bluuebunny/crossref_metadata_2025 huggingface dataset:
Centrifugal innervation of goldfish retina from ganglion cells of the nervus terminalis
Authors: Springer Alan D.
Published: December 2004

Cobaltous‐lysine was applied to one optic nerve of normal goldfish in order to determine the source of the centrifugal innervation of the retina. Cobalt‐filled cells were not observed in the optic tectum, pretectum, thal‐amus, or hypothalamus. However, filled cells were observed outside the central nervous system either interspersed between the olfactory nerve fibers orrostrally along the ventromedial aspect of the olfactory bulbs. These cells appear to correspond to the ganglion cells of the nervus terminalis. The cells were located bilaterally and had dendrites that branched in close proximity to the cell body and axons that coursed caudally through the medial olfactory tract. The axons traveled in the ventral forebrain and entered the optic tracts. The axons also gave off fine branches that appeared to terminate in the vicinity of the anterior commissure and in the preoptic region. Application of cobaltous‐lysine to a cut olfactory tract resulted in cobalt‐filled fibers in the optic tracts, retinal optic fiber layer, and retinal ganglion cell layer. However, the precise terminations of these fibers within the retina could not be readily established. The results are discussed with respect to the plethora of sources of retinopetal cells observed by others in fish and with respect to the innervation of the retina by luteinizing hormone‐releasing hormone axons.
Distribution patterns of individual medial lemniscal axons in the ventrobasal complex of the monkey thalamus
Authors: Jones E. G.
Published: December 2004

Twenty‐seven medial lemniscal axons were traced to their terminations in the thalamic ventrobasal complex of monkeys, following injection of horseradish peroxidase into the lemniscus at midbrain levels.

Most axons had terminal ramifications at one horizontal level in the ventrobasal complex. All terminations were focal, many were anteropos‐teriorly elongated, though none were sufficiently long to occupy more than one‐third to one‐half of the anteroposterior extent of the VPLc nucleus. All terminal ramifications were compressed sagittally into a slab 200–300 μm wide. There was modest overlap in the terminal territories of adjacent labelled axons and, as judged light microscopically, only a small amount of convergence onto the vicinities of single cells.

Axons terminating selectively in the anterodorsal shell or central core of VPLc could be identified. In the anterodorsal shell (of neurons responding to stimulation of deep tissues) axons tended to terminate either in the part projecting to area 3a or in that projecting to areas 3a and 2 of the cortex. In the central core (of neurons responding to cutuneous stimulation and projecting to areas 3b and 1) larger ramifications were present in its center and smaller ramifications in its ventral part.

A few axons had terminal ramifications at two dorsoventral levels in the cutaneous core; others had terminations in both the dorsal deep shell and the cutaneous core. In both cases, one ramification was always smaller than the other.

The termination of lemniscal axons at defined foci instead of along the dorsoventral extent of the representational lamellae of the ventrobasal complex has implications for the nature of the body representation in the nuclei. Their tendency to be focal implies that not all members of an anteropos‐teriorly elongated rod of place‐and‐modality‐specific ventrobasal cells that project their axon to a single column in the somatic sensory cortex receive afferent inputs from the same lemniscal fibers.
Interneurons in the flight system of the locust: Distribution, connections, and resetting properties
Authors: Robertson R. M. , Pearson K. G.
Published: December 2004

The organization and functional properties of interneurons in the flight system of the locust, Locusta migratoria, were investigated by using intra‐cellular recording and staining techniques. Interneurons were found to be distributed within the three thoracic and the first three abdominal ganglia, and they could be subdivided into three organizational categories: (1) members of one of two serially homologous groups controlling either the forewing or the hindwing, (2) unique individuals with no known homologues in other ganglia, and (3) members of a set of serial homologues in the metathoracic and first three abdominal ganglia. Interneurons in the last two categories influenced both forewing and hindwing motoneurons in a similar manner. Thus interneuronal organization is not characterized by two distinct homologous groups of interneurons for the separate control of forewing and hindwing motor activity.

Flight interneurons may also form two separate functional categories: (1) those making short latency connections to motoneurons (premotor interneurons), and (2) those which reset the flight rhythm when depolarized by brief current pulses (pattern generator interneurons). None of the ten premotor interneurons we identified influenced the flight rhythm when depolarized and none of the three groups of pattern generator interneurons were found to form short latency connections with motoneurons. This separation of function may allow phase‐shifts in motor output for flight control without changes in wingbeat frequency. Pattern generator interneurons influence motor output to both forewings and hindwings. Thus we conclude that the flight rhythm is generated in a distributed neuronal oscillator driving both pairs of wings.

The organization of flight interneurons is considerably more complex than predicted from existing models of the flight system, or anticipated from the relative simplicity of the motor output. Our finding of homologous sets of interneurons in the abdominal ganglia supports the notion that insect flight evolved from a behavior using appendages distributed along the thorax and the abdomen. Thus the organization of flight interneurons may reflect an interneuronal system which controlled the behavior from which flight evolved.
Claustroneocortical projections studied in the cat by means of multiple retrograde fluorescent tracing
Authors: Macchi G. , Bentivoglio M. , Minciacchi D. , Molinari M.
Published: December 2004

The topographical interrelations of Claustroneocortical cells and their degree of divergent collateralization were investigated in cat by means of retrograde fluorescent double labeling. The tracers Fast Blue (FB) and Nuclear Yellow (NY) were injected in several combinations in two different cortical fields. FB‐labeled and NY‐labeled cells were found in all cases in the insular portion of the ipsilateral claustrum (C1I). The distributions of labeled cells confirmed the organization reported in previous studies. In some cases the two labeled cell populations were segregated in different parts of the C1I; in other cases there was more or less overlap in the two distributions. The degree of overlap was not simply related to the topographic proximity of the injected cortical territories.

In all cases the vast majority of cells were single labeled. In one case both FB and NY were injected in the same cortical area in order to control that claustral axons can retrogradely transport two tracers back to the same parent cell bodies. In this control case C1I cells were double labeled. All together these data indicate that widely divergent Claustroneocortical projections take origin mainly from separate cells.
The growth of nerves in relation to the formation of premuscle cell masses in the developing chick forelimb
Authors: Bennett M. R. , Davey D. F. , Marshall J. J.
Published: December 2004

A description is given of the growth of segmental nerves 13 to 16 (SN13 to SN16) from the brachial myotomes into the ventral and dorsal premuscle cell masses of the chick forelimb. At stage 25 (Hamburger and Hamilton, 1951), segmental nerves have converged to form two nerve trunks which enter the ventral and dorsal premuscle cell masses. These nerves grow into the limb, parallel to its proximodistal axis. The nerve trunk in the ventral compartment, the brachialis longus inferior (bli n), grows on the brachial artery as far as the metacarpals. The nerve trunk in the dorsal compartment, the brachialis longus superior (bls n), grows on the precartilage adjacent to a dorsal premuscle density as far as the metacarpals.

The brachialis longus inferior and superior nerve trunks give rise to a number of nerves during their growth to the metacarpals. Each of these nerves appears at the time of formation of a new premuscle cell density. At late stage 25, a posterior and ventral premuscle density forms in the middle of the stylopodium; posterior fascicles of the bli n diverge at this level and grow toward this new density to form the ulnar nerve. By stage 26 a posterior and ventral premuscle density is prominent over the bli n, at the junction of the stylopodium and the zeugopodium; ventral fascicles of the bli n grow into this density to form the flexor digitorum profundus nerve. At this stage a posterior and dorsal premuscle density forms just beyond the junction of the stylopodium and zeugopodium. Posterior fascicles of the bls n diverge at this level and grow toward this density to form a nerve from which the extensor metacarpi ulnaris, extensor digitorum communis, and radialis la‐terialis nerves are destined to form. At stage 29 the premuscle cell masses of the autopodium have formed. The remaining nerve fascicles comprising the bls n (the radialis profundus nerve) grow into the autopodium and branch to innervate each of the dorsal premuscles. The remaining nerve fascicles comprising the bli n (the middle nerve) grow into the autopodium and branch to innervate each of the ventral premuscles.
3H‐GABA uptake selectively labels identifiable neurons in the leech central nervous system
Authors: Cline Hollis T.
Published: December 2004

Segment ganglia of the leech ventral nerve cord synthesize the neurotransmitter γ‐aminobutyric acid(GABA) when incubatyed in the presence of the prescursor glumate, suggesting that there may be GABA‐ergic neurons in the leech nerve cord. GABA‐accumulating neurons of the two taxonomically distant leech species, Haementeria ghilianii and Hirudo nedicinalis, have been labeled by takeing advantage of their high‐affinity uptake system for the neurotransmitter. Autoradiography of sectioned segmental ganglia previously exposed to 3H‐GABA reveals a reproducible pattern of about thirty 3labeled neurol cell bodies are bilaterally paired, although some apparently unpaired cell bodies also accumulate label. Neuronal processes were reproducibly labeled by GABA uptake and could be traced in the neuropil through commissures and fiber tracts into the segmental nerve roots and interganglionic connectives, respectively.
Morphology and migration of cultured schwann cells transplanted into the fimbria and hippocampus in adult rats
Authors: Brook Gary A. , Lawrence Jean M. , Raisman Geoffrey
Published: December 2004

Schwann cells cultured from neonatal rat peripheral nerve were injected into the fimbria and hippocampus of syngeneic adult rats by a microtransplantation technique which causes minimal disturbance to the host brain structure at the site of implantation, and thus allows the grafted cells to come into immediate contact with intact host tissue.

Numerous Schwann cells could be identified for up to 6 weeks (and with decreasing frequency for up to 3 months) by intense immunoreactivity for low affinity nerve growth factor receptor. The transplanted cells adopted a distinctive elongated form, with a central, ovoid nucleus flanked by processes which were up to 300 μm long, and which ranged from swollen segments with a diameter as large as 12 μm down to thread‐like fibres of 1 μm or less. This morphology is different from that of any of the host cells. The transplanted Schwann cells migrated freely into the host tissue along blood vessels and according to the position of the grafts, they either entered the hippocampal neuropil, or migrated (for distances of up to 2 mm) along the longitudinal axis of the fimbria, where they were interspersed in parallel with the interfascicular glial rows and axons.

The host astrocytes did not appear to impede the migration of the donor Schwann cells. Although the host astrocytic processes became hypertrophic, with increased glial fibrillary acidic protein and vimentin expression, the predominant longitudinal orientation of the astrocytic tract processes was maintained.

The transplanted Schwann cells did not form peripheral myelin (as detected by Po immunoreactivity), and it is not clear whether they survive beyond the period at which we detect them. © 1993 Wiley‐Liss, Inc.
Astrocytic GABA receptors
Authors: Fraser Douglas D. , Mudrick‐Donnon Lori A. , Macvicar Brian A.
Published: December 2004

GABA receptors are distributed widely throughout the central nervous system on a variety of cell types. It has become increasingly clear that astrocytes, both in cell culture and tissue slices, express abundant GABAA receptors. In astrocytes, GABA activates Cl−‐specific channels that are modulated by barbiturates and benzodiazepines; however, the neuronal inverse agonist methyl‐4‐ethyl‐6, 7‐dimethoxy‐β‐carboline‐3‐car‐boxylate enhances the current in a subpopulation of astrocytes. The properties of astrocytic GABAA receptors, therefore, are remarkably similar to their neuronal counterparts, with only a few pharmacological exceptions. In stellate glial cells of the pituitary pars intermedia, GABA released from neuronal terminals activates postsynaptic potentials directly. The physiological significance of astrocytic GABAA‐receptor activation remains unknown, but it may be involved in extracellular ion homeostasis and pH regulation. At present, there is considerably less evidence for the presence of GABAB receptors on astrocytes. The data that have emerged, however, indicate a prominent role for second‐messenger regulation by this receptor. © 1994 Wiley‐Liss, Inc.
Excitatory amino acid receptors in glial progenitor cells: Molecular and functional properties
Authors: Gallo Vittorio , Patneau Doris K. , Mayer Mark L. , Vaccarino Flora M.
Published: December 2004

We have analyzed the molecular and biophysical properties of glutamate‐gated channels in cells of the oligodendrocyte lineage, using both the CG‐4 primary cell line (Louis et al: J. Neurosci. Res. 31:193‐204, 1992a) and oligodendrocyte progenitors purified from the rat cerebral cortex. CG‐4 progenitor cells, as well as primary progenitors, were stained with a specific anti‐GABA antibody. In whole‐cell patch‐clamp recordings, rapid perfusion of the agonists L‐glutamate, kainate, and AMPA produced rapidly desensitizing currents in CG‐4 cells. NMDA was ineffective. Both rapidly desensitizing and steady‐state components of responses to kainate were inhibited by the kainate/AMPA receptor antagonist CNQX. Northern blot analysis of total mRNA isolated from CG‐4 cells revealed co‐expression of both AMPA‐ and kainate‐preferring glutamate receptor subunits. The activation of glutamate receptors in CG‐4 cells caused a rapid and transient elevation of mRNAs for the immediate early gene NGFI‐A. © 1994 Wiley‐Liss, Inc.
Plasticity of astrocytes
Authors: Shao Yanping , McCarthy Ken D.
Published: December 2004

It is becoming apparent that astrocytes carry out a large number of different functions in brain and are able to modify their characteristics throughout life, that is they exhibit a high degree of plasticity in their phenotype. For example, the morphology of astrocytes changes markedly during neuronal migration, maturation, and degeneration. It is conceivable that these cells must constantly adjust their abilities to meet changes in brain environment. Several examples of astrocytic plasticity are presented in this review. First, the ability of astrocytes to recognize neuronal signals can change qualitatively as well as quantitatively; evidence suggests that the expression of glial receptors may be developmentally regulated by both intrinsic and extrinsic signals. Second, the expression of adrenergic receptors by astrocytes in adult brain can change in response to neuronal degeneration. The up‐regulation of β‐adrenergic receptors in this case suggests that these receptors play a role in function of reactive astrocytes. Finally, glial morphology can be reciprocally regulated by neurotransmitters such as norepinephrine and glutamate. This reciprocal regulation may be significant since both ß‐adrenergic receptors and glutamate transporters are found predominantly in astrocytes in the brain. The change in glial morphology may also affect neuronal activity by changing the volume of the extracellular space. © 1994 Wiley‐Liss, Inc.
Neurotransmitter‐mediated signaling between axons and glial cells
Authors: Chiu S. Y. , Kriegler S.
Published: December 2004

Neurotransmitter‐mediated signaling is not restricted to the synaptic regions of the nervous system but also takes places along fiber tracts lacking vesicular means of releasing neuroactive substances. The first demonstration for dynamic signaling of this type came in the early 1970s from studies by Villegas and co‐workers in squid axons and their satellite Schwann cells. In this invertebrate system, glutamate has been identified as the mediator of this signaling in being first released from the active axons thus setting off a series of cascades, leading to a cholinergic activation of the Schwann cell membrane. Recent evidence suggests that receptor‐mediated signaling also exists between glial cells and axons in vertebrates. In the frog optic nerve, axonal activity facilitated the activity of glial ion channels. In the neonatal rat optic nerve, electrical activity of axons triggered oscillations in intracellular calcium in a subset of glial cells. These observations have been postulated to reflect receptor‐mediated signaling, including a mechanism in which glutamate is released from axons via the reversal of a transporter and induces intracellular calcium spiking in glial cells via metabotropic glutamate receptors. The efficacy of “axon‐to‐glia” transmission may, like that in “neuron‐to‐neuron” transmission, be modulated by co‐release of multiple neuroactive substances. One possibility is that adenosine, which is known to be released from fiber tracts, can modulate glutamate signaling in white matter by modulating the periaxonal glutamate concentration through an effect on the glial glutamate uptake system. © 1994 Wiley‐Liss, Inc.
Functional differences between auditory cortices of the two hemispheres revealed by whole‐head neuromagnetic recordings
Authors: Mäkelä J. P. , Ahonen A. , Hämäläinen M. , Hari R. , Llmoniemi R. , Kajola M. , Knuutila J. , Lounasmaa O. V. , McEvoy L. , Salmelin R. , Salonen O. , Sams M. , Simola J. , Tesche C. , Vasama J‐P.
Published: December 2004

We recorded auditory evoked magnetic fields from nine healthy subjects with a 122‐channel whole‐head SQUID magnetometer. This type of measurement ensures that responses from both hemispheres are collected in the same stage of vigilance. The stimuli were 50‐ms 1‐kHz tones, delivered alternately to the two ears at interstimulus intervals (ISIs) of 1, 2, 4, 8, and 16 s per ear. In both hemispheres, the prominent 100‐ms response (N100m) was, on average, 22% larger and 9 ms earlier for contralateral than ipsilateral tones. The N100m amplitude increased as a function of ISI and saturated at ISIs of 8–16 s. The average ISI dependence of N100m was similar over both hemispheres and for both contralateral and ipsilateral stimuli, implying that tones leave neural traces of similar duration in both hemispheres. Differences were observed as well: the response waveforms were clearly asymmetric in one subject, and four subjects displayed an additional right‐hemisphere‐dominant 250‐ms deflection (N250m). © 1993 Wiley‐Liss, Inc.
13C‐Kernresonanzspektroskopische und elektromotorische Untersuchungen der Wechselwirkung von neutralen Carriern mit Ionen in Membranen
Authors: Büchi Rolf , Pretsch Ernö , Morf Werner E. , Simon Wilhelm
Published: December 2004

Investigation of the interaction of neutral carriers with ions in membranes by 13C‐NMR. and EMF.‐measurements.

Applying a simple model, information on the interaction of neutral carriers with cations as well as on the ion pair formation may be obtained through 13C‐NMR. and potentiometric studies of PVC‐supported ion selective liquidmembranes in contact with aqueous solutions. The results indicate that carriers for K+ (nonactin) and synthetic ionophores for Ca2+ show an association of the carrier‐complexes with lipophilic anions. The extent of complex formation of the carrier in the presence of lipophilic anions in the sample solution is in agreement with earlier interpretations of the anion interference of cation selective liquid‐membrane electrodes.
Synthese von [D‐Alanin1, 4′ ‐azido‐3′, 5′ ‐ditritio‐L‐phenylalanin2, norvalin4]α‐melanotropin als «Photoaffinitätsprobe» für Hormon‐Rezeptor‐Wechselwirkungen
Authors: Eberle Alex , Schwyzer Robert
Published: December 2004

Synthesis of [D‐alanine1, 4′‐azido‐3′, 5′‐ditritio‐L‐phenylalanine2, norvaline4]α‐melanotropin as a ‘photoaffinity probe’ for hormone‐receptor interactions.

The synthesis of an α‐MSH derivative containing 4′‐azido‐3′,5′‐ditritio‐L‐phenylalanine is described: Ac · D‐Ala‐Pap(3H2)‐Ser‐Nva‐Glu‐His‐Phe‐Arg‐Trp‐Gly‐Lys‐Pro‐Val · NH2. This hormone analogue is being used for specific photoaffinity labelling of receptor molecules. The synthesis was performed in a way to minimize the number of radioactive steps and to introduce the radio‐active and the photoaffinity label exclusively into position 2. The dipeptide N(α)‐acetyl‐D‐alanyl‐ (4′‐amino‐3′,5′‐diiodo)‐L‐phenylalanine was tritriated and transformed into the azido compound, N(α)‐acetyl‐D‐alanyl‐(4′‐azido‐3′,5′‐ditritio)‐L‐phenylalanine which was then condensed with H · Ser‐Nva‐Glu(OtBu)‐His‐Phe‐Arg‐Trp‐Gly‐Lys(BOC)‐Pro‐Val · NH2 to the tridecapeptide. The α‐MSH analog displayed a specific activity of 11 Ci/mmol, and a biological activity of about 4 · 109 U/mmol (10% of α‐MSH).
Über die Verbreitung der stereomeren Muscarine innerhalb der Ordnung der Agaricales
Authors: Stadelmann René Josef , Eugster Conrad Hans , Müller Emil
Published: December 2004

Investigations on the distribution of the stereoisomeric muscarines within the order of agaricales.

Stereomeric muscarines (muscarine, epi‐muscarine and allo‐muscarine), albeit in low concentrations (⩽ 2 mg/100 g dry weight), have been found in fruiting bodies of the following species of agaricales: Amanita pantherina, Amanita phalloides, Boletus calopus, Boletus luridus, Clitocybe dealbata, Clitocybe hydrogramma, Clitocybe gibba (= Cl. infundibuliformis s.s. auct. plur.), Clitocybe vermicularis, Clitopilus intermedius, Collybia peronata, Hygrocybe mgrescens, Hypholoma fasciculare, Lactarius rufus, Lactarius trivialis, Mycena pelianthina, Mycena pura, Paxillus involutus, Rhodophyllus rhodopolius, Rhodophyllus sinuatus, Russula emetica, Tricholoma sulphureum, Tylopilus felleus. Collections of the same species from different sites showed pronounced variation in the relative amounts of stereoisomers, e.g. with Clitocybe dealbata and Rhodo phyllus rhodopolius. epi‐allo‐Muscarine could not be detected in any of the species tested.
13C‐NMR. Spectroscopy of Naturally Occurring Substances. XLV. Iboga Alkaloids
Authors: Wenkert Ernest , Cochran David W. , Gottlieb Hugo E. , Hagaman Edward W. , Filho Raimundo Braz , de Abreu Matos Francisco José , Lacerda Machado Madruga Maria Iracema
Published: December 2004

The carbon shifts of the Iboga‐type alkaloids catharanthine, voacangine, coronaridine, ibogaine, dihydrocatharanthine and epiibogamine were recorded and correlated with the conformation of the natural bases. A 13C‐NMR. analysis of heyneanine determined its C(19) configuration and a similar study of epiheyneanine proved its structure.
Carbenic Behaviour of Isocyanoamines generated by Flash Pyrolysis of 4‐Arylhydrazono‐isoxazol‐5‐ones. Rearrangement to Cyanamides and Indazoles. Preliminary communication
Authors: Reichen Werner , Wentrup Curt
Published: December 2004

Flash pyrolysis of the 4‐arylhydrazono‐3‐methyl‐isoxazol‐5‐one (1) yields carbon dioxide, acetonitrile, and isocyanoarylamines 2 which under the reaction conditions rearrange to either arylcyanamides 3 or indazoles 4. It is shown by deuterium labelling that only the isocyanoamines not the isomeric nitrile imines are intermediates in the formation of indazoles.
Struktur des Hydrazinolyseproduktes von N‐(3‐Oxo‐1‐isoindolinyliden)‐alanin‐äthylester
Authors: Chaloupka Stanislav , Bieri Jost H. , Heimgartner Heinz
Published: December 2004

Hydrazinolysis of N‐(3‐Oxo‐1‐isoindolinyliden)alanin Ethyl Ester, Structure of the Product

Treatment of N‐(3‐oxo‐1‐isoindolinyliden)alanin ethyl ester (6) with hydrazine hydrate leads to 4‐methyl‐2,3,4,6‐tetrahydro[1,2,4]triazino[3,4‐a]isoindole‐3, 6‐dione (8, Scheme 3) and not to the previously postulated 6‐hydroxy‐2‐methyl‐2,3‐dihydro‐imidazo [2,1‐a]phthalazin‐3‐one (7, cf. [2]). The structure of 8 has been established by an independent synthesis as well as by the X‐ray analysis of the reaction product 11 from 8 and 3‐dimethylamino‐2,2‐dimethyl‐2 H‐azirine (1, Scheme 4). A reaction mechanism for the formation of 8 from 6 is suggested in Scheme 5.
63Cu‐NMR.Studies of Copper(I)tetrapyridine and Copper(I)tetraacetonitrile Solvates
Authors: Ochsenbein Ueli , Schläpfer Carl W.
Published: December 2004

63Cu‐NMR.‐Spectra of Cu(CH3CN)4X (X = ClO, BF, PF) and Cu(C5H5N)4X (X = ClO, BF) in solution are reported at different temperatures and concentrations. The influence of temperature on the linewidth and chemical shift indicates an equilibrium of Cu(CH3CN) and Cu(C5H5N) with another complex of lower symmetry. The preferential solvation of Cu (I) by pyridin in a mixture acetonitrile/pyridine is clearly shown.
Stereochemistry‐Odor Relationships in Enantiomeric Ambergris Fragrances
Authors: Ohloff Günther , Vial Christian , Wolf Hans Richard , Job Kurt , Jégou Elise , Polonsky Judith , Lederer Edgar
Published: December 2004

Twelve tricyclic ethers of the labdane and ent‐labdane series, 5–16, have been synthesized; compounds 6–15 are new. The intramolecular C18‐acetals 1–4 and the tricyclic ethers 5–16 were submitted to an olfactory test which was characterized by an exceptionally high percentage of ‘wrong’ answers (cf. Table 1, footnote b). For most compounds specific anosmia, rapidly ensuing fatigue and a high percentage of odor deviation were the most salient features.

Pronounced ambergris‐like odors were only noted in compounds of the labdane series, and were strongest in ethers 1, 5 and 15, followed by the ethers 9 and 11. In contrast, both labdane derivatives 3 and 7 were practically odorless. Their enantiomers 4 and 8, on the other hand, have relatively strong odors which can only to a limited extent be associated with ambergris‐type odors. The pairs of ethers 3/4 and 7/8 are the first recorded examples of optical antipodes in which only one isomer possesses olfactory properties.
Some Comments on the Conformations of Methyl Phenyl Sulfides, Sulfoxides and Sulfones
Authors: Mohraz Manijeh , Jian‐qi Wang , Heilbronner Edgar , Solladiéa‐Cavallo Arlette , Matloubi‐Moghadam Firouz
Published: December 2004

13C‐NMR. and He (Iα) photoelectron spectra of alkyl phenyl sulfides, sulfoxides and sulfones have been used to probe how their conformations depend on the size of the alkyl groups R. The results are interpreted to indicate that in the sulfides the S, R‐bond is twisted out of the planar conformation with increasing size of the alkyl group, whereas in the sulfoxides and sulfones the preferred conformation with the S, R‐bond perpendicular to the phenyl group plane seems to be independent of the size of R. These conclusions are in agreement with previous work on the alkyl phenyl sulfides and provide strong support for previous conjectures concerning the preferred conformations of alkyl phenyl sulfoxides and sulfones.
Hindered Nucleophilic Displacement (SN 2) Reactions of 2exo‐ and 2endo‐ Norbornyl Derivatives. Norbornane) Series 4
Authors: Grob Cyril A. , Lutz Erich
Published: December 2004

The reactions of 2exo‐ and 2endo‐norbornyl bromide (1e and 2e, respectively) in 90% ethanol with a large excess of potassium hydroxide, and of 2exo‐norbornyl p‐toluenesulfonate (1g) with excess sodium thiophenolate in methyl cellosolve, have been studied. They obey the first order rate law and are zero order with respect to the base‐nucleophile. However, the ratio of 1,2‐ and 1,3‐elimination to exo‐substitution products depends strongly on the base‐nucleophile concentration. Ion pair intermediates are indicated. The extreme inertness of 2‐norbornyl derivatives in displacement reactions is due to severe steric hindrance of rearside nucleophilic attack, a feature they have in common with other bi‐ and tricyclic molecules bearing nucleofugal groups adjacent to one or two bridgehead atoms.
Photochemische Reaktionen 119. Mitteilung [1] Zur Photospaltung konjugierter γ,δ‐Epoxyenone. UV.‐Bestrahlung von 3‐(1′,2′‐Epoxy‐2′‐methyl‐prop‐1′‐yl)‐5,5‐dimethyl‐2‐cyclohexen‐1‐on
Authors: De Weck Guy , Wolf Hans Richard
Published: December 2004

Photocleavage of Conjugated π,π‐Epoxyenones. UV.‐Irradiation of 3‐(1′,2′‐Epoxy‐2′‐methyl‐prop‐1′‐yl)‐5,5‐dimethyl‐2‐cyclohexene‐1‐one

On 1π,π*‐excitation (δ = 254 nm) 9 undergoes cleavage of the C(δ), C(δ)‐bond yielding 17 and a, which gives 18 by photofragmentation. In presence of maleinic ester the photolysis of 9 yields 20, in presence of methanol 21 and 22 are obtained. By photocleavage of the C(δ), O‐bond 9 is converted into b giving 14. Photolysis of 14 yields 15 (A + B) and 16.

On 1n,π*‐excitation (δ λ⩾ 347 nm) of 9 cleavage of the C(δ), O‐bond (9 → b) seems to be the preferred reaction, whereas products of a are formed in traces, only.
Approaches to the Synthesis of Cytochalasans. Part 3. Synthesis of a substituted tetrahydroisoindolinone moiety possessing the same relative configuration as proxiphomin
Authors: Schmidlin Tibur , Züurcher Werner , Tamm Christoph
Published: December 2004

The total synthesis of the tetrahydroisoindolinone moiety corresponding to proxiphomin (1) is described, bearing functional groups for the attachment of the macrocyclic ring. Knoevenagel‐Cope condensation of racemic 2‐(benzyloxycarbonyl‐amino)‐3‐phenylpropanal (2) with methyl (4‐methyl‐2,4‐hexadienyl) malonate (3) yielded a mixture of the (E)‐ and (Z)‐olefins 4a and 4b, which upon heating underwent intramolecular Diels‐Alder cyclization (cf. Scheme 1). From the resulting products the tetrahydroisoindoline derivative 6 was isolated. X‐ray analysis of 6[5] revealed the same relative configurations at C(3), C(4), C(5) and C(8) as in 1, but not at C(9). Hydrolysis of 6 with KOH was accompanied by a change in configuration at C(9) yielding the hydroxy acid 14 which was converted into the hydroxy ester 11 (cf. Scheme 4). The presence of a cis‐anellated lactam ring in 11 has been confirmed by X‐ray analysis of its O‐acetyl derivative 16 [5]. Ring closure of the hydroxy acid 14 gave the lactone 17, corresponding to the natural product 1 as to the configuration. The presence of the N‐benzyloxycarbonyl group in lactone 6 has been shown to be essential for the above‐mentioned ‘inversion’ at C(9), because no configurational change occurred with the N‐unprotected lactone 8 when treated under the same conditions. The only product obtained was the hydroxy ester 10 possessing the same configuration at C(9) as 8. Along with stereochemical considerations, mechanistic aspects of the reactions are discussed.
Selectivities in the Reactions of Alkyl‐, Aryl‐ and Heterosubstituted Organotitanium Compounds Preliminary Communication
Authors: Weidmann Beat , Widler Leo , Olivero Alan G. , Maycock Christopher D. , Seebach Dieter
Published: December 2004

Solutions of the title compounds R‐Ti(OR′)3 (1) are generally available from organolithium (or magnesium) derivatives according to equation 1. It is shown (Table 1) that some heterosubstituted organotitanium compounds are more stable thermally than their lithium counterparts. The reagents 1 are highly selective carbonylophiles (Tables 1 and 2), their reactivity can be modified by variation of the R′O‐group (Table 3) and with the chiral (S)‐2‐methyl‐l‐butoxy group an enantioselective addition can be achieved [equ. 2].
Dediazoniations of Arenediazonium Ions in Homogeneous Solution. Part XIV. 15N‐CIDNP. Investigation of the reactions of diazonium ions in weakly alkaline aqueous solutions
Authors: Dreher Eberhard‐Ludwig , Niederer Paul , Ricker Anton , Schwarz Wolfgang , Zollinger Heinrich
Published: December 2004

15N‐CIDNP. spectra recorded during the reaction of diazonium cations with OH− in weakly alkaline aqueous solutions show that the dediazoniation is at least partially homolytic. The polarizations observed for the diazonium and trans‐diazotate ions can be explained by reaction proceeding via a cage involving diazenyl and diazotate radicals using Kaptein's rules and simple intensity considerations.
Preferential Solvation of the Sodium Cation in Binary Mixtures of Tetrahydrofuran with Unidentate Nitrogen Ligands
Authors: Delville Alfred , Detellier Christian , Gerstmans André , Laszlo Pierre
Published: December 2004

23Na‐chemical shifts for the NaClO4solute depend markedly upon the composition of binary solvent mixtures of THF with amines (pyridine, piperidine, pyrrolidine, aniline, propylamine, and isopropylamine). These changes, analyzed in a novel application of theHillformalism, show equality of the intrinsic equilibrium constant K for the successive steps, upon displacement of THF from sodium coordination by one of these amines. The results, which are entirely consistent with tetracoordination of the sodium cation by these solvents, also indicate proportionality of the K values to the amine chemical shifts.
Dérivés de désoxy‐hydroxylamino‐sucres et radicaux libres diglycosylnitroxydes correspondants. Communication préliminaire
Authors: Tronchet Jean M. J. , Winter‐Mihaly Eva , Habashi Ford , Schwarzenbach Dominique , Likić Ubavka , Geoffroy Michel
Published: December 2004

Deoxy‐hydroxylamino‐sugar Derivatives and Corresponding Diglycosylnitroxides Radicals

A number of sugar aldonitrones, including C,N‐diglycosylnitrones, and ketonitrones have been treated with Grignard reagents or cyanide anion leading to the corresponding deoxy‐hydroxylamino‐sugars. On oxidation (air, H5IO6 or PbO2), these compounds gave the corresponding nitroxide radicals whose ESR. spectra are reported. Analogues of disaccharides, in which the interglycosidic O‐bridge is replaced by a hydroxyimino group, have been obtained by reacting a partially blocked sugar bearing a free hemiacetal group either with a deoxy‐hydroxylaminosugar or with hydroxylamine, followed by reaction with an aldehydosugar and a reducing agent (NaBH4). These reactions represents the key synthetic steps for the oligosaccharide‐type synthesis of deoxy‐hydroxyimino‐oligosaccharides. Their oxidation yielded the corresponding nitroxide radicals whose ESR. spectra gave information on the conformation about the ‘interglycosidic’ bridge. This type of compounds should constitute useful spin markers for biological studies.
Anil‐Synthese. 24. Mitteilung. über die Herstellung von Styryl‐ und Stilbenyl‐Derivaten des 1H‐Benzotriazols
Authors: Siegrist Adolf Emil
Published: December 2004

Preparation of Styryl and Stilbenyl Derivatives of 1H‐Benzotriazoles

1‐(p‐Tolyl)‐substituted 1H‐benzotriazoles react with anils of aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide to yield the corresponding 1‐(styr‐4′‐yl)‐1H‐benzotriazoles and 1‐(stilben‐4′‐yl)‐1H‐benzotriazoles, respectively (‘anil synthesis’). Further, under the same reaction conditions, the Schiff's bases derived from p‐chloroaniline and 4‐(1′H‐benzotriazol‐1′‐yl)benzaldehydes give, with p‐tolyl‐substituted heterocycles, the corresponding heterocyclic substituted stilbenyl derivatives.
Conformations of the Ten‐membered Ring in 5, 10‐Secosteroids. III: (Z)‐3β‐ and (Z)‐3α‐Hydroxy‐5, 10‐seco‐1 (10)‐cholesten‐5‐one Esters and (Z)‐5, 10‐seco‐1 (10)‐Cholestene‐3, 5‐dione
Authors: Fuhrer Hermann , Lorenc Ljubinka , Pavlović Vladimir , Rihs Grety , Rist Günther , Kalvoda Jaroslav , Mihailović Mihailo Lj.
Published: December 2004

(Z)‐3β‐Acetoxy‐ and (Z)‐3 α‐acetoxy‐5, 10‐seco‐1 (10)‐cholesten‐5‐one (6a) and (7a) were synthesized by fragmentation of 3β‐acetoxy‐5α‐cholestan‐5‐ol (1) and 3α‐acetoxy‐5β‐cholestan‐5‐ol (2), respectively, using in both cases the hypoiodite reaction (the lead tetraacetate/iodine version). The 3β‐acetate 6a was further transformed, via the 3β‐alcohol 6d to the corresponding (Z)‐3β‐p‐bromobenzoate ester 6b and to (Z)‐5, 10‐seco‐1 (10)‐cholestene‐3, 5‐dione (8) (also obtainable from the 3α‐acetate 7a). The 1H‐and 13C‐NMR. spectra showed that the (Z)‐unsaturated 10‐membered ring in all three compounds (6a, 7a and 8) exists in toluene, in only one conformation of type C1, the same as that of the (Z)‐3β‐p‐bromobenzoate 6b in the solid state found by X‐ray analysis. The unfavourable relative spatial factors (interdistance and mutual orientation) of the active centres in conformations of type C1 are responsible for the absence of intramolecular cyclizations in the (Z)‐ketoesters 6 and 7 (a and c).
Über den Anteil sigmatroper 1, 5‐Wanderung von Kohlenwasserstoffgruppen bei der thermolytischen Skelettisomerisierung 5,5‐disubstituierter 1, 3‐Cyclohexadiene
Authors: Schiess Peter , Dinkel Rolf
Published: December 2004

On the Extent of Sigmatropic 1, 5‐Migration of Hydrocarbon Groups in the Thermolytic Skeletal Rearrangement of 5,5‐Disubstituted 1,3‐Cyclohexadienes

The uncatalyzed skeletal isomerization of 5, 5‐disubstituted 1, 3‐cyclohexadienes was investigated with the aim to establish the extent to which sigmatropic 1,5‐shifts of hydrocarbon groups are participating in these reactions.

Gas phase pyrolysis of 5,5‐diethyl‐1,3‐cyclohexadiene (7) at 460° followed by chloranil aromatization yields only 4% of 1,3‐diethylbenzene resulting from 7 through a 1, 5‐ethyl migration in the primary reaction step. 2, 3‐Dimethylethylbenzene (56%) and 1, 4‐diethylbenzene (4%) are obtained as other C10‐compounds. This shows that isomerization proceeds mainly through a sequence of electrocyclic and 1, 7‐shift reactions. Ethylbenzene (24%) and other aromatic C8‐ and C9‐hydrocarbons are formed to a considerable extent, indicating that C, C‐bond cleavage is a major competing process and that the 1, 3‐diethylbenzene found is the result of a radical recombination reaction and not of a concerted sigmatropic shift of the ethyl group.

5‐Methyl‐5‐phenyl‐1, 3‐cyclohexadiene (12) yields 3‐methylbiphenyl (14) and biphenyl upon thermolysis and aromatization. Through 13C‐substitution of the methyl group in 12 it is shown that in solution at 300° skeletal isomerization proceeds through electrocyclic and 1, 7‐H‐shift reactions exclusively. In the gas phase at 500° 4% of the isomerization product is formed by a 1, 5‐shift of a substitutent, presumably of the methyl group, through a dissociative mechanism.

Thermolysis of 5, 5‐diphenyl‐1, 3‐cyclohexadiene (22) at 560° in the gas phase leads to 1, 1‐diphenyl‐1, 3, 5‐hexatriene (23) and 1‐vinyl‐4‐phenyl‐1, 2‐dihydronaphthalene (24) through electrocyclic reaction steps. In addition a small amount of m‐terphenyl is obtained at high conversion of 22. This indicates that sigmatropic 1,5‐phenyl migration can participate in product formation only at high temperature and in the absence of other irreversible pathways to stable products.
Electrochemical Properties of Hydroxyphenazine‐Coated Electrodes
Authors: Haas Otto , Zumbrunnen Hans‐Rudolf
Published: December 2004

Glassy carbon and gold electrodes were coated with 1‐hydroxyphenazine, and the electrochemical properties of these electrodes were tested using them as a rotating disc electrode to reduce Ru (bipy)33+, Fe3+, quinoxaline, O2, and to oxidize Eu2+. The fixed redox couple can be reversibly reduced and oxidized, and acts as an intermediate medium for the electron transfer. For example the Ru(bipy)33+ (E1/2= 1010 mV vs. SCE. (saturated calomel electrode) on a glassy carbon electrode in 1M H2SO4) is only reduced at 50 mV, whereas the oxidation of Eu2+ (E1/2= −460 mV vs. SCE. on a Hg‐electrode in 1M HCl) takes place at − 100 mV. The heterogeneous rate constant depends on the second order reaction between the attached coating and the redox couple in solution. Depending on this rate constant, selectivity of the electrode is observed.
Zur Konfiguration des Vitamin‐D3‐Metaboliten 25, 26‐Dihydroxycholecalciferol: Synthese von (25S,26)‐ und (25R,26)‐Dihydroxycholecalciferol
Authors: Barner Richard , Hübscher Josef , Daly John J. , Schönholzer Peter
Published: December 2004

Configuration of the Vitamin‐D3‐Metabolite 25,26‐Dihydroxycholecalciferol: Synthesis of (25S,26)‐ and (25R,26)‐Dihydroxycholecalciferol

For selective synthesis of the title compounds, (25S)‐1b and (25R)‐1b (Scheme 1), the protected cholesterol precursors (25S)‐6 and (25R)‐6 were prepared from stigmasterol‐derived steroid‐units 4a‐d and C5‐side chain building blocks 5a–d by Grignard‐ or Wittig‐coupling (Scheme 2), the configuration at C(25) of the target compounds being already present in the C5‐units. Conversion of the cholesterol intermediates to the corresponding vitamin‐D3 derivatives was carried out via the 7,8‐didehydrocholesterol compounds (25S)‐2b and (25R)‐2b (Scheme 1), using the established photochemical‐thermal transformation of the 5,7‐diene system to the seco‐triene system of cholecalciferol. The configuration at C(25) of the cholesterol precursors as assigned on basis of the known configuration of the C5‐units used, was found to be in agreement with the result of a single crystal X‐ray analysis on compound 11. The configuration at C(25) remained untouched on conversion of the cholesterol ring system to the seco‐triene system of vitamin D3 as evident from comparison of the lanthanide‐induced CD. Cotton effects observed for (25S)‐3b and (25S)1b. 25,26‐Dihydroxycholecalciferol observed as a natural vitamin‐D3 metabolite has (25S)‐configuration.
Wittig‐Reaktionen von sulfonierten Phosphoniomethylstrylaromaten mit aromatischen und heteroaromatischen Aldehyden
Authors: Märky Michael
Published: December 2004

Wittig Reactions of Phosphoniomethylaryl Compounds with Sulfonated Aromatic and Heteroaromatic Aldehydes

Bis (triphenylphosphoniomethyl)aryl dichloride derivatives react with aromatic or heteroaromatic aldehydes which have a sulfonic or carboxylic group attached to the ring system, to yield stilbene compounds of a betaine‐type structure. These betaines are reacted further with various aromatic or heteroaromatic aldehydes yielding asymmetrically substituted derivatives in excellent yields. This new method is widely applicable to the preparation of water‐soluble, fluorescent whitening agents of the bis‐stilbene type.
A Note on Stereochemical Observations of the Deprotonation of Ethyl 2‐Alkenoates
Authors: Krebs Ernst‐Peter
Published: December 2004

Deprotonation of ethyl (E)‐2‐alkenoates 1, 3 and 4 yields after protonation the double bond migrated (3 Z)‐isomers 5, 7 and 9 as major products. In contrast, deprotonation and reprotonation of ethyl (Z)‐2‐pentenoate (2) gives the (3 E)‐isomer 6 exclusively. These findings are explained by reaction paths starting from different ester conformations.
Synthesis of Reactive Intermediates for Natural Cyclopentane Derivatives from (−)‐Quinic Acid: Preparation of 11α‐hydroxy‐13‐oxaprostanoic acid
Authors: Barrière Jean‐Claude , Chiaroni Angèle , Cléophax Jeanine , Géro Stephan D. , Riche Claude , Vuilhorgne Mare
Published: December 2004

We describe a flexible, stereocontrolled synthesis of enantiomerically pure substituted cyclopentenes and cyclopentanes ‐ including 11α‐hydroxy‐13‐oxaprostanoic acid 20 ‐ (−)‐quinic acid via an acyclic precursor 6 by an intramolecular aldolisation‐dehydration reaction.
Chiral 1, 4‐Benzodiazepin‐2‐one, template for enantioselective synthesis of α‐amino acids and their α‐deuterio congeners. Preliminary communication
Authors: Decorte Enio , Toso Roberto , Sega Alessandro , Šunjié Vitomir , Ružić‐Toroš Živa , Kojić‐Prodić Biserka , Bresciani‐Pahor Nevenka , Nardin Giorgio , Randaccio Lucio
Published: December 2004

Absolute conformation of 7‐chloro‐5‐phenyl‐1‐[(S)‐α‐phenylethyl]‐1, 3‐dihydro‐2H‐1, 4‐benzodiazepin‐2‐one (1c) in crystal, and its inversion rate in solution were determined, enabling prognosis of direction of asymmetric induction during C(3)‐alkylation.
Total Synthesis of All Eight Stereoisomers of α‐Tocopheryl Acetate. Determination of their diastereoisomeric and enantiomeric purity by gas chromatography
Authors: Cohen Noal , Scott Clifford G. , Neukom Christian , Lopresti Rocco J. , Weber Giuseppe , Saucy Gabriel
Published: December 2004

All eight stereoisomers of α‐tocopheryl acetate have been synthesized in a state of high chemical and stereoisomeric purity. Key chiral side‐chain intermediates were prepared from (+)‐(S)‐3‐hydroxy‐2‐methylpropanoic acid. New routes to (2R, 4′ RS, 8′ RS)‐α‐tocopheryl acetate, a mixture of four diastereoisomers, were also developed. A sensitive gas chromatographic method was developed to determine the diastereoisomeric and enantiomeric purity of α‐tocopherol samples as the methyl ethers. It was established for the first time that naturally occurring α‐tocopherol is essentially a single enantiomer (2 R, 4′ R, 8′ R), synthetic all‐rac‐α‐tocopherol an equimolar mixture of four racemates, and that natural (E)‐(7 R, 11 R)‐phytol is diastereoisomerically and enantiomerically homogeneous.
2‐Oxocephems and 2‐Acetylpenems ‐ Selective Formation in an Intramolecular Wittig Reaction
Authors: Ernest Ivan , Main Alan J. , Woodward Robert B.
Published: December 2004

Selective formation ‐ in intramolecular Wittig condensations ‐ of the 2‐oxocephem‐4‐carboxylate 8a and of the 2‐acetylpenem‐3‐carboxylate 9, respectively, was observed as a consequence of different carbonyl reactivities in two homologous α‐oxoacylthio groupings. Free, racemic and 7‐unsubstituted 2‐oxocephem‐4‐carboxylic acid (10) was prepared from 8a for biological testing. Attempts to prepare the free 2‐acetylpenem‐3‐carboxylic acid from 9 failed, probably due to the high lability of the β‐lactam system.
Röntgenstrukturanalyse eines neuartigen spirocyclischen Diglycosides, eines Abbauproduktes der Antibiotika Papulacandin A, B and C
Authors: Rihs Greti , Traxler Peter
Published: December 2004

X‐Ray Analysis of a Novel Spirocyclic Diglycoside, a Degradation Product of the Antibiotics Papulacandin A, B and C

Structure 4 has been established for a novel spirocyclic diglycoside which is a degradation product of the antibiotics papulacandin A, B and C. By X‐ray analysis the diglycoside was shown to consist of a galactose moiety connected by a β‐1, 4‐linkage to a glucose. This diglycoside is further connected by a spiro union to a oxaindan‐diol moiety.
Nucleotide. XIV. Substituierte β‐Phenyläthyl‐Gruppen. Neue Schutzgruppen für Oligonucleotid‐Synthesen nach dem Phosphorsäuretriester‐Verfahren
Authors: Uhlmann Eugen , Pfleiderer Wolfgang
Published: December 2004

XIV. Substituted β‐Phenyl‐ethyl Groups. New Blocking Groups for Oligonucleotide Syntheses by the Phosphotriester Approach

Various o‐ and p‐substituted β‐phenylethanols (2–10) have been synthesized and investigated as blocking groups in the phosphotriester approach. A large number of 5′‐O‐tritylated thymidine‐3′‐phosphotriesters (13–36) with two different phosphate protecting groups have been prepared, characterized, and studied according to their chemical stability and usefullness for oligonucleotide syntheses. The combination of a 5′‐O‐monomethoxytrityl‐ and a 3′‐(2,5‐dichlorophenyl, p‐nitrophenylethyl)‐phosphate function as in 18 turned out to possess optimal properties as a monomeric nucleotide building block due to the fact that these blocking groups can be quantitatively and selectively be removed without harming each other by trifluoroacetic acid in chloroform to 41, by oximate to 42, and by DBU to 43. The base‐catalyzed removal of the monosubstituted phenylethyl groups by DBU or DBN respectively as well as the disubstituted phenylethyl groups by triethylamine in aprotic solvents is a β‐elimination process leading to phosphodiesters without attack on the P‐center.