
    Additional Material: 3 Ill.
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  • 43
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    Die Acylierung von Acetylenen mit β, γ-ungesättigten Säurechloriden. Eine neue Synthese von 5-CyclopentenonenTeilweise vorgetragen an der Versammlung der Schweizerischen Chemischen Gesellschaft am 15. Oktober 1982 in Bern; als vorläufige Mitteilung erschienen in [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 73-85 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Acylation of Acetylenes with β,γ-Unsaturated Acid Chlorides, A New Synthesis of 5-Substituted 2-CyclopentenonesThe acylation of acetylenes with α,α-disubstituted, β,γ-unsaturated acid chlorides under Friedel-Crafts-type conditions leads to 5-substituted 2-cyclopentenones. Phenols are formed with β,γ-unsaturated acid chlorides bearing at least one α-H-atom. These transformations are explained by the intramolecular cyclization of the initially formed vinyl cation, which, in the cases of α,α-disubstituted acid chlorides, is followed by ring contraction. The reaction leading to 2-cyclopentenones is applied to the synthesis of some spiro[4.4]nona- and spiro[4.5]deca-2,6-dienones.
    Additional Material: 1 Tab.
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  • 44
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    Palladium-promoted Cyclization of Tetra-alkylated 1-Arylazonaphthalenes to 2-Aryl-benzo[g]indazoles (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 113-119 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Arylazonaphthalenes with all the potential cyclopalladation sites (one peri- and three ortho-positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2-arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670114
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    Photochemical reactions. 132nd communication131st Communication, see [1]. Photochemistry of 5,6-epoxy-5,6-dihydro-7-methyl-β-ionine: Influence of a methyl group at the enone side chain on the oxirane cleavagePresented in Part by B. F. at the IXth IUPAC Symposium on Photochemistry, July 25-30 1982, Pau (France). (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 120-128 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1n, π*-Excitation of the γ,δ-epoxy-enone (E)-3 leads exclusively to the conformers (Z)-3A + B. On 1π, π*-excitation of (E)-3, in addition to (Z)-3A + B, products 6-9 arising from a carbene intermediate e are formed. However, products of an isomerization via C(γ), O-bond cleavage of the oxirane were not formed on either mode of excitation. On thermolysis, at 80° the conformer (Z)-3A is transformed into (Z)-3B, which on photolysis returns to (Z)-3A and (E)-3. At 160°, however, (Z)-3B rearranges to the isomers 6, 10 and 11.
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  • 46
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    Selective Photoinduced Oxidation of Benzylic Methylen Groups through UV Irradiation in Presence of Ferric Chloride (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 866-869 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selective oxidation of benzylic methylene groups through UV irradiation in acetone/water/FeCl3 mixtures is reported. This method applied to a series of model compounds, provides an easy access to the corresponding 1-oxo derivative. Thus, tetralin gives a 100% yield of 1-tetralone, indane leads to 60% of 1-indanone, and diphenylmethane is oxidized to benzophenone with 80% yield. However, under the same conditions, alkyl-substituted aromatic hydrocarbons such as toluene, ethyl- and propylbenzene lead to low yields of aldehydes or ketones. Isochromane furnishes a mixture of two substances which can be interconverted, namely the expected l-isochromanone (9%) and the corresponding hydroxy acid (23%). We failed to apply the method to nitrogen heterocycles containing benzylic groups such as 1,2,3,4- and 5,6,7,8-tetrahydroquinoline as they do not react due to the formation of complexes which precipitate from the solutions.
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    URL: http://dx.doi.org/10.1002/hlca.19840670327
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    High performance liquid chromatography (HPLC) of natural products part VI.For part V, see [1] Sulfoxides of penicillin N and cephalosporin c and their role in biosynthesis of β-lactam antibiotics (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 876-884 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pure pencillin N α-sulfoxide (1) and penicillin N β-sulfoxide (2) were obtained by HPLC and tested as substrates for deacetoxycephalosporin C synthetase (DXCS). Neither one of the sulfoxides was utilized under conditions of conversion of penicillin N (8) to deacetoxycephalosporin C (9). The cephalosporin C α and β-sulfoxides (3 and 4, resp.) were also prepared. Relative stabilities of the sulfoxides 3 and 4 are discussed by interpretation of the 13C-NMR spectra.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670329
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    Die Busseine C, D, E, F, G, H, J, K, L und M, zehn neue Tetranortriterpene aus Entandrophragma bussei Harms.Herrn Prof. D.A.H. Taylor, University of Natal, Durban, Natal, South Africa, danken wir bestens für die Überlassung von Extrakten. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 885-901 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Business C,D,E,F,G,H,J,K,L und M, Ten New Tetranortriterpenes from Entandrophragma Bussei HarmsTen new tetranortriterpenes, busseins C, D, E, F, G., H, J, K, L and M have been isolated from the petroleum ether extract of the timber of Entandrophragma bussei Harms. utilizing separation by high-pressure liquid chromatography (HPLC). The structural assignments are based mainly on spectral evidence. For the 1H-NMR spectroscopy extensive use of nuclear Overhauser effects (NOE) was made.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670330
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    Mitteilungen-Communiacations (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 928-930 
    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.19840670335
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    The Synthesis and Application of Novel Nitrating and Nitrosating AgentsWork supported by the Shiraz University Research Council. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 906-915 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alcohols and phenols are efficiently nitrated with thionyl chloride nitrate or thionyl nitrate, even in the presence of an aromatic moiety. While thionyl chloride nitrate is suitable for nitration of primary OH-groups in carbohydrates, thionyl nitrate is reactive enough to react with secondary OH-groups as well. These reagents permit the highly selective nitration of the 5′-,2′5′- and 3′, 5′-OH-groups of ribonucleosides to produce either mono-or diprotected nitro derivatives in high yields. Carbon acids and the enol form of some ketones are efficiently nitrated with trifluoromethanesulfonyl nitrate/potassium tert-butoxide. Lutidine N-oxide (2,6-(CH3)2C5H3N O) was found to have a marked effect on nitration reactions. Similarly, thionyl chloride nitrite and thionyl nitrite exhibit an excellent capacity for nitrosation of the aforementioned substrates.
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    Radical Ions of Conjugated Polycyclic Hydrocarbons Containing Two Phenalenyl π-Systems (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 934-938 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical cations and the radical of 1,2-bis(phenalen-1-ylidene)ethane (1), 1,2-bis(phenalen-1-ylidene)ethene (2) and pentaleno[1,2,3-cd: 4,5,6-c′ d′]diphenalene (3) have been characterized by ESR and ENDOR spectroscopy. The ease of formation of these radical ions and their π-spin distributions are interpreted in terms of a simple model correlates the frontier orbitals of 1, 2 and 3 with the nonbonding MO's of two phenalenyl π-systems.
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    URL: http://dx.doi.org/10.1002/hlca.19840670403
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    The Synthesis and Reactions of 1-(2-Propynyl)pyidinium Salts (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 939-946 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 1-(2-propynyl)pyridinium salts 3 described. Compounds 3 react with a second pyridine molecule, in the presence of the corresponding hydrochloride, to form products of type 4, Certain bases cause the 1-(2-propynyl)pyridinium salts 3 to rearrange into 1-propadienylpyridinium salts. 5. Diethylamine converts compounds 3 into 1-acetonylpyridinium salts 8. Moreover, treatment of 3 or 5 with sodium methoxide gives enol ether sof type 9, which can be hydrolyzed to teh ketones 8. Addition of bromine to some of teh unsaturated compounds is also reported.
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    HNO, an Intermediate in (Light-induced) Rearrangement Reactions of Nitrosooxy Compounds and Nitrosamines (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 953-958 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: IR-spectroscopic investigations of light-induced rearrangement reactions of nitrosooxymethane (CH3ONO3), nitrosooxyethane (CH3CH2ONO) and N,N-dimethylnitrosamine ((CH3)2NNO) in low-temperature rare-gas matrices have established that these molecules are transformed in two photolysis steps to the previously unknown C-nitroso compounds nitrosomethanol (CH2(OH)(NO)), 1-nitrosoethanol (CH3CH(OH)(NO)), and methyl(nitrosomethyl)amine CH2(NO)(NH)(CH3). Evidence for a similar rearrangement reaction has been advanced for N-Nitrosopyrrolidine which is converted to C-nitrosopyrrolidine . The matrix-isolation technique in combination with wavelength-selective irradiation allowed to trap and characterize an intermediate of rearrangement which revealed to be nitroxyl (HNO) complex (CH2…HNO, CH3CHO…HNO, CH3N = CH2…HNO, and ). Since these findings have a close resemblance with rearrangement reactions of more complex nitrosooxy compounds, nitrosamines, or nitrosohydrazines used in organic synthesis, it is suggested that also in these reactions nitroxyl is present as an intermediate species.
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    1,2-Epoxycarotinoide. 3. Mitteilung. Isolierun von 1,2-Epoxy-1,2-dihydrolycopin aus Tomaten (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 964-967 
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    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-dihydrolycopene from TomatoesThe optically active, 1,2-epoxy-1,2-dihydrolycopene was isolated from tomatoes. Its constitution was established by comparison with the racemic synthetic compound.
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    1,2-Epoxycarotinoide. 4. Mitteilung. Synthese, 1H-NMR- und CD-Studien von (S)-1,2-Epoxy-1,2-dihydrolycopin und (S)-1′,2′-Epoxy-1′,2′-dihydro-γ-carotin (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 968-985 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids: Synthesis, 1H-NMR and CD Studies of (S)-1,2-Epoxy-1,2-dihydrolycopene and (S)-1′,2′-Epoxy-1′, 2′ -dihydro-γ-caroteneThe synthesis of (S)-1,2-epoxy-1,2-dihydrolycopene ((S)-1) and (S)-1′, 2′ -epoxy- 1′, 2′ -dihydro-γ-carotene ((S)-2) are described. The CD spectra of the (all-E)-isomers and of the isomers (7Z, S)-1 and (7′Z, S)-2 are discussed. The comparison of the CD spectra of the synthetic (S)-1 and the compound isolated from the tomatoes proves the (S)-configuration of the natural product.
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    Plectranthone A, B, C und D. Diterpenoide Phenanthren-1,4-dione aus Blattdrüsen einer Plectranthuus sp. (Labiatae) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1003-1011 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plectranthons A, B, C, and D. Diterpenoid Phenanthrene-1,4-diones from Leaf-glands a Plectranthus sp. (Labiatae)The following structures of four new 1,4-phenanthraquionones, isolated in minute amounts from the coloured leaf-glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3-hydroxy-5, 7,8-trimethyl-2-(2-propenyl)phenanthrene-1, 4-dione), plectranthon B (2; 2-(2ξ-acetoxypropyl)-3-hydroxy-5,7,8-trimethylphenanthrene-1,4-dione), plextranthon C (3; 3-hydroxy- 7,8-diemethyl-2-(2-propenyl)phenanthrene-1,4-dione), and plectranthon D (4; 3-hydroxy-7,8,10-trimethyl-2-(2-propenyl)phenanthrene-1,4-dione). 2-(2ξ-Hydroxypropyl)-3,6-dihydroxy-5,7,8-trimethylphenanthrene-1,4-dione (11), a compound very similar to 1-4, was prepared by a Wagner-Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20-phenanthrenes of diterpenoid origin.
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    Stereoselective Control in the Base-Catalyzed H/D Exchange of 5,6-Dimethylidene-2-bicyclo[2.2.n]alkanone Tricarbonyliron Complexes. Revision of the Structures of Tricarbonyliron Complexes of 5,6-Dimethylidenebicyclo[2.2.2]oct-2-ene and 5,6-Dimethylidenebicyclo[2.2.1]hept-2-eneA preliminary communication was presented at the Autumn Meeting of the Swiss Chemical Society, Bern, October 14, 1983. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 986-999 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative hydroboration of exo- (1) and end-Fe(CO)3 (2) complexes of 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene are highly stereoselective and give endo -alcohol 3 and exo -alcohol 4 as major products, respectively, Collins oxidations of 3 and 4 furnish the corresponding exo -Fe(CO)3 -complexed 5,6-dimethylidene-2-bicyclo-[2.2.2]octanone 7 and 8. NaBH4 reduction of exo-complexes 7 gives a mixture of 3 and isomeric exo-alcohol 18, whereas reduction of endo-complexes 8 gives the endo-alcohol, endo-complexes 19, as the sole product. The base-catalyzed H/D exchange of 7 and 8 afford the dideuterated exo-complex 35 and the monodeuterated endo-complex 32, respectively. Oxidative hydroborations of the exo-(9) and endo-Fe(CO)3 (10) complexes of 5,6-dimethylidenebicyclo[2.2.1]hept-2-ene give the corresponding exo-alcohols 39 and 40. Oxidation of 39 and 40 gives the exo- and endo-complexes 41 and 42, respectively, of 5,6-dimethylidene-2-bicyclo[2.2.]heptanone. Only Hexo —C(3) can be exchanged in 42, wheres both H-atoms at C(3) in 41 are exchangeable. The endo-Fe(CO)3 group in 8 and 42 blocks the base-catalyzed H/D exchange of Hendo —C(3), thus providing a test for the configuration of Fe(CO)3 group in these systems. These studies have led to a revision of the iron configurations proposed by Hansen et al, [2] for 1, 2, 9 and 10.
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    Mitteilungen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 361-364 
    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.19840670143
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    Parallelism Between Nucleophilically Solvent-Assisted and Phenyl-Assisted Reactions. Possible Existence of Nucleophilically β-Phenyl-Solvated Ion Pairs (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 352-360 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvolysis rate constants in MeOH and t-BuOh are compared for β-methyl and β-phenyl derivatives of two cycloakyl systems. It appears that the β-phenyl derivatives solvolyse at te same rate as the β-methyl ones. The lack of deceleration is attributed to phenyl assistance. It is established by configurational analysis of the reaction products, that those products which necessarily originate from a cationic species are the most abundant ones. It is suggested that these reactions could proceed through ion-pair intermediates, which are nucleophilically solvated by phelyl or by the solvent. A parallel between phenyl assistance and ‘SN2 (intermediate)’ mechanism, suggested by Bentely & Schleyer, is drawn.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670142
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    Percolative Phenomena in Microemulsions of the ‘One-Component Macrofluid’ Type (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 361-372 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of the water self-diffusion coefficients (D), as well as those of low- and high-field (stationary and time-dependent) specific conductivities (K), have been determined in the percolation regime of ternary mixtures of water, AOT, and oil. For the first time a pronounced similarity in the behavior of D and κ was detected giving instructive hints about the large variations in the specific conductivities of these systems. Results from kinetic and stationary experiments are consistent with a network-structure model of micro phases in the percolation regime in which the micro phases retain their discrete character.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670202
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    Synthèse facile de dérivés du diphényl-2,4-aza-3-bicyclo[3.3.1]nonane et du diphényl-7,8-aza-8-bicyclo[4.3.1]décaneUne partie de ce travail a fait l'object d'une communication préliminaire [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1291-1297 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Facile synthesis of derivatives of 2,4-diphenyl-3-azabicyclo[3.3.1]nonane and 7,9-diphenyl-8-azabicyclo[4.3.1]decaneThe facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4-diphenyl-3-azabicyclo[3.3.1]nonanone and 7,9-diphenyl-8-azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.
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    Fragmentation of 6-Deoxy-6-halo-hexono-1,5-ortholactones: A Concerted, Nonstereospecific Process (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1328-1347 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the D-arabino- and D-ribo-ortholactones 13a-f and 15b-f and their treatment with Zn leading to the unsaturated esters 14a-d and 16a-d are described. Possible fragmentation mechanisms are discussed. The results were only compatible wit a concerted, nonsynchronous process, where both the axial lone pair of the ring oxygen atom and the lone pair formed during rupture of the C(5), O-bond participate in the elimination of the axial and of the equatorial C(1)-alkoxy groups, respectively.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670519
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    Electron-Transfer-Induced Conformational Changes. The Example of 1,8-Dimethyl[14]annulene (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1368-1373 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This communication reports ESR-spectroscopic investigations of the radical anion of 1,8-dimethyl[14]annulene (1) which possesses a flexible molecular framework allowing configurational and conformational mobility. The ESR and ENDOR spectra indicate that at higher temperatures (T 〉 160 K), \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{- \atop \dot{}} $\end{document} exists as a mixture of several distinct isomers. One of them, the sole product at T 〈 160 K, is found to be energetically preferred. The configuration and the conformation of this species can be determined by interpretation of the hyperfine data in terms of a singly occupied MO of the 14-membered π-perimeter.
    Additional Material: 2 Ill.
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    Dimers of 3,7-dehydrotroponesFor this nomenclature, see [1a]. (bicyclo[3.2.0]hepta-1(7),2,4-trien-6-ones) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1386-1396 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-(tert-Butyl)-3,7-dehydrotropone (7-(tert-butyl)bicyclo[3.2.0]hepta-1(7),2,4-trien-6-one; 1) was found to dimerize reversibly to 2A by [2 + 4]-cycloaddition/cycloreversion reaction. The equilibrium lies on the side of the highly strained dimer 2A in the solid state, and on the side of the monomer 1 in solution. The [2 + 4]-reaction is fully perisite-, regio- and stereoselective. Above room temperature, 1 irreversibly formed a decarbonylated dimer 6, probably via the intermediate 9A or 9B, which resulted either from a dimerisation of 1 by [4 + 6]-cycloaddition or from a sigmatropic rearrangement of the originally formed dimer 2A or 2B. Similary, the 6-bromo derivative 14 afforded the corresponding decarbonylated dimer 15. Should the formation of 6 and 15 be due to a primary cycloaddition then that reaction is fully peri-, site- and regioselective. Mild LiAlH4-reduction of 6 and subsequent acetylation yielded the acetate 11, the structure of which was established by an X-ray analysis. More vigorous LiAlH4-treatment also reduced the terminal fulvenoid double bond of 6 and acetylation of the crude product led to the acetated 12 and 13.
    Additional Material: 2 Ill.
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    Mitteilungen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1427-1428 
    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.19840670530
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    Elektromotorisches Verhalten von Flüssigmembranelektroden-Messketten mit enantiomerenselektiven chiralen Ionophoren (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1427-1438 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electromotive Behaviour of Liquid-membrane Electrode Assemblies Based on Enantiomer-selective Chiral IonophoresA comprehensive theoretical treatment is given for the potentiometric behavior of enantiomer-selective membrane electrodes based on chiral ionophores and plasticizers. The membrane model allows for free and complexed enantiomeric or racemic ions (e.g. ephedronium and l-phenylethylammonium ions) as well as for achiral interfering ions. Experiments are derived for the determination of the stoichiometry and the relative stability of enantiomeric ion/enantiomeric ligand complexes, and for the analytical measurement of the enantiomeric excess of ions in solution.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670602
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    Water-Exchange Mechanism of Tetraaquapalladium(II). A Variable-Pressure and Variable-Temperature Oxygen-17 NMR StudyPart 23 of the series ‘High-Pressure NMR Kinetics’. For part 22, see [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1453-1460 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water exchange of square-planar Pd(H2O)24+ has been studied as a function of temperature (240 to 345 K) and pressure (0.1 to 260 MPa, at 324 K) by measuring the 17/O-FT-NMR line-widths of the resonance from coordinated water at 27.11 and 48.78 MHz. The following exchange parameters were obtained: k298ex = (560 ± 40) s-1, ΔH* = (49.5 ± 1.9) kJ mol-1, ΔS* = - (26 ± 6) J K-1 mol-1 and ΔV* = - (2.2 ± 0.2) cm3 mol-1. The values refere to an aqueous perchlorate medium with an ionic strength between 2.0 and 2.6 m and a perchloric-acid concentration between 0.8 and 1.7 m, and are interpreted in terms of an associative (a) activation for the exchange. The exchange rate for Pd(H2O)24+ is 1.4 × 106 times faster than for Pt(H2O)24+ at 298 K. A comparison with reactions between other nucleophiles and Pd(H2O)24+ is also made.
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    Etudes sur les composés organométalliques partie XXPartie XIX, v. [5]. Sélectivité de l'addition 1,4 de composés benzyliques du titane IV avec la benzylidéneacétone (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1475-1477 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of Organometallic Compounds, XX. Selectivity of 1,4-Addition of Benzyltitanium Compounds with BenzylildenacetoneTetrabenzyltitanium and dialkoxydibenzyltitanium compounds give essentially 1,4- addition with trans-4-phenyl-3-buten-2-one.
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    Aminierende, reduktive Kupplung aromatischer Aldehyde mit Tris(dialkylamino)methylvanandium (IV) zu N,N,N′,N′-Tetraaalkyl-1,2-diaryläthylendiaminen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1496-1502 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminative Reductive Coupling of Aromatic Aldehydes to N,N,N′,N′-Tetraalkyl-1,2-diarylethylenediamines, Induced by Tris(dialkylamino)methylvanadium (IV)In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p-methoxybenzaldehyde, 1-naphthaldehyde, furan-2-carbaldehyde) and secondary amines are coupled to give N,N,N′,N′-tetraalkyl-1,2-diarylethylenediamines 1-6. The reagents are tris(dialkylamino)methylvanadium(IV) compounds (cf. Eqn. 2). These are generated in situ either from isolable chlorotris(dialkylamino) vanadium(IV) (Eqn. 3), or preferably, from an Et2O/pentane solution of VCl4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and 0.8 equiv. of an aromatic aldehyde, to give the products 1-6 in a one-pot preparation (Scheme 2). The yields range from 14 to 54%. The diastereoisomeric mixtures (meso- and (±)-forms) obtained are separated by chromatography (Al2O3, petroleum ether/Et2O/Et3N), and the pure stereoisomers fully characterized. A mechanism of the reductive coupling induced by CH3V (NR2)3 is proposed (Scheme 1).
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    Functionalized Cycloheptanes from Bicyclo[4.2.1]nonanes (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1506-1514 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several oxidative, reductive and C,C-cleavage reactions were performed starting from the three bicyclo[4.2.1]nona-3,7-diene-2-one derivatives 1, 5 and 18. The oxidations were selective and led to the diols 2,8 and 9, and the epoxides 6,9, and 20. The reductions were selective only in the case of 20 21; otherwise they led to mixtures of the alcohols 10 and 11, and of the dienes 14 and 15. The periodate ring cleavages afforded the functionalized cycloheptane derivatives 3, 12, 13 and 16. Configurational assignments were made on the basis of detailed 1H-NMR and X-ray analysis of 20.
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    Drüsenfarbstoffe aus tropischen Labiaten: Parviflorone aus Plectranthus strigosus BENTH. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1531-1534 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Red-Coloured Abietanoids from Leaf-Glands of Plectranthus strigosus BENTH.Chromatographic examination of the red-coloured diterpenoids from the South-African title plant yielded the following compounds: parviflorone A(1), parviflorone B (2), parviflorone C(3), parviflorone E (4) parviflorone D (5), parviflorone F (6), parviflorone G (7), and parviflorone H (8). Compounds 7 and 8 represent new variants of these quinone methides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670617
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    Drüsenfarbstoffe aus Labiaten: Die polaren Diterpenoide aus Plectranthus argentatus S. T. BLAKEVorangehende Arbeiten s. [1] [2] und darin zitierte frühere Publikationen. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1523-1530 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polar Diterpenoids from Leaf-Glands of Plectranthus argentatus S. T. BLAKEFrom the red leaf-glands of the Australian Plectranthus argentatus the following novel diterpenoids were isolated: coleon-U-quinone (1), 8α,9α-epoxycoleon-U-quinone (3), 6β-formyloxy-7α-hydroxyroyleanone (7), and 5,6-dihydrocoleon U (10), besides the already known compounds 6β, 7α-dihydroxyroyleanone (4), 7α-acetoxy-6β-hydroxyroyleanone (5), and 7α-formyloxy-6β-hydroxyroyleanone (6). Epoxydation of 1 by perborate led in 32% yield to the epoxyquinone 3.
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    Deoxy-nitrosugars 8th communication7th Communication: [1]. Convenient preparation of 1-C-nitroglycosyl chlorides. Halonitro ethers from hydroxy oximes (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1568-1571 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partially protected 4- or 5-hydroxy-sugar oximes were transformed into 5- or 6-membered 1-C-nitroglycosyl chlorides, respectively, by reaction with NaOCl under phase-transfer conditions. With the exception of the oxidation of the gluco-derivative 1 giving the anomers 6 and 7, the reactions were completely diastereoselective.
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    The synthesis and transition temperatures of benzoate ester derivatives of 2-fluoro-4-hydroxy-and 3-fluoro-4-hydroxybenzonitriles (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1572-1579 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and the liquid-crystal temperatures of sixty 4-cyano-2-fluorophenyl and 4-cyano-3-fluorophylen 4-substituted benzoates are described. The nematic-isotropic liquid transition temperatures of the most of these novel esters are only marginally lower than those of the corresponding esters containing an H-atom in place of the F-substituent. In several instances, the clearing points of the F-substiuted-phenyl esters are higher than those of the non-substituted-phenyl esters. The nematic ranges of several of the new esters are markedly broader than those of the analogous non-F-substituted-phenyl esters.
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    URL: http://dx.doi.org/10.1002/hlca.19840670623
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    An Example of Head-to-Head Dimerization of β4.4-Helices (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1588-1592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-NMR and vapor-pressure osmometry results are presented, which indicate the occurrence of a rapid equilibrium involving the head-to-head dimerization of β44-helices in chloroform solutions of HCO-L-Ile-(D-AIle-L-Ile)4-OMe. This equilibrium typifies the one that, in Urry's view, would be responsible for the formation and breaking down of the ion-conducting channels formed by gramicidin A in lipid bilayers.
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    URL: http://dx.doi.org/10.1002/hlca.19840670625
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    The synthesis and transition temperatures of ester derivatives of 2-fluoro-4-hydroxy- and 3-fluoro-4-hydroxybenzonitriles also incorporating aliphatic ring systems (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1580-1587 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and liquid-crystal transition temperatures of forty ester derivatives of 2-fluoro-4-hydroxybenzonitrile and 3-fluoro-4-hydroxybenzonitrile are reported. The esters contain the trans-1,4-disubstituted cyclohexane or the 1,4-disubstituted bicyclo[2.2.2]octane rings (some contain an additional phenyl ring). Many of the novel F-substituted esters exhibit substantially higher nematic-isotropic transition temperatures than the corresponding unsubstituted esters. The order of clearing points of these laterally substiuted esters differing only in the presence of a benzene ring and the above-mentioned rings id established.
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    URL: http://dx.doi.org/10.1002/hlca.19840670624
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    Synthese von neuen Morphin-Teilstrukturen des Typs 15,16-Secomorphinan (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1598-1602 
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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 New Morphine Partial Structure 15,16-SecomorphinanThe synthesis of a new morphine partial structure, 15,16-secomorphinan, is described. One of the series, (±)-15, 16-secocyclorphan (5), has the analgesic potency of morphine and exhibits good binding to the opiate receptor.
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    Diastereoselektive synthese neuartiger Mannich-BasenAusführliche Übersichten über die klassische Mannich-Reaktion: [1-4]. mittels titanderivatenÜbersichtsartikel über die Verwendung von Organotitanverbindungen in der organischen Synthese: [5-8]., vorläufige mitteilung (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1593-1597 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diastereoselective Synthesis of Novel Mannich (Bases1) through Titanium ReagentsTrichlorotitanium dialkylamino-alkoxides (2; titanates of N, O-hemiacetals) are generated either from the corresponding lithium alkoxides and titanium tetrachloride (Scheme 1) or by addition of trichloro-dialkuylamino-titanium to aldehydes. The electrophilic (dialkylamino) alkylating reagents 2 are used to convert lithium enolates to β-dialkylamino-ketones and -esters 5 (Mannich bases), see Scheme 2 and Table. One diastereoisomer of the products 5g-5p thus obtained with cyclohexenolate is formed preferentially (66-84%). The configuration of the products of this first diastereoselective version of the Mannich reaction could not yet be determined. A typical procedure for carrying out the reaction is given.
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    Optical resolution of 7-oxabicyclo[2.2.1]hept-21-ene derivatives. Diastereoselectivity in the formation of cyanohydrine-brucine complexes (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1612-1615 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new, practical method for the optical resolution of bicyclic ketones if illusttrated by the preparation of (+)-(1R,4R)-7-oxabicyclo[2.2.1]bept-5-en-2-one ((+)-1) and (+)-(1R, 2S,4R)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yul acetate ((+)-4). It involves the diastereoselective formation of a brucine complex with the corresponding cyanhydrine mixture.
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    URL: http://dx.doi.org/10.1002/hlca.19840670629
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  • 80
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    Transition metal complexes with bidentate ligands spanning trans-positions part XVPart XIV: See [1]. X-ray structural and 31P-NMR solution studies of some three-coordinate silver complexes of 2,11-bis[di(tert-butyl)phosphinomethyl]benzo[c]phenathrene and related ligands (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1603-1611 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of three-coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t-Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P-NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X-ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag-P = 2.463(4) Å and 2.433(5) Å, P-Ag-P=141.6(2)° in the bromo complex, Ag-P = 2.457(2) Å and 2.427(2) Å, P-Ag-P = 142.6(1)° ion the chloro complex, and Ag-P = 2.394(2) and 2.393 (2) Å, P-AG-P = 161.5(1)° in the perchlorato complex.
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  • 81
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    Further Syntheses of Optically Active Verrucarinic Acid, 43rd Communication of Verrucarins and Roridins42nd Commun. : [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1625-1629 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new syntheses of verrucarinic acid (2S, 3R-dihydroxy-3-methylpentanoic acid) and its derivatives, suitably protected for the further conversion to macrocyclic trichothecenes, are described. The first one makes use of a diastereoselective alkylation of a (-)-(S)-malic acid ester and the regioselective reductin of one carboxyl function toa methyl group. The second approach involves a stereoselective addition of an allylsilane to a chiral glyoxylate.
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  • 82
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    Steuerung der katalytischen Pyridinsynthese aus Alkien and Nitrilien durch (η6-Borinato)-Liganden am CobaltHerrn Prof. Dr. R. Köster, Mülheim a. d. Ruhr, mit herzlichen Wünschen zum 60. Geburtstag gewidmet (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1616-1624 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of the Catalytic Synthesis of Pyridine from Alkynes and Nitriles by the (η6-Borinato)-Nigands at Cobaltη6-Borinato groups as ligands at cobalt have unique effects on the chemo- and negioselectivity of the catalytic co-cyclization of alkynes and nitriles. The turnover number of the conversion of acrylonitrile and acetylene to give 2-vinylpyridine is considerably enhanced. Cyano compounds wih polar substitutents such as amino or thio groups can also be reacted. The homogeneous reaction of HCN with acetylene giving pyridine has been achieved for the first time.
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  • 83
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    Chemo- and Stereoselective Coordination of 5,6-Dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene by d8- and d6-Metal Carbonyls. Diels-Alder reactivity of Dienes Perturbed by Remote Olefin Complexation (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1630-1637 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The endocyclic double bond C(2), C(3) in 5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene (1) can he coordinated selectively on its exo-face before complexation of the exocyclic s-cis-butadiene moiety. Irradiation of Ru3(CO)12 or Os3(CO)12 in the presence of 1 gave tetracarbonyl [(1R,2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene)]ruthenium (6) or -osmium (8). Similarly, irradiation of Cr(CO)6 or W(CO)6 in the presence of 1 gave pentacarbonyl[(1R, 2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]chromium (10) or -tungsten (11). Irradiation of complexes 6 and 11 in the presence of 1 led to further CO substitution giving bed-tricarbonyl-ae-bis[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]ruthenium (7) and trans-tetracarbonyl[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo-[2.2.1]hept-2-ene)]tungsten (12), respectively. The diosmacyclobutane derivative cis-m̈-[(1R,3R,3S,4S)-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hepta-2,3-diyl)]bis(tetracarbonyl-osmium) (Os-Os) (9) wa also obtained. The Diels-Alder reactivity of the exocyclic s-cis-butadiene moiety in complexs 7 and 8 was found to be significantly higher than that of the free triene 1.
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    Monoolefin and Diene Cycloaddition Induced by Transition-Metal Carbonyls. Cyclodimerization of 5,6-Dimethylidene-7-oxabicyclo[2.21]hept-2-ene Catalyzed by Dodecacarbonyltriosmium (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1638-1646 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products generated by heating 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene (1) with Fe2(CO)9, Ru3(CO)12, Os3(CO)12, Cr(CO)3(MeCN)3, (or W(CO)5(MeCN) or by treatment with Fe-atoms have been characterized by spectroscopic methods. Apart from the expected η2- and η4-complexes of the triene 1, condensation products are formed which arise from the formal [4 + 2]-cyclodimerization of 1 involving the endocyclic double bond of one molecule and the diene moiety of a second. The [4 + 2]-cyclodimerization is catalyzed by Os3(CO)12 in MeOH and gives 1,4-epoxy-7-methoxy-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene (15)). Fe-Atoms induce a stereoselective [2 + 2]-cyclodimerization pf 1 which involves its endocyclic double bond and produces the dimer 8.
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  • 85
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    Synthese von 2,3-unsubstituierten, N-acylierten Indolen durch sigmatrope[3,3]-Umlagerung von O-Vinyl-N-phenylhydroxylaminderivaten (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1647-1649 
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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 2,3-Unsubstituted N-Acylindoles by [3,3]-Rearrangement of the N-Phenyl-O-vinylhydroxylamine DerivativesSummary, Treatment of N-phenylhydroxamic acids with vinylacetate in the presence of Li2PdCl4 affords 2,3-unsubstituted N-acylindoles via hetero-Cope-rearrangement of the intermediate N-O-vinylhydroxylamine derivatives.
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  • 86
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    Mitteilugen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1669-1669 
    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.19840670637
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  • 87
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    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.19840670701
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  • 88
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    Photoreaction of (RS,SR)-3-Phenyl-6-hepten-2-ol. Benzene-Olefin Cycloadditions as a Synthetic Route to [5.5.5.5] Fenestranes. Part IIIFor part II of the series ‘Planarization of Tetracoordinate Carbon Atom’, see [1b]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1930-1941 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation of (RS,SR)-3-Phenyl-6-hepten-2-ol (3n) gave the photoproducts 6n-10n. Some reactions of 6n and 8n are reported. The regio- and diastereoselectivity observed in the photoreaction of substituted 5-phenylpentenes is discussed with respect to conformational preferences of the compounds to be irradiated.
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  • 89
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    Benz[cd]indoles. Part III. A New Stereospecific Synthesis of Dihydrolysergic Acid and an Entry to 14-Substituted DerivativesPart of this work has been presented at the ‘Herbstversammlung der Schweizerischen Chemischen Gesellschaft’ at Berne, on October 18, 1982. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1942-1951 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new convenient synthesis of dihydrolysergic acid is described, which allows the preparation of substituted derivatives, especially those with different substitutents in the aromatic ring. Starting from appropriately substituted 5-nitro-2-tetralones, the synthesis leads via a tricyclic isonitrile to the indole-ring closure as the last step, thus circumventing the troublesome protection/deprotection of the latter.
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  • 90
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    Triaziridines. Part IIIPart II, see [1].. Triaziridine, azimine, and triazene: A SCF study of the energy and structure of N3H3-isomers (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1918-1929 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The portions of the N3H3 singlet potential energy surface corresponding to triaziridines (1), azimines (2) and triazenes (3) have been calculated by ab initio SCF using 3-21G, 6-31G, and 6-31G** basis sets. Minima and transition states were located by force gradient geometry optimization. The most important computation results are: (1) Triaziridines (1): The configuration at the 3 N-atoms is pyramidal. There are 2 stereoisomers, 1a and 1b. The c,t-isomer 1a has less energy than the c,c-isomer 1b. The 2 stereoisomerizations by N-inversion hve rather high activation energies. The N,N bonds in 1 are longer and weaker (STO-3G estimation) than in hydrazine. The N-homocycle 1 exhibits less ring strain than the C-homocycle cyclopropane or three-membered heterocycles. (2) Azimine (2): All 6 Atoms are in the same plane. There are 3 stereoisomers, 2a, 2b, and 2c. The order of ground state energies is (Z,Z) 〈 (E,Z) ≫ (E,E). The 2 N,N bond lengths correspond to multiplicity 1½. The electronic structure of 2 corresponds to a 1,3-dipole with almost equal delocalization of the 4 π-electrons over all 3 N-atoms. The negative net charge at the central N-atom is much less than that at the terminal N-atoms. Azimines should behave as π-donors in complexation with transition metals (3) Triazene (3): All 6 atoms are in the same plane. There are 2 stereoisomers, 3a and 3b. The order of ground-state energies is (E) 〈 (Z). The stereoisomerization proceeds as pure N-inversion. N-Inversion has a high energy barrier inversion at N(1) is faster than at N(2). One of the N,N bond lengths is typical for a double, the other for a single bond. The electronic structure of triazene 3 entails rather localized π- and p-electron pairs at N(1),N(2) and at N(3). Triazenes should behave as p-donors in complexation with transition metals. (4) -N3H3-Isomers: The order of ground-state energies is 3 〈 2 〈 1. The energy differences between these constitutional isomers are much larger than between the stereoisomers of each. The [1,2]-H shifts for conversions of 2 to 3 and the [1,3]-H shift for tautomerization of 3 have relatively high activation energies; both shifts can be excluded as modes of thermal, unimolecular transformations.
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  • 91
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    The Reaction of 4-Hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with Acetaldehyde. Formatino of the Bis(peroxyacetal) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1952-1956 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 4-hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with acetaldehyde using trimethylsilyl trifluoromethanesulfonate as catalyst gives 1,1′-bis[(1,3,5-trimethyl-4-oxo-2,5-cyclohexadienyl) peroxy]diethyl ether (7) in 70% yield. The structure of this unusual acetal was determined by X-ray analysis.
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  • 92
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    The chemistry of drugs part IVPart III, see [1]., Configurations of antimalarials derived from qinghaosu: Dihydroqingyhaosu, artemether, and artesunic acid (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1515-1522 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of the antimalarials dihydroqinghaosu (2), artemether (3), and artesunic acid (7a) derived from qinghaosu were elaborated by 1H-NMR spectroscopy, and supported with X-ray data obtained for 2 and 3. Several new derivatives, useful for the chemical characterization of dihydroqinghaosu (2) and artesunic acid (7a), were prepared.
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  • 93
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    Deoxy-nitrosugars, 7th communication6th Communication: [1]. Synthesis of methyl shikimate and of diethyl phosphashikimate from D-ribose (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1562-1567 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chain elongation of the deoxy-nitroribose 6 by a Michael addition to the vinyl-phosphonate 7 followed by a solvolysis gave the heptulosephosphonate 11 (87%). From 11, the key intermediates 15 and 16 (77%) were obtained by a highly diastereoselective reduction, followed by detritylation, periodate cleavage, and silylation. Methoxycarbonylation of 15 and 16 gave 17 and 18 which were converted into methyl shikimate (21; 79%) by intramolecular olefination and partial deprotection. Similarly, phosphonoylation of 16 gave 22 (99%) which was transformed into the diethyl phosphashikimate 2 (53% from 6).
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    Mitteilungen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2029-2030 
    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.19840670743
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  • 95
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    Errata (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2028-2028 
    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.19840670742
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  • 96
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    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.19840670801
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  • 97
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    On the Nature of the 7-Norbornadienyllithiums. Preliminary Communication (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2029-2036 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithium reductions of 7-chloronorbornadiene and of bis(7-norbornadienyl)mercury both provide (C7H7)2Li2 (5a). This product is accompanied by C7H7Li2Cl (5c) in the first case, and by C7H7Li (5b) in the second. The theoretically anticipated properties of all three organolithiums are apparent in the consistent Cs symmetry of their hydrocarbon ligands, their protolytic destruction by 12-crown-4, and their significant J(C(7), Li) (5a, 7.6; 5b, 16.0; 5c 8.9 Hz).
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    Novel Variant of the Tricyclooctanone Approach to Cyclopentanoid Natural Products. Synthesis of (±)-Coriolin. Preliminary Communication (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2023-2027 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A total synthesis of the antitumor sesquiterpene coriolin (9; racemic) in 11 steps from 3,3,6-trimethylbicyclo[2.2.2]oct-7-ene-2,5-dione (2a/2b) is described (yield 2a/2b→8: 28%). The sequence is unprecedentedly short and avoids difficult separation problems. The key step in the scheme is a novel facet of oxadi-π-methane photochemistry, i.e., the steering by subtle steric effects of the β,γ-unsaturated ∊-diketone to undergo a regioselective photorearrangement involving one β,γ-enone partial chromophore. Furthermore, the overall phototransformation, which can be carried out at unusually high concentrations (≥20% solutions), involves also a Norrish type I process equilibrating the two epimeric starting enediones 2a and 2b in favour of the desired stereoisomer.
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  • 99
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    Synthese von optisch aktiven Carotinoiden mit 3,5,6-Trihydroxy-5-6-dihydro-β-Endgruppen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2043-2056 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of Optically Active Carotenoids with 3,5,6-Trihydroxy-5,6-dihydro β-End GroupsFor the specification of the relative and absolute configuration in carotenoids with 3,5,6-trihydroxy-5-6-dihydro β-end groups, several ionone derivatives and carotenoids bearing this end group were synthesized. Acid-catalyzed hydrolysis of (3S,5S,6R)- acetoxy-5,6-epoxy-5,6-dihydro-β-ionone (7) and of its (3S,5R,6S)-isomer (13) gave the diols 8 and 15, respectively, with exclusive inversion at c(5) (Scheme 2). Compared to this, mild acid hydrolysis of caroten-5-6-expoxides in the presence of H2O resulted in the formation of 5,6-diols with either inversion or retention of the configuration at C(6) (Scheme 3). Spectroscopic data allowed us to distinguish the relative configurations (3R*,5S*,6S*) (see A), (3R*,5R*,6R*) (see B), (3R*,5S*,6R*) (see C), and (3R*,5R*,6S*) (see D), of the 3,5,6-trihydroxy-5-6-dihydro β-end groups. Syntheses of the optically active carotene-hexols 20 and 21 and comparison with published data led to a revision of the structure of mectrazanthin (now formulated as 20), heteroxanthin (now formulated as 28), and further carotenoids with 3,5,6-trihydroxy end groups.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670804
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  • 100
    Electronic Resource
    Electronic Resource
    The Photoisomerization of 1,2,3,4,5-Pentamethyl-5-vinyl-1,3-cyclopentadiene (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2057-2062 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 1 is shown to give, both upon direct irradiation at 254 nm and upon acetophenone-sensitized photolysis at 300 nm, the syn-vinyl-pentamethylhousene 5, which spontaneously rearranges in a [3,3]0sigmatropic process to give the bicyclo[3.2.0]heptadiene skeleton 2. Based on the photochemical behaviour of selectively deuterated starting material, the suggestion is made that the direct photolysis produces the vinylhousene skeleton by a classic electrocyclization, whereas the sensitized reaction reaches the same target via a di-π-methane rearrangement. The bicyclo[3.2.0]heptadiene derivative 2 give pentamethylhomoprismane 3 upon prolonged irradiation at 254 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670805
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