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  • 1990-1994
  • 1975-1979  (1.982)
  • 1965-1969
  • 1960-1964  (2.075)
  • 1955-1959
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  • 1
    Digitale Medien
    Digitale Medien
    Commissural projection to the amygdala through the fimbria fornix system in the cat (1977)
    Springer
    Experimental brain research 27 (1977), S. 61-70 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Amygdala ; Commissural fibers of the fimbria ; Electrophysiology ; Lesions ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Single shock stimulations have been applied stereotaxically and bilaterally in the region of the caudo-thalamic groove of the cat. These stimulations elicit diphasic potentials in the amygdala. Using combined methods of stimulation and lesion, it has been demonstrated that these electrical responses are due to the excitation of fibers projecting rostrally in the lateral border of the contralateral fimbria and caudally in the homologous part of the homolateral fimbria. A commissural path has been identified in the rostral part of the fimbria-fornix. Analysis of the experimental data has shown that the projection system consists of a discrete bundle of fibers which probably reaches the amygdala directly, in the dorsal part of the basal nucleus. The length of the explored portion of this pathway has been measured. The calculated conduction velocity of this amygdalopetal commissural component of the fimbria is 4.5 m/sec.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234825
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  • 2
    Digitale Medien
    Digitale Medien
    Discharges of superior colliculus neurons during head and eye movements of the alert cat (1977)
    Springer
    Experimental brain research 27 (1977), S. 131-141 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Colliculus superior ; Single neurons ; Eye movements ; Head movements ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 452 single neurons from the superior colliculus were recorded in awake and non-paralysed cats. 75 neurons were obtained from cats with unrestrained horizontal head movements. 228 neurons remained unaffected by saccadic eye movements. Eye movement related discharge followed the onset of saccades in 156 neurons either only in the presence of a visual pattern (92 neurons) or in darkness, too (64 neurons). The latter reaction type probably depends on eye muscle afferents. In 48 neurons eye movement related activity preceded the onset of eye movements. 12 neurons fired in synchrony with eye movements of any direction (type I). 30 neurons were excited during contralaterally directed eye versions within or into the contralateral head related hemifield. They were inhibited when the eyes moved within or into the ipsilateral head related hemifield (type II). 6 neurons with constant maintained activity during fixation were inhibited by ipsilaterally directed saccades, but remained unaffected by contralateral eye movements. Head movement related discharge followed the onset of head movements in 20 neurons only in presence of a visual pattern and also in darkness in 6 neurons. Ipsilateral head movements or postures strongly suppressed maintained activity and visual responsiveness of some neurons. 15 neurons discharged in synchrony with and prior to contralateral head movements. Ipsilateral head movements inhibited these neurons. Activation or inhibition were usually related to movement and to posture, exceptionally to movement or to posture. Electrical stimulation of recording sites of these neurons through the recording microelectrode elicits contralateral head movements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237694
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  • 3
    Digitale Medien
    Digitale Medien
    Descending connections between the superior olivary and cochlear nuclear complexes in the cat studied by autoradiographic and horseradish peroxidase methods (1977)
    Springer
    Experimental brain research 27 (1977), S. 397-412 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Descending auditory pathways ; Superior olivary complex ; Cochlear nuclear complex ; Axoplasmic flow ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The descending pathways from the superior olivary complex (SO) to the cochlear nuclear complex (CN) were investigated in 58 cats using labelled aminoacid and horseradish peroxidase transport techniques. Descending connections were found coursing bilaterally through the trapezoid body (TB) and ipsilaterally in the intermediate and dorsal acoustic striae. The dorsolateral periolivary nucleus (DLPO) sends fibres through both the intermediate and dorsal striae, which are joined by others from the lateral preolivary nucleus (LPO). Both the latter nucleus and the medial preolivary nucleus (MPO) give rise to a bilateral descending projection which traverses TB. The distribution of these descending pathways within CN is described (although the technique did not permit precise synaptic identification). The possible implications of these pathways for response patterns at the level of CN are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235512
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  • 4
    Digitale Medien
    Digitale Medien
    Dendritic spread of dorsal horn neurons in cats (1977)
    Springer
    Experimental brain research 28 (1977), S. 153-166 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Spinal cord ; Dorsal horn ; Dendritic fields ; Golgi stain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Observations of neurons in dorsal horn laminae IV–VI of the lumbosacral segments of Golgi-stained spinal cords in kittens and adult cats revealed laminar differences in dendritic architecture. Many neurons in lamina IV had dense, bushy dendritic fields. Lamina V contained, in addition to bushy cells similar in appearance to those of lamina IV, increasing numbers of neurons with radiating dendritic fields. Lamina VI was composed almost exclusively of neurons with radiating dendritic fields. These qualitative differences among laminae were accompanied by systematic variations in mean dendritic spread, which increased more than two-fold in adult cats between laminae IV and VI. A second gradient of dendritic spread was found within individual laminae: dendritic spread, particularly medial to lateral spread, increased for successively more lateral cells within a lamina. These differences in the spread of dendrites for neurons in different regions of the dorsal horn may be related to variations in the areas of peripheral receptive fields of dorsal horn neurons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237093
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  • 5
    Digitale Medien
    Digitale Medien
    Temporal aspects of spatial vision in the cat (1977)
    Springer
    Experimental brain research 28 (1977), S. 325-333 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Spatial contrast sensitivity ; Cat ; Grating pattern ; Flicker ; X- and Y-cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Using behavioral techniques, contrast sensitivity for flickering and stationary gratings was measured in ordinary cats. Gratings of low spatial frequency were more easily detected by the cat when temporal modulation was present, but at high spatial frequencies temporal modulation reduced grating visibility. These psychophysical results are consistent with neurophysiological evidence for the existence of two classes of visual cells in the cat, which are distinguishable in terms of their spatio-temporal response properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235714
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  • 6
    Digitale Medien
    Digitale Medien
    Influence of the presentation of remote visual stimuli on visual responses of cat area 17 and lateral suprasylvian area (1977)
    Springer
    Experimental brain research 29 (1977), S. 107-122 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Area 17 ; Lateral suprasylvian area ; Remote visual stimuli ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Single units were recorded extracellularly from area 17 and lateral suprasylvian area (LSSA) in curarized cats. Visual stimuli, usually a 10 ° black spot, were introduced abruptly in the visual field remote from the discharge area of a neuron's receptive field and moved at a speed of about 30 °/sec. The effect of these remote stimuli (S2) on the response to a restricted visual stimulus (S1) crossing the discharge area was studied. It was found that most units in area 17 were not affected by the presentation of remote stimuli, the remainder being either slightly facilitated or slightly inhibited. In contrast the LSSA neurons were usually inhibited by the presentation of S2: this effect was strong, was present in all classes of LSSA neurons and was independent of the relative directions of movement of S1 and S2. On the basis of these data and those previously obtained from the superior colliculus it is concluded that the way the extrageniculate centres respond to a stimulus abruptly introduced in the visual field is substantially different from that of the striate cortex. Only in the extrageniculate centres a new stimulus, besides exciting the neurons which correspond to the position of the stimulus in the field, concomitantly decreases the responses of neurons located in positions of the visual field remote from that stimulus. Possible behavioral implications of the findings are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236879
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  • 7
    Digitale Medien
    Digitale Medien
    Efferent projections of the pretectum in the cat (1977)
    Springer
    Experimental brain research 30 (1977), S. 89-105 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Extrageniculate visual system ; Pretectum ; Efferent connections ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Direct projections from the pretectum in the cat were investigated by means of the Nauta-Gygax and the Fink-Heimer method in an attempt to identify the morphological substrates subserving possible neural mechanisms involved in visual behaviour and reflexes. Degeneration in the diencephalon was found ipsilaterally in the nucleus limitans, lateral pulvinar nucleus, lateral posterior nucleus, lateral dorsal nucleus, dorsal and ventral lateral geniculate nuclei, centre medianparafascicular complex, central medial nucleus, paracentral nucleus, central lateral nucleus, ventroanterior and ventrolateral nuclear complex, zona incerta, H field of Forel and the reticular nucleus. The pretectal fibers projecting to the ventral lateral geniculate nucleus appeared to be topically organized. In the midbrain, the pretectal fibers were observed to terminate ipsilaterally within the superior colliculus, nucleus of Darkschewitsch, dorsolateral portion of the red nucleus, lateral terminal nucleus of the accessory optic tract and the reticular formation, and bilaterally within the central gray, interstitial nucleus of Cajal and the rostral portion of the nucleus of Edinger-Westphal. Degeneration in the superior colliculus was marked in laminae II, III and IV. The fibers arising from more anterior part of the pretectum appeared to be distributed more medially in laminae II and III. The pretectopontine fibers terminated ipsilaterally in the paramedial and the dorsolateral pontine nuclei as well as the reticular formation. In the inferior olivary complex, degeneration was found in caudal levels of the dorsal cap and β-nucleus, and additionally in the rostral portion of the dorsal accessory olive.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237861
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  • 8
    Digitale Medien
    Digitale Medien
    Direction-specific optokinetic modulation of monosynaptic hind limb reflexes in cats (1977)
    Springer
    Experimental brain research 30 (1977), S. 155-160 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Postural reflexes ; Visual and vestibular reflex modulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The excitability of hindlimb extensor and flexor motoneurons is tonically modulated by animal tilt and a large visual stimulus rotating about the animal's line of sight. This direction-specific modulation is opposite for extensor and flexor motoneurons and opposite for optokinetic and vestibular stimuli, thus combining to a functionally significant pattern of postural reflexes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237867
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  • 9
    Digitale Medien
    Digitale Medien
    Differential responsiveness of simple and complex cells in cat striate cortex to visual texture (1977)
    Springer
    Experimental brain research 30 (1977), S. 275-296 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Striate cortex ; Simple and complex cells ; Visual texture ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The responsiveness of 254 simple and complex striate cortical cells to various forms of static and dynamic textured visual stimuli was studied in cats, lightly anaesthetised with N2O/O2 mixtures supplemented with pentobarbitone. Simple cells were unresponsive to all forms of visual noise presented alone, although about 70% showed a change in responsiveness to conventional bar stimuli when these were presented on moving, rather than stationary, static-noise backgrounds. Bar responses were depressed by background texture motion in a majority of cells (54%), but were actually enhanced in a few instances (16%). In contrast, all complex cells were to some extent responsive to bars of static visual noise moving over stationary backgrounds of similar texture, or to motion of a whole field of static noise. The optimal velocity for noise was generally lower than for bar stimuli. Since moving noise backgrounds were excitatory for complex cells, they tended to reduce specific responses to bar stimulation; in addition, directional bias could be modified by direction and velocity of background motion. Complex cells fell into two overlapping groups as regards their relative sensitivity to light or dark bars and visual noise. Extreme examples were insensitive to conventional bar or edge stimuli while responding briskly to moving noise. In many complex cells, the preferred directions for motion of noise and of an optimally oriented black/white bar were dissimilar. The ocular dominance and the degree of binocular facilitation of some complex cells differed for bar stimuli and visual texture. Preliminary evidence suggests that the deep-layer complex cells (those tolerant of misalignment of line elements; Hammond and MacKay, 1976) were most sensitive to visual noise. Superficial-layer complex cells (those preferring alignment) were less responsive to noise. Only ‘complex-type’ hypercomplex cells showed any response to visual noise. We conclude that, since simple cells are unresponsive to noise, they cannot provide the sole input to complex cells. The differences in the response of some complex cells to rectilinear and textured stimuli throw a new light on their rôle in cortical information-processing. In particular, it tells against the hypothesis that they act as a second stage in the abstraction of edge-orientation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237256
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  • 10
    Digitale Medien
    Digitale Medien
    Visual field measurements in monocularly deprived and normal cats (1977)
    Springer
    Experimental brain research 30 (1977), S. 353-368 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Visual deprivation ; Cat ; Behavior ; Perimetry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Visual fields of 15 monocularly deprived (MD) cats and 2 monocularly tested normal adult cats, were measured using stationary stimuli at fixed distances in the horizontal plane. Compared to the visual fields of monocularly tested normal cats, those of the deprived eyes of MD cats were found to be restricted to the ipsilateral hemifield up to the midline. This finding appeared to be permanent since it was measured both in cats tested early (4 cases) and late (11 cases) after deprivation. In addition, it seemed to be independent whether the nondeprived eye was closed by reverse suturing (13 cases), or was left open after deprivation and closed only temporarily during testing (2 cases). Visual fields were also found to be restricted to the ipsilateral hemifield, if MD cats were tested at several levels above the horizontal plane or in a hemisphere (23 cm radius) in which the superior and inferior segment of the visual space could be tested (6 cases). The results are controversial to those of Sherman (1973) who described the visual fields of MD cats to be restricted to the monocular (60–90 ° ipsilateral) segment. The differences observed in our results compared to those of Sherman could not be explained by experimental factors, since testing MD cats by the method employed by Sherman (8 cases) also resulted in visual fields covering the monocular as well as the binocular part of the ipsilateral side. Consequently, Sherman's hypothesis (1974b), that for MD cats the geniculocortical pathways dominate in the visual behavior and that retinotectal pathways are somehow suppressed, could not be confirmed by our results. In our experiments the visual behavior demonstrated by MD cats seemed to be developed mainly through retinotectal pathways. In MD cats in which after the deprivation period the non-deprived eye remained open, the monocular part seemed to be of more importance than the binocular segment; permanent closure of the normal eye seemed to lead to a further shift towards the binocular segment. Therefore, in non-reverse sutured MD cats some suppression of retinotectal pathways by imbalanced corticotectal pathways may be present, but not as elaborate as described by Sherman. This slight suppression is overcome by reverse suturing. The mechanism of release from suppression of retinotectal pathways is unknown, its possible localisation is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237262
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  • 11
    Digitale Medien
    Digitale Medien
    The effects of monocular deprivation on different neuronal classes in the lateral geniculate nucleus of the cat (1977)
    Springer
    Experimental brain research 28 (1977), S. 259-278 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Lateral geniculate nucleus ; X- and Y-cells ; Visual deprivation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Retrograde axonal transport of horseradish peroxidase (HRP) was used to identify two populations of cells in the lateral geniculate nucleus (LGN) of the cat. HRP was injected into area 17 and 18 separately in the same animal, and the neuronal somata giving rise to thalamo-cortical axons, identified by the presence of granular HRP reaction product within them, were measured. The mean size of LGN neurones labelled by injections in area 17 (“17-relay” cells) was less than of neurones filled from area 18 (“18-relay” cells). Similar separate injections into area 17 and 18 of monocularly deprived kittens also showed that in non-deprived LGN laminae 17-relay cells were, on average, smaller than 18-relay cells. In deprived laminae, 17-relay cells were some 20% smaller than in nondeprived laminae, but deprived 18-relay cells were 50–60% smaller than normal, being on average, actually smaller than deprived 17-relay cells. We conclude that the population of large LGN neurones projecting to area 18 is more severely affected by monocular deprivation than the smaller neurones projecting to area 17, and discuss the relationship of the morphological results to physiologically defined X and Y cells in the LGN.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235708
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  • 12
    Digitale Medien
    Digitale Medien
    The pontine projection to the cerebellar anterior lobe. An experimental study in the cat with retrograde transport of horseradish peroxidase (1977)
    Springer
    Experimental brain research 29 (1977), S. 233-248 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Pons ; Cerebellum ; Pontocerebellar projection ; HRP method ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary By use of the retrograde axonal transport of horseradish peroxidase (HRP) the projection to the anterior lobe from the pontine nuclei was mapped in detail. In 18 cats 0.1–0.5 gml of a,50% suspension of Sigma VI or Serva HRP was injected in the anterior lobe under visual guidance or stereotactically. The main findings are as follows: 1. The projection to the vermis of the anterior lobe is bilateral with a contralateral preponderance (about 3/4). 2. The vermis of the anterior lobe receives afferents from a restricted, laterally located region in the caudal part of the pons. Dorsal parts of this region project anteriorly (lobules I–III), ventral parts posteriorly (lobulus V). 3. The projection to the intermediate-lateral part is almost exclusively contralateral and is considerably heavier than the projection to the vermis. 4. The intermediate-lateral part receives afferents from two pontine regions. One is located laterally and coincides caudally with the region projecting to the vermis. The other is located medially and projects only sparsely to the vermis. 5. Within the projection from the lateral pontine region to the intermediate part there is a somatotopical pattern corresponding to that within the projection to the vermis. Within the medial pontine region the somatotopical pattern is less clear, but there is a tendency for cells projecting to lobules III–IV to be located more ventrolaterally than those sending their fibres to lobulus V. 6. The pontine regions projecting to the anterior lobe seem to coincide closely with those receiving fibres from the primary sensorimotor cortex, particularly the lateral part of the anterior sigmoid gyrus and medial part of the posterior sigmoid gyrus, as determined previously (P. Brodal, 1968a).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237044
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  • 13
    Digitale Medien
    Digitale Medien
    Dark adaptation and receptive field organisation of cells in the cat lateral geniculate nucleus (1977)
    Springer
    Experimental brain research 27 (1977), S. 35-50 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Lateral geniculate nucleus ; Cat ; Dark adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The receptive fields of LGN cells were investigated with stationary light and dark spot and annulus stimuli. Stimulus size and background intensity were varied while stimulus/background contrast was kept constant. The speed of dark adaptation varied considerably from cell to cell. Dark adaptation made responses more sustained in all neurones and eliminated the oscillatory on-responses evoked under some conditions in the light-adapted cells. Dark adaptation led also to a disappearance of early phasic inhibition in on-responses, and increased response rise time and latency. The power of surround responses to inhibit centre responses decreased slightly at low levels of light adaptation in LGN cells but much less than in retinal ganglion cells. Some other traces of changing retinal surround effects also appeared in the LGN on dark adaptation. For example, the functional size of receptive fields increased at low levels of illuminance as has been observed in retinal ganglion cells and the receptive fields as estimated from response peaks were larger than those estimated from sustained components.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234823
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  • 14
    Digitale Medien
    Digitale Medien
    The distribution of enzymes in the epidermis of the domestic cat (1977)
    Springer
    Archives of dermatological research 260 (1977), S. 29-38 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Cat ; Epidermis ; Histochemistry ; Enzymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Mit Hilfe von enzymhistochemischen Methoden wurden die Verteilung und die Aktivitäten verschiedener oxydativer und hydrolytischer Enzyme in der Epidermis der Hauskatze untersucht. Deutliche Aktivitäten oxydativer Enzyme konnten mit Ausnahme des Stratum corneum in allen epidermalen Zellagen beobachtet werden. Unter den nachgewiesenen hydrolytischen Enzymen zeigte besonders die unspezifische Esterase stark positive Reaktionen im Stratum granulosum und in den basalen Anteilen des Stratum corneum. Cholinesterase-Aktivitäten waren in der Epidermis der Katze nicht festzustellen. Die vorliegenden Ergebnisse von der Epidermis der dicht behaarten Hauskatze werden im Zusammenhang mit den Ergebnissen entsprechender Untersuchungen an der Epidermis spärlich behaarter Säugetierarten (z.B. Hausschwein und Mensch) diskutiert. Insgesamt weist das Enzymmuster der Katzenepidermis nur bedingt Parallelen zu demjenigen der Epidermis des Menschen auf, wobei speziell in der Verteilung und den Aktivitäten von Esterasen Abweichungen auftreten.
    Notizen: Summary With the help of enzyme histochemical methods, the distribution and activities of several oxidative and hydrolytic enzymes in the epidermis of the densely-haired domestic cat have been studied. Distinct oxidative enzyme activity could be demonstrated in all epidermallayers except the stratum corneum. Among the hydrolytic enzymes investigated, strong reactions for non-specific esterases were visible especially in the str. granulosum and the basal lamellae of the str. corneum. Positive reactions for cholinesterases could not be observed in the cat epidermis. The results are discussed in relation to corresponding investigations on the epidermis of sparsely-haired mammals, e. g. the domestic pig and man. Generally the enzyme pattern of the cat epidermis only shows limited parallels to man, especially where esterase distribution is concerned.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00558011
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  • 15
    Digitale Medien
    Digitale Medien
    Paraplegia due to actinomyces viscosus infection in a cat (1977)
    Springer
    Acta neuropathologica 39 (1977), S. 231-235 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Actinomyces viscosus ; Epidural space ; Spinal cord ; Cat ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In a 3 year old female domestic cat a suppurative, granulomatous lesion of the tail and sacral area penetrated into the epidural space, causing paraplegia. A. viscosus was isolated from the inflammatory tissues. A comparative light and electron-microscopic study of the bacterial elements and the architecture of the granules (Drusen) show that the latter are in-vivo microcolonies of the agent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00691702
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  • 16
    Digitale Medien
    Digitale Medien
    Direct projections from thalamic intralaminar nuclei to extra-striate visual cortex in the cat traced with Horseradish peroxidase (1977)
    Springer
    Experimental brain research 28 (1977), S. 133-139 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Intralaminar nuclei ; Visual cortex ; Horseradish peroxidase ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Thalamic projections to the visual cortex were investigated using the Horseradish peroxidase tracing technique. Besides confirmation of a distinct origin of thalamic projections to striate and extra-striate visual cortex, afferents of the intralaminar nuclei (ILN) to visual cortex were demonstrated. These projections of ILN were shown to be specific in that they terminate in areas 18, 19 and Clare Bishop but not area 17. The coupling of these intralaminar projections on to the extra-striate visual system is considered with respect to orientation of gaze.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237091
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  • 17
    Digitale Medien
    Digitale Medien
    Compensation of postural effects of hemilabyrinthectomy in the cat. A sensory substitution process? (1977)
    Springer
    Experimental brain research 28 (1977), S. 249-257 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Hemilabyrinthectomy ; Compensation ; Postural deficits ; Vision ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A photographic technique was used to study the evolution of lateral head-tilt following hemilabyrinthectomy in adult cats. Animals were maintained post-operatively in normally lit conditions (LM cats), in total darkness (DM cats), or in stroboscopic light. In LM cats, the head tilt peaked at 45 degrees (with the lesionned side down) on the second post-operative day, and decreased to about 0 degree within about 10 days. This evolution was followed by rebounds of head-tilt to larger angles before a stable compensated head position could be maintained (approximately at the end of the third post-operative month). In DM cats, the head remained tilted by a large angle throughout the duration of the dark period. Re-exposure to light was followed by a rapid decrease of head-tilt. In stroboscopic light, the evolution of head-tilt was found to be closely similar to that in the normally lit condition. Finally, when put back in the dark at a late post-operative stage, already compensated animals were found to loose their symmetrical head position, and to re-acquire a strong head tilt. This effect resumed on re-exposure to light. It is inferred that static visual input is a necessary condition for compensation of the postural deficits of hemi-labyrinthectomy in the cat. Maintenance of a stable head posture also depends upon continuous availability of visual input.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235707
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  • 18
    Digitale Medien
    Digitale Medien
    Degeneration of two of nine types of synapses in the putamen after center median coagulation in the cat (1977)
    Springer
    Experimental brain research 28 (1977), S. 345-361 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Putamen ; Cat ; Center median parvocellular neurons ; Ultrastructure ; Degenerated boutons (type VII and IV)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The cat putamen contains the identical nine types of synapses and the same proportion of axo-dendritic (or axo-somatic) synapses as described for the fundus striati. However, type III (cortico-striatal) (31∶16%) and type V (axon-collateral) (13∶1%) occur much more frequently and type I (nigro-striatal) much less frequently (14∶34%) in the putamen than in the fundus striati. Of the axo-spinous synapses only type IV, with densely arranged small round vesicles and interrupted, asymmetric contact, shows a dark degeneration after center median lesions, mainly in the parvocellular part. Of the six axo-dendritic (or axo-somatic) synapses, only type VII, with densely packed small round vesicles and asymmetric contact, is degenerated after the same lesion in the center median nucleus. However, after such lesions type VII synapses are much more frequently degenerated in the putamen than those of type IV.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235716
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  • 19
    Digitale Medien
    Digitale Medien
    The mode of synaptic linkage in the cerebro-ponto-cerebellar pathway investigated with intracellular recording from pontine nuclei cells of the cat (1977)
    Springer
    Experimental brain research 29 (1977), S. 123-136 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Pontine nuclei cells ; Unitary EPSPs ; Synaptic organization ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Intracellular potentials of pontine nuclei (PN) cells were recorded in cats anesthetized with pentobarbitone sodium. 2. Stimulation of the cerebellar nuclear regions or the brachium pontis induced an antidromic action potential composed of IS-SD spikes, after-depolarization and after-hyperpolarization. 3. Cerebellar stimulation produced EPSPs only in a few PN cells. 4. Activation of the corticopontine or pyramidal tract produced in all PN cells an EPSP built up from the unitary components with variable amplitudes and time courses. Paired or repetitive activation revealed a property of the frequency potentiation of the EPSP. 5. Unitary EPSPs also occurred spontaneously. A great majority of these spontaneous EPSPs were cerebral in origin, and had amplitudes and time courses comparable with those evoked by stimulation of the corticopontine or pyramidal tract. 6. The half-width versus time to peak relationship of these unitary EPSPs suggested a dendritic location of the synapses with variable distances from the soma. It is assumed that large, proximal synapses serve for efficient relay of signals while small, distal synapses for their integration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236880
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  • 20
    Digitale Medien
    Digitale Medien
    Responses of cells in the cat lateral geniculate nucleus to moving stimuli at various levels of light and dark adaptation (1977)
    Springer
    Experimental brain research 27 (1977), S. 51-59 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Lateral geniculate nucleus ; Cat ; Dark adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The responses of neurones in laminae A and A1 of the cat lateral geniculate nucleus to moving stimuli were investigated at different background luminances. Moving bright slits, dark bars and edges were employed; the contrast of stimuli against the background was held constant. Background intensities varied from 10−3 to 102 td. Responses as stimuli passed across the centres of LGN receptive fields became stronger with increasing levels of light adaptation up to 10−1–101 td and then remained constant. Responses as stimuli passed through surround regions altered qualitatively with adaptation level, generally increasing in strength and complexity with background luminance. As a bright slit for on-centre cells or dark bar for off-centre cells left the surround, in almost all units a strong secondary peak could be elicited by an appropriate selection of the adaptation conditions. Many features of the responses to moving stimuli could not be predicted from the responses to stationary stimuli under different adaptation conditions described in the previous paper.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234824
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  • 21
    Digitale Medien
    Digitale Medien
    The distribution of degenerating axons after small lesions in the intact and isolated visual cortex of the cat (1977)
    Springer
    Experimental brain research 27 (1977), S. 419-440 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Visual cortex ; Intrinsic connections ; Degeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The extent of the spread of axonal degeneration was investigated in the visual cortex of the cat after making small lesions restricted to the grey matter. Two series of experiments were undertaken. In the first, normal adult cats were used, and in the second, the cortex of the postlateral gyrus was isolated from its extrinsic afferents by surgical undercutting 3 months before making the lesions. The results were similar in the two series in most respects. 1. Horizontal fibres extended in considerable numbers for some 500 μm from the lesion, mainly in layers I, III/IV and V, a few reaching 2–3 mm. These fibres were better seen in the intact than in the isolated cortex. Their spread was usually asymmetrical, being greater posteromedially than anterolaterally. 2. Oblique axons ran downwards from the middle layers into layers V and VI, or upwards into layers I and II. 3. Axons arising from layers II to VI descended vertically into the white matter. Degeneration patterns after lesions in areas 17 and 18 were compared.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235514
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  • 22
    Digitale Medien
    Digitale Medien
    A study of binocular convergence in cat visual cortex neurons (1977)
    Springer
    Experimental brain research 28 (1977), S. 21-35 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Visual cortex ; Binocular convergence ; Ocularity stripes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The average latency of cortical neuronal responses to electrical optic nerve (ON) stimulation was 3.0±0.7 s.d. msec. No significant difference between latencies to ipsi- and contralateral ON stimulation was found. Binocularly excitable cells showed almost equal response latencies to stimulation of both nerves. The average latency of subcortically recorded geniculo-cortical fibers was 0.3 msec less, but showed the same variance as that of cortical cells, suggesting that in all cases direct monosynaptic excitation of cortical cells by fibers of either ocularity is possible. Classes of ocular dominance based on electrical stimulation were positively, but not 100% correlated with classes of ocular dominance to visual stimulation. An anatomical study revealed that in cat terminals of geniculo-cortical projection are segregated to a lesser degree into ocularity stripes than in monkey. Direct monosynaptic excitation of cells by fibers of either ocularity which was found physiologically would also on these grounds appear possible for all cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237083
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  • 23
    Digitale Medien
    Digitale Medien
    Visual movement perception in the cat is directionally selective (1977)
    Springer
    Experimental brain research 29 (1977), S. 429-432 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Visual movement perception ; Cat ; Contrast sensitivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Behavioral experiments show that the visual system of cat contains mechanisms which are selective for direction of stimulus movement. The cat's contrast detection threshold for a drifting grating is unaffected by the addition of a grating moving in the opposite direction; this same pattern of results is found for human observers. The convergence of cat and human psychophysical data suggests that man's brain may hold direction-specific neurons, similar to those known to exist in the cat brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236181
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  • 24
    Digitale Medien
    Digitale Medien
    Effects of monocular deprivation on excitatory and inhibitory pathways in cat striate cortex (1977)
    Springer
    Experimental brain research 30 (1977), S. 25-41 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Visual cortex ; Deprivation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effects of monocular deprivation from contour vision were investigated in the striate cortex of cats. In addition to the receptive field (RF) properties of single cells responses to electrical stimulation of the deprived and the experienced optic nerve were analyzed: Evoked potentials as well as intra- and extracellularly recorded single unit responses were evaluated. The main goals were: 1. to determine to what extent the responses to electrical stimulation reflected the shift in ocular dominance apparent from the RF analysis, 2. to determine the relative effects of deprivation on excitatory and inhibitory responses and 3. to locate the site of impaired transmission in the pathway from the deprived eye. The results show that the responses to electrical stimulation reflect precisely the shift in ocular dominance apparent from the RF analysis. The evoked potentials elicited from the deprived nerve further indicate that deprivation had also affected the afferent system at the LGN level or (and) at the terminal field of the thalamo-cortical fibers. In contrast to the reduction of short latency excitatory responses to stimulation of the deprived nerve, oligosynaptic inhibition with latencies of 4–6 msec was equally well elicited by stimulation of either eye. The same was true for delayed excitatory responses which frequently occur with latencies between 40 and 80 msec after nerve stimulation. It is concluded from these results 1. that transmission between thalamic afferents and inhibitory interneurones in the cortex is less affected by deprivation than transmission in those pathways which relay cortical excitation, 2. that there is another deprivation resistant indirect pathway from the retina to the visual cortex which is probably relayed through mesencephalic structures and 3. that deprivation effects are not confined to transmission failure at the thalamo-cortical synapses but include alterations already at the presynaptic level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237856
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  • 25
    Digitale Medien
    Digitale Medien
    Neuronal responses to eye muscle stretch in cerebellar lobule VI of the cat (1977)
    Springer
    Experimental brain research 27 (1977), S. 101-111 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Eye muscle afferents ; Stretch receptors ; Cerebellar cortex ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Extraocular proprioceptive input to cerebellar vermis, lobule VI, was investigated in cats under N2O analgesia by recording neuronal responses to eye muscle stretch. Both optic tracts were transected and the periorbital skin and conjunctiva were locally anaesthetized. Eye rotation within the physiological range was achieved by applying a pull of predetermined length and tension to each of the eight musculi recti at their insertion to the globe. Within lobule VI, only small patches of cortex receive stretch receptor afferents. The information made available by these afferents corresponds to a change of eye position. Minimal responses were dependent upon angular deflections of a few degrees. Maximal response amplitudes were obtained within the physiological range of angular deflections and angular velocities for the units tested. Most cells responded to stretch of more than one muscle. Three types of convergence were found: (1) neurons responding according to a certain direction of a conjugated movement of both eyes, (2) neurons responding to movements in either direction of one plane, (3) more complicated response patterns.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234828
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  • 26
    Digitale Medien
    Digitale Medien
    The role of vision in compensation of vestibulo ocular reflex after hemilabyrinthectomy in the cat (1977)
    Springer
    Experimental brain research 28 (1977), S. 235-248 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Vestibulo-ocular reflex ; Hemilabyrinthectomy ; Role of vision ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. A new description of vestibulo-ocular responses to angular velocity steps has been used to quantify vestibular compensation in right hemilabyrinthectomized cats. The amplitudes (VM and CM) and the times of occurrence (tM and to) from stimulus onset of the peaks of slow phase eye velocity and slow cumulative eye position were computed for velocity steps directed towards the lesioned side (clockwise, CW) and towards the intact side (counterclockwise, CCW). In addition, the values of these parameters were corrected from the effects of spontaneous nystagmus, when present. 2. In animals recovering in normal laboratory conditions, spontaneous nystagmus disappeared within 10 days after operation. In CCW responses, vm decreased by about 45% during the first 3 days and then remained stationary during the next 2 weeks. In CW responses VM showed a rapid increase during the first 3 days, and then remained stationary. After 2 weeks, VM increased in both CW and CCW responses. CM changes substantially reproduced those of VM. 3. In animals put in the dark immediately after operation, spontaneous nystagmus persisted until re-exposure to light (up to 31 days) and then disappeared rapidly. VM in both CW and CCW responses remained at a low value during the dark period and became more or less doubled after one week of exposure to light. CM also increased rapidly in CW and CCW responses, after re-exposure to light. 4. In the discussion these results are compared with those concerning activity of single vestibular neurons during compensation. It is concluded that vision is a primary factor conditioning disinhibition of vestibular nuclei spontaneous activity after the critical phase of compensation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235706
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  • 27
    Digitale Medien
    Digitale Medien
    Extraocular proprioceptive projections to the visual cortex (1977)
    Springer
    Experimental brain research 28 (1977), S. 421-425 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Visual system ; Cat ; Proprioceptive receptors ; Extraocular muscles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electrical stimulation of the intraorbital part of the motor branches of extraocular muscles, where proprioceptive fibers run, evokes responses in 25% of the units of the striate cortex of the cat. The latency ranges between 25 and 40 msec. Mechanical stretch of extraocular muscles evokes multiunit responses in the striate cortex. The response is abolished by injection of xylocaine into the stretched muscle. The suppression of the response is reversible.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235720
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  • 28
    Digitale Medien
    Digitale Medien
    Spatial frequency and orientation tuning curves of visual neurones in the cat: Effects of mean luminance (1977)
    Springer
    Experimental brain research 27 (1977), S. 335-345 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Spatial frequency ; Visual neurones ; Mean luminance ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Experiments have been performed on unanaesthetized and paralysed cats. The tuning curves for spatial frequency of retinal, lateral geniculate and simple and complex cells of the cortex have been determined in response to sinusoidal gratings of various spatial frequencies at different levels of mean luminance. For all neurones, decreasing the mean luminance leads to a progressive loss of spatial resolution and contrast sensitivity. Retinal ganglion cells of type X show, for scotopic levels of luminance, a flattening of their spatial frequency tuning curves in the low spatial frequency range. For geniculate and cortical neurones, on the contrary, the spatial frequency characteristics at the various levels of luminance remain practically invariant in their bandwidth. On the average, complex cells still respond to mean luminances ten times lower than simple cells. The tuning curves for orientation of cortical cells maintain, to a first approximation, the same shape at the various levels of mean luminance. The results are discussed, comparing the electrophysiological with psychophysical data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235508
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  • 29
    Digitale Medien
    Digitale Medien
    Electrodermal reflexes in the cat's paws elicited by natural stimulation of skin (1977)
    Springer
    Pflügers Archiv 369 (1977), S. 27-32 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Electrodermal reflexes ; Natural stimulation of skin ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Electrodermal reflexes recorded from the central pads on the hind- and forepaws were elicited by natural stimulation of skin in ketamine anaesthetised cats. 2. Stimuli which excite the Pacinian corpuscles in the paws (air jet stimuli applied to the paw, vibrational stimuli produced by tapping on the experimental frame) and the cutaneous nociceptors (mechanical and thermal noxious stimuli) elicit electrodermal reflexes. Stimuli exciting hair follicle receptors on the trunk or legs or slowly adapting receptors in the feet are without effect. 3. Electrodermal reflexes elicited by non-noxious mechanical stimulation of skin in the hindpaws have a clear-cut spatial organization. Air jet stimuli can only produce them from the distal hindpaws but not from any other skin area indicating that this reflex may be organized at the spinal level. Electrodermal reflexes on noxious stimulation too have some spatial organization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00580806
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  • 30
    Digitale Medien
    Digitale Medien
    Effects of systemic hypoxia and hypercapnia on cutaneous and muscle vasoconstrictor neurones to the cat's hindlimb (1977)
    Springer
    Pflügers Archiv 368 (1977), S. 71-81 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Vasoconstrictor neurones ; Skin ; Muscle ; Systemic hypoxia ; Systemic hypercapnia ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Reactions of cutaneous and muscle vasoconstrictor neurones to the hindlimb on systemic hypoxia and systemic hypercapnia were investigated in chloralose anaesthetized cats. Mainly four types of preparations were used: brain intact and decrebrate (pontomedullary) animals with and without cartotid sinus (CSN) and vagal nerves (VN). 2. In brain intact animals with intact CNS and VN most cutaneous vasoconstrictor neurones were depressed and most muscle vasoconstrictor neurones were excited during systemic hypoxia and hypercapnia. The responses to hypercapnia were smaller than those to hypoxia. 3. In brain intact deafferented animals and in decerebrate animals with and without intact CSN and VN systemic hypoxia and hypercapnia induced excitation in both cutaneous and muscle vasoconstrictor neurones. The responses to hypoxia were significantly smaller in deafferented preparations when compared to those in preparations with intact CSN and VN. Furthermore in muscle vasoconstrictor neurones the size of the responses was not significantly different in decerebrate preparations from that in brain intact preparations. 4. These results indicate a distinct neuronal organization of the chemoreceptor reflexes in the vasoconstrictor systems in the brain stem. Suprapontine brain structures are most important for producing the inhibition of the cutaneous vasoconstrictor neurones during hypoxia and hypercapnia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01063457
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  • 31
    Digitale Medien
    Digitale Medien
    Vestibular and somatosensory interaction in the cat vestibular nuclei (1977)
    Springer
    Pflügers Archiv 371 (1977), S. 155-160 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Vestibular nuclei ; Cat ; Somatosensory integration ; Neck movement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The vestibular nuclei of cats were explored extracellularly with micropipettes to locate units with a resting discharge rate which responded to rotation in the horizontal plane. These units were examined for somatosensory input from neck and limbs. Fewer than half responded to somatosensory stimulation. The neck region was the body area most effective in influencing unitary activity. The response pattern most often noted was an increase and decrease in discharge frequency when the body was moved towards and away from the recording electrode respectively. Change in discharge rate was observed to be primarily dependant upon neck velocity and not upon absolute neck position. Half of the somato-sensory units received input from either the forelimbs or the hindlimbs, while the remaining half responded to both.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00580784
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  • 32
    Digitale Medien
    Digitale Medien
    Kinetics of distribution of amphetamine in cats (1977)
    Springer
    Psychopharmacology 54 (1977), S. 209-215 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Amphetamine ; Para-hydroxy-amphetamine ; Distribution ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The distribution and metabolic fate of amphetamine were studied in cats. In the brain, high levels of drug were detected in the grey matter structures at short intervals after administration, while at longer intervals distribution between white and grey matter areas was more uniform. In peripheral tissues the greatest concentration of the drug was seen in the highly vascularized organs. Para-hydroxyamphetamine was found in minimal amounts in the liver and kidneys and only at trace quantities in the brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00426782
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  • 33
    Digitale Medien
    Digitale Medien
    Hereditary deafness in the cat. An electron microscopic study of the stria vascularis and Reissner's membrane (1977)
    Springer
    European archives of oto-rhino-laryngology and head & neck 217 (1977), S. 199-217 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Hereditary deafness ; Cat ; Electron microscopy ; Stria vascularis ; Reissner's membrane ; Microcirculation ; Cellular metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The auditory pathway potentials have been recorded from a series of 35 cats, and the stria vascularis and Reissner's membrane examined with the electron microsope. The ages varied from the first postnatal day to at least 6 years. 30 of the animals had white coats, and 45 of the ears lacked potentials. The basal processes of the marginal cells fail to develop in pathological ears, and appear displaced towards the endolymphatic surface by a layer of grossly swollen, chromophobe cells. These features are already present at the 3-day stage, and persist until the third week. Thereafter, increasing electron density of all cell types is found, with progressive reduction in strial thickness. Swelling of the capillary endothelial cells and descent of Reissner's membrane are found in the first coil at 2 weeks. Obliteration of capillaries, and development of vacuolar cytoplasmic outgrowths from the vestibular membrane mesothelial cells occur at later stages. These findings are discussed and compared with the pathological changes produced by a variety of endogenous and exogenous factors in both man and animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00665540
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  • 34
    Digitale Medien
    Digitale Medien
    Azimine. IITeil I, siehe [1].. Synthese und thermische Fragmentierung von cis- und trans-2,3-Diphenyl-1-phthalimido-2,3-di[15N]-aziminTeilweise vorgetragen in der Versammlung der Schweizerischen Chemischen Gesellschaft am 8./9. Oktober 1976 in Genf und als Autoreferat veröffentlicht [2]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 831-843 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Azimines. IITeil I, siehe [1]. . Preparation and Thermal Fragmentation of cis- and trans-2,3-Diphenyl-1-phthalimido-2,3-di[15N]-azimine Teilweise vorgetragen in der Versammlung der Schweizerischen Chemischen Gesellschaft am 8./9. Oktober 1976 in Genf und als Autoreferat veröffentlicht [2].cis- and trans-2,3-Diphenyl-1-phthalimido-2,3-di[15N]-azimine (11 and 12) wer synthesized from cis-di[15N]-azobenzene (10) and phthalimido-nitrene (2), the latter generated by lead tetraacetate oxidation of N-aminophthalimide (1). Useful information was obtained from the comparison of several data of 11 and 12 with those of the unmarked diphenyl-azimines 5 and 6 (R = C6H5).The 15N- and 13C-NMR. spectra of 11 and 12 were interpreted to furnish additional evidence for the azimine structure and for the indicated configurations. The IR. spectra permitted identification of two bands in the 1200 to 1450 cm-1 region, probably characteristic for the functionality of diaryl-phthalimido-azimines. Comparison of the mass spectrum of 11/12 with that of the unmarked analogues 5/6 (R = C6H5) permitted the interpretation of the fragmentation path of 1-phthalimidoazimines. The major path may be the purely thermal decomposition to 13 and 7 (R = C6H5), respectively. Two other competing fragmentation paths are discussed.Prolonged thermolysis of 11 at 61° in solution gave 83% of N,N′-diphenyl-N N′-phthaloyl-di[15N]-hydrazine (13) of 98% isotope purity, which means that the imide nitrogen atom and N(1) of the azimine function are removed in this reaction. A mechanism passing through an intermediate cyclic tetrazene 16 is considered.Benzocyclobutenedione (14) added to trans-azobenzene (4, R = C6H5) under the influence of a high pressure lamp in a quarz apparatus to give N,N′-diphenyl-N,N′-phthaloyl-hydrazine (7, R = C6H5). This reaction was found not to take place in the dark, even after prolonged heating in trichloromethane.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600313
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  • 35
    Digitale Medien
    Digitale Medien
    Azimine. I. Bildung und Stereoisomerie von 2, 3-Diaryl- und 2, 3-Dialkyl-1-phthalimido-aziminenTeilweise vorgetragen in der Versammlung der Schweizerischen Chemischen Gesellschaft in Lausanne am 7./8. Mai 1971 und als Autoreferat veröffentlicht [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 816-830 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Azimines. I. Synthesis and Stereoisomerism of 2, 3-Diaryl- and 2, 3-Dialkyl-1-phthalimido-aziminesTeilweise vorgetragen in der Versammlung der Schweizerischen Chemischen Gesellschaft in Lausanne am 7./8. Mai 1971 und als Autoreferat veröffentlicht [1].Special examples of a new class of compounds, the open-chain azimines (1), have been prepared and their properties examined.Addition of phthalimido-nitrene (4), generated by lead tetraacetate oxidation of N-aminophthalimide (3), to cis- and trans-azobenzene (6 and 5), -azo-p-toluene (8 and 7), and to trans-azomethane (9), -azoethane (10) and -azo-α-phenylethane (11) afforded the separable cis- and trans-isomers of 2, 3-diphenyl- (12 and 13), 2, 3-di-p-toyl- (14 and 15), 2, 3-dimethyl- (16 and 17), 2, 3-diethyl- (18 and 19) and 2, 3-di-(α-phenylethyl)-1-phthalimido-azimines (20 and 21) in different ratios (see Scheme 1).The constitution of the nitrene azo compound adducts as azimines was derived from their properties, especially from the conjugation effect (visible in the UV. spectra) of the aryl-substituted compounds and from the non-equivalence (shown by the 1H-NMR. spectra) of the substituents on the two nitrogen atoms derived from the azo compounds. This evidence excluded the triaziridine 22 and an alternative azimine constitution 23 for the adducts.Of the two stereoisomers obtained for each of the azimines, the aryl-substituted examples 12/13 and 14/15 were readily interconverted by warming in solution, the cis-isomers 12 and 14 exceeding the trans-isomers 13 and 15 in the equilibrium. The dialkyl-azimines appear to be configurationally more stable, since interconversion of the dimethyl-azimines 16 and 17 was not possible under the same conditions, and also not before another thermal reaction took place (see below).The identification of the N(2)-N(3) bond as the stereogenic center, i.e. that the stereoisomerism of the azimines is due to the difference in relative position at N(2) and N(3) of the substituents derived from the azo compounds, as well as a configurational assignment was possible in the aryl-substituted examples on the basis of the UV. spectroscopic comparison of the isomeric azimines with the corresponding stereoisomeric azoxy compounds: The cis-azimines 12 and 14 showed absorptions similar to those of cis-azoxybenzene and cis-azoxy-p-toluene, and the trans-azimines 13 and 15 showed absorptions similar to those of the respective trans-azoxy compounds. With respect to the configuration of the alkyl-substituted azimines, it was observed that the isomers 17 and 19, which from their formation and chromatographic behaviour are likely to be the trans-isomers, show a visible coupling (∽ 1 Hz) between the two H (α)'s in the 1H-NMR. spectrum, whereas the dimethyl isomer 16 (cis) does not exhibit such a coupling.Thermal treatment of four azimines, namely 12, 14, 16 and 17, in solution for a longer time afforded the corresponding N, N′-disubstituted N, N′-phthaloyl-hydrazines 27, 28 and 29. The order of velocity of this fragmentation with nitrogen extrusion was 12/13 ≍ 14/15 〉 16(cis) 〉 17(trans).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600312
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  • 36
    Digitale Medien
    Digitale Medien
    Photochemistry of Chlorinated 2-Cycloalkenones (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 874-881 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 6-chloro-2-cyclohexenones 3, 6 and 11, and the 5-chloro-2-cyclopentenone 15 were newly synthesized. The results obtained with compounds 3 and 15 in photocycloadditions to olefins show that the oxetane vs. cyclobutane product ratio is reduced by the substitution of florine by chlorine in the α′ -position of the enone. No oxetanes are formed in the intramolecular photocycloaddition of 6. Compound 11 does not photoadd to olefins. The newly synthesized 2-chloro-3-cyclohexenones 8 and 9 are also photostable towards light of λ=366 nm, but π-π*-excitation (λ=254 nm) in pentane leads to the formation of 4,4-dimethylcyclohexanone (29).
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600316
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  • 37
    Digitale Medien
    Digitale Medien
    Mehrkernige Kobaltkomplexe. II. Herstellung und Struktur von [(tren) (NH3)Co(O2)Co(NH3) (tren)](SCN)4 · 2H2OI: siehe [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 867-873 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Polynuclear Cobalt Complexes. II. Preparation and Structure of [(tren) (NH3)Co(O2)Co(NH3) (tren)](SCN)4 · 2H2OThe title compound is obtained on oxygenation of [Co(tren)(H2O)2]2+ in 6M aqueous ammonia or by ligand exchange starting from [(NH3)5Co(O2)Co(NH3)5]-(NO3)4. An X-ray structure determination was made. The substance forms monoclinic crystals, space group P21/c, lattice constants a=10,135, b=8,473, c=19,484 Å, β=108,58°, with two formula units in the cell. The final R is 0,066. The binuclear cation has a center of symmetry, so the Co—O—O—Co unit is planar; the Co—O—O angle is 111,5°. The tertiary nitrogen atoms of both chelate groups are cis to the O2 bridge, as found in doubly bridged [(tren)Co(O2,OH)Co(tren)](ClO4)3 · 3H2O.On acidification in solution, the singly bridged cation [(tren) (NH3)CoO2Co(NH3)(tren)]4+ (a) loses the bound O2 completely. But unlike the doubly bridged cation b, the rate of dissociation of a is independent of pH (Fig. 5). At higher pH (8-10) bridging a→b (Fig. 2) occurs. Both reactions must have the same rate determining step, the first order rate constants being of the order of 2 · 10-3 s-1 (25°, 0,35M KCl).
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600315
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  • 38
    Digitale Medien
    Digitale Medien
    Isolation and Identification of Three Major Metabolites of Retinoic Acid from Rat Feces (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 881-887 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Following the intraperitoneal administration of high doses of 14C- and 3H- labelled retinoic acid (1) to rats, three major metabolites and the intact compound were isolated from the feces in microgram amounts by use of column, thin-layer and high-pressure liquid chromatography. Their structures were elucidated by mass spectrometry and Fourier Transform 1H-NMR. spectroscopy as 2 (all-trans-4-oxoretinoic acid), 3 (7-trans-9-cis-11-trans-13-trans-5′-hydroxy-retinoic acid).Hydroxylation of the 5-methyl group of the cyclohexene ring, oxidation of the cyclohexene ring in position 4 and cis-trans isomerisation of the nonatetraenoic acid side chain were the reactions, which produced these products from retinoic acid. The metabolites 2 and 4 each accounted for about 4% of the radioactivity administered. The metabolite 3 and the parent compound accounted for about 16% and 17% of the dose, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600317
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  • 39
    Digitale Medien
    Digitale Medien
    Nouveaux types de sucres acétyléniques. Communication préliminaireUne communication plus détaillée paraîtra ultérieurement. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 892-895 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Novel types of acetylenic sugarsThe coupling, following Cadiot's procedure, of a 6-bromo-5,6-dideoxy-1,2-O-isopropylidène-3-O-methyl-α-D-xylo-hex-5-yno-1, 4-furanose (1) with phenylacetylene, 2-propyn-1-ol or terminal acetylenic sugars gave with excellent yields the expected diynes (an enediyne when the terminal acetylene was the 3,5, 6-trideoxy-1,2-O-isopropylidene-α-D-glycero-hex-3-en-5-yno-1,4-furanose 7). The chloro analogue 8 of 1 on treatment with lithium thiophenate gave the corresponding phenylthio-acetylenic sugar 9. An acetylene was also formed by reacting the gem-difluoro-olefinic sugar 10 with butyllithium whereas the same olefinic sugar and its 3-O-benzyl analogue 11 gave only a gem-fluoro-arylthio-olefinic sugar (13-15) as a mixture of the Z and E isomers (Z/E 〉 4) when treated with the conjugate base of an arylmercaptan.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600319
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  • 40
    Digitale Medien
    Digitale Medien
    Nouveaux exemples de radicaux libres stables de dérivés hétérocycliques de sucresDérivés C-glycosyliques XXXIV. Pour la 33c communication v. [1].. Communication préliminaireUne communication plus détaillée paraîtra ultérieurement. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 888-891 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Some more examples of stable free radicals of carbohydrate heterocyclic derivatives2-Glycosyl-4,4,5,5-tetramethylimidazoline- 3-oxide-1-oxyls and 2-glycosyl-4,4,5,5-tetramethylimidazoline 1-oxyls have been prepared in nine carbohydrate series, which proves the generality of the method. The hyperfine coupling constant between the free electron and the α-proton of the glycosyl group is never very large (0-2.3 G) but a correlation between its value and the structure of the aglycone has been noted. Free radicals of that type, stable in aqueous solutions, are potentially interesting for biological studies.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600318
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  • 41
    Digitale Medien
    Digitale Medien
    The Structure of the Antibiotic Hedamycin. I. Chemical, Physical and Spectral PropertiesPresented in part at the fall meeting on the Swiss Chemical Society in Aarau, October 4, 1975. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 896-906 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Interpretation of the chemical and spectral (IR., UV., 1H- and 13C-NMR.) properties of the antitumor antibiotic hedamycin (C41H50N2O11) suggests that the molecule contains a methyl substituted 1-hydroxyanthraquinone nucleus, an α, β-unsaturated ketone, two sugar-like tetrahydropyran rings (4 and 8) and an aliphatic chain 2, presumably with an epoxy group (see the Scheme).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600320
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  • 42
    Digitale Medien
    Digitale Medien
    Halogenierte Pyridine und 1,8-Naphthyridine. VI (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 907-921 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Halogenated pyridines and 1,8-naphthyridines. VI.The principle of the synthesis of 3-halomethyl-2,6-dichloro-pyridines has been extended to compounds with side chains of more than one carbon atom in the 3-position. Feasible synthetic routes are outlined starting from cheap, commercially available α-methylideneglutaronitrile and trichloroalkyl functional compounds which yield the intermediate 1,3,5-trisubstituted alkanes. These are cyclized by aqueous mineral acid or by hydrogen bromide in an organic solvent to 2-substituted glutarimids or hexahydronaphthyridinones, depending on the mode of cyclization. The final aromatization provides a simple route to pyridines or 1, 8-naphthyridines.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600321
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  • 43
    Digitale Medien
    Digitale Medien
    Über Pterinchemie. 62. Mitteilung. Protonenkatalysierte [1,2]-H-Verschiebung bei der Umlagerung von 6,7-Diphenyl-5,6-dihydropterin zu 6,7-Diphenyl-7,8-dihydropterin (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 922-924 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Proton catalysed [1,2]-H-shift in the rearrangement of 6,7-diphenyl-5,6-dihydropterine (I) to 6,7-diphenyl-7,8-dihydropterine (III)The arrangement from I to the thermodynamically more stable III undergoes through a acid catalysed [1,2]-H-shift (intramolecular 6,7-hydride rearrangement) (see Scheme 1).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600322
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  • 44
    Digitale Medien
    Digitale Medien
    Reactions of 1,3,5,7-Tetramethyl-anti-tricyclo[5.1.0.03,5] octane-2,6-diols and their 4,4,8,8-Tetrachloro- and 4,8-Dichloro-Derivatives with Diphosphorus TetraiodideFrom the planned dissertation of R. A. Dyllick-Brenzinger, ETH Zürich. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1403-1415 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaktionen von 1,3,5,7-Tetramethyl-anti-tricyclo[5.1.0.03,5]octan-2,6-diolen und deren 4,4,8,8-Tetrachlor- und 4,8-Dichlorderivaten mit DiphosphortetrajodidEs wurden die P2I4-Reaktionen mit 1,3,5,7-Tetramethyl-anti-tricyclo[5.1.0.03,5]-octan-2,6-diolen (3/6), mit dem 4,8-Dichlorderivat 4 und mit den 4,4,8,8-Tetrachlorderivaten 5/7 untersucht. Dabei entstanden die Styrolderivate 9 und 12, die anti-Bishomobenzolderivate 8 und 11, ein Homotropylidenderivat 10, ein Cyclo-octatetraenderivat 13 und ein 9-Oxabicyclo[4.2.1]nona-2,4,7-trienderivat 15. Die Ausbeuten lagen zwischen 1 und 10%. Die Bildung aller dieser Produkte liess sich unter der Annahme der primären Umwandlung einer oder beider Hydroxylgruppen in Abgangsgruppen X oder X und Y (wahrscheinlich X=Y=I) mechanistisch deuten. Die Reaktion der Deschlorderivate 3/6 lieferte nach Substitution beider Hydroxyl-gruppen durch X und Y: (a) unter Abspaltung von HX und HY das Styrolderivat 9 (Schema 2) und (b) unter Abspaltung von XY das Homotropylidenderivat 10 (Schema 3a) und das Bishomobenzolderivat 8 (Schema 3b). Die Reaktion des 4,8-Dichlor-derivates 4 lieferte nach Substitution beider Hydroxylgruppen durch X und Y: (a) unter Abspaltung von HX und HY das Styrolderivat 12 (Schema 2), und (b) unter Abspaltung von XY das Bishomobenzolderivat 11 (Schema 3b). Die Reaktion mit den 4,4,8,8-Tetrachlorderivaten 5/7 lieferte: (a) nach Substitution beider Hydroxyl-gruppen durch X und Y unter Abspaltung von XCl und YCl das Cyclooctatetraen-derivat 13 (Schema 4), und (b) nach Substitution nur einer Hydroxylgruppe durch X unter Abspaltung von XCl und HCl das bicyclische Derivat 15 (Schema 5). Alle diese Reaktionen sind zusätzlich zu den angegebenen Fragmentierungen und Eliminierungen noch teilweise von Umlagerungen des Kohlenstoffgerüstes begleitet.Die thermische Umlagerung von 1,5-Dichlor-2,4,6,8-tetramethyl-cycloocta-1,3,5,7-tetraen (13) in das Styrolderivat 12 wurde in Abhängigkeit der Lösungs-mittelpolarität untersucht und mit der analogen thermischen Umlagerung von Brom-cyclooctatetraen und Chlor-cyclooctatetraen verglichen.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600432
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  • 45
    Digitale Medien
    Digitale Medien
    Diterpenoide Drüsenfarbstoffe: Coleone S und T aus Plectranthus caninus ROTH(Labiatae), ein neues Diosphenol/trans-A/B-6,7-Diketon-Paar aus der Abietanreihe (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1443-1447 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Leaf-gland Pigments: Coleons S and T from Plectranthus caninus ROTH (Labiatae), New Hydroquinones of the Abietane Series with a Diosphenol/trans-A/B-6,7-Diketone Structure.Coleons S and T were isolated from the more polar fractions from extracts of the above mentioned plant. Coleon S, C20H26O6, has been shown to have structure 1a, and coleon T, C20H26O6, structure 2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600436
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  • 46
    Digitale Medien
    Digitale Medien
    Über eine Synthese des angulären Di(cyclobuteno)benzols (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1452-1455 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: On a Synthesis of the angular Di(cyclobuteno)benzolIn the course of our studies aimed at better understanding the Mills-Nixon effect, we have also prepared the angular di(cyclobuteno)benzene (1), the synthesis of which has been recently described by another group [3]. Our completely different and essentially simpler synthetic approach will be pointed out. A special pyrolysis apparatus is designed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600438
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  • 47
    Digitale Medien
    Digitale Medien
    Erratum (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1455-1455 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600439
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  • 48
    Digitale Medien
    Digitale Medien
    Mitteilungen (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1456-1458 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600440
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  • 49
    Digitale Medien
    Digitale Medien
    Masthead (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977) 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600501
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  • 50
    Digitale Medien
    Digitale Medien
    Iron Carbonyl Induced Reactions of Norbornene Derivatives with Substituted Acetylenes (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2160-2170 
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    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photochemical reactions of norbornadiene with substituted acetylenes in the presence of Fe(CO)5 gave various products of different types, depending on the nature of the acetylene. The results are summarized in Table 1. The cyclopentanone 1 was always formed in these reactions. In the reaction of disubstituted acetylenes such as dimethyl acetylenedicarboxylate and ethyl phenylpropiolate, the cyclopentenones 2 and 5 were formed, respectively. By contrast, propiolic esters produced the cyclohexenones 3 and 4, in which the ester group was attached on the β carbon with respect to the keto group. Plausible mechanisms for the formation of these products are shown in Schemes 7 and 8. The reaction of diphenylacetylene gave the cyclohexendione 7 as well as the cyclopentenone 6. Two enedione products 8 and 9 were obtained from the reaction of phenylacetylene. Compound 9 was converted to the aromatic diacetate 13 by heating with acetic anhydride in pyridine. On irradiation in the presence of Fe(CO)5 norbornene reacted similarly with dimethyl acetylenedicarboxylate and phenylacetylene to give the cyclopentenone 14 and the cyclohexenone 15, respectively. Compound 15, upon heating, isomerized to hydroquinone 16, which on acetylation gave the diacetate 17.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600708
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  • 51
    Digitale Medien
    Digitale Medien
    Application of the Equivalent Bond Orbital Model to the C2s-Ionization Energies of Saturated Hydrocarbons (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2234-2247 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown that the ab initio STO-3G treatment applied to simple saturated linear, branched and cyclic hydrocarbons, assuming standard geometries, yields orbital energies ∊jSTO-3G for their canonical orbital ϕj which correlate perfectly with the observed C2s ionization energies Ijm, if Koopmans' approximation is accepted.Applying the Foster-Boys localization procedure to these canonical orbitals ϕj leads to localized orbitals λμ and their corresponding Hartree-Fock matrix Fλ = (Fλ,μv). An examination of the matrix elements Fλ,μv, i.e. of the self-energies Aμ = Fλ,μμ of the localized CC- and CH-orbitals λμ and of the cross terms Fλ, μv (μ ≠ v) between them, leads to the conclusion that a satisfactory approximation should be obtained by setting Aμ = A for all μ, Fλ,μv = B if λμ and λv are vicinal and neglecting all other cross terms. The resulting model is nothing but the well-known equivalent bond orbital model of Lennard-Jones & Hall, which however can now be calibrated using the known C2s-ionization energies of hydrocarbons. Due to the discrete structure and the wider range (∽ 8 eV) of the C2s band systems in the photoelectron spectra of these molecules this leads to a more satisfactory parametrization than using the narrower and badly resolved C2p band system.Comparison of calculated band positions using the calibrated model with observed C2s-band ionization energies for a series of hydrocarbons reveals that the simple equivalent bond orbital model is better than one might have expected.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600715
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  • 52
    Digitale Medien
    Digitale Medien
    Der Metabolismus des Retinoids Ro 10-9359. Isolierung und Identifizierung der Hauptmetaboliten aus Plasma, Urin und Faeces des Menschen sowie aus der Galle der Ratte Synthese von drei Urinmetaboliten (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2309-2325 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Metabolism of the Retinoid Ro 10-9359. Isolation and Identification of the Major Metabolites in Human Plasma, Urine and Feces Synthesis of Three Urinary MetabolitesAfter oral administration of therapeutic doses of the 3H-labelled aromatic retinoic acid analog (retinoid) Ro 10-9359 (ethyl all-trans-9-(4-methoxy-2,3,6-trimethyl-phenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate) to humans 75 and 15% of the 3H-dose were excreted within the first five days in the feces and the urine, respectively. Using chromatographic procedures including high pressure liquid chromatography 18 metabolites could be isolated from human urine. Their structures were elucidated by mass spectrometry and FT-1H-NMR. spectroscopy. In these urinary metabolites the tetraene side chain of the parent compound Ro 10-9359 is shortened. The radioactivity of the identified urinary metabolites accounted for about 11% of the dose. Three urinary metabolites were synthesized. The main part of the radioactivity excreted within the first five days in the feces consisted of unchanged drug (60% of the dose). A smaller (amount 15% of the dose) could not be identified. The unchanged drug and a major metabolite, the corresponding acid, were found in human plasma.In an experiment with bile-duct cannulated rats the radioactively labelled retinoid Ro 10-9359 was injected intravenously. About 70% of the 3H-dose was excreted in the bile, within the first 48 hours. The whole radioactivity of the rat bile consisted of polar metabolites. No unchanged drug could be found. After enzymatic hydrolysis of the bile conjugates three metabolites were isolated. The main metabolite (49% of the i.v. dose) was a conjugate of the corresponding acid of the parent drug, already found as free compound in human plasma. The other bile metabolites (9 and 7% of the i.v. dose) had an intact side chain, too.An enterohepatic recycling of the bile metabolites was observed in the rat.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600722
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  • 53
    Digitale Medien
    Digitale Medien
    Stabilité en solution aqueuse de complexes de métaux lourds avec des ligands diaza-polyoxamacrocycliques (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2633-2643 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stability in aqueous solution of some complexes of heavy metals with diaza-polyoxamacrocyclic ligandsStability of metal complexes (Mn+ = Cu2+, Ni2+, Co2+, Zn2+, Pb2+, Ag+ and Cd2+) with five diaza-polyoxamacrocycles (L = [2.1.1], [2.2.1], [2.2.2], [2.1] and [2.2] ) have been determined at 25°, in 0.1 M Et4N+ClO4- aqueous solutions, by means of potentiometric titrations. All cations form MLn+ complexes; Cu2+ also forms the MHL(n+1)+ protonated species with both [2.2.1] and [2.1.1] ligands. The stability of these complexes has been discussed in terms of structure and by considering the ionic radii of the cations together with the radii of the macrocyclic cavities. Different behaviour is observed between some of these complexes and the well known alkali and alkaline-earth cryptates, partly due to the more covalent nature of bonds formed by the investigated cations and the donor sites of the ligands. The effect of the substitution of two oxygen by two sulfur atoms in the pentadentate ligand [2.1] on the stability of the complexes is reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600815
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  • 54
    Digitale Medien
    Digitale Medien
    Electron Transfer in Monolayer Assemblies with Incorporated Ruthenium (II) ComplexesHerrn Dr. Guido Schetty zum 65. Geburtstag freundlich zugeeignet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2608-2632 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An arrangement for light induced vectorial charge separation is discussed in which the electron of the excited dye is transferred to an acceptor and the dye is recovered by electron tunneling through a high and narrow potential barrier. The possible relevance of the model in connection with photosynthesis is considered. Monolayers of Ru(II)-bipyridine complexes with long chain hydrocarbon substituents were investigated which may be useful as component in such arrangements.The surface pressure area isotherms of the monolayers were measured for various ionic compositions of the subphase, and the results demonstrate a strong effect of these ions on the structure of the layers. The layers were deposited on different substrates. The luminescence and its change by contacting the sample with water and by subsequent drying were found to be strongly dependent on the architecture of the layer assembly. Attempts of a photochemical cleavage of water with these assemblies failed.The pH-dependence of the absorption and the luminescence of a Ru(II) bipyridine-dicarboxylic acid complex in solution is interpreted by assuming that the electron in the excited state is localized in one pyridine part of the substituted ligand, the conjugation with the second half of the bipyridine carboxylic acid being negligible. Monolayer assemblies for measuring the energy transfer from the ruthenium complex to an adequate energy acceptor and from an adequate energy donor to the ruthenium complex were investigated. The results demonstrate that the deactivation of the excited ruthenium complex occurs mainly by passing the luminescent state.Assemblies were investigated for measuring the electron transfer from the excited ruthenium complex to an appropriate electron acceptor positioned in the carboxylate portion at the same interface as the electron donor. With bipyridinium ions as acceptor the ruthenium complex luminescence is quenched at average distances between acceptor molecules of about 10 Å, while this distance is 30, 60 und 75 Å for different cyanine dyes used instead of the ruthenium complex. A correlation between this distance and the ionization energy in the excited state of the donor is observed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600814
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  • 55
    Digitale Medien
    Digitale Medien
    Synthese von Nickelkomplexen mit porphinoidem Ligandsystem2. Mitt. über Synthese und Reaktionen von Metallkomplexen mit porphinoidem Ligandsystem. 1. Mitt. siehe [1].Herrn Dr. Guido Schetty zu seinem 65. Geburtstag gewidmet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2644-2652 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of nickel complexes with a porphine-type ligand systemIn the presence of nickel(II) salts the bicyclic vinylogous amidine 1 is dimerized to the diamagnetic (1-amino-10,20-diaza-octahydroporphinato)nickel(II) complex 3. The condensation proceeds through a paramagnetic octahedral nickel(II) complex 2. Starting from 3, the (hexadecamethyl-10,20-diaza-hexahydroporphin)nickel bis (tetrafluoroborate) 7 (a (hexaaza [16]annulene)nickel(II) complex) was prepared in two steps. This highly electrophilic compound adds methoxide ions in consecutive and reversible steps to form first the (1-methoxy-10,20-diaza-octahydroporphinato)nickel tetrafluoroborate 8 and then the [cis-1, 11-dimethoxy-decahydroporphinato (2-)]nickel 6. 6, 7 and 8 were fully characterized and interconverted by addition and elimination reactions.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600816
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  • 56
    Digitale Medien
    Digitale Medien
    The Reaction of Biadamantylidene with Singlet Oxygen in the Presence of Dyes [1] (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2673-2685 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Singlet oxygen, generated chemically or photogenetically, reacts with biadamantylidene to give the corresponding dioxetane and epoxide only. When methylene blue (MB) or meso-tetraphenylporphin (m-TPP) is used as sensitizer the normal reaction course occurs giving dioxetane as the preponderant product in 2-propanol, ethyl acetate, acetone, pinacolone, methylene chloride, chloroform, carbon tetrachloride and benzene, although in the last two solvents some 10-25% of epoxide is formed. When erythrosin and rose bengal (RB) are used, epoxide becomes the main product (70-95%). Epoxide does not derive from chemical reaction with the solvent. Pinacolone, for example, is not oxidized to t-butyl acetate.The rose bengal reaction involves both singlet oxygen and radicals, since diazabicyclooctane (DABCO) and di-t-butyl-p-cresol interfere with the oxidation. A mechanistic scheme is proposed in which sensitizer and oxygen combine to produce sensitizer radical cation and superoxide radical anion. Subsequently, hydroperoxy radical, deriving from superoxide, reacts with substrate to give epoxide and hydroxy radicals. The latter adds to substrate to give a new radical which captures triplet oxygen. Epoxide is formed by loss of hydroperoxy radical and the chain starts anew. The dioxetane is formed separately either by [2+2]-cycloaddition or stepwise addition.
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600818
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  • 57
    Digitale Medien
    Digitale Medien
    Photochemische und nicht-photochemische A/D-Secocorrin→Corrin-Cyclisierungen bei 19-Carboxy- und 19-Formyl-1-methyliden-1,19-secocorrinaten. Decarboxylierbarkeit und Deformylierbarkeit von Nickel (II)-19-carboxy- bzw. 19-formyl-corrinaten. Vorläufige MitteilungLetzterschienene Mitteilungen über Corrinoide siehe [1-3] und die Zusammenfassung dieser Arbeiten in [4]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2653-2672 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photochemical and non-photochemical A/D-secocorrin→corrin-cyclizations of 19-carboxy- and 19-formyl-1-methylidene-1,19-secocorrinates. Decarboxylation (and deformylation) of nickel(II)-19-carboxy-(resp. 19-formyl)-corrinatesNickel (II) 1-methylidene-2,2,7,7,12,12-hexamethyl-15-cyano-19-carboxy-1,19-secocorrinate can be induced to cyclize with concomitant decarboxylation to the corresponding corrinate (Scheme 9). Experiments with deuterated derivatives (Scheme 10) indicate that in this decarboxylative A/D-secocorrin→corrin-cyclization the ring closure step precedes decarboxylation. In accord therewith is the finding that the corresponding intermediate nickel(II) 19-carboxy-corrinate (synthesized via photochemical cyclization of the corresponding cadmium complex, Schemes 6 and 9) decarboxylates under very mild conditions.Nickel(II) 1-methylidene-2,2,7,7,12,12-hexamethyl-15-cyano-19-formyl-1,19-secocorrinate cyclizes smoothly to the corresponding 19-formyl-corrinate in the presence of acetic acid/triethylamine. The formyl group of the cyclization product can be eliminated hydrolytically in essentially quantitative yield by treatment with 2N KOH in ethanolic solution (Scheme 11). The non-photochemical (A→D)-cyclization of 19-formyl-1,19-secocorrinoids represents formation of the corrin chromophore at the oxidation level of porphyrinogens and exemplifies how a C1-fragment that eventually leaves the ligand can fulfill a specific function in the (A→D)-ring closure to a corrin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600817
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  • 58
    Digitale Medien
    Digitale Medien
    Diterpenoide Drüsenfarbstoffe aus Labiaten: 3β-Acetoxyfuerstion, Nilgherron A und Nilgherron B, neue Chinomethane aus Plectranthus nilgherricus BENTH.; absolute Konfiguration von Fuerstion (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2789-2803 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Leaf-gland Pigments: 3β-Acetoxyfuerstione, Nilgherron A and Nilgherron B, New Quinomethanes from Plectranthus nilgherricus BENTH. (Labiatae); Absolute Configuration of FuerstioneWe have isolated from leaf-glands of the above mentioned plant the following deeply coloured quino-methane derivatives: (1) traces of the already known fuerstione (1a); 11,15-dihydroxy-5,7,9 (11), 13-abietatetraen-12-one; (2) the new 3β-acetoxy-fuerstione (1b); (3) nilgherron A (5a, I or II), a new dimeric diterpenoid quinomethane, C40H52O7, formed in the plant obviously by cycloaddition of the o-quinone 8 (9aS, 11R)-11 -hydroxy-2-(1-hydroxy-1-methylethyl-9,9-dimethyl-3,4,7,8,9,9a,10,11- octahydro-5H-dibenzo [a, d]cycloheptene-3,4-dione) with fuerstione; (4) nilgherron B (5b, I or II), C42H54O9, likewise a new compound, formed by the same type of cycloaddition (heterodiene synthesis) of 8 with 3β-acetoxyfuerstione. On the basis of 1H-NMR. shift arguments structure I is slightly preferred to II for 5a and 5b. Model experiments have shown the easy formation of the dihydrodioxin ring by reaction of an o-benzoquinone with p-quinomethanes. The absolute configuration of fuerstione and 3β-acetoxyfuerstione has been determined by chiroptical methods.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600832
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  • 59
    Digitale Medien
    Digitale Medien
    Transition metal complexes with bidentate ligands spanning trans-positions. IVPart III: see [1].. Preparation and properties of some rhodium and iridium complexes of 2,11-bis(diphenylphosphinomethyl)benzo [c]phenanthrene (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2804-2814 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The bidentate phosphine 2,11-bis(diphenylphosphinomethyl)benzo [c]phenanthrene (1) has been used to prepare the mononuclear, square planar complexes trans-[MX(CO)(1)] and trans-[M(CO)(CH3CN)(1)][BF4] (M = Rh, Ir; X = Cl, Br, I, NCS). It is found that the tendency of these complexes to form adducts with CO, O2 and SO2 is significantly lower than that of the corresponding Ph3P complexes. The oxidative-addition reactions of complexes trans-[IrX (CO) (1)] with hydrogen halides give the six-coordinate species [IrHX2(CO) (1)]. The complexes [IrH2I (CO) (1)] and [IrH2L (CO) (1)] [BF4] (L = CO and CH3CN) have been obtained from hydrogen and the corresponding substrates. The model compounds trans-[MCl (CO) (Ph2PCH2Ph)2] (M = Rh, Ir), trans-[Ir (CO) (CH3CN) (Ph2PCH2Ph)2] [BF4], [IrHCl2(CO)(Ph2PCH2Ph)2] and [IrH2(CO)2(Ph2PCH2Ph)2] [BF4] have been prepared and their special parameters are compared with those of the corresponding complexes of ligand 1. The influence of the static requirements of this ligand on the chemistry of its rhodium and iridium complexes is discussed.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600833
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  • 60
    Digitale Medien
    Digitale Medien
    Transition metal complexes with bidentate ligands spanning trans-positions. VIPart V: See [1].. The preparation of some diaryl- and dialkyl derivatives of 2,11-bis (phosphinomethyl)benzo [c]phenanthrene (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2824-2829 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation of the ditertiary phosphines 2,11-bis (di-m-tolylphosphinomethyl)benzo [c]phenanthrene (1b), 2,11-bis (di-p-anisylphosphinomethyl)benzo-[c]phenanthrene (1c), 2,11-bis (di-m-trifluoromethylphenylphosphinomethyl) benzo-[c]phenanthrene (1d), 2,11-bis (dicyclohexylphosphinomethyl)benzo [c]phenanthrene (1e) and 2,11-bis [di-(t-butyl)phosphinomethyl]benzo [c]phenanthrene (1f), by a combination of synthetic routes is described.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600835
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  • 61
    Digitale Medien
    Digitale Medien
    Isolierung von (-)-Dunnion aus Calceolaria integrifolia MURR. (Scrophulariaceae) (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 945-947 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Isolation of (-)-dunnione from the leaves of Calceolaria integrifolia, MURR. (fam. Scrophulariaceae)From the leaves of Calceolaria integrifolia, a plant often used in horticulture. partially racemic (-)-dunnione (1) has been isolated. This seems to be the first record of its occurrence outside the family Gesneriaceae, where it previously has been found in two species as the (+)-enantiomer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600324
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  • 62
    Digitale Medien
    Digitale Medien
    Eine chiral ökonomischeDie Autoren bezeichnen diejenigen Totalsynthesen als chiral ökonomisch, die eine totale Transformation des achiralen Ausgangsmaterials zum angestrebten Enantiomere erlaube. Vgl. dazu: [1] [2] [3]. Totalsynthese von (R)- und (S)-Muskon via EpoxysulfoncyclofragmentierungIn memoriam Prof. Dr. Dr. h.c. Hans Schmid (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 925-944 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A chiral economic synthesis of (R)- and (S)-muscone using the cyclofragmentation of epoxysulfonesStarting with isobutyric acid (2) and using a microbiological oxidation with pseudomonas putida (S)-β-hydroxy-iso-butyric acid (3) has been prepared. From this /pseudosymmetrical: (see text) intermediate the two enantiomeric bromo derivatives 8 (R) and 20 (S) have been synthesized (cf. scheme 4) by altering the sequence of the reactions (cf. scheme 3). A Grignard reaction starting from the two bromo compounds 8 and 20 and from cyclododecanone 1 produced after hydrogenolysis the two enantiomeric dialcohols 9 and 21 (1 + 8 → 9, 1 + 20 → 21, cf. scheme 5). The subsequent transformations led to the two enantiomeric olefin derivatives 12 and 24. Oxidation of 12 with peracid produced a mixture of the two epoxy-sulfones 13 and 14 (cf. scheme 6). The olefin-derivative 24 was oxidized to the corresponding mixture of 25 and 26. A one pot cyclofragmentation (cf. [4] and scheme 6) produced a mixture of (E)- and (Z)-3-methylcyclopentadec-4-en-1-one (13 + 14 → 15 + 16, 25 + 26 → 27 + 28). The final hydrogenation led to natural (R)- and unnatural (S-muscone (3-methylcyclopentadecanone). The achiral starting material has been transformed to the desired optically active target products without loss of material with undesired absolute configuration. The authors used the notion of chiral economic synthesis to characterize synthetic sequences with the above mentioned features.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600323
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  • 63
    Digitale Medien
    Digitale Medien
    13C-NMR. Spectra, Structure and Reactivity of Cyclic Oxocarbons13C-NMR. Spectroscopy, Part XVII; for Part XVI see [1].In memory of the late Prof. Hans Schmid (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 948-958 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The structures of cyclic polyketones, their hydrates and reduction products were studied in different solvents by 13C-NMR. spectroscopy. In dimethylsulfoxide solution rhodizonic acid (1), croconic acid (2) and squaric acid (3) exhibit signal averaging. In anhydrous tetrahydrofuran 1 and 2 could be observed as non-dynamic species. The spontaneous reactions of dodecahydroxycyclohexane (5) and decahydroxycyclopentane (‘leuconic acid’) (6) and the sequence of formation of ring-contracted products were investigated. Key intermediates could be clearly identified which support the mechanism proposed earlier involving a benzylic acid type rearrangement followed by decarboxylation and subsequent redox reactions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600325
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  • 64
    Digitale Medien
    Digitale Medien
    Hormone-Receptor Interactions. Carboranylalanine (Car) as a Phenylalanine Analogue: Reactions with Chymotrypsin (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 959-963 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In order to test the effects of the replacement of phenylalanine by carboranylalanine (Car) in biological ligand-acceptor interactions, Z · Ala-Ala-Car · OH (1) and Ac · Car · OEt (2) were synthesized and their reactions with chymotrypsin studied. The two compounds proved to be good inhibitors with K(i) values of 3 · 10-4M (1) and 8.6 · 104M (2); the K(i) of Z · Ala-Ala-Phe · OH (1a) is 1 · 10-3M. The inhibition constants were determined by a new photolytic technique, inhibition of photoaffinity labelling by Z · Ala-Ala-Phe(pN3) · OH. Ac · Car · OEt is not hydrolysed by chymotrypsin. The findings indicate that the carboranyl group can interact with the ‘phenyl recognition site’ of the enzyme to produce the binding that is characteristic of aromatic amino acid residues. However, some kind of distortion in the region of the ‘mechanistic site’ must be postulated in order to account for the failure of hydrolysis. Some possible effects of the replacement of aromatic amino acids by Car in peptide hormones on hormone-receptor interactions are discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600326
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  • 65
    Digitale Medien
    Digitale Medien
    1,3-Cyclobutandionderivate aus Keten (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 975-977 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,3-Cyclobutanedione derivatives from keteneThe dimerisation of ketene leads mainly to the methylidene-β-lactone ‘Diketene’ 2c. It is shown, that also a small amount of the symmetrical dimer, 1,3-cyclobutadione 1c is produced, which under the reaction conditions is acetylated to 3-acetoxycyclo-butenone (5).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600328
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  • 66
    Digitale Medien
    Digitale Medien
    Synthesis of 4-(4′-Methyl-2′-oxo-cyclohex-3′-en-1′-yl)-pentanal and its Conversion into Derivatives of Spiro[4.5]decane and of 1,6,7,7a-Tetrahydro-2H-indene (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 964-974 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthese von 4-(4′-Methyl-2′-oxo-cyclohex-3′-en-1′-yl)-pentanal und dessen Umwandlung in Spiro[4.5]decan- und 1,6,7,7a-Tetrahydro-2H-inden-DerivateEs wird die Synthese von 4-(4′-Methyl-2′-oxo-cyclohex-3′-en-1′-yl)-pentanal als ein (1:1)-Gemisch von zwei Diastereoisomeren 10A und 10B auf folgendem Weg beschrieben: Die Umsetzung des Grignard-Reagens von 1,1-Äthylendioxy-3-brom-propan (2) mit 2-Methoxy-4-methyl-acetophenon (1) ergab 1,1-Äthylendioxy-4-hydroxy-4-(2′-methoxy-4′-methyl-phenyl)-pentan (3), welches sich mit methanolischer Salzsäure in 2-Methoxy-5-(2′-methoxy-4′-methyl-phenyl)-5-methyl-tetrahydrofuran (7A,B) umwandeln liess. Durch Birch-Reduktion von 7A,B wurde 4-(2′-Methoxy-4′-methyl-cyclohexa-1′,4′-dien-1′-yl)-pentan-1-ol (8), und danach durch milde Hydrolyse 4-(4′-Methyl-2′-oxo-cyclohex-3′-en-1′-yl)-pentan-1-ol (9A,B)2 erhalten. Oxydation von 9A,B lieferte schliesslich den erwähnten Keto-aldehyd 10A,B. Einige Produkte von Nebenreaktionen, nämlich 4, 5, 11, 12 und 13A,B, sind auch beschrieben.Der Keto-aldehyd 10A,B liess sich in ein Gemisch, bestehend aus drei Diastereo-isomeren A, B und C von 1-Hydroxy-4,8-dimethyl-spiro[4.5] dec-7-en-6-on (15) und aus zwei Diastereoisomeren A und B von 1,5-Dimethyl-1,6,7,7a-tetrahydro-2H-inden-3-carbaldehyd (14), umwandeln. Für diese aldolartigen Cyclisierungen wurden vier verschiedene Methoden verwendet: (a) Stehenlassen in Tetrachlorkohlenstoff-lösung, (b) Behandlung mit etwas Trifluoressigsäure in Chloroformlösung, (c) und (d) Schütteln einer Ätherlösung mit wässeriger Salzsäure oder Natronlauge. Oxydation von 15A und 15C lieferte eines der Diasteroisomeren von 4,8-Dimethyl-spiro[4.5]-dec-7-en-1,6-dion (16A), und Oxydation von 15B führte zum anderen (16B).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600327
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  • 67
    Digitale Medien
    Digitale Medien
    Synthese von Fulvenen über 1-Chloralkyl-acetate18. Mitt. über Fulvene und Fulvalene. 17. Mitt. siehe [1].Über einen Teil der Arbeit wurde kurz in [2] berichtet. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1061-1072 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of fulvenes via 1-chloroaklyl-acetatesThe synthesis of fulvenes (5) via l-chloroalkyl acetates (3) is extended to 6-alkyl-fulvenes with branched side-chains, to 6-phenylfulvene (5f) and 6-(2-furyl)fulvene (5g), as well as to 6-vinylfulvenes (5h and 5i) containing chlorine and acetoxy-substituents in ω-position. The reaction is carried out at low temperature under water-free conditions. The purification of the reaction products is simple. - An improved procedure for the preparation of pure fulvene (5a, R=R′=H) is reported.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600331
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  • 68
    Digitale Medien
    Digitale Medien
    Aktivierte Chinone: Substitution von Azulenen, Benzofuran und Indolen durch 2-Methoxycarbonyl-1,4-benzochinon. Regiospezifische Synthesen von Polymethoxy-fluorenonen und eine neue Synthese des 2,6-Dihydro-naphtho[1,2,3-cd]indol-6-on-Systems (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1033-1060 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Activated quinones: substitution reactions by methoxy-carbonyl-1,4-benzoquinone of azulenes, benzofuran and indoles; regiospecific syntheses of polymethoxy-fluorenones; a new synthesis of the 2,6-dihydro-naphtho[1,2,3-cd]indol-6-one system.We present new electrophilic substitution reactions of azulenes and 5-membered heterocyclics by methoxy-carbonyl-1,4-benzoquinone. Hydroquinones 3a and 5 are prepared from azulene, and 3b from guaiazulene (see Scheme 1). Benzofuran undergoes α- and β-substitution (hydroquinones 9 10) (see Scheme 2). Only β-substitution is observed with indole (hydroquinone 20) (see Scheme 4). After methylation, saponification and intramolecular acylation of the substituted indoles 22c, 22d, derivatives of 2,6-dihydro-naphtho[1,2,3-cd]indol-6-one have been obtained. Spectral data prove the presence of the methylidenequinone tautomer. By protonation or alkylation at the carbonyl group of 23, the violet, highly delocalized 16π-electron systems 25 are generated. Analogously, polymethoxy-fluorenones have been prepared from methoxylated diphenylquinones 15 (see Scheme 3). They also are transformed by protonation and alkylation to the highly coloured and delocalized 12 π-electron systems 18. By contrast, anthracene is not substituted by methoxycarbonyl-1,4-benzoquinone, but undergoes cycloaddition to the triptycene derivative 1 (see Scheme 1). A summary is presented of previously described reactions of activated quinones.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600330
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  • 69
    Digitale Medien
    Digitale Medien
    Stereoelectronic Properties, Stereospecificity and Stabilization of α-Seleno Carbanions. An ab initio StudyStereoelectronic Effects, Part 6; Part 5, see [2]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1239-1246 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An ab initio study of α-seleno carbanions show that they are subject to appreciable polarization and stereoelectronic effects. Like in α-thia carbanions, the equatorial e forms are more stable than the axial a forms, one of the stabilizing contributions being the conformation dependent (C-lone pair, σ* Se—Z) interaction. The carbanion stabilizing effect of the α-Se atom is about 3 kcal/mol larger than that of the sulfur analog. As in the case of the sulfur no specific effect of the d orbitals is found.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600413
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  • 70
    Digitale Medien
    Digitale Medien
    Isomerization of the Radical Anions of 6a-ThiathiophthenesIn the IUPAC notation, 6a-thiathiophthene, (I(H)), is [1,2]dithiolo[1,5-b][1,2]dithiole. An alternative trivial name for I(H) is 1,6,6a-trithiapentalene. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1220-1225 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The radical anions of 6a-thiathiophthenes ([1,2]dithiolo[1,5-b] [1,2]dithioles), I(R), convert into those of 4H-thiapyran-4-thiones, III(R), via cis-trans isomerization. The reaction is slowed down when the size of the substituent R in the 2,5-positions of 6a-thiathiophthene increases, and it is prevented by the introduction of a 3,4-polymethylene bridge. The primary and the secondary radical anions, I(R)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document} and III(R)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, respectively, exhibit very similar hyperfine splitting patterns. E.g., in the case of the unsubstituted 6a-thiathiophthene, I(H), and 4H-thiapyran-4-thione, III(H), the proton coupling constants are aH2,5=6.72 and aH3,4=1.73 Gauss for I(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, and aH2,6=6.35 and aH3,5=2.07 Gauss for III(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. In contrast to I(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, cis-trans isomerization could not thus far be proved to occur with its 1,6-dioxa-analogue, IV(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, since no ESR. spectrum of the radical anion of 4H-pyran-4-thione, V(H), was detected upon reduction of IV(H).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600410
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  • 71
    Digitale Medien
    Digitale Medien
    Diterpenoide Drüsenfarbstoffe: Coleon L, ein neues Diosphenol aus Coleus somaliensis S. MOORE; Revision der Strukturen von Coleon H, I, I′ und K (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1233-1238 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Leaf-gland Pigments: Coleon L, a New Diosphenolic Compound from Coleus somaliensis, S. MOORE; Revision of the Structures of Coleon H, I, I′ and KFrom leaf-glands of C. somaliensis a new, highly oxidized diosphenolic hydroquinone belonging to the abietane series was isolated in minute quantities. The new compound, coleon L (4c; C24H30O10), is very labile and transformed into its tautomer coleon K (5d) on standing in solution. 1H-NMR. spectra of coleon L showed clearly that the points of attachment of the two acetoxy groups are at C(3) and C(16) contrary to the positions expected from our previously published structure 3 for coleon K. Application of a recently elaborated conversion of trans-A/B-6,7-diketones of type 5 into the cis-isomers 6 allowed to assign unambiguously the β-configuration to the hydroxyl group at C(3) using pyridin induced solvent shifts. This confirmed structure 4c and 5d for coleon L and K, respectively. Based on similar reasons, the configuration at C(3) of coleon H, I and I′ had to be revised, the structures of these coleons being 4b, 5b and 5c, respectively.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600412
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  • 72
    Digitale Medien
    Digitale Medien
    The ESR. Spectrum of the Diphenylcyclopropenone Radical Anion (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1226-1232 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ESR. spectrum of the relatively unstable radical anion of diphenylcyclo-propenone (II) has been observed upon electrolytic reduction of II in N,N-di-methylformamide and 1,2-dimethoxyethane. Simple MO models account well for the π-spin distribution and for the restricted rotation of the phenyl substituents in II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. A rather facile loss of a CO molecule by II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document} results in formation of the radical anion of tolane (diphenylacetylene; III). No ESR. spectra could be obtained for the radical anions of dialkylcyclopropenones which are even shorter-lived than II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, although decay by decarbonylation seems to be less favoured with them than with II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. In presence of air, electrolytic reduction of either II or its dimethyl and di-t-butyl analogues yields the correspondingly disubstituted semidione anions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600411
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  • 73
    Digitale Medien
    Digitale Medien
    Reaktionen mit γ-Chloracetessigesterderivaten (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1256-1261 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions with derivatives of γ-chloroacetoacetic acidEthyl γ-chloroacetoacetate reacts with ammonia to give ethyl β-amino-γ-chloro-crotonate; with aniline, however, β-anilino-crotonic acid γ-lactone is formed. The reaction of ethyl α-cyano-γ-chloro-acetoacetate with arylamines yields 1-aryl-2-amino-3-ethoxycarbonyl-pyrrolin-4-ones.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600415
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  • 74
    Digitale Medien
    Digitale Medien
    Die Struktur von Cyclosporin CHerrn Prof. C. A. Grob zum 60. Geburtstag gewidmet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1247-1255 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Structure of Cyclosporin CThe structure of cyclosporin C (2), a minor antifungal metabolite from Trichoderma polysporum (Link ex Pers.) RIFAI has been elucidated. Hydrolytic cleavage and spectroscopic evidence show that cyclosporin C is a neutral oligopeptide of 11 amino acids linked together in a 33-membered ring. Cyclosporin C (2) differs from the main metabolite cyclosporin A (1) [2] [4] only by containing L-threonine in the place of L-α-aminobutyric acid as has been shown by the conversion of 2 into 1. 13C-NMR. spectra and study of molecular models suggest that cyclosporin C (2) has the same molecular conformation as 1, which is best described as a twisted β-pleated sheet held together in a conformationally stable form by intramolecular hydrogen bonding.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600414
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  • 75
    Digitale Medien
    Digitale Medien
    Einbauversuche mit (3H und 14C)-doppelmarkiertem Farnesol in Cantharidin. 5. Mitteilung zur Biosynthese des Cantharidins4. Mitt.: siehe [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1262-1272 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Incorporation experiments with (3H and 14C) doubly labelled farnesols into cantharidinAfter injection of 11′, 12-[3H]-7-[14C]-farnesol or 11′, 12-[3H]-5,6-[14C]-farnesol, the 3H-label is located specifically in the C(9)-methyl-group of cantharidin, whereas the 14C-labelling pattern follows an incorporation via acetic acid (Scheme 4). C-Atoms 5, 6 and 7 from the middle part of the farnesol molecule are utilized for cantharidin biosynthesis to an extent that is about 2.1-11% of the incorporation rate of the methyl groups C(11′) and C(12), depending on the position of the 14C-label in farnesol. These results confirm our earlier hypothesis [1] that the C10-molecule cantharidin is biosynthesized from the C15-precursor farnesol which is cleaved between C(1)-C(2), C(4)-C(5), and C(7)-C(8). The synthesis of 7-[14C]-farnesol and of 5,6-[14C]-farnesol is described.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600416
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  • 76
    Digitale Medien
    Digitale Medien
    Synthese und NMR.-Spektren von neuartigen Lanthanoid-Kobalt-Sandwichkomplexen (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1296-1303 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and NMR. Spectra of Novel Lanthanide-Cobalt Sandwich CompoundsThe reaction of [(C5H5)Co{P(O)(OR)2}2{P(OH)(OR)2}] (3, R = CH3, C2H5) with lanthanide(III) compounds yields the cationic trinuclear complexes [{(C5H5)Co[P(O)(OR)2]3}2Ln]⊕X⊖ (2, R = CH3, C2H5; Ln = La, Eu, Pr; X = BF4, BPh4). According to thermogravimetric and NMR. studies these compounds do not contain additional coordinated water molecules. It is therefore supposed that the central lanthanide ion has a regular sixfold coordination of phosphoryl ligands. The 31P- and 1H-NMR. spectra of 2 (R = CH3; Ln = La, Eu, Pr) and 3 are discussed. It can be shown that the Fermi contact shift as well as the coordination shift make significant contributions to the observed lanthanide induced shift of the cyclopentadienyl signal.The dominating influence of the Fermi contact interaction on the 31P chemical shift is in accord with theoretical considerations and comparable experimental values. The temperature dependence of the proton chemical shifts of 2 (R = CH3; Ln = Eu) is also discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600418
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  • 77
    Digitale Medien
    Digitale Medien
    Stereoselektivität und Reaktivität bei der 1,3-dipolaren Cycloaddition chiraler N-(Alkoxyalkyl)nitroneHerrn Prof. Dr. R. B. Woodward zum 60. Geburtstag gewidmet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1273-1295 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stereoselectivity and Reactivity in the 1,3-Dipolar Cycloaddition of Chiral N-(Alkoxyalkyl)nitronesThe stereoselectivity in the reaction of hydroxy-oxime 1 with acetaldehyde and methyl methacrylate yielding the diastereomeric isoxazolidine-ribosides 9-12 was determined to be 93%. The predominant adducts 9 and 10 were cleaved to the diastereomeric isoxazolidines 19 and 20, respectively, which upon oxidation gave the same optically active 2-isoxazoline 21, thus demonstrating the participation in the cycloaddition of both (E/Z)-isomeric nitrones 13 and 14. Based upon comparison of the optical rotations, the isoxazolidines 7, 8, 19 and 20 and the 2-isoxazolines 21 and 22 possess the same chirality, found to be R by correlating 7 with (+)-(S)-citramalic acid. - Since the hydroxy-oximes 1 and 36 showed the same stereo-selectivity in the reaction with formaldehyde and methyl methacrylate, the trityl group of 1 does not influence the stereoselectivity in the cycloaddition. The hydroxyoxime 38 led in the same type of reaction to the isoxazolidines 7, 8, 19 and 20 possessing (S)-chirality, the stereoselectivity (79-95%) being similar to the one observed with 1 (67-95%). The explanation of this stereoselectivity is based upon a stereoelectronic effect in the transition state of the cycloadditions (kinetic anomeric effect). As predicted, the N-(alkoxyalkyl)nitrones showed enhanced reactivity in the cycloaddition with unactivated olefins (leading to 47, 48, 50 and 51). The importance of exo vs. endo approach of the dipolarophile was evidenced by reacting 1 with formaldehyde and methyl acrylate giving predominantly 57 with (5S)-configuration. - Use of the hydroxy-oxime 65 allows synthesis of optically active isoxazolidines with regeneration of the starting hydroxy-oxime.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600417
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  • 78
    Digitale Medien
    Digitale Medien
    Die Konstitution des Loroglossins. 163. Mitt. über organische Naturstoffe162. Mitt. über Alkaloide s. [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1304-1311 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Constitution of LoroglossineLoroglossine, a characteristic constituent of orchids, is shown to be bis[4-(β-D-glucopyranosyloxy)-benzyl]-(2R, 3S)-2-isobutyl-tartrate (1). Base catalysed hydrolysis and esterification with diazomethane gave 1 mol-equiv. of dimethyl (+)-2-isobutyl-erythro-tartrate ((+)-3) and 2 mol-equiv. of a glucoside which after acetylation formed 4 identical with a synthetic sample. The structure of (+)-3 follows from the synthesis of (±)-3 by osmium tetroxide oxidation of isobutyl-maleic acid anhydride and subsequent esterification. The absolute configuration of (+)-3 was based on Horeau experiments and NMR. data of the diastereomeric mixture of its esters 15 and 16 and pure 15 with (S)-(+)- and (R)-(-)-α-phenyl-butyric acid, respectively.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600419
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  • 79
    Digitale Medien
    Digitale Medien
    Diénamines hétérocycliques. III. Réexamen de la réaction de la base de Fischer avec le tétracyanoéthylène (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1312-1321 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Heterocyclic dienamines III. A re-examination of the reaction of Fischer's base on tetracyanoethyleneDepending on the order of addition, Fischer's base 5 (1,3,3-trimethyl-2-methylidene-indoline) reacts 1:1 with tetracyanoethylene to give either the tricyanovinylation product 6 or the spiro compound 7. A skeletal rearrangement of a zwitterionic intermediate can explain the formation of the spiro compound. The latter undergoes a thermal isomerization yielding by ring expansion the tetrahydroquinoléine 8. On reaction with LiAlH4 or CH3ONa 7 and 8 lead both to triazatetracycles. All structures are assigned on the basis of spectral data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600420
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  • 80
    Digitale Medien
    Digitale Medien
    Heterotricyclodecane. XXIV.Teil XXIII, vgl. [1]. 2-Aza-7-oxa-twistane (bzw. 2-Oxa-7-aza-twistane)Die nicht mit den IUPAC-Regeln übereinstimmende Numerierung (b): 2-Aza-7-oxa-twistane, Substituent an C(10) (vgl. Korrekte Nomenklatur (a): 2-Oxa-7-aza-twistane, Substituent an C(5)), wurde zwecks besserer Übersicht und Vergleichsmöglichkeit mit anderen 2,7-Dihetero-twistanen und -isotwistanen, Für eine umfassende Übersicht vgl. [2], speziell auch mit den korrekt numerierten C(10)-substituierten 2-Aza-7-oxa-isotwistanen c deshalb gewählt, weil dadurch in diesen beiden Verbindungstypen b und c, welche chemisch ineinander überführbar sind (vgl. vorliegende Arbeit), sich entsprechende Atome gleich numeriert werden Können. Dadurch erhält je das den Substituenten tragende C-Atom die Nummer 10 und je das zwischen C(10) und N(2) liegende Brückenkopfatom die Nummer 1. Beim Twistan d wurde die Doppelbindung entsprechend ihrer Herkunft aus einem C(10)-substituierten Twistan b als in Stellung 9 bezeichnet. Vollständigkeitshalber sind die der korrekten Nomenklatur (vgl. a) entsprechenden Namen der Verbindungen 10-13 und 22, 23 und 25 nachfolgend aufgeführt; 10: 5N (7)-Brom-2-oxa-7-aza-twistan; 11: N(7)-Methyl-5N (7)-2-oxa-7-aza-twistan; 12: 2-Oxa-7-aza-twist-4-en; 13: N(7)-Methyl-2-oxa-7-aza-twist-4-en; 22: N(7)-Methyl-5O (2)-acetoxy-2-oxa-7-aza-twistan; 23: N(7)-Methyl-2-oxa-7-aza-twistan-5O (2)-ol; 25: N(7)-Methyl-2-oxa-7-aza-twistan. und 2-Aza-7-oxa-isotwistane (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1435-1442 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 2-Aza-7-oxa-twistanes (or 2-oxa-7-aza-twistanes, respectively)Die nicht mit den IUPAC-Regeln übereinstimmende Numerierung (b): 2-Aza-7-oxa-twistane, Substituent an C(10) (vgl. Korrekte Nomenklatur (a): 2-Oxa-7-aza-twistane, Substituent an C(5)), wurde zwecks besserer Übersicht und Vergleichsmöglichkeit mit anderen 2,7-Dihetero-twistanen und -isotwistanen, Für eine umfassende Übersicht vgl. [2], speziell auch mit den korrekt numerierten C(10)-substituierten 2-Aza-7-oxa-isotwistanen c deshalb gewählt, weil dadurch in diesen beiden Verbindungstypen b und c, welche chemisch ineinander überführbar sind (vgl. vorliegende Arbeit), sich entsprechende Atome gleich numeriert werden Können. Dadurch erhält je das den Substituenten tragende C-Atom die Nummer 10 und je das zwischen C(10) und N(2) liegende Brückenkopfatom die Nummer 1. Beim Twistan d wurde die Doppelbindung entsprechend ihrer Herkunft aus einem C(10)-substituierten Twistan b als in Stellung 9 bezeichnet. Vollständigkeitshalber sind die der korrekten Nomenklatur (vgl. a) entsprechenden Namen der Verbindungen 10-13 und 22, 23 und 25 nachfolgend aufgeführt; 10: 5N (7)-Brom-2-oxa-7-aza-twistan; 11: N(7)-Methyl-5N (7)-2-oxa-7-aza-twistan; 12: 2-Oxa-7-aza-twist-4-en; 13: N(7)-Methyl-2-oxa-7-aza-twist-4-en; 22: N(7)-Methyl-5O (2)-acetoxy-2-oxa-7-aza-twistan; 23: N(7)-Methyl-2-oxa-7-aza-twistan-5O (2)-ol; 25: N(7)-Methyl-2-oxa-7-aza-twistan. and 2-aza-7-oxa-isotwistanes
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600435
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  • 81
    Digitale Medien
    Digitale Medien
    Generation and Reactions of Tetrasubstituted N-Lithiomethyl-succinimides (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1459-1471 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Of the isoelectronic 6-electron systems 1a, 1b, 1c (Table 1) the deprotonated amides 2 might be useful derivatives for amine acidification (eq. (1)) if the carbonyl group is sterically protected as shown in 3. The tetrasubstituted succinimides 4, 5, 7, 8 and 9 (diacylamines) undergo the reactions (b), (c) and (d) of Scheme 1 with various bases. Besides deprotonation, the ‘self addition’ to give dimers 4b, 5b, 8b and 9b is the most prominent transformation (Table 2). Only in 9 is the steric hindrance to carbonyl addition large enough to get the lithiomethyl-succinimides 9c in 80% yield (sec.BuLi/THF/HMPT/-100°) as evidenced by derivatization with alkyl halides, aldehyde, ketones, methyl benzoate, and chloro trimethylsilane (→9d - 9j, Table 3). The possible structures and bonding descriptions for 9c which ‘decomposes’ above -40° are discussed; the acidity of the precursor 9 is shown by equilibration studies to be comparable with that of diphenylmethane.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600502
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  • 82
    Digitale Medien
    Digitale Medien
    Electrochemical Reduction of Cyclohex-2-enones (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1472-1477 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electrochemical reduction of the cyclohex-2-enones 1a-1e (mercury cathode, CH3CN, Bu4NBF4) was studied by means of cyclic voltammetry, d.c. polarography, coulometry and chemical product analysis. Compounds 1a-1c give a mixture of the hydrodimers 4 and 5 via formation of the radical anion 2 by an irreversible one electron transfer, followed by protonation and dimerization of the allylic radical 3. The 6-halocyclohex-2-enones 1d and 1e exhibit two distinct reduction waves. The first corresponds to an irreversible two electron transfer with formation of the halide anion and the enolate anion 6 which gives 1b by protonation. The second wave corresponds to a quasi-reversible one electron transfer to 6 to afford the radical dianion 7 (Scheme 2).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600503
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  • 83
    Digitale Medien
    Digitale Medien
    Zum basenkatalysierten H/D-Austausch des acetylenischen Wasserstoffatoms in aromatischen Alkinylverbindungen (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1478-1486 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: On the Base-Catalysed H/D-Exchange of the Acetylenic Hydrogen Atom in Aromatic Alkynyl CompoundsH/D-exchange rates for a number of compounds of the general type 1 (X = p-CH3O, m-CH3O, p-CF3, m-CF3, p-CH3, p-Cl, H; Z — O, NH, CH2) were determined in N-methyl-pyrrolidine (NMP)/D2O mixtures at 25° (see Table 1).It is shown that the log k values of the H/D-exchange correlate nicely (r = 0.995) with the chemical shift of the acetylenic proton in 1. Thus, the H/D-exchange rate is given by log k (min-1) = 2.91 · δ (ppm) - 7.79 for the NMP/D2O mixture at 25°.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600504
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  • 84
    Digitale Medien
    Digitale Medien
    Isomerism and Protonation of α-Diazocarbonyl Compounds. A Molecular Orbital Study (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1487-1495 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: CNDO/2, MINDO/3 and ab initio molecular orbital calculations are used in a study of conformational isomerism, protonation site and mechanism of protonation of the title compounds.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600505
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  • 85
    Digitale Medien
    Digitale Medien
    Access to Optically Active Ipsdienol from Verbenone (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1496-1500 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Verbenone 1 or 2 is converted in three steps to ipsdienol 9 or 10 respectively. The diastereoisomeric 2(10)-pinen-4-ols 6 and 7 (or 5 and 8), wich have identical chirality at the carbon atoms bearing OH groups, afford ipsdienol 10 (or 9 respectively) with the same optical purity as the starting material.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600506
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  • 86
    Digitale Medien
    Digitale Medien
    n-π-Interaction in Enamines and Enaminoketones. A 15N-NMR. Study15N-NMR. Spectroscopy, Part III; Part II [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1501-1509 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 15N-Chemical shifts of 32 enamines, 11 enaminoketones and 28 closely related amines have been determined with the isotope in natural abundance. In order to eliminate substituent effects, differential chemical shifts Δδ(N) are defined as δN(amine)-δN(enamine). This parameter is shown to correlate well with the free enthalpy of activation ΔG# for restricted rotation about the N—C(α) bond in enamines with extended conjugation. Δδ(N) values of substituted anilinostyrenes correlate also with 13C-chemical shifts of the β-carbon in the enamine system and with Hammett σ-constants of the aniline substituents. The experimental results suggest that differential 15N shifts are a useful probe to study n, π-interaction in enamines.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600507
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  • 87
    Digitale Medien
    Digitale Medien
    Neue β-Lactam-Antibiotika. Zur Funktionalisierung von 3-Hydroxy-3-cephem-4-carbonsäureestern durch die Wittig-Reaktion. Modifikationen von Antibiotika. 16. Mitteilung [1]Die hier mitgeteilten Ergebnisse wurden an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft in Genf am 9.10.1976 vorgetragen. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1510-1521 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New β-lactam antibiotics. Functionalisation of 3-hydroxy-3-cephem-4-carboxylic esters through the Wittig reactionThe 3-hydroxy-ceph-3-em-esters 1a, b reacted smoothly with stabilized phosphor-ylids to give a series of derivatives which were converted into the microbiologically active acids 14a, c, 15c and 20 by known procedures. The synthesis of the amides 23, 24, 26 and of the ester 28 from the 3-carboxymethyl-derivative 19 is also reported.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600508
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  • 88
    Digitale Medien
    Digitale Medien
    Verrucarin K, the First Natural Trichothecene Derivative Lacking the 12,13-Epoxy Group. Verrucarins and Roridins. 34th Communication [1]Dedicated to Professor Dr. T. Reichstein on the occasion of his 80th birthday (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1522-1527 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new metabolite, verrucarin K (C27H34O8) has been isolated from a strain of Myrothecium verrucaria (ALBERTINI et SCHWEINITZ) DITMAR ex FRIES. On the basis of spectral and chemical evidence structure 1 was assigned to the new compound. Base-catalysed hydrolysis yielded verrucarinolactone (5), E,Z-muconic acid (6) and trichotheca-9, 12-diene-4,15-diol (3). The implications of 1 in the trichothecane biosynthesis are discussed.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600509
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  • 89
    Digitale Medien
    Digitale Medien
    Synthesis and Rearrangement of 7-Halobicyclo[3.2.0]hept-2-en-6-ols (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1528-1544 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthese und Umlagerung von 7-Halo-bicyclo[3.2.0]hept-2-en-6-olenDie Reaktion von verschiedenen 7-halogen-substituierten Bicyclo[3.2.0]hept-2-en-6-onen mit komplexen Metallhydriden oder mit Methylmagnesiumiodid zu den entsprechenden 7-Halo-bicyclo[3.2.0]hept-2-en-6-olen verläuft unter Angriff des Nucleophils trans zum Halogen, um dem vicinalen Kohlenstoff-Halogen-Dipol auszuweichen. In Gegenwart von starken Basen unterliegen die Halohydrine einer Umlagerung, die je nach der durch die intramolekularen Wechselwirkungen bedingten Konformation, entweder unter Hydridverschiebung zu Bicyclo[3.2.0]hept-2-en-6-onen oder, unter Ringverengung, zu Bicyclo[3.1.0]hex-2-en-6-carbaldehyden führt.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600510
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  • 90
    Digitale Medien
    Digitale Medien
    Synthesis and X-Ray Analysis of 2-(2-2H-benzotriazolyl)-N-(6-quinoxalinyl)aniline, the Rearrangement Product from 1,2-Bis(2-aminophenylazo)benzene and Glyoxal. Macrocyclic Aza Compounds. IVPart III: Skrabal, Steiger & Zollinger [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1545-1550 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The title compound 2 was synthesized from the intermediates 3 and 4. It is identical with the rearrangement product of 1 and glyoxal, of which the X-ray structure analysis is described.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600511
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  • 91
    Digitale Medien
    Digitale Medien
    Acid-Catalysed Dehydration of Tricyclic Unsaturated Alcohols (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1551-1567 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The tricyclic alcohols 3-7, derived from the corresponding ketones 1 and 2 (Scheme 1), by action of acids underwent dehydration with skeletal rearrangements. Dehydration of 3 and 4 with POCl3/pyridine (procedure A) afforded the polycyclic hydrocarbons 9, 10, and 12, 13, respectively. With TsOH (procedure B), on the other hand, 3 and 4 gave homo-triquinacenes 10 and 14 respectively, as well as the polycyclic ethers 11 and 15 (Scheme 2). Hydrocarbon 9 (or 12) was converted into 10 FSO3H to the tertiary alcohol 16 (Scheme 4). Plausible mechanisms for these transformations are summarized in Scheme 8. Dehydration of the secondary alcohols 5 and 7 was effected by procedure A. While treatment of alcohol 5 with POCl3/pyridine yielded two isomeric hydrocarbons 17 and 18, similar dehydration of its epimeric alcohol 7 afforded hydrocarbon 21 as the sole product. The tertiary alcohol 6 was dehydrated by both procedures to yield two isomeric hydrocarbons 19 and 20 (Scheme 5). Hydrocarbon 20 was converted into 19 by procedure B (mechanisms, Scheme 10). Reaction of ketone 2 with CF3COOH gave the addition product 22 converted into vinylsulfonyl fluorides 24 and 25 by treatment with FSO3H (Scheme 6). Homo-triquinacenes 10 and 14 reacted smoothly with 4-phenyl-1,2,4-triazoline-3,5-dione to give the ‘ene’-reaction products 26 and 27, respectively.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600512
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  • 92
    Digitale Medien
    Digitale Medien
    Neue Cyclopeptide aus Trichoderma polysporum (LINK EX PERS.) RIFAI: Die Cyclosporine B, D und EHerrn Prof. T. Reichstein zum 80. Geburtstag gewidmet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1568-1578 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New Cyclopeptides from Trichoderma polysporum (LINK EX PERS.) RIFAI: Cyclosporins B, D and ECyclosporins represent a new group of biologically active metabolites produced by Trichoderma polysporum (LINK EX PERS.) RIFAI and other fungi imperfecti. The structures of the main components, cyclosporins A (1) and C(3) have been determined as neutral cyclic oligopeptides composed of 11 amino acids, among them a new C9-amino acid [2-4]. In addition, three minor metabolites, cyclosporins B, D and E, have now been isolated and characterized. Chemical investigation, spectroscopic evidence and X-ray analysis led to the structural formulae of cyclosporins B (2) and D (4). Both compounds have the same sequence of amino acids as cyclosporin A (1), with the exception of L-α-aminobutyric acid, replaced in cyclosporin B (2) by L-alanine and in cyclosporin D (4) by L-valine, respectively. Cyclosporins undergo a characteristic intramolecular N,O-acyl migration to furnish the corresponding basic isocompounds. The antifungal activities of cyclosporins are reported.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600513
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  • 93
    Digitale Medien
    Digitale Medien
    Neue 18-substituierte Steroide. I. 18-Methylidenprogesteron über Steroide 232. Mitteilung231. Mitt. vgl. [1].Herrn Prof. Dr. O. Jeger zum 60. Geburtstag gewidmet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1579-1588 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New 18-Substituted Steroids. I. 18-MethylideneprogesteroneThree independent syntheses of 18-methylideneprogesterone, the first representative of a new group of biologically highly active steroidal compounds, are described. In the first approach 3-acetoxy-20-oxo-5-pregnen-18-carbonitril (2) is transformed into the final product by a reaction sequence involving the Cope degradation of the N-oxide 6 of the corresponding tertiary aminomethyl derivative. The Wittig reaction 3,3,20,20-Bis(äthylendioxy)-5-pregnen-18-al (11) represents the crucial step in the second synthesis. In the last procedure the 18-methylidene-20-oxo grouping is generated by fragmentation of an 18,21-bridged 1,3-diol system (19). The two former methods are very versatile and generally applicable for the synthesis of other analogues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600514
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  • 94
    Digitale Medien
    Digitale Medien
    Synthese, Kristallstruktur und thermische Entwässerung von CsMnF4 · 2H2OZum ehrenden Andenken an Prof. Dr. Dr. h.c. Hans Schmid (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1589-1600 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis, crystal structure and thermal dehydration of CsMnF4 · 2H2OThe preparation of a new fluoromanganate (III)-complex CsMnF4 · 2H2O is reported. It crystallizes in the monoclinic space group C2 with a = 11.891(2) Å, b = 6.589(1) Å, c = 10.558(1) Å, β = 131.46(1)° and Z = 4. The crystal structure has been solved from diffractometer data by heavy-atom methods and refined to a conventional R-value of 1.8% (including the contributions of three hydrogen atoms in measured and one in calculated positions). The structure is characterized by isolated, tetragonally distorted [MnF4(OH2)2]-octahedra with Mn-F-distances from 1.801(8) Å to 1.870(7) Å and Mn-O-distances of 2.146(6) Å and 2.268(6) Å. Cesium exhibits an irregular 10-coordination by 8 F-atoms and 2 O-atoms (mean values for the two independent cesium ions: Cs-F = 3.17 Å and 3.21 Å, Cs-O = 3.32 Å and 3.29 Å). The [MnF4(OH2)2]-octahedra are connected to six neighbouring octahedra by hydrogen bonding.The dehydration of the complex has been studied by thermoanalytical methods and power x-ray-diffractometry. The unit cell of the dehydrated compound, CsMnF4, is tetragonal with a = 7.936(1) Å and c = 6.341(1) Å. A close relationship to the structure of CsFeF4, which is a superstructure variant of the T1A1F4-type[6], is indicated by the similarity of the corresponding unit cells and preliminary structure factor calculations. A proposition for the crystal structure of CsMnF4 is developed on the basis of (2 + 2 + 2)-orthorhombic distorted MnF6-octahedra.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600515
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  • 95
    Digitale Medien
    Digitale Medien
    Über Reaktionen oxygenierter Kobalt(II)-Komplexe. IX. Oxydative Eigenschaften von Tetrakis(äthylendiamin)-μ-peroxo-μ-hydroxo-dikobalt(III)VIII s. [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1601-1606 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions of oxygenated cobalt(II) complexes. IX. Oxidative properties of tetrakis(ethylenediamine)-μ-peroxo-μ-hydroxo-dicobalt(III)VIII s. [1].[(en)2Co(O2, OH)Co(en)2]3+ (a) reacts with I- in acidic aqueous solution according to: CoIII(O2, OH)CoIII + 21- + 5H+ ⇀ 2CoIII + 3H2O + I2. Using I- in excess first order rate constants are obtained which, to a first approximation, are independent of [I-]. Comparison with kinetic data of deoxygenation of [(en)2Co(O2, OH)Co(en)2]3+ under analogous conditions suggests that both reactions have the same rate determining step. The singly bridged species [(en)2(H2O)CoO2Co(H2O) (en)2]4+ is shown to be the reactive intermediate in the iodide oxidation (Schema 2).
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600516
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  • 96
    Digitale Medien
    Digitale Medien
    Etude de l'action de l'oxyde d'azote (III) sur l'indène et ses homologues (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2089-2098 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Addition of nitrogen trioxide to indene and alkylindenesN2O3 adds to indene and homologous yelding pseudonitrosites which are converted to aminoindanes. Treatment of the pseudonitrosites with alcoholic potassium hydroxide gives the correspondent nitroindenes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600631
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  • 97
    Digitale Medien
    Digitale Medien
    Kreuzkonjugierte Cyanine und Merocyanine aus Salzen des 1-substituierten 2,3-Dimethylchinoxalins (Vinyloge von Indigo-imiden mit cyclisch eingebauter Imidfunktion). Vorläufige MitteilungEine ausführliche Mitteilung soll später in dieser Zeitschrift erscheinen. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2082-2084 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Crossed conjugated Cyanines and Merocyanines, obtained from Salts of 1-substituted 2,3-Dimethyl-quinoxalines. (A second type of vinylogous Indigo-imides.) Preliminary Communication.On dissolving quaternary salts of 2,3-dimethylquinoxaline in dimethylformamide or dimethylsulfoxide, a spontaneous reaction takes place: the title compounds are isolated from the reaction mixtures; they are easily oxidized, e.g. by MnO2. Mechanistic aspects are discussed.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600629
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  • 98
    Digitale Medien
    Digitale Medien
    Mitteilungen (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2107-2109 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600635
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  • 99
    Digitale Medien
    Digitale Medien
    Totalsynthese von (+)-D-Homoöstron-3-methyläther (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2258-2269 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Total Synthesis of (+)-D-Homoestrone 3-methyl etherA novel total synthesis of (+)-D-homoestrone 3-methyl ether (21) is described starting from (S)-8a-methyl-3,4,8,8a-tetrahydro-2H, 7H-naphthalene-1,6-dione (1) as a chiral synthon for the rings C and D. The key step involves alkylation of the derived 3 with m-methoxyphenacyl bromide (4) as an AB-building block to give the dioxo-secosteroid 5. Hydrogenation of 5 affords the trans-decalone 11. As by-products the epimeric cis-decalones 12 and 13 were characterized. Cyclization of 11 leads under kinetic control predominantly to the Δ9(11)-tetraene 14. Catalytic hydrogenation of 14 and subsequent modification in ring D give the title compound 21. It was found that 14 and also the derived Δ8-isomer 15a add hydrogen from the α-face of the molecule to an extent of about 80%. The 8α-D-homoestrone derivatives 20a and 23 as well as the 9β-isomers 19a and 22 were characterized.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600717
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  • 100
    Digitale Medien
    Digitale Medien
    A Simple Equivalent Bond Orbital Model for the Rationalization of the C2s-Photoelectron Spectra of the Higher n-Alkanes, in Particular of Polyethylene (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2248-2257 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The higher homologues of n-alkanes H(CH2)NH with N 〉 ∽ 13 yield photoelectron spectra in which the C2s-bands merge to form a double humped, unresolved C2s-band system in the interval of I=15 to 25 eV [1]. It is shown that with the help of an equivalent bond orbital model one can derive a closed formula, which gives the individual C2s-band positions Ijm=-εj in function of N and j with sufficient accuracy, assuming the validity of Koopmans' approximation. The calculated Ijm values (j=1 to N) folded with an appropriate shape function for the individual C2s-bands reproduce the observed Franck-Condon envelope of the C2s-band system within narrow limits of error. However, a comparison of the observed total width of the C2s-band system with the computed one, indicate that for large n-alkanes (N≥ ∽ 13), the simplification which consists of taking into account only the interaction matrix elements between vicinal bond orbitals [2], is no longer a satisfactory one.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600716
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