bluuebunny/crossref_metadata_2025 huggingface dataset:
Nachbarǵruppeneffekte bei der Hydrolyse von Acetonyl‐Estern
Authors: Schätzle Elsbeth , Urheim Hans , Thürkauf Max , Rottenberg Max
Published: December 2004

Kinetic studies revealed that esters of hydroxyacetone undergo alkaline hydrolysis with participation of neighbouring groups, its rate being higher by a factor of at least 20 than could have been anticipated on the basis of inductive effects alone. The mechanism is discussed in terms of either nucleophilic or electrophilic intra‐molecular catalysis.
Neue Umlagerungen von Aryl‐allyl‐äthern und Allylphenolen. (Vorläufige Mitteilung)
Authors: Borgulya J. , Hansen H.‐J. , Barner R. , Schmid H.
Published: December 2004

In position 3 (and 5) substituted phenyl‐γ‐methyl (and phenyl)‐allylethers when subjected to the thermal CLAISEN‐rearrangement not only yield the expected o‐allyl‐phenols but in addition considerable amounts of the P‐allylated phenols. Migration to the para‐position is favoured by non‐polar solvents. This para‐migration of the substituted allylgroup is attributed mainly to steric factors. With sterically hindered, in ortho‐ or para‐position allylated phenols there was furthermore found an allyl‐phenol‐rearrangement: on sufficient heating to 200° these substances are transformed to the thermodynamically more stable para‐ resp. ortho‐allylphenols with inversion of the allyl group.
Verteilung der Radioaktivität in der Ratte nach Verabreichung von [14C]‐d,l‐α‐Tocopheryl‐acetat
Authors: Gloor U. , Weber F. , Würsch J. , Wiss O.
Published: December 2004

1. The radioactivity in various organs of rats was determined after peroral administration of 2 and 5 mg of [14C]d,lα‐tocopheryl acetate at intervals of half an hour to 88 days.
Synthese des 17,18‐Diornithin‐β‐corticotropin‐(1–24)‐tetracosapeptides, eines biologisch aktiven Analogons des adrenocorticotropen Hormons
Authors: Tesser G. I. , Schwyzer R.
Published: December 2004

β‐Corticotropin (ACTH) possesses a striking sequence of basic amino‐acids‐Lys‐Lys‐Arg‐Arg‐ (No. 15–18) which is apparently necessary for the corticotropic activity: synthetic N‐terminal peptides containing this sequence are active, those lacking for example the two arginines as in the hexadecapeptide II [2] [3] [4] are essentially inactive. We have synthesized 17,18‐diornithine‐β‐corticotropin‐(1–24)‐tetracosapeptide (III), an analogue of the highly active β‐corticotropin‐(1–24)‐tetracosapeptide (I), in which the arginine residues 17 and 18 are replaced by ornithine. Quite unexpectedly this analogue is as highly potent in vitro (SAFFRAN & SCHALLY) and in vivo (s.c. application, SAYERS test) as the tetracosapeptide with the ‘natural’ sequence. This equal potency holds also for lipotropic and melanotropic activity. We may conclude that the two guanidino groups of the arginines in pos. 17 and 18 are not essential for biological activity, but that they may be replaced by amino groups, as in ornithine. Due to the replacement of the guanidino groups by the more easily protectable amino group, the diornithine analogue III is more readily synthesized than the original diarginine polypeptide I.
Komplexometrische Mikrobestimmung von Schwermettallen mit Kobalt‐60 als radioaktivem Indikator
Authors: Fuchs A.
Published: December 2004

Nanogrammengen von Kobalt und anderen Schwermetallen können komplexometrisch bestimmt werden mit 60Co als radioaktivem Indikator, indem Kation und Chelat papierelektrophoretisch getrennt werden.
Etudes sur les matières végétales volatiles CXCVIII. Contribution à la connaissance des farnésènes
Authors: Naves Yves‐René
Published: December 2004

The dehydration of farnesols or nerolidols is similar to that of geraniol and nerol or linalool. It yields a mixture of hydrocarbons including trans‐β‐farnesene, two allofarnesenes, α‐curcumene, α‐, β‐ and γ‐bisabolenes, and triterpenes. The triterpenes result from dienisation of β‐farnesenes or α‐farnesenes with β‐farnesenes, or dimerization of allofarnesenes.
Die Reaktion von Isonitrilen und Nitrilen mit Alkali‐ und Erdalkalimetallen
Authors: Büchner W. , Dufaux R.
Published: December 2004

Isocyanides RNC and the isomeric nitriles, RCN, reacting with alkali or alkaline earth metals in liquid ammonia undergo reductive fission to metal cyanides and carbanions R−. The latter are ammonolized to the corresponding hydrocarbons.
Die Struktur des Alstonia‐Alkaloides Villalstonin
Authors: Hesse M. , Bodmer F. , Gemenden C. W. , Joshi B. S. , Taylor W. I. , Schmid H.
Published: December 2004

Es werden die Experimente beschrieben, die zur Aufstellung der Konstitutionsformel 2 für das «dimere» Indolalkaloid Villalstonin aus Alstonia macrophylla WALL. führten.
Synthèse de nouvelles tryptamines substituées
Authors: Stauffer Roland
Published: December 2004

1° Les esters des acides indolyl‐3‐acétiques sont obtenus avec de bons rendements à l'aide de résine sulfonique Dowex comme catalyseur d'estérification.
3‐Phenyl‐2‐azanaphtochinon
Authors: Felner I. , Schenker K.
Published: December 2004

The synthesis and some addition reactions of 3‐phenyl‐2‐azanaphtoquinone are described.
Langsame Inversion am pyramidal gebundenen Stickstoff: Isolierung und Epimerisierung diastereomerer N‐Methoxy‐3,3‐di‐methoxycarbonyl‐5‐cyan‐1, 2‐oxazolidine. Vorläufige Mitteilung
Authors: Müller K. , Eschenmoser A.
Published: December 2004

Two crystalline diastereomeric N‐methoxy‐3, 3‐di‐methoxycarbonyl‐5‐cyano‐1, 2‐oxazolidines (II and III) have been isolated. The pyramidal arrangement at the respective nitrogen atoms does not invert at room temperature. The ARRHENIUS activation energy for the epimerization of the thermodynamically less stable isomer to the more stable one in bromoform solution is 29,2 ± 0,5 kcal/Mol (log A = 14,2 ± 0,3).
Kristallstruktur und absolute Konfiguration von (+)‐Meloscin‐Nb‐methobromid
Authors: Oberhänsli W. E.
Published: December 2004

The crystal structure of the Nb‐methobromid of the alcaloid meloscin has been determined by three‐dimensional X‐ray crystallographic methods. The crystals belong to the orthorhombic space group P212121 with four molecules per unit cell. The cell constants are a = 10.01, b = 17.79, c = 11.43 Å. The absolute configuration has been obtained by the use of anomalous dispersion effects.
Revidierte Struktur von Verrucarin E. Eine Synthese des Antibioticums und verwandter β‐Acetyl‐Pyrrol‐Derivate. Verrucarine und Roridine, 18. Mitteilung [1]
Authors: Pfäffli P. , Tamm Ch.
Published: December 2004

The structure of Verrucarin E, an antibiotic isolated from Myrothecium verrucaria, has been corrected (cf. [4]) and shown to be that of 3‐acetyl‐4‐hydroxymethyl‐pyrrole (2) by comparison with a variety of β‐acetylpyrrole‐derivatives, whose NMR. chemical shifts and coupling constants are reported. Verrucarin E (2) has been synthesized in low yield from 3‐acetylpyrrole (12). The following previously unknown β‐acetylpyrrole‐derivatives are described: 3‐acetyl‐5‐methyl‐pyrrole‐2‐carbonic‐acid (11), 4‐acetyl‐2‐methyl‐pyrrole (13), 3‐acetyl‐4‐formyl‐pyrrole (7), 3‐acetyl‐1‐hydroxymethyl‐pyrrole (14), 3‐(3‐hydroxypropionyl)‐pyrrole (15), 3‐(3‐hydroxy‐2‐hydroxymethyl‐propionyl)‐pyrrole (16), and 3‐(3‐acetyl‐pyrr‐1‐yl)‐1‐(pyrr‐3‐yl)‐propan‐1‐one (17).
Gomphogenin‐Teilsynthese und Struktur des Calotropagenins. Glykoside und Aglykone, 319. Mitteilung
Authors: Lardon A. , Stöckel K. , Reichstein T.
Published: December 2004

Gomphogenin = 2α, 3β, 14β‐trihydroxy‐5α‐card‐20:22‐enolide (6) was synthetised through hydroxylation of uzarigenone (4), followed by reduction with LiAlH[OC(CH3)3]3. Treatment of its di‐O‐acetylderivative (7) with SOCl2 in pyridine gave di‐O‐acetyl‐β‐anhydro‐gomphogenin (3). 3 was identical with the product obtained by WATSON AND WRIGHT from Gomphocarpus fruticosus; this proves that the formulae suggested by COOMBE AND WATSON are correct.

From the mixture of about 7 unidentified cardenolides obtained by MITTAL et al. after WOLFF‐KISHNER reduction of ene‐dihydrocalactin we could now isolate and identify dihydrogomphogenin (6), dihydrocoroglaucigenin (11) and dihydro‐uzarigenin‐19‐acidlactone‐(19→3) (13). These results, together with former evidence and spectra, prove the structure of calotropagenin as 2α, 3β, 14β‐trihydroxy‐19‐oxo‐5α‐card‐20:22‐enolide (15) and give support to the formulation of calactin and calotropin as stereoisomers of formula 8, analogous to the formula of gomphoside established by COOMBE AND WATSON.
Bestimmung scheinbarer Aciditätskonstanten von schwachen Säuren in flüssigem Ammoniak durch Titration mit Hilfe von Glaselektroden
Authors: Baumann W. M. , Simon W.
Published: December 2004

A titration method for the determination of apparent acidity constants of weak acids in liquid ammonia (−38°C) using glass electrode cell assemblies is described.
Die Glykoside von Calotropis procera, R. BR.. Glykoside und Aglykone, 320. Mitteilung
Authors: Brüschweiler F. , Stöcklin W. , Stöckel K. , Reichstein T.
Published: December 2004

From the latex of Calotropis procera, HESSE et al. [2] had isolated free calotropagenin (8) and six of its glycosides. We now obtained three additional compounds: uzarigenin (4), syriogenin [10] (a 3 β, 14α, x‐trihydroxy‐card‐(20:22)‐enolide) and proceroside. The latter is a new glycoside containing a sugar moiety identical or stereoisomeric with those present in gomphoside, calactin and calotropin. Its aglycone, not yet known in free form, contains one (probably secondary) hydroxyl group more than calotropagenin and is most probably a 2α, 3β, 14β, x‐tetrahydroxy‐card‐(20:22)‐enolide.
Strahlungschemie von Kohlenwasserstoffen. 17. Mitteilung. Hexan‐NO
Authors: Menger André , Gäumann Tino
Published: December 2004

The influence of NO on the radiolysis of hexane at −70°C has been studied. The results allow the following interpretations: The bimolecular part of the hydrogen production is in contrary to N2O efficiently quenched by NO. This part involves non‐thermal hydrogen atoms and has a G‐value of about 1.4. All olefins are suppressed, probably in a secondary chain reaction with NO. The radical yield is drastically reduced by very low concentrations of NO, but by higher concentrations this decrease is slowed down. A reaction scheme proposed by BURRELL is able to explain these results.
Cardenolid‐korksäurehalbester und weitere Bufadienolid‐korksäurehalbester in Ch' an Su. Über Krötengifte, 36. Mitteilung
Authors: Höriger Niklaus , Živanov Dobrila , Linde Horst H. A. , Meyer Kuno
Published: December 2004

From the toad venom Ch'an Su the methyl esters of the cardenolide hydrogen suberates 3 and 6 were isolated, as well as a number of new bufadienolide hydrogensuberates. The partial synthesis of some of these compounds is described.
Synthèse électrochimique du phénylcyclopropane et du cyclopropanol. Note de laboratoire
Authors: Gerdil Raymond
Published: December 2004

The electrochemical synthesis of three‐membered carbocycles is described.
Photochromism in Bianthrone and Related Compounds. Part VI. The structure of the photocromic isomers of bianthrones
Authors: Korenstein R. , Muszkat K. A. , Fischer E.
Published: December 2004

The cyclic structure III is assigned to the C photochromic isomer of 1, 8′‐dimethylbianthrones on the basis of spectral and chemical evidence. Similar considerations indicate that this does not apply to the B photoisomers of bianthrones.
Mesomeric Vinyl Cations. Part III. Stereochemistry of cations derived from 2‐bromo‐1, 3‐dienes
Authors: Grob C. A. , Pfaendler H. R.
Published: December 2004

In contrast to their acyclic analogues, 2‐bromocyclohexa‐1, 3‐diene (11a) and 3‐bromo‐1, 5‐dimethyl‐cyclohexa‐1, 3‐diene (11b) do not react with silver ion, nor do they undergo solvolysis in 80% ethanol at temperatures up to 180°. The inertness to ionization of these cyclic bromodienes is attributed to steric inhibition of mesomerism involving the π electrons of the second double bond in the planar vinyl cation 12 and to the bent structure of this hypothetical intermediate.
Synthèses dans la série des bis‐indéno‐anthracènes, I Le tétraoxo‐5, 10, 15, 16‐tétrahydro‐5, 10, 15, 16‐bis‐indéno [2.1‐a; 2′.1′‐c] anthracène et le dihydro‐5, 16‐bis‐indéno [2.1‐a; 2′.1′‐c] anthracène
Authors: Chardonnens Louis , Schorderet François , Salamin Luc , Sunder‐Plassmann Paul
Published: December 2004

Starting from 5‐carboxy‐6‐methyl‐7, 12‐dioxo‐7, 12‐dihydro‐indeno [1.2‐a] fluorene (phthalacone‐carboxylic acid) the first title compound, XI, has been synthesized in 4 steps (overall yield 28%). By anindependent way the corresponding hydrocarbon (second title compound, IV) has been obtained in 3 steps (overall yield 35%) starting from 2, 3′‐bi‐indenyle and 1, 4‐naphthoquinone.
Synthesen von 2‐Pyronen aus α, β‐ungesättigten Säurechloriden und tertiären Aminen
Authors: Rey M. , Dunkelblum E. , Allain R. , Dreiding André S.
Published: December 2004

A new synthesis of 2‐pyrones has been developed. Two molecules of α, β‐unsaturated acid chlorides (8, 12 and 18) condense, with loss of two molecules hydrogen chloride, to pairs of substituted 2‐pyrones (9 and 10, 13 and 14, 19 and 20) when treated with triethyl amine in chloroform or methylene chloride at room temperature. In the case of 18, two additional products were obtained, namely the resorcinol derivative 21 and traces of the 1, 3‐cyclobutanedione derivative 22. Under the same conditions the α, β‐unsaturated acid chlorides 8, 15, 18 and 41 were condensed with trichloroacetyl chloride to give 6‐trichloromethyl‐2‐pyrones (42, 43, 44 and 46). These 2‐pyrones are valuable intermediates for the synthesis of 6‐carboxy‐2‐pyrones and 6‐methyl‐2‐pyrones.

A methyl group in β‐position of the α, β‐unsaturated acid chloride appears to be essential for the described condensations, for the acid chlorides 16 and 17 did not yield defined products and the acid chloride 40 reacted with trichloroacetyl chloride in a very low yield. It is considered that the described reactions proceed via the 1, 4‐addition of an acid chloride to a vinyl ketene or through the acylation of an intermediate anion by an acyl derivative as outlined in reaction scheme 1. The structures of the 2‐pyrones were confirmed by their spectroscopic properties, summarized in table 3, and by some of their chemical transformations.
Demethylierung des Lysergsäuregerüstes. 73. Mitteilung über Mutterkornalkaloide [1]
Authors: Fehr T. , Stadler P. A. , Hofmann A.
Published: December 2004

The N‐demethylation of the lysergic acid skeleton could be achieved by a new modification of the von Braun reaction. The formed cyanamide was reduced either with zinc in acetic acid or with hydrogen and Raney nickel.
Photochemische Umwandlungen, XXXVII [1]. Synthese von Methylen‐tetracyclo[3.2.0.02,7.04,6]heptan‐Derivaten
Authors: Prinzbach H. , Rivier J.
Published: December 2004

Several isopropylidene‐, benzylidene‐ and benzhydrylidene‐norbornadiene derivatives (11, 16) have been synthesized. The [2π+2π] cycloadditions leading to the tetracyclic isomers 12 and 17 resp. upon direct photoexcitation proceed practically quantitatively in the case of the trienes 11, much less specifically, however, with 16. Sensitization by acetone or fluorenone allows the isolation of the quadricyclanes 17 in 20–90% yields.
Recherches dans la série des cyclitols, XLI. Synthèses de deux cyclopentane‐pentols
Authors: Wolczunowicz G. , Bors L. , Cocu F. , Posternak Th.
Published: December 2004

Two new cyclopentane‐pentols, namely the 1, 2, 3, 4/5‐ and 1, 2, 3/4, 5‐isomers have been prepared by hydroxylation of the three 3, 4, 5‐trihydroxy‐1‐cyclopentenes. The stereoselectivity of some hydroxylating agents is discussed.
The Interaction of Nonbonding Orbitals in Carbonyls
Authors: Swenson Jerrald R. , Hoffmann Roald
Published: December 2004

In dicarbonylen wie Glyoxal oder Benzochinon bilden die nichtbindenden Sauerstofforbitale delokalisierte Molekelorbitale mit verschiedenen Energien. Wir berichten über EHT‐ und CNDO/2‐Berechnungen einiger Dione und Trione. Die berechnete Aufspaltung zwischen den «nichtbindenden» Kombinationen wird auf der Grundlage der «through‐space» und «through‐bond» Wechselwirkung analysiert. Bei den tiefliegenden nichtbindenden Orbitalen der Carbonylgruppen scheint der zweite Faktor zu dominieren. Gerüst‐σ‐Orbitale und nichtbindende Sauerstofforbitale sind stark miteinander gemischt.
Vibrations de valence CH/CD fondamentales et harmoniques de dérivés halogénés du méthane et du deutériométhane
Authors: Avanessoff M. , Thang Ho Dac , Gäumann T.
Published: December 2004

The fundamentals and overtones of the CH stretching vibrations of a number of halogenated methanes and deuteriomethanes are compared with a hypothetical model consisting of isolated groups. The anharmonicity constants are evaluated and lie between −20 cm−1 and −130 cm−1 for the CH and CD stretching vibrations. The value of the anharmonicity constant for a coupling between two different modes of vibration is always greater (in absolute numbers) than its value for an overtone of one frequency. The constant is larger for a symmetric mode than for an asymmetric mode in the case of a CH vibration; the contrary is true for a CD bond. Complex interactions between different vibrations often strongly modify the spectra of the overtones. It is shown, however, that the conception of an isolated group is helpful for evaluating the spectra of these substances.
The Structure of 2,5‐Semiquinones derived from 1,6‐Bridged [10] Annulenes
Authors: Gerson F. , Müllen K. , Vogel E.
Published: December 2004

ESR. spectra are reported for the radical anions of the diketones I and II (see below), recently prepared from 1, 6‐methano[10]annulene and its 11, 11‐difluoro‐derivative, respectively [1]. The π‐spin populations of I⊖ and II⊖ are shown to be incompatible with the structure A an enedione‐norcaradiene. Although the alternative structure B of a [10]annulenequinone is acceptable for both I⊖ and II⊖, the ESR. data is more satisfactorily rationalized in terms of a structure ‘intermediate’ to A and B. This is particularly true for the radical anion I⊖, for which the π‐spin populations suggest a structural ‘shift’ B → A relative to II⊖. Structures A and B were postulated [1] for the neutral diketones I and II, respectively.
Recherches en vue de la synthèse de barbituriques organostannylés, II
Authors: Maire Jean Claude , Van Rietschoten Jurphaas
Published: December 2004

(a) The synthesis of 2,4,6‐trioxo‐1, 3‐di‐tributylstannyl‐hexahydropyrimidine is described.

(b) Trimethyltin hydride is found to add in a photochemical reaction to the terminal double bond of diethyl allyl malonate and allyl methyl malonate, giving respectively diethyl‐(3‐trimethylstannylpropyl)‐ (1) and diethyl‐(3‐trimethylstannylpropyl) (2) methyl‐malonates.

Treated with urea under the usual conditions, (1) and (2) yield organostannyl barbituric acids.
A Photoelectron‐spectroscopic investigation of the Homoconjugative Interaction between π‐ and Walsh‐Orbitals in endo‐ and exo‐Cyclopropano‐norbornene
Authors: Bischof P. , Heilbronner E. , Prinzbach H. , Martin H. D.
Published: December 2004

Photoelectron spectra of endo‐ and exo‐cyclopropano‐norbornene ( = endo‐ and exo‐tricyclo[3.2.1.02.4]octa‐6‐ene) show that a significant homoconjugation exists between the π‐orbital of the double bond and the symmetric Walsh‐es‐orbital of the cyclopropane ring in the exo‐isomer, whereas the interaction is negligeable in the endo‐derivative.
Alkaloide Von Bulbocodium vernum L Inhaltstoffe der Liliaceae‐Wurmbaeoideae. 75. Mitteilung
Authors: Šantavý F. , Sedmera P. , Snatzke G. , Reichstein T.
Published: December 2004

From whole plants of Bulbocodium vernum L. the flavone luteoline (I) and the alkaloids colchicine (II), N‐formyl‐N‐deacetylcolchicine (III), 3‐demethylcolchicine (V), (+)‐bulbocodine (IX) and (−)‐kreysigine (XI) were isolated in crystals. The presence of 2‐demethylcolchicine (IV), ß‐ (VII) and γ‐lumicolchicine (VIII), demecolcine (VI) and five not identified alkaloids was demonstrated by thin‐layer chromatography. On the basis of ultraviolet, infrared and mass spectra, PMR.‐analysis (Overhauser effect), and circular dichroism, the (6a‐R, 8a‐S)homo‐proaporphine structure IX, with one methoxy group at C‐2, has been assigned to (+)‐bulbocodine. The (6a‐R)‐structure (XI) was deduced for (−)‐kreysigine by comparing its optical rotation and circular dichroism which the values of (−)‐multifloramine (X), the structure of which is known.
Isolierung und Abbau von Sordarin. 1. Mitteilung über Sordarin
Authors: Hauser D. , Sigg H. P.
Published: December 2004

Sordarin (C27H40O8), an antifungal mould metabolite of Sordaria araneosa, has been degraded to the aglykon sordaricin (C20H28O4) and 6‐desoxy‐4‐O‐methyl‐D‐altrose, a hitherto unknown sugar.
The Structure of the Ferrocenyl‐Methyl Cation. Preliminary communication
Authors: Gleiter Rolf , Seeger Rolf
Published: December 2004

Using a modified Extended Hückel (S. C. C.) procedure the structure of the ferrocenyl‐methyl cation has been calculated. The result is a structure (V) with about equal overlap population between all FeC bonds. The methylene group is bent towards the iron atom and both rings are tilted.
Solvolysis and Isomerization of cis‐ and trans‐1‐Bromo‐1‐(p‐anisyl)‐propene (α‐Bromoanethole) Mesomeric Vinyl Cations, Part V
Authors: Grob C. A. , Nussbaumer R.
Published: December 2004

The influence of a β‐methyl group on the reactivity of two stereoisomeric vinyl bromides has been studied. In 80% ethanol cis‐(8) and trans‐α‐bromoanethole (9) undergo first order reactions leading to p‐methoxypropiophenone (15), 1‐ethoxy‐1‐(p‐anisyl)‐propene (16) and p‐anisylpropyne (12). Solvolysis of the cis isomer 8 is accompanied by isomerization to the more stable trans isomer 9 which is approx. eight times less reactive than 8. Cis‐trans isomerization is also observed in nitrobenzene at 150°.

These results are in agreement with the unimolecular substitution‐elimination (SN1−E1) mechanism which competes with cis‐trans isomerization at the ion pair stage.

The solvolysis rate of 9 is slightly lower and that of 8 somewhat higher than the rate of α‐bromo‐p‐methoxystyrene (3c). In the absence of other effects a β‐methyl group therefore slightly depresses the ionization rate, presumably by steric hindrance of solvation. These results confirm the negligible polar influence of a β‐methyl substituent on the stability of vinyl cations.
Composés d'addition des halogénures de niobium (V) et de tantale(V): III. Détermination de constantes de stabilité par résonance magnétique nucléaire
Authors: Merbach A. , Bünzli J. C.
Published: December 2004

In view of a systematic study of the Lewis acidity of niobium (V) and tantalum (V) halides, NMR. methods for the determination of stability constants are discussed. In the case of rapid exchange chemical shifts are used to determine the relative amounts of adduct(s) and free base(s) in equilibrium. In the case of slow exchange the relative concentrations of the species are given by the peak areas.
Konfigurative Zusammenhänge in der Muscarinreihe; Chiralität des epi‐, allo‐ und epiallo‐Muscarins, des Muscarons und allo‐Muscarons. Zur biogenese des muscarins 37. Mitteilung über muscarin und verwandte stoffe
Authors: Bollinger H. , Eugster C. H.
Published: December 2004

The chirality of all stereoisomeric muscarines has been determined. (–)‐Muscarine chloride was converted to (+)‐normuscarine, which in turn was oxidized to (+)‐normuscarone. Epimerisation by acid catalysis of the latter gave a mixture of the C(2)‐epimers, namely (+)‐normuscarone and (–)‐allo‐normuscarone. From these were prepared by reduction with LiAlH4 optically active stereoisomeric noralcohols. The natural stereoisomeric muscarines so far isolated are: (+)‐(2S, 3R, 5S)‐muscarine, (–)‐(2S, 3R, 5R)‐allo‐muscarine and (+)‐(2S, 3S, 5S)‐epi‐muscarine. Identical chirality appears only at C(2). This fact has to be taken into consideration for further speculations about the biogenesis of muscarines.

Optically active muscarone and normuscarone exhibit a strong Cotton effect at 300 nm, which is interpreted in terms of absolute configuration by analogy to optically active substituted cyclopentanones. Optically active allo‐normuscarone exhibits a very weak Cotton effect only, presumably because of predominant pseudo‐rotation.

The relative stability of the stereoisomeric norketones has been determined. Normuscarone (cis‐2,5) is by 0,39 kcal/mol more stable than allo‐normuscarone (trans‐2,5).
Unusual Features in the ESR. Spectra of 1, 6‐Methano[10] annulene Radical Anion. A modified mcconnell equation for non‐planar π‐radicals
Authors: Gerson F. , Müllen K. , Vogel E.
Published: December 2004

ESR. spectra of the radical anions of 1, 6‐methano[10]annulene (I) and its 2,5,7,10‐tetradeuterio derivative II are reported for a temperature range of over 100°. The abnormally small magnitudes of the α‐proton coupling constants are attributed to the deviation of the tenmembered π‐perimeter from planarity; an extension of the McConnell equation is proposed to achieve agreement between theory and experiment. It is suggested that the marked temperature‐dependence of the ESR. spectra arises from slight changes in geometry which for I⊖ should have a more pronounced effect on the α‐proton coupling constants than for planar π‐radicals.
Steroid Total Synthesis, Part IV; (±)‐13β‐ethyl‐17β‐ethynyl‐17β‐hydroxy‐gon‐4‐en‐3‐one
Authors: Rosenberger M. , Fraher T. P. , Saucy G.
Published: December 2004

The title compound (Norgestrel), a potent progestational agent, has been prepared by a new total synthesis. The scheme is based on earlier work with BCD‐tricyclic intermediates, condensation of 2‐ethyl‐cyclopentane‐1,3‐dione with 2‐[2‐diethylamino‐ethyl]‐6‐[4‐t‐butoxy‐pentyl]‐tetrahydropyran‐2‐ol being the key step. The synthesis features the addition of acetylene to a Δ5(10)‐4‐oxa‐17‐keto intermediate, followed by a novel transformation to the final product.
Eine neuartige Fragmentierung bicyclischer Enoläther Verfahren zur Darstellung macrocyclischer Lactone
Authors: Becker J. , Ohloff G.
Published: December 2004

Vicinal α‐hydroperoxy‐tetrahydropyranyl ethers annelated to cyclododecane are smoothly converted by homolytic fission in about 75% yield to a mixture of the macrocyclic lactones 3, 4, and 5. Based on this observation, an economically feasible synthesis of Exaltolide1 (>65% yield) has been developed. The mechanism of this new β‐fragmentation reaction is discussed.
Eine neuartige radikalinduzierte intramolekulare Gruppenübertragung. Synthese von 18‐Cyan‐corticosteroiden. Über Steroide, 225. Mitteilung
Authors: Kalvoda J. , Botta L.
Published: December 2004

A radical‐induced transfer of an entire functional group in steroid derivatives is described: the photolysis of an 11β‐nitrite function initiates the migration of a nitrile group from the 20‐ to the 18‐position. The reaction was used for the synthesis of new 18‐cyano‐corticoids.
Über tribenzylierte D‐Gluco‐ und D‐Galaktopyranoside. 2. Mitteilung über verätherte Kohlenhydrate
Authors: Stanek J. , Sele A. , Jaques R. , Rossi A.
Published: December 2004

The synthesis of ethyl‐3,4,6‐tri‐O‐benzyl‐D‐glucopyranoside and of ethyl‐3,4,6‐tri‐O‐benzyl‐D‐galactopyranoside is described. These compounds are isomers of ethyl‐3,5,6‐tri‐O‐benzyl‐D‐glucofuranoside, GLYVENOL®, a substance displaying interesting pharmacological actions.
Eine neue Synthese des Antibioticums Pyrrolnitrin
Authors: Gosteli J.
Published: December 2004

2‐Methyl‐4‐(2‐nitro‐3‐chloro‐phenyl)‐5‐ethoxycarbonyl‐pyrrole is prepared in six steps from 2‐amino‐3‐chloro‐toluene. As the former compound has been converted into pyrrolnitrin by Nakano et al. [4], the reaction sequence described here constitutes a novel synthesis of the antibiotic.
Hetarylnitrenes V. Reactions of Tetrazolopyrazine Ring Contraction of Nitrenodiazines in Solution. Preliminary communication
Authors: Wentrup Curt
Published: December 2004

Thermolysis of tetrazolopyrazine (1) in organic solvents gives pyrazinylnitrene (2) which undergoes ring contraction to 1‐cyanoimidazole (3). 7‐Methyl‐5‐methylthio‐tetrazolo[1,5‐c]pyrimidine (4) likewise gives 1‐cyano‐2‐methylthio‐4‐methyl‐imidazole (6). The two tetrazoles also undergo ring contraction to 1‐cyanoimidazoles by gas chromatography, and 1 gives a low yield of 3 by photolysis. Thermolysis of 1 and 4 in cyclohexane gives aminopyrazine (7) and 6‐amino‐4‐methyl‐2‐methylthio‐pyrimidine (8), respectively. Tetrazolo[1,5‐a]pyrimidines (9) give only 2‐aminopyrimidines (10).

1‐Cyanoimidazole, formed by thermolysis of 1 in acetic acid, reacts further to give 1‐acetylimidazole, which with more acetic acid gives imidazole and acetic anhydride. An earlier report [2] of ring expansion of pyrazinylnitrene in acetic acid is discredited.

In protic deuteriated solvents (D3O, CH3OD), tetrazolopyrazine reacts as an enamine, specifically exchanging HC(6) for deuterium.
Uber Pterinchemie. 41. Mitteilung [1]. Eine neue Synthese von D, L‐Biopterin
Authors: Viscontini M. , Frei W. F.
Published: December 2004

– Die Kondensation von D, L‐2,3‐O‐Isopropyliden‐4‐methyl‐erythrulose mit 2,4,5‐Triamino‐6‐hydroxypyrimidin wird beschrieben. Die Luft‐Oxydation des hydrierten Kondensationsproduktes führt zu D, L‐1′,2′‐O‐Isopropyliden‐biopterin ohne Abspaltung der Seitenkette. Durch hydrolytische Abspaltung der Isopropylidengruppe wird in guter Ausbeute reines, isomerenfreies D, L‐Biopterin erhalten.
Intramolekulare Übertragung von elektronischer Anregungsenergie in Spiroverbindungen
Authors: Labhart H. , Pantke E. R. , Seibold K.
Published: December 2004

It is shown that the observation of the degree of polarization of the fluorescence of 9,9′‐spirobifluorene VI and of 2,2′‐diamino‐7,7′‐dinitro‐9,9′‐spirobifluorene VII allows a determination of the rate constant for energy transfer from the initially excited to the unexcited part. The rate constants are of the order of 108 s−1 for VI and 3 · 109 s−1 for VII. The corresponding electronic matrix elements of interaction are evaluated. They are rather due to the Coulomb‐interaction of the transition densities than to spiroconjugation. In VI the coupling vanishes in the equilibrium conformation, vibronic effects must be evoked for explaining its existence.
Aktivierungsanalytische Bestimmung von seltenen Erden in Gesteinsstandards und in Mondproben
Authors: Krähenbühl U. , Rolli H. P. , von Gunten H. R.
Published: December 2004

The content of rare earth elements was analysed in USGS‐standard rocks BCR‐1 and G‐2 and in lunar fines samples from Apollo‐12 using activation analysis techniques.
Kinetics of Oxygen Exchange in the System BrO ‐ H2O (D2O)
Authors: Gamsjäger H. , Grütter A. , Baertschi P.
Published: December 2004

The kinetics of oxygen exchange between water (H2O, D2O) and 18O‐labelled bromate ion has been investigated over the range of 1.7 ≤ pH ≤ 14.3 and 20 ≤ °C ≤ 95. At 60° and ionic strength I ≃ 1.0M (NaNO3), the experimental results were consistent with the rate laws (R in moll−1 s−1):

From the temperature dependence of the rate constants the activation parameters ΔH≠, ΔS≠ and ΔC≠ were derived.

In the acid‐catalysed region the form of the rate law and the direction of the solvent isotope effect were the same as previously found, but the numerical values of ΔH≠ and k2H/k2D differ considerably. For the spontaneous and the OH−‐catalysed exchange reactions bimolecular displacement mechanisms are proposed.
Photochemische Reaktionen. 68. Mitteilung. Die Photoisomerisierung von α,β‐ungesättigten γ,δ‐Epoxyketonen: 9α, 10α‐ und 9β, 10β‐Oxido‐3‐oxo‐17β‐acetoxy‐Δ4‐östren
Authors: Bauer D. , Lizuka T. , Schaffner K. , Jeger O.
Published: December 2004

Irradiation in the n→π* absorption band of the α,β‐unsaturated γ,δ‐epoxyketone 5 in ethanol at −65° exclusively afforded the rearranged ene‐dione 13, whereas at + 24° under otherwise unchanged reaction conditions or upon triplet sensitization with Michler's ketone and with acetophenone at + 24° essentially identical mixtures of 13 (major product), 14, and 15 were obtained. Selective π→π* excitation of 5 at −78° and + 24° led to similar product patterns. The 9β,10β‐epimeric epoxyketone 7 selectively isomerized to 14 and 15 at + 24° and n → π* or π → π* excitation.

Neither the epoxyketones 5 and 7 nor the photoproducts 13–15 were photochemically interconverted. In separate photolyses each of the latter gave the double bond isomers 16, 18, and 19, respectively. Cleavage of 13 to the dienone aldehyde 17 competed with the double bond shift (→ 16) when photolyzed in alcoholic solvents instead of benzene.

The selective transformations 5 → 13 (at −65° and n → π* excitation) and 7 → 14+15 are attributed to stereoelectronic factors facilitating the skeletal rearrangements of the diradicals 53 and 55, the likely primary photoproducts resulting from epoxide cleavage in the triplet‐excited compounds 5 and 7, via the transition states 54, 56, and 57. The loss of selectivity in product formation from 5 at higher temperature and n → π* excitation or triplet sensitization is explicable in terms of radical dissociation into 58 and 59 increasingly participating at the secondary thermal transformations of 53. The similar effect of π → π* excitation even at −78° indicates that some of the π,π* singlet energy may become available as thermal activation energy. It is further suggested that the considerably lesser ring strain in 14 and 15, as compared with 13, is responsible that selectivity in product formation from 7 is maintained also at +24° and at π → π* excitation.
Photochemische Cycloadditionen von 3‐Phenyl‐2H‐azirinen mit aktivierten Doppelbindungen. Vorläufige Mitteilung
Authors: Jackson B. , Märky M. , Hansen H.‐J. , Schmid H.
Published: December 2004

Irradiation of 2‐methyl‐ (1a), 2,2‐dimethyl‐ (1b) and 2,3‐diphenyl‐2H‐azirine (1c) in the presence of diethyl mesoxalate yields the corresponding 4‐phenyl‐5,5‐diethoxycarbonyl‐3‐ oxazolines 3a–c. Similar cycloadducts are observed (cf. 6) by irradiation of 1b and 1c in the presence of trifluoroacetophenone. When ethyl cyanoformate is used as trapping agent photolysis of 1b or 1c leads to cycloadducts with the carbonyl and nitrile group, respectively which are present in the cyanoformate.
Photochemie in der Vitamin D‐Reihe. I. Kinetik und Quantenausbeuten der Ergosterinbestrahlung bei λ = 253,7 nm
Authors: Pfoertner K. , Weber J. P.
Published: December 2004

Irradiation of Δ5,7‐9α, 10β‐steroids in solution with λ = 253,7 nm yielded no Δ5,7‐9β, 10α‐steroids andvice versa. No back reaction from precalciferol2to ergosterol could be detected by kinetic measurements. This leads to the conclusion that with the mercury resonance line only ring opening and 6,7‐cis/transisomerization but no ring closure occurs.
Photochemie in der Vitamin D‐Reihe. II. Die Wellenlängenabhängigkeit der Photoisomerisationen des Präcalciferols
Authors: Pfoertner K.
Published: December 2004

In addition to the known ring opening at shorter wavelengths it was found that ring opening in Δ5,7‐steroids occurs also at λ > 300 nm. Ring closure of the corresponding seco‐ steroids in this region was confirmed. The existence of three rotational isomers with respect to the 5,6‐bond is assumed to be responsible for the observed wavelength dependency of the photoisomerizations of previtamin D. In this case the 5,6‐s‐trans isomer should absorb uv light at shorter wavelengths yielding tachysterol whereas the two 5,6‐rotational isomers with skew conformation should absorb at longer wavelengths yielding lumisterol and ergosterol, respectively.
Thermisches Verhalten von 1,2‐Dipropenylbenzolen
Authors: Heimgartner H. , Hansen H.‐J. , Schmid H.
Published: December 2004

1‐cis, 2‐cis‐Dipropenylbenzene (cis, cis‐1) isomerises thermally at 215–235° with 1st order kinetics to give trans, cis‐1 and vice versa. At equilibrium 89% trans, cis‐ and 11% cis, cis‐1 are present. It is shown by thermal rearrangement of cis, cis‐2′, 2″‐d2‐1 that the isomerisation is attributable to aromatic [1, 7a]‐sigmatropic H‐shifts. trans, trans‐1 rearranges thermally at 225–245° to yield 2, 3‐dimethyl‐1, 2‐dihydronaphthalene (2). The formation of 2 can be visualized by disrotatory ring closure followed by an aromatic [1, 5s]‐sigmatropic H‐shift. 2 is also formed when, cis, cis‐ or trans, cis‐1 are heated for 153 h at 225°. Besides 2 a small amount (3%) of 1‐ethyl‐1, 2‐dihydronaphthalene (5) is formed. The rearrangement of trans, trans‐1 and trans, trans‐2′, 2″‐d2‐1 shows a secondary isotope effect kH/kD = 0,90.
The π‐Orbital Sequence in Norbornadiene and Related Hydrocarbons
Authors: Heilbronner E. , Martin H.‐D.
Published: December 2004

A method outlined previously [1] is used to show that in norbornadiene (3) the b2(π) orbital lies above a1(π), as predicted by theory. This indicates that in 3 through‐space interaction between the two basis π‐orbitals πa and πb is more important than through‐bond interaction.

Analysis of the PE.‐spectra of 8‐isopropylidene‐tricyclo[3.2.1.02,4]‐octane (13) and the corresponding octene (15) confirms that the π‐orbital πc of the exocyclic double bond conjugates more strongly with the symmetric Walsh‐orbital es of the cyclopropano moiety than with the π‐orbital πa of a double bond in the same position.
Reactions of Group 3 Metal Alkyls in the Gas Phase. Part 10: The addition of olefins to the monomeric diisobutylaluminiumhydride
Authors: Egger Kurt W.
Published: December 2004

The relative rate constants for adding ethylene (k1), propylene (k2) and 2‐methyl‐but‐1‐ene (k3) to gaseous diisobutylaluminium hydride produced in situ from AliBu3 have been measured in the temperature range 104–169° in the presence of an excess of equimolar olefin mixtures. The following temperature dependences of the relative rate constants have been obtained:

Two compensating factors determine the rate of addition of olefins to AlH and AlC bonds: (a) the steric effect, reflected in the differences in the preexponential factors and (b) the polar effects, reflected in differences in the activation energies.

In the addition of olefins to R2AlH bonds in contrast to R2AlC bonds, the steric effect (a) does not always overrule the opposing energy effect. At temperatures below 125° e.g., isobutene adds slightly faster to HAliBu2, than ethylene. These results are in perfect agreement with expectations based on a reaction mechanism involving a tight asymmetric quadrupolar 4‐centre transition state similar to that postulated earlier for the addition of olefins to AlC bonds.
Untersuchungen der Symmetrieverhältnisse in äquatorial koordinierten 2:1‐Arylazo‐CoIII‐Komplexen mit Hilfe der Protonenresonanz
Authors: Schetty G. , Steiner E.
Published: December 2004

The magnetic equivalence of ligand protons was examined with aid of NMR. spectroscopy for a large number of 1:2 CoIII‐complexes of tridentated azo dyestuffs forming a representative cross section of the whole class of substances. It was established by this investigation that ligands with a moderately polarised azo group have a particular inclination to form asymmetrical complexes in which the protons of the two ligands are not magnetically equivalent. On the other hand, ligands having a non‐polarised or a strongly polarised azo group tend to form symmetrical complexes. In three cases both symmetrical and asymmetrical complexes were isolated. As in previous investigations [1], up to a total of 5 complexes were again observed, which indicates at least two causes governing the symmetry conditions. The phenomena described here could be explained with an alternative coordination of the two azo nitrogen atoms. On the basis of the NMR. results, however, preference is given to an exchange of the azo with the hydrazone form.
Notiz über das Vorkommen von 4′,5‐Dihydroxy‐3,3′,6,7‐tetramethoxyflavon (Chrysosplenetin) in Plectranthus marrubioides HOCHST (Labiatae)
Authors: Hensch M. , Eugster C. H.
Published: December 2004

Chrysosplenetin (4′, 5‐dihydroxy‐3,3′, 6,7‐tetramethoxyflavon) has been isolated from the leaves of Plectranthus marrubioides HOCHST (Labiatae).
Synthèse en phase solide de la thyrocalcitonine humaine
Authors: Rivaille Pierre , Milhaud Gérard
Published: December 2004

A convenient and rapid synthesis of humain thyrocalcitonin using the benzylhydrilamine resine is reported.
Eine neue 2‐Allylphenol‐Cumaran‐Umlagerung
Authors: Schmid E. , Fráter Gy. , Hansen H.‐J. , Schmid H.
Published: December 2004

2‐(1′‐Arylallyl)‐phenols (9, 10, 11, 12, 13, 14, 15, 16) are transformed on heating in N, N‐diethylaniline at 225° into trans‐2‐aryl‐3‐methyl‐coumarans (26, 29, 32, 34, 36, 38, 40, 42) in excellent yields. The corresponding cis‐coumarans are minor products. Similar thermal behaviour is shown by 2‐(1′‐vinylallyl)‐phenols (7, 8) which are thermally converted into trans‐3‐methyl‐2‐vinyl‐coumarans (24, 19) and 5‐methyl‐2,5‐dihydro‐(1‐benzoxepins) (25, 18). The latter compounds are thermally unstable and rearrange to give approximatively 3:1 mixtures of trans‐ and cis‐3‐methyl‐2‐vinyl‐coumarans (24, 19). Reaction mechanisms for these new thermal rearrangements are discussed in schemes 2, 3 and 4.

The 2‐(1′‐arylallyl)‐phenols 9, 12 and 14 yield under acidic conditions (HBr/HOAc) the expected 3‐aryl‐2‐methyl‐coumarans 28, 35, 39 along with 2‐aryl‐3‐methyl‐coumarans 26, 34, 38 and 2‐aryl‐2‐methyl‐coumarans 44, 45, 46. The intervention of phenonium ions is discussed for these reactions (cf. scheme 5).

When the 2‐(1′‐arylallyl)‐phenols 12 and 14 were irradiated in benzene solution with a mercury high pressure lamp, the main products obtained were 3‐aryl‐2‐methyl‐coumarans 35 and 39 which were formed rapidly. 2‐Aryl‐3‐methyl‐coumarans yield also 3‐aryl‐2‐methyl‐coumarans, when irradiated in benzene solution.
On the Correlation between Photoelectron and Electronic Spectra. Part. II: Experimental indications about the shape of lone pair orbitals
Authors: Haselbach E. , Schmelzer A.
Published: December 2004

For a π‐molecular system containing two symmetry‐equivalent heteroatoms, a qualitative relationship between the difference in the n‐ionization potentials (ΔIP) and the difference between the n → π* excitation energies (ΔΔE) is derived, using semi‐localized orbitals as a basis. The comparison between ΔIP and ΔΔE yields information about the energies and/or the shapes of the two lone pair MO's in the model system. The results provide further insight into ‘through space’ and ‘through bond’ interaction concept introduced by Hoffmann.
Recherches dans la série des cyclitols XLIV. Synthèses de cycloses dérivés du cyclopentane
Authors: Cocu F. G. , Posternak Th.
Published: December 2004

The conversion to free ketoses by transketalisation of ethylene‐ketal and/or isopropylidene derivatives of polyhydroxy‐cyclopentanones has been investigated. The preparation of 2, 3‐dihydroxy‐cyclopentanone and of 2, 3‐dihydroxy‐cyclopentenone has been described.
The Photodecarbonylation of α‐Aryl Aldehydes: 1‐Formyl‐1‐methyl‐indan and heterocyclic analogues
Authors: Wolf H. , Gonzenbach H.‐U. , Müller K. , Schaffner K.
Published: December 2004

The singlet photodecarbonylation of the indanyl aldehyde 7 – a benzohomologue of laurolenal (1) and also a conformationally rigid ‘out‐of‐plane’ analogue of the α‐aryl aldehyde 4 previously studied [5] [6], – and of the heterocyclic derivatives 8–10 in degassed solutions, has been investigated. While 7 decarbonylates uniformly to the niethylindan 30 in close analogy to the examples studied previously, 8 and 9 decompose to the corresponding Δ2‐unsaturated compounds 33, 35 in addition to decarbonylation to 32, 34. The results provide an independent indication for intermediate photolytically formed radical pairs (a) in which heteroatoms facilitate radical removal of hydrogen from C(2), and thus introduce disproportionation to give unsaturated products + CH2O, competing with the otherwise exclusive alternative affording saturated products +CO.
Extraction liquide‐liquide par des esters alkylphosphoriques. II. Extraction des nitrates de béryllium et des autres alcalino‐terreux par le tri‐n‐butylphosphate
Authors: Brunisholz G. , Hirsbrunner W. , Aerny J.
Published: December 2004

The solvent extraction systems Be(NO3)2HNO3H2OTBP/kerosene and M(NO3)2H2OTBP/kerosene (TBP = tri‐n‐butylphosphate, M = Be, Mg, Ca and Sr) have been studied. The alkaline earths elements are poorly extracted. Only very high acidities allow better extraction of beryllium. The sequence of extraction of the alkaline earths elements by the TBP depends on the concentration of the cations and is Ca > Be > Sr > Mg if the metal concentration is lower than 2 M.
Quinazolines et benzodiazépines‐1, 4. LVI. Oxadiazolo‐1, 2, 4[4, 5‐d] benzodiazépines‐1, 4: synthése et passage aux oxazolo [3, 2‐d] benzodiazépines‐1, 4
Authors: Jaunin R. , Oberhänsli W. E. , Hellerbach J.
Published: December 2004

The tricyclic derivatives 4–14 can be prepared by 1, 3‐dipolarcycloaddition of the appropriate nitrile oxides on the corresponding 1, 4‐benzodiazepines. NaBH4 reduction of the esters 12–14 was found to proceed very readily; starting from 13 it is possible, by proper reaction conditions, to get in good yield either the monoalcohol 19 or the aminodiol 20. The alcohols 19 and 23 undergo an acid‐catalysed rearrangement which produces the amidoximes 24 and 26. The determination of the structure of 24 by X‐ray diffraction analysis is also presented.
Vier neue Metabolite von Giberella zeae: 5‐Formyl‐zearalenon, 7′‐Dehydrozearalenon, 8′‐Hydroxy‐ und 8′‐epi‐Hydroxy‐zearalenon
Authors: Bolliger G. , Tamm Ch.
Published: December 2004

From cultures of Gibberella zeae ergosterol, zearalenone (1) and hitherto unknown minor metabolites, i.e.. 5‐formyl‐zearalenone (6), 7′‐dehydrozearalenone (8), 8′‐hydroxyzearalenone (9) and 8′‐epi‐hydroxyzearalenone (11) were isolated. The production of zearalenone and its congeners proved to be very strongly dependent on the conditions of culture.

5‐Formyl‐zearalenone (6) as well as 3‐formylzearalenone (4) were synthesized from zearalenone (1) and characterized by the di‐O‐methyl derivatives 7 and 5 respectively. The structure of 7′‐ dehydrozearalenone (8) was deduced from spectral data. The di‐O‐methyl derivatives 10 and 12 respectively of the two corresponding epimeric 8′‐hydroxy derivatives 9 and 11 yielded the same β‐diketone 13. The keto‐enol equilibrium of 13 was studied.
Zur Kinetik der Perkow‐Reaktion
Authors: Konecny J. , Dousse R. , Rosales J.
Published: December 2004

The Perkow reaction of CH3COCHClCONHCH3 with (CH3O)3P is first order in both reactants. The reaction rates, the activation energies and the high negative entropies of activation have comparable values in benzene and in acetonitrile solutions.
Kinetic Investigation of a (6 + 4) Cycloaddition
Authors: Tanida Hiroshi , Pfaendler H. R.
Published: December 2004

Kinetics of the [6+4] Cycloaddition of tropone to cyclopenta‐1, 3‐diene were investigated. It was concluded that the mechanism of this cycloaddition is similar to that of the classic Diels‐Alder reaction.
Pyrazines. 2ème communication [1]. II. Synthèse de dihydro‐6,7‐5H‐cyclopenta[b]pyrazines alkylées
Authors: Flament Ivon , Sonnay Philippe , Ohloff Günther
Published: December 2004

Alkyl‐5H‐6,7‐dihydrocyclopenta[b]pyrazines are prepared by condensation of cyclopentenolones with alkylenediamines or of aliphatic α‐diketones with 1,2‐diaminocyclo pentanes. Products so obtained were dehydrogenated using palladium on activated charcoal, or copper chromite. NMR. and mass spectra are given for 21 bicyclic pyrazines and intermediates, and their IR. spectra are compared.
Synthèse du tétraéthoxycarbonyl‐1,1,6,6‐cyclodécadiyne‐3,8
Authors: Etournaud Alain , Wyler Hugo
Published: December 2004

A cyclisation of 1‐bromo‐5,5,10,10‐tetraethoxycarbonyl‐2,7‐decadiyne (9b) using NaH in dilute solution gives 1,1,6,6‐tetraethoxycarbonyl‐cyclodeca‐3,8‐diyne (8) in 17,6% yield. 9b is prepared by condensation of 1,1,6,6‐tetraethoxycarbonyl‐3‐hexyne with 1,4‐dibromo‐2‐butyne.