bluuebunny/crossref_metadata_2025 huggingface dataset:
Arsenomethane Polymer: A ladder structure
Authors: Daly J. J. , Sanz F.
Published: December 2004

Purple arsenomethane crystallises in the orthorhombic system, space group Ima2 (C) with a = 5.81, b = 5.79, c = 13.64 Å and 8 units of CH3As in the cell. The structure is polymeric, the arsenic atoms lying on infinite coplanar ladders parallel to a. The distance between two arsenic atoms on one rung of the ladder is 2.4 Å, the distance between two arsenic atoms on the same upright and adjacent rungs is 2.9 Å, and the shortest distance between two arsenic atoms in neighbouring ladders is 3.4 Å. Each arsenic atom is bonded to one methyl group (1.97 Å), and along the ladder upright or on any one rung these methyl groups lie on alternate sides of the ladder.
Über die Struktur eines neuartigen Indolalkaloids, des Talbotins. 141. Mitteilung über Alkaloide [1]
Authors: Pinar M. , Hanaoka M. , Hesse M. , Schmid H.
Published: December 2004

From the leaves of the African Apocynacea Pleiocarpa talbotii Wernham a novel indole alkaloid, talbotine, C21H24N2O4, has been isolated. Talbotine (1) contains a secondary N(b)‐atom and a cyclic hemiacetal group. Catalytic hydrogenation leads to 19, 20‐dihydrotalbotine (6), hydrogenation in the presence of formaldehyde gives N(b)‐methyl‐19, 20‐dihydrotalbotine (8). In the presence of sodium methoxide and methanol, 1 is converted into the lactone 12 and the methyl ester 13. In these reactions carbon 17 is lost as formic acid. These data, together with the analyses of the NMR. spectra of talbotine and its derivatives as well as the interpretation of the various types of the mass spectral fragmentation, lead to formula 1 for the alkaloid.

Dehydrogenation of talbotine methyl ether (3) with palladium and maleic acid gives the ß‐carboline derivative 26. The N(b)‐methiodide of the latter is converted into N(b)‐methyl‐talbotine methyl ether on reduction with sodium borohydride. From these data as well as from the analyses of NMR. and IR. spectra the complete relative stereochemistry of talbotine could be derived. Application of the Horeau method to the nitrogen atom b of the methyl ether 3 on the one hand and to the hydroxyl group on C17 in N(b)‐methyl‐19, 20‐dihydrotalbotine (8) on the other hand gives consistent results and establishes S configuration of centre 15.
Die Kristallstruktur der 2,4, 6‐Trimethylpimelinsäuren 1. Mitteilung
Authors: Brufani M. , Fedeli W.
Published: December 2004

The crystal structure of the stereoisomer m.p. 130° of 2,4,6‐trimethylpimelic acid has been determined by three‐dimensional X‐ray analysis. The cristals are monoclinic, a = 10.35, b = 10.70, c = 11.61 Å, β = 110°12′, Z = 4, space group P2 1/c, the structure has been solved by direct methods and refined by least‐squares methods.

The configuration of the acid is given by formula I; the chirality of the asymmetric centres is (2‐R, 4‐r, 6‐S).
Crystallographic Studies of Synthetic Corrinoids. I. Nickel(II)‐1, 8, 8, 13, 13‐pentamethyl‐5‐cyano‐trans‐corrin chloride
Authors: Dunitz J. D. , Meyer E. F.
Published: December 2004

The crystal and molecular structure of nickel(II)‐1, 8, 8, 13, 13‐pentamethyl‐5‐cyano‐trans‐corrin chloride has been determined by X‐ray analysis. The shape and dimensions of the corrin nucleus are discussed in some detail.
The 35Cl Nuclear Quadrupole Resonance Frequencies of Complexes of Boron Trichloride
Authors: Ardjomand S. , Lucken E. A. C.
Published: December 2004

Les fréquences de résonance quadripolaire du noyau 35CI dans les complexes du tri chlorure de bore avec une variété de donneurs organiques ont été mesurées à 77 K. Quoique ces fréquences dans l'accepteur soient assez peu sensibles à la nature du ligand, la tendance observée est en accord avec d'autres mesures du pouvoir donneur des ligands. Certains des ligands étudiés ici contiennent un atome de chlore et les changements de fréquence amenés par la complexation sont également en accord avec les résultats prévus. Le trichloracetonitrile et le dichloracétonitrile réagissent avec le trichlorure de bore pour donner un composé d'addition sur la triple liaison do groupementCN plutǒt qu'un complexe donneur‐accepteur. Ce comportement est clairement mis en évidence par la spectroscopie de résonance quadripolaire.
13C‐, 14N‐ und 1H‐kernresonanzspektroskopische Untersuchungen an m‐/p‐substuierten N‐Methylpyridiniumjodiden
Authors: Wehrli F. W. , Giger W. , Simon W.
Published: December 2004

In a series of 21 m‐/p‐substituted N‐methylpyridinium salts, N‐methyl proton, carbon‐13 and pyridinium nitrogen‐14 chemical shifts were determined by heteronuclear double resonance, and partly in the case of the 14N nucleus and the methyl protons by direct measurement. In a few compounds the quadrupole relaxation times proved to be too short for the 14N coupling to be detected. This problem was overcome by adequately rising the sample temperature. For all three nuclei a marked dependence of the chemical shifts on the nature of the substituent could be established. Increased nitrogen π‐electron density shifts the resonances towards higher fields. In the case of the 14N shieldings, this tendency is attributed to changes in the paramagnetic screening term, whereas for 13C and 1H an interpretation is given in terms of a neighbour anisotropy contribution. The latter explanation is based on the observation that the calculated carbon and hydrogen charge densities show no significant variations throughout the series. Excellent shift correlations were obtained with Hammett substituent constants when σ+‐values were used for donor substituents. A similar substituents, dependence could be observed for the direct 13CH methyl coupling constants, whose magnitude increases with decreasing nitrogen charge density.
Absolute Konfiguration von δ‐Carotin aus der Tomatenmutante Del/Del 65–3–54–5
Authors: Buchecker R. , Eugster C. H.
Published: December 2004

(+)‐δ‐Carotene (II) isolated from a tomato mutant is shown by comparison of its circular dichroism with that of (+)‐α‐carotene to possess at C(6) the chirality of natural (+)‐α‐carotene (I) and ε‐carotene (III).
Schmelzreaktionen mit Aluminiumchlorid. 6. Mitteilung [1]. Zur kenntnis der carbazolierung von anthrimiden in aluminiumchlorid‐schmelzen
Authors: Wick A. K.
Published: December 2004

The behaviour of di‐(1‐anthraquinonyl)‐amine, when cyclised in pyridine‐aluminium chloride or pure aluminium chloride fusions, has been compared. The formation of blue educt complexes with aluminium chloride in the latter case has been revealed as a factor which inhibits cyclisation. The results are discussed and generalised, classifying carbazolation of anthrimides as an intramolecular Scholl‐type reaction.
Über Pterinchemie. 35. Mitteilung [1]. Herstellung von 6‐aminomethyl‐6‐methyl‐5,6,7,8‐tetrahydropterin, ein Beitrag zur frage der Existenz von parachinoid‐dihydropterinen
Authors: Viscontini M. , Frater‐Schroeder M. , Argentini M.
Published: December 2004

Die erste Synthese eines 6, 6‐disubstituierten Tetrahydropterins, nämlich des 6‐Aminomethyl‐6‐methyl‐5, 6, 7, 8‐tetrahydropterins, wird beschrieben: Das durch Anlagerung von Blausäure an 6‐Methyl‐7, 8‐dihydropterin entstandene 6‐Cyano‐6‐methyl‐5, 6, 7, 8‐tetrahydropterin wird acetyliert, reduziert und anschliessend desacetyliert. Entgegen unserer Erwartung bildet das 6‐Aminomethyl‐6‐methyl‐tetrahydropterin bei der Oxydation durch Luftsauerstoff unter physiologischen Bedingungen kein Parachinoid‐dihydropterin, sondern wird direkt zu 6‐Methyl‐7, 8‐dihydropterin, Formaldehyd und Ammoniak abgebaut.
Zur Photochemie des Benzfurazans
Authors: Georgarakis M. , Rosenkranz H. J. , Schmid H.
Published: December 2004

Irradiation of benzofurazan (1) in benzene solution yields the azepine derivative 3 as the main photoproduct. Addition of methanol in the dark to the irradiated benzene solution of 1 results in the isolation of 3 together with a new product, methyl‐1‐cis, 3‐cis‐N‐(4‐cyano‐buta‐1, 3‐dien‐1‐yl)‐carbamate (1‐cis, 3‐cis‐2). Irradiation of 1 in methanol solution gives a mixture of the stereoisomeric methyl N‐(4‐cyano‐buta‐1, 3‐dien‐1‐yl)‐carbamates, from which the 1‐trans, 3‐cis isomer of 2 could be isolated in pure form.

The observed photoproducts are formed via the reactive intermediates a, a nitrile‐(nitrile oxide), and c, a nitrene, neither of which was isolated.
Hormon‐Rezeptor‐Beziehungen: Synthese und eigenschaften von Nε‐dansyllysin21‐adrenocorticotropin‐(1–24)‐tetrakosipepid
Authors: Schwyzer R. , Schiller P. W.
Published: December 2004

We are investigating interactions between hormones and their potential receptor molecules by means of biologically active, synthetic hormone derivatives. The substituents are so chosen that they can supply quantitative information about specific contacts or convert the hormone to an ‘affinity marker’. We describe the synthesis of Nε‐dansyllysine21‐adrenocorticotropin‐(1–24)‐tetrakosipeptide. In fat cells and in adrenal cells of the rat the dansyl substituent does not seem to impair the interaction between the peptide moiety and its biological receptors. It allows for affinity studies by fluorescence depolarisation and for measurement of intramolecular and intermolecular distances by means of energy transfer (fluorescence sensibilisation).
Über den Einfluss des Kontaktterms auf die Lantlianiden‐Verschiebung der NMR.‐Signale aromatischer stickstoffheterocyclen
Authors: Huber H. , Pascual C.
Published: December 2004

The inclusion of a contact term in the calculation of the paramagnetic shifts induced by Eu(tmhd3) does not Improve the predicted values.
Synthese von lipophil substituierten ACTH‐Peptiden
Authors: Brugger M.
Published: December 2004

With a view to rendering ACTH peptides absorbable by the oral route, a series of such peptides with increased lipophilic character was built up. This paper describes the synthesis of eleven derivatives of the ACTH peptide [D‐Ser1, Lys17,18]‐β‐corticotrophin‐(1–19)‐nonadeca‐peptide, containing lipophilic alkyl substituents of different kinds and sizes, bound to the carboxyl of terminal proline either by ester or amide linkage.

The unsubstituted peptide [D‐Ser1, Lys17,18]‐β‐corticotrophin‐(1–19)‐nonadecapeptide, and its C‐terminal amide were also synthesized.
Photochemisches Verhalten von 3,4‐Diarylsydonen. Vorläufige Mitteilung
Authors: Märky M. , Hansen H.‐J. , Schmid H.
Published: December 2004

3, 4‐Diphenyl‐sydnone (1a) and 3‐p‐tolyl‐4‐phenyl‐sydnone (1b) on irradiation with a mercury high‐pressure lamp in pyrex vessels yield 2,4,5‐triphenyl‐ (3a) and 2‐p‐tolyl‐4,5‐diphenyl‐1,2,3‐triazole (3b), respectively. Irradiation of 1a and 1b in the presence of dimethyl acetylene‐dicarboxylate or indene leads to the formation of the pyrazoles 4a and 4b and the Δ2‐pyrazolines 5a and 5b, respectively. Reactive intermediates of the photoreaction of 1a and 1b seem to be the diazirines 2a and 2b, which open to give the 1,3‐dipolar structures 8a and 8b.
Computer‐Drawn Molecular Orbitals: An aid for the users of MO‐programs
Authors: Haselbach E. , Schmelzer A.
Published: December 2004

A computer program is described, which generates a simplified pictorial representation of computed molecular orbitals. As examples, the highest occupied MO's of the two C8‐rotamers of the cyclopropylcarbinylcation (C4H7+), of pyridine and of barrelene (bicyclo[2.2.2]octatriene) are given.
Die Kristallstruktur des (−)‐O‐Methyllaurepukins (1, 2‐Methylendioxy‐11‐methoxy‐6a, β‐aporphin‐6β‐oxid)
Authors: Oberhänsli W. E.
Published: December 2004

The crystal and molecular structure of the O‐methyl derivative of the aporphine alkaloid laurepukin has been determined by direct methods, which are described. A short discussion of the structure is given.
The Synthesis of 7,7‐Difluoronorbornene. Preliminary communication
Authors: Jefford C. W. , Broeckx W.
Published: December 2004

The synthesis of 7, 7‐difluoronorborn‐2‐ene and its endo‐5‐phenyl derivative is described.
The Synthesis and Borohydride Reduction of some Alloxazine Derivatives
Authors: Müller Franz , Dudley Kenneth H.
Published: December 2004

Unequivocal syntheses of N(1 or 3)‐mono‐substituted 7, 8‐dimethylalloxazines are described. The borohydride reduction of various alloxazines has been studied under aerobic and anaerobic conditions, in the absence of light. These reactions are discussed in relation to other work on 7, 8‐dimethylisoalloxazines (flavins) and on certain flavoproteins.
Etudes sur les composés organométalliques, XIII [1] Action d'organomagnésiens sur la benzalacétone
Authors: Dubsky George Jon , Jacot‐Guillarmod André
Published: December 2004

The reactions of benzalacetone with n‐BuMgBr and PhMgBr have been compared with the corresponding reactions with the diorganomagnesium complexes of ether and pyridine. The results obtained by using different mole ratios of reactants and orders of addition show that the conjugated addition reaction is enhanced if a monomeric diorganomagnesium reagent is available; this condition can be realized either by adding a diorganomagnesium complex to the ketone or by complexing the diorganomagnesium with pyridine. Probable reaction mechanisms for normal and conjugated addition reactions are suggested.
Organic phosphorus compounds 53 preparation and properties of bis‐(chloromethyl)‐phosphinic and ‐thiophosphinic acid derivatives as well as tertiary phosphine oxides and sulfides containing two ClCH2 groups [1]
Authors: Maier Ludwig
Published: December 2004

Bis‐chloromethyl‐phosphinates, ‐thiophophinates, and ‐phosphinic amides are formed in fair yield by treating either bis‐chloromethyl‐phosphinic or‐thiophosphinic chloride with alcohols, thiols, or amines in the presence of equivalent amounts of acid binding agents. Unexpectedly, the thiophosphinates show no insecticidal activity and only the β‐cumaryl derivative exhibits a low herbicidal activity.

Reduction of bis‐chloromethyl‐thiophosphinic chloride to bis‐chloromethyl‐phosphinous chloride is effected with (PhO)3P at 170°. Interaction of this chloride, (ClCH2)2PCl, with Grignard reagents yields tertiary phosphines, which at slightly above room temperature are unstable, but which may be characterized as oxides or sulfides.
Equilibres conformationnels de glucides au niveau de liaisons s̀ sp2‐sp3 CC. II Dérivés d'hydrozones d'aldéhydo‐sucres
Authors: Tronchet J. M. J. , Baechler Br. , Jotterand A. , Perret Mlle F.
Published: December 2004

A series of alkyl‐and aryl‐hydrazones of different types of aldehydo‐sugars with blocked hydroxy groups have been studied, mainly by PMR. spectroscopy. No traces of the azoalkane or ene‐hydrazine forms were detected; the hydrazones were found to exist only in the syn form, except for the cases where an intramolecular hydrogen bond between the ‘amino’ hydrogen of the hydazono group and an oxygen o the glycosyl group provides an extra‐stabilization to the anti isomer. Most of these syn hydrazones seem to exist as an equilibrium of the ‘classical’ eclipsed rotamers. The influence of solvent polarity both on configurational and conformational equilibria has been examined.

The factors which determine the relative stability of the conformers about a sp2‐sp3 s̀ bond, particularly some kind of non‐bonded attraction, are discussed.
Thermische Umlagerungen von (+)‐Isopinocampheol und (−)‐Isopinocamphon
Authors: Schulte‐Elte K. H. , Gadola M. , Ohloff G.
Published: December 2004

Short‐path thermolysis of (+)‐isopinocampheol (1) at about 330° in the gas phase yields mainly (—)‐(3 S, 4 S)‐3, 7‐dimethyl‐octa‐1,6‐dien‐4‐ol (2). Longer heating of 2 at about 290–330° yields as main products the diastereoisomeric hydroxy‐Δ8‐iridenes 3, 4 and 5 in ratios dependent on temperature. Above 400°, formation of 4‐methylpent‐3‐en‐1‐al (7) and 2‐butene (8) predominates. Compounds 7 and 8 also appear as the stable final thermolysis products of 3, 4 and 5 above 500°. Small quantities of (+)‐iso‐dihydrocarveol (6) always occur as by‐product in the thermolysis of 1.

Short‐path thermolysis of (—)‐isopinocamphone (13) at about 430° leads, with slight epimerisation, to the three diastereoisomeric oxo‐Δ8‐iridenes 15, 18 and 17 via (+)‐(3 S)‐3, 7‐dimethylocta‐1, 6‐dien‐4‐one (14). Structure and stereochemistry of all reaction products are established spectroscopically and chemically.
Photochemische Reaktionen. 65.(vorläufige) Mitteilung. Spezifisch π → π*‐induzierte Photoisomerisierungen von 10‐Dimethoxymethyl‐Δ1,9‐octal‐2‐on. Ein photochemischer Zugang zu [4.4.3]‐12‐Oxapropellan‐Derivaten
Authors: Gloor J. , Schaffner K. , Jeger O.
Published: December 2004

Selective n → π* excitation of the α,β‐unsaturated enone 1 in hydrocarbon solvents resulted in a deconjugation reaction to 3, reminiscent of results previously reported for similar systems [2], whereas the photoreactivity of 1 in alcohol solvents at wavelengths >3400 Å was so small that only product 4 has been identified as yet.

Excitation of the π → π* transition of compound 1 at 2537 Å initiated additional phototransformations which could not be effected by irradiation in the first absorption band. The [4.4.3]‐12‐oxapropellane derivative 2 was identified as one of the two new major photo‐isomers. A 6:8 mixture of products 2 and 3, plus about 1 part of an isomer of still unknown structure (see however, the Addendum), were readily formed in hydrocarbon solvents, and a 1:10 ratio of 2 and the unknown product was obtained in methanol. Abstraction of a methoxyl hydrogen by the ketone oxygen is proposed to account for the primary photochemical step in the cyclization to 2. A hydrogen‐deuterium isotope effect of 2.7 was observed in a competitive experiment using 1 and 1‐d6. 34% of one deuterium atom were exchanged for hydrogen when 1‐d6 was photolyzed to 2‐d6 in t‐butyl alcohol, which suggests an intermediate of type a in the pathway 1 → 2 possessing a readily exchangeable proton.

Steric considerations would require a strongly distorted, non‐planar excited‐state geometry of the enone group of 1 for the oxygen to approach a methoxyl hydrogen. The transformation 1 → 2 represents a novel reaction type in photochemical processes of conjugated enones which are specifically induced by π → π* excitation only.
Über die flüchtigen Anteile der Ananas
Authors: Näf‐Müller Regula , Willhalm B.
Published: December 2004

A gas chromatographic investigation of the volatile part of a pineapple concentrate led to the identification of 59 substances, 35 of which were not previously found in pineapple. The identifications and syntheses of some esters (Δ3‐ and Δ4‐unsaturated, β‐hydroxy, β‐acetoxy, and δ‐acetoxy) and of a new sulfur compound are given.
The Isolation, Structure, and Synthesis of Davana Ether, an Odoriferous Compound of the Oil of Artemisia pallens Wall.
Authors: Thomas Alan F. , Pitton Gertrud
Published: December 2004

Several stereoisomers of 2,6,10‐trimethyl‐2:5, 7:10‐diepoxy‐dodeca‐3,5,11‐triene (3) have been isolated from the oil of Artemisia pallens. The synthesis of the isomeric mixture is described.
Die farbstoffsensibilisierte Photo‐Oxygenierung von β‐Damascol. Ein einfaches Verfahren zur Darstellung von β‐Damascenon
Authors: Schulte‐Elte K. H. , Müller B. L. , Ohloff G.
Published: December 2004

The oxirane derivative 2a of β‐damascone which appears as the main product in the photo‐oxygenation of β‐damascol (1a), besides the α‐hydroxy‐hydroperoxides B and C, can easily be transformed into β‐damascenone (8) [1] by a sequence of acid catalyzed reactions.

The structure and stereochemistry of the photo‐oxygenation products of 1 a and its derivatives 1 b and 1 c are determined. The epoxyketone 2 is a secondary product of the unstable allylhydroperoxide A, while ketones 12 and 13 result from an α‐hydroxy‐hydroperoxide fragmentation of B and C, respectively.
Farbstoffsensibilisierte Photo‐Oxygenierung von 6,6‐Dimethylfulven. Eine neue 1,2‐Dioxolan‐Umlagerung
Authors: Skorianetz W. , SchulteW‐Elte K. H. , Ohloff G.
Published: December 2004

The dye sensitized photo‐oxygenation of 6,6‐dimethylfulvene (1) in solution at 15° gives enol lactone 2, along with ketoles 3 and 4. The following mechanism is proposed: initially formed endoperoxide 11 undergoes a 1,2‐dioxolan rearrangement to give allen epoxide 12, which then isomerizes to cyclopropanone 13. 13 can then cyclise to give 2 and 3.
Theoretical Study of the Structure and the Physico Chemical Properties of 1,2‐Benzyne
Authors: Haselbach E.
Published: December 2004

The structure of 1,2‐benzyne (I) has been optimized with respect to its total molecular energy using the MINDO/2 SCF‐procedure. The results indicate a bond length of ∼1.26 Å for the strained triple bond. The overall geometry suggests that I possesses considerable resonance energy. The calculated heat of formation (ΔHf(I) = 107 kcal/mole) is in good agreement with an estimate from mass spectrometric studies (ΔHfexp(I) = 118 ± 5 kcal/mole). From model calculations for bent acetylene the strain energy of I is estimated to be about 60 kcl/mole. Some chemical reactions of I are discussed in the light of the results.
Kernquadrupolresonanz von 35Cl in Chloracetylenen
Authors: Gerber P. , Labhart H. , Kloster‐Jensen Else
Published: December 2004

Nuclear quadrupole coupling constants of 35Cl observed in a series of chloroacetylenes are compared with results from quantum‐chemical estimates of different degree of refinement. The correlation with values calculated by an iterative Extended Hückel procedure in the Townes‐Dailey approximation is bad. It can be strikingly improved by introducing a correction proportional to the net charge on the carbon atom adjacent to the Cl‐atom. The correlation is then of the same quality as with ab initio calculations by Straub & McLean.
Solvolysis of α‐Bromo‐p‐aminostyrene. Mesomeric vinyl cations, Part IV
Authors: Grob C. A. , Pfaendler H. R.
Published: December 2004

The preparation of α‐bromo‐p‐aminostyrene (1b) and its solvolysis rates and products have been reexamined in detail. In buffered 50 vol % aqueous dioxane between pH* 13 and 3 the reaction rate is independent of hydrogen ion concentration. The ratio of the solvolysis products, viz. p‐aminoacetophenone (3b) and p‐aminophenylacetylene (5a), however, varies with the pH* and with the buffer concentration.

These findings confirm the unimolecular (SN1‐E1) mechanism involving an intermediate vinyl cation. The acid‐catalysed hydration mechanism proposed by Schubert & Barfknecht is thereby excluded.
On the Mechanism of the Thermal and Photolytic Cyclization of Diphenylamines to Carbazoles
Authors: Wentrup C. , Gaugaz M.
Published: December 2004

The product of photolysis of di‐p‐tolyamine in petroleum ether is 3,6‐dimethylcarbazole. The primary product of gas‐phase thermolysis of di‐p‐tolylamine at 850–1000°/0.01–0.05 Torr is also 3,6‐dimethylcarbazole. In the higher temperature range monomethylcarbazole and carbazole are also formed. Thermolysis of tetra‐p‐tolylhydrazine at 800–1000° gives only di‐p‐tolylamine, the latter decomposing further in the higher temperature range. It is concluded that carbazole formation involves in both cases an electrocyclization of the ortho‐positions, and not a rearrangement, and that diphenylaminyl is not an intermediate.
Photoinduzierte nucleophile Substitution von 3‐substituierten 2,1‐Benzisoxazolen (unter Ringöffnung)
Authors: Giovannini E. , Rosales J. , De Souza B.
Published: December 2004

On UV.‐irradiation in strongly acidic solution 3‐alkyl‐ and 3‐aryl‐2,1 benzisoxazoles, respectively, yield 5‐substituted 2‐aminophenylketons.
Alkaloide aus Evonymus europaea L.
Authors: Klásek A. , Šantavý F. , Duffield M. A. , Reichstein T.
Published: December 2004

From the seeds of Evonymus europaea L. (Celastraceae) the three previously described alkaloids A, B and C were isolated and their empirical formulae determined by mass spectrometry. Alkaloid B, now named evozine, C32H39NO15 (14), alkaloid A, now named evorine, C34H41NO16 (15), and alkaloid C, shown to be identical with Parter's & Libiseller's evonine, C36H43NO17 (17), are respectively tri‐, tetra‐, and penta‐O‐acetyl derivatives of deacetylevonine (13), C26H33NO12. Vigorous alkaline hydrolysis of the latter yields the previously known evonic acid (3).

Deacetylevonine (13) is an ester of evonic acid (3) and a hypothetical polyhydroxy compound C15H24O10 (2), which is unstable on alkaline hydrolysis.

By partial saponification and partial acetylation, these three alkaloids can be converted into each other, at the same time giving rise to a fourth alkaloid D (16), C34H41NO16, which we name iso‐evorine. This had been obtained already by M. Osowiecki (unpublished).
Base‐Catalyzed Hydrogen‐Deuterium Exchange in Sulfonium Cations
Authors: Barbarella G. , Garbesi A. , Fava A.
Published: December 2004

The effects of various structural changes on the kinetic acidity of protons alpha to a sulfonium function are reported. These effects are consistent with a transition state closely resembling a carbanion. Strong rate enhancements are observed for the 4‐membered cyclic sulfonium cation but not for the other ring systems.

In 5‐membered cyclic sulfonium cations the diastereotopic ring protons show high stereoselectivity towards abstraction by a base. Such stereoselectivity is diminished in going from D2O to dimethyl sulfoxide‐d6‐D2O mixtures. By contrast no stereoselectivity is exhibited by the ring protons of the 6‐ and 7‐membered cyclic sulfonium cations.

Although the rates for acyclic and cyclic sulfonium cations are closely similar, the activation parameters are characteristically different. It is suggested that solvation phenomena may be responsible for this behaviour.
Hydrolyse acide du p‐nitrophényl‐diazométhane dans les mélanges H2OD2O: analyse des effets isotopiques
Authors: Diderich G. , Dahn H.
Published: December 2004

The velocity of the hydrogen ion catalysed hydrolysis of p‐nitrophenyl‐diazo‐methane (I) has been measured in H2OD2O mixtures, giving an isotopic αi = 0.49. The product isotope effect r = 5.1, determined from product analyses, combined with the (overall) solvent isotope effect kH/kD = 2.81, yields the primary kinetic isotope effect (kH/kD)I = 3.8, and the secondary kinetic isotope effect (kH/kD)II = 0.75. The CICH2COOH‐catalysed hydrolysis of I in H2OD2O mixtures gave a straight‐line plot of kn/kH versus the atomic fraction n of deuterium. With four carboxylic acids, as catalysts, values of about 4.3 for the kinetic (overall) isotope effects were observed.
‘Alkaloids’ in Mammalian Tissues. I. Condensation of L‐Dopa and its two mono‐O‐methyl ethers with formaldehyde and acetaldehyde
Authors: Brossi A. , Focella A. , Teitel S.
Published: December 2004

In der Annahme, dass gewisse Aminosäuren im Gewebe von Säugetieren Vorläufer für «alkaloidische» Tetrahydro‐isochinoline sein könnten, wurden L‐Dopa und dessen zwei Monomethyläther mit Formaldehyd und Acetaldehyd kondensiert. Die absolute Stereochemie der erhaltenen 1‐Methyl‐substituierten Tetrahydro‐isochinoline wurde durch Röntgen‐Analyse einer Schlüsselverbindung sichergestellt.
Über die Anlagerung von Thioäthern an Chinone und Chinonimine in stark sauren Medien
Authors: Bosshard H.
Published: December 2004

By adding thioethers to protonated quinones or quinone imines, hydroquinone sulfonium compounds are prepared in good yields. A mechanism running over carbenium ions is proposed.
A Novel Synthesis of 2,6‐Diolefinic Esters: Ethyl and methyl trans‐2,cis‐6‐dodecadienoate, two Bartlett pear constituents
Authors: Näf F. , Degen P. , Ohloff G.
Published: December 2004

Ethyl and methyl trans‐2, cis‐6‐dodecadienoate, two Bartlett pear constituents, have been prepared by a novel two‐step synthesis: 1,6‐addition of lithium di‐cis‐1‐heptenylcuprate to ethyl or methyl trans‐2,4‐pentadienoate gave exclusively the 3,6‐diolefinic esters, which were isomerized to the desired 2,6‐diolefinic esters. The double‐bond geometry of the vinyl unit is retained during the addition step.
Quinacridones: Structure and Mechanism of Formation
Authors: Altiparmakian R. H. , Bohler H. , Kaul B. L. , Kehrer F.
Published: December 2004

The NMR. spectra of two acridones and twenty‐two quinacridones in (CD3)2SONaOD are reported. A NMR. technique is described for determining the composition of mixtures of various substituted quinacridones. A general mechanism is proposed for quinacridone formation via cyclodehydration of 2,5‐diarylamino‐terephthalic and 2,5‐diarylamino‐1,4‐benzoquinone‐3,6‐dicarboxylic acids/esters.
Bromdioxid: Spektroskopische Eigenschaften des Radikals
Authors: Bossy J. M. , Leoni M. W. , Bühler R. E.
Published: December 2004

Pulse radiolysis of oxygen‐saturated bromobenzene yields a transient absorption with λmax = 480 nm at pulse end, which is identified as due to the BrO2‐radical. To confirm this assignment the same radical was produced by flash photolysis of a Br2/O2‐gas mixture and by chemical synthesis at low temperature. The absorption spectra of these BrO2‐samples present a maximum between 480 and 380 nm dependent on the solvent. The influence of complex‐formation on this absorption band is discussed. The ESR.‐spectrum of chemically synthesized BrO2 is given.
Zur Diazotierung aromatischer Amine in Schwefelsäure
Authors: Konecny J. , Wenger H.
Published: December 2004

The diazotization of 2‐chloro‐4,6‐dinitroaniline, 2,6‐dichloro‐4‐nitroaniline, and 4‐nitroaniline in concentrated sulfuric acid is very strongly catalysed by water. At a given water concentration the reaction rates of these amines are in the ratio 50/20/1. The relation between the bimolecular rate constants k and the acidity function H0 is very simple, the plots of log k versus H0 being linear with a slope of 2.
Anil‐Synthese. 5. Mitteilung. Über eine neue Basen‐katalysierte Umlagerung von 4‐(Benzyl‐alkyl‐amino)‐4′‐styryl‐azobenzolen zu 4‐Benzoyl‐4′‐styryl‐azobenzolen
Authors: Weickhardt B. , Siegrist A. E.
Published: December 2004

4‐(Benzyl‐alkyl‐amino)‐4′‐methyl‐azobenzole ergeben mit Anilen aromatischer Aldehyde in Dimethylformamid in Gegenwart von Kaliumhydroxid bei 40–45° Styrylderivate; bei höheren Temperaturen kann als Folge‐Reaktion deren Benzylalkylaminogruppe sich unter Oxydation zu einer N‐Alkyl‐benzimidoyl‐Gruppe umlagern, die durch anschliessende saure Hydrolyse in den Benzoylrest übergeht.
Temperaturabhängigkeit der Ultraviolett‐Spektren von H2O2 und von HO2‐Radikalen
Authors: Kijewski H. , Troe J.
Published: December 2004

The absorption spectra of H2O2 and of HO2 radicals have been investigated in shock waves at 1950 ⩽ λ ⩽ 2900 Å and temperatures of 650 and 1100 K. By comparison with room temperature experiments, information on the nature of electronic transitions involved may be obtained.
Photoelectron Spectra of Azabenzenes and Azanaphthalenes: I. Pyridine, diazines, s‐triazine and s‐tetrazine
Authors: Gleiter R. , Heilbronner E. , Hornung V.
Published: December 2004

The experimental and theoretical basis of a recently proposed reassignment of the bands in the PE. spectra of pyridine, pyridazine, pyrimidine and pyrazine is discussed in detail. A characteristic feature of the derived orbital sequence is that it takes the ‘through‐space’ and ‘through‐bond’ interaction between the ‘lone pair’ basis orbitals explicitly into account. A simple parametrization of the orbital energies, based on HMO‐type models for the π‐orbitals and for the ‘lone pair’ linear combinations, yields excellent agreement with the observed band positions in the PE. spectra of s‐triazine and s‐tetrazine. Our new assignment is compared to those proposed previously.
Notiz über die Photoelektronen‐Spektren des Nortricyclens und des Triasterans
Authors: Haselbach E. , Heilbronner E. , Musso H. , Schmelzer A.
Published: December 2004

The photocelectron spectra of nortricyclene (=tricyclo[2.2.1.02,6]heptane) and of triasterane (=tetracyclo[3.3.1.02,8.04,6]nonane) have been recorded and a tentative assignment of the bands has been put forward on the basis of MINDO/2 SCF calculations.
Antigen Synthesis: The Preparation of Selected Dodecapeptide Carriers with Systematically Altered Structures by a Two‐Phase Method
Authors: Schneider C. H. , Wirz W.
Published: December 2004

The synthesis of a series of dodecapeptide ethyl esters containing L‐leucine, L‐ala‐nine, glycine and L‐lysine is described. These peptides are suitable carriers for the preparation of haptenic conjugates to be used in antigenicity studies. The strategy for preparing intermediary hexapeptides has been called a two‐phase approach since the elongation of the peptide chain is carried out stepwise in a water‐immiscible organic phase, whereas removal of side‐products and excess reagent is effected by means of a suitably adapted aqueous phase. The method allows an efficient production of relatively large amounts of fully defined peptide antigens.
Le blocage de la lysine par la réaction de Maillard. II. Propriétés chimiques des dérivés N‐(désoxy‐1‐D‐fructosyl‐1) et N‐(désoxy‐1‐D‐lactulosyl‐1) de la lysine
Authors: Finot P. A. , Mauron J.
Published: December 2004

Lysine is often inactivated by ‘Maillard‐type’ reactions in food proteins; the values obtained for it by different methods cannot be compared because the chemical behaviour of inactivated lysine is unknown. In this paper, the behaviour of an important form of inactivated lysine, namely its 1‐deoxyketosyl derivatives, during acid hydrolysis as well as on the different assays for available lysine (F‐DNB, TNBS, pipsylchloride and guanidination) is studied. The relative proportions of regenerated lysine and of formed furosine and pyridosine are established as a function of the conditions of hydrolysis. The validity of the methods used to estimate available lysine from its 1‐deoxyketosyl derivatives is discussed.
Phénylhalogénohydrodigermanes
Authors: Rivière Pierre , Satgé Jacques
Published: December 2004

The symmetric and unsymmetric phenylchlorohydrodigermanes can be isolated or characterized via partial halogenation of the GeH bonds of the symmetrical phenylhydrodigermanes Ph2(H)GeGe(H)2Ph, Ph(H)2GeGe(H)2Ph by chloromethyl methyl ether and carbontetrachloride. Some of these phenylchlorohydrodigermanes are formed by insertion of phenylchlorogermylene (PhGeCl) on the GeH or GeCl bonds of the phenylchlorohydrogermanes.

The hydrolysis of the monochloro phenylhydrodigermanes Ph2(Cl)GeGe(H)2 and Ph(Cl)(H)GeGe(H)2Ph leads to the phenyl phenylhydrogermyl digermoxanes [Ph2(H)GeGePh2]2O and [Ph(H)2GeGe(H)Ph]2O. Treatment of these oxides with the concentrated aqueous solutions of hydracides leads to the monofluorinated, brominated and iodinated phenylhydrodigermanes Ph2(H)GeGe(X)Ph2 and Ph(H)2GeGe(H)(X)Ph (X) = F, Br, I).

Phenylchlorohydrodigermanes decompose thermally by α‐elimination on one germanium atom with formation of germylene and phenylchlorohydrogermane.

The physico‐chemical IR. and NMR. study of these phenylhalogenohydrodigermanes indicates that, if the vGeH frequency variations are mostly linked to the inductive effects of the substituents on the same germanium, the variations of the chemical shifts of the GeH protons seem to be due to many factors and especially to the inductive effect of the substituents on the germanium and the magnetic anisotropy of the GeX bonds.
Die Synthese von menschlichem adrenocorticotropem Hormon (αh‐ACTH) mit revidierter Aminosäuresequenz
Authors: Sieber P. , Rittel W. , Riniker B.
Published: December 2004

We demonstrated recently that the amino acid sequence of human ACTH (αh‐ACTH1) differs in four positions from the structure reported in 1961 by Lee and coworkers. The synthesis of the revised sequence and a method of verifying the identity of the synthetic peptide with the naturally occurring hormone are described. The two preparations can most readily be compared by examining the mixture of fragments obtained upon degradation with trypsin. In this mixture, fragments 22–39 of natural αh‐ACTH and of the synthetic peptide are identical and easily distinguishable from the corresponding synthetic fragment of the previously postulated sequence. This is demonstrated by thin layer‐chromatography and ‐electrophoresis as well as by reference to the rate of deamidation under alkaline conditions.
α,β‐Epoxyketon → Alkinon‐Fragmentierung II: Pyrolytischer Zerfall der Hydrazone aus α,β‐Epoxyketonen und N‐Amino‐aziridinen. Über synthetische Methoden, 4. Mitteilung
Authors: Felix Dorothee , Müller Robert K. , Horn U. , Joos R. , Schreiber J. , Eschenmoser A.
Published: December 2004

Numerous examples illustrate the course of the thermolysis of hydrazones derived from α,β‐epoxyketones and 2‐phenyl‐ or trans‐2,3‐diphenyl‐1‐amino‐aziridines. This process constitutes a preparatively useful method for the fragmentation of α,β‐epoxyketones to acetylenic carbonyl compounds including acetylenic aldehydes.

Monohydrazones from phenylglyoxal and substituted N‐amino‐aziridines decompose smoothly and stereospecifically to the corresponding olefins and diazoacetophenone; such a process might also be useful for the preparation of other α‐diazocarbonyl compounds.
Steroid Total Synthesis, Part VII; (±)‐estr‐4‐ene‐3, 17‐dione and (±) 13β‐ethyl‐gon‐4‐ene‐3, 17‐dione
Authors: Rosenberger M. , Duggan A. J. , Saucy G.
Published: December 2004

An efficient and practical synthesis of the title compounds is described. The novel route is based on earlier results and uses (±)‐5‐hydroxy‐9,9‐o‐phenylenedioxy‐decanoic acid lactone as the starting material. The results demonstrate the usefulness of pyrocatechol for the protection of an aliphatic ketone.
A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.). II. Medium‐Volatile, free Acidic Constituents (b.p. ∼84–114°/0.001 Torr)
Authors: Demole Edouard , Berthet Dominique
Published: December 2004

The acidic part of a fraction b.p. 84–114°/0.001 Torr from Burley Tobacco condensate was investigated. Among the 22 compounds identified, 9 appeared to be new tobacco flavour components. This result increased to 208, the total number of Burley tobacco constituents so far isolated and identified in this laboratory.
Stabilité des paires ioniques europium et terbium‐iodate, bromate et chlorate
Authors: Roulet R. , Chenaux R.
Published: December 2004

The stability constants of ion pairs formed in aqueous solution between europium, terbium and iodate, bromate and chlorate have been determined by a liquid‐liquid extraction technique. These inorganic anions form 1:1 outer sphere complexes, as indicated by negative entropies of formation.
Conformational Studies of Cyclic Pentapeptides by Proton Magnetic Resonance Spectroscopy
Authors: Meraldi J. P. , Schwyzer R. , Tun‐Kyi A. , Wüthrich K.
Published: December 2004

The proton magnetic resonance spectra of c‐(‐Gly‐L‐Ala‐Gly‐Gly‐L‐Pro‐) (I) and four analogous cyclopentapeptides are presented. At ambient temperature the spectra contain two sets of resonances which correspond to two different molecular conformations of the peptides. The relative concentrations of the two forms depend on the peptide, the solvent, and the temperature. For the two molecular species of peptide I in DMSO solution, the NMR. data imply that the peptide linkage involving the nitrogen of proline is respectively in the cis‐ and the trans‐form, and both conformations contain intramolecular hydrogen bridges. Replacement of L‐alanine in I by L‐cysteine leaves the molecular conformations essentially unalteed. On the other hand substitution of L‐proline by L‐proline, or replacement of the two glycines in positions 3 and 4 by two sarcosyl residues gives rise to markedly different types of peptide backbone conformation.
Heuristic Programming as an Ion Generator in Mass Spectrometry. I. Generation of Primary Ions with Charge Localization
Authors: Delfino Allan B. , Buchs Armand
Published: December 2004

Un programme connu sous le nom de ION GENERATOR a été élaboré. Pour le moment ce programme est capable de créer, à partir de n'importe quelle molécule organique, les ions primaires résultant de la tragmentation de l'ion moléculaire et de proposer des mécanismes de fragmentation pour expliquer la formation des ions.
The Mechanism of the Acid‐catalysed Hydrolysis of 1‐Aryl‐2,2,2‐trifluorodiazoethanes
Authors: Diderich Georges
Published: December 2004

The rates of the acid‐catalysed hydrolysis of a series of 1‐aryl‐2,2,2‐trifluorodiazoethanes la‐d have been measured in dioxan/water/HClO4. The results are well correlated with the Hammett equation when σp substituent constants are used (ϱH = −1.74 and ϱD = −1.75). Kinetic solvent isotope effects, about 2.1, and general acid catalysis indicate that proton transfer is rate‐determining (A‐SE2 mechanism). Rate measurements have also been made at pressures up to 1400 atm. The evaluated activation volumes, about −20 cm3/mole, indicate that at least one water molecule is bound in the transition state of protonation. Rate measurements at low water concentrations indicate that no apparent change in mechanism has occured.
Exchange Equilibrium of Oxygen Isotopes between BrO, ClO, IO and Water
Authors: Agarwal S. C. , Baertschi P. , Gamsj H.
Published: December 2004

The liquid phase fractionation factors αH = (18O/16O)H2O/(18O/16O)xo and αD = (18O/16O)D2O/(18O/16O)xo (X = Cl, Br, I) were calculated quantum mechanically between 0 and 100°. Experimental values were obtained in the case of BrO at 60° showing good agreement with the calculated results.
Isolierung von 11α, 11′α‐Dihydroxychaetocin aus Verticillium tenerum
Authors: Hauser D. , Loosli H. R. , Niklaus P.
Published: December 2004

Based on 13C‐NMR. and other physico‐chemical evidence, the structure of 11α, 11′α‐dihydroxychaetocin (3) has been assigned to a new antibacterial and antimitotic metabolite, isolated from the fungus Verticillium tenerum.
α‐Chlor‐nitrone II: Eine Methode zur Darstellung von γ‐Lactonen aus Olefinen. Über synthetische Methoden, 6. (vorläufige) Mitteilung
Authors: Das Gupta T. K. , Felix Dorothee , Kempe U. M. , Eschenmoser A.
Published: December 2004

The addition products obtained by the Ag+‐induced reaction of α‐chloro‐aldonitrones with olefins (see preceding communication) can be utilized efficiently for making γ‐lactones (see scheme 1).
Studies in the Helicene Series NMR. Evidence of ‘Helicene‐like’ Conformations in the cis 1,2‐Diarylethylenes. Part XVII
Authors: Martin R. H. , Defay Nicole , Figeys H. P. , Lê van K. , Ruelle J. J. , Schurter J. J.
Published: December 2004

The cis and trans isomers of eight 1,2‐diarylethylenes, precursors of helicenes, have been studied by NMR. spectroscopy. The observed differences in chemical shifts, specific solvent effects and steric effects (bromo derivatives) can be explained by the contribution of ‘helicenelike’ conformers in the cis isomers.
Reaction of 2‐Methylenenorbornane with N‐Bromosuccinimide
Authors: Jefford C. W. , Wojnarowski W.
Published: December 2004

The reaction of 2‐methylenenorbornane with N‐bromosuccinimide produced a mixture of six monobromides in an overall yield of about 60%. By irradiation in the presence of benzoyl peroxide exo‐ and endo‐3‐bromo‐2‐methylenenorbornanes, 2‐bromomethylnorborn‐2‐ene, Z‐ and E‐2‐bromomethylenenorbornanes and 1‐bromomethylnortricyclene were found in a percentage ratio of 43.0, 7.5, 6.5, 19.0, 19.0 and 5.0. Without benzoyl peroxide, in the dark, the same products were obtained, but in a percentage ratio of 23.0, 3.0, 17.0, 26.0, 26.0 and 7.0. These results are rationalized in terms of an ionic mechanism in concurrence with some radical mechanism contribution.
The Migratory Aptitude of the Ethoxycarbonyl Group in the Pinacol Rearrangement. Preliminary communication
Authors: Kagan Jacques , Agdeppa Dalmacio A. , Singh S. P.
Published: December 2004

The migratory aptitude of the ethoxycarbonyl group in the pinacol rearrangement was deduced from the structure of the products observed after treatment of 2‐substituted 2,3‐dihydroxy‐3‐phenylbutyrates with fluorosulfonic acid at 0° for 3 minutes. The migratory aptitude of ethoxycarbonyl is comparable to that of ethyl, greater than that of methyl or hydrogen, but smaller than that of phenyl. Cyclization and fragmentation reactions were also observed.
Amino‐nucléosides III. Dérivés des amino‐3‐didésoxy‐3,5‐D‐lyxo et D‐ribo‐pentoses
Authors: Tronchet J. M. J. , Graf R.
Published: December 2004

The 3‐amino‐3,5‐didesoxy‐1,2‐O‐isopropylidene‐α‐D‐ribofuranose and ‐β‐D‐lyxo‐furanose and several derivatives thereof have been prepared by hydride reduction of the corresponding oximes.
Anil‐Synthese. 7. Mitteilung.. Über die basenkatalysierte Umsetzung von methylsubstituierten 2‐Phenyl‐2H‐benzotriazolen mit Anilen aromatischer Aldehyde
Authors: Siegrist A. E. , Zweidler R.
Published: December 2004

2‐(p‐Tolyl)‐2H‐benzotriazole und 2‐Phenyl‐5‐methyl‐2H‐benzotriazole können mit Anilen aromatischer Aldehyde in Dimethylformamid in Gegenwart von Kaliumhydroxid in 2‐(Stilben‐4‐yl)‐2H‐benzotriazole bzw. 2‐Phenyl‐5‐styryl‐2H‐benzotriazole über geführt werden («Anil‐Synthese»). Durch Einführung von Substituenten wie Chlor oder Methoxy gruppen kann die Lage des Fluoreszenzspektrums in Dimethylformamid eine erhebliche batho chrome oder hypsochrome Verschiebung erfahren.
Germa‐2‐dioxa‐1,3‐cycloalcanes
Authors: Satgé J. , Dousse G.
Published: December 2004

The action of the α‐, β‐ and γ‐diols on the dialkyl(aryl)‐bis(dialkylamino) germanes R2Ge(NR'2)2 leads, in high yields, to the dialkyl(aryl)‐2,2‐germa‐2‐dioxa‐1,3‐cycloalkanes.

The IR. and NMR. spectral study in the presence of Eu(Dpm)3 allowed to demonstrate a dimerisation by coordination in some of these heterocycles. In this complex, the germanium is hexacoordinated by association with the two oxygens of the second associate molecule. Its hybridation state is sp3d2 or spd4 (D3h symmetry, prismatic structure).

These low energy association are ruptured in solution at moderate temperatures; these heterocycles are monomers by ebulliometry in benzene.

This association is disfavoured by the presence of substituents on the cycle and by hindering substituents with donor effect on the germanium.

The diminution of nucleophilicity of the oxygens by mesomeric effect with neighbouring π systems also prevents any association.
The Photoelectron Spectra of NSCl, NSF and NSF3
Authors: Cowan D. O. , Gleiter R. , Glemser O. , Heilbronner E.
Published: December 2004

The photoelectron spectra of NSCl and NSF3 have been recorded. By comparison with the PE.‐bands of NSF and semiempirical calculations the first bands of NSCl and NSF3 are assigned.
Intracatenare Vernetzung von Gelatine mit Carbodiimid
Authors: Gardi A. , Nitschmann Hs.
Published: December 2004

Under suitable conditions it is possible to introduce into dissolved denatured gelatin molecules intracatenar cross‐links. Working with 2% solutions of commercial gelatin (Mn approximately 40000) at 40° and pH 5,75 and with water‐soluble carbodiimid as a condensing agent we succeeded in inserting 7–8 intracatenar amide bonds per molecule. The number of cross‐links introduced was determined by the decrease of free NH2 and COOH groups.

Using 4% solutions a gel melting point of the cross‐linked preparations below 0° was obtained as compared with the gel melting point of untreated gelatin at 28°.

The low viscosity and the behaviour in gel chromatography on Sepharose 6B show that the cross‐linked peptide chains are fixed as rather dense coils.

A small amount of the cross‐linking reagent remains covalently bound to the protein, as was shown with tritium labeled carbodiimid. The side reactions possibly responsible for this occurrence are discussed. The bonds between reagent and gelatin are fairly stable at acidic pH, but labile at alkaline pH.

The results of optical measurements (UV. and CD.) on cross‐linked gelatin will be reported in another paper.
9‐Methyl‐cis‐decalin‐1,3‐dion: Stereochemische Untersuchungen an 9‐Methyl‐cis‐decalin‐Derivaten. 5. Mitteilung über cyclische β‐Diketone
Authors: Zurflüh R. , Tamm Ch.
Published: December 2004

The synthesis and the spectral properties of the hitherto unknown 9‐methyl‐cis‐decalin‐1,3‐dione (16) are described. The keto‐enol equilibrium of 16 in various solvents was determined by NMR. spectroscopy. The configuration and conformation of a large number of intermediates and derivatives were determined.
Neue β‐Lactam‐Antibiotika. Über die Darstellung der 8‐β‐Phenylacetamido‐homoceph‐4‐em‐5‐carbonsäure (1). Modifikationen von Antibiotika, 7. Mitteilung
Authors: Scartazzini R. , Gosteli J. , Bickel H. , Woodward R. B.
Published: December 2004

The thiazolidine β‐lactam 3 adds acrolein in a Michael type reaction. The resulting 'carbinolamide 4 is converted to 8‐β‐phenylacetamido‐homoceph‐4‐em‐5‐carboxylic acid (1) by previously described methods.