摘要:

Prostaglandins and Prostaglandin Intermediates. VIII. Synthesis of (1S, 5S)‐5‐Methyl‐2‐oxa‐bicyclo[3.3.0]octane‐3,6‐dione, an Important Intermediate for 8‐Methylprostaglandin C2The bicyclic lactone5is prepared by Meerwein‐Ponndorf‐Verley‐reduction of the chiral cyclopentyl acetic acid3. The stereoselectivity of this reaction is compared with that of complex met

ISSN:0021-8383    

DOI:10.1002/prac.19833250402

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

On Regularities of the π‐Electronic Structure of Heteroanalogous Polyvinylidene CompoundsStarting with simple forms of the equations for the eigenvalues and eigencoefficients of the π‐system of heteroanalogous polyvinylidene compounds3several regularities in the π‐electronic structure of these systems are derived and compared with known experimental facts. In this line several predictions are given for the properties of compounds unknown u

ISSN:0021-8383    

DOI:10.1002/prac.19833250403

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Kinetic Studies on the Autoxidation of OlefinsThe oxidabilities\documentclass{article}\pagestyle{empty}\begin{document}$ {{{\rm k}_{\rm p} } \mathord{\left/ {\vphantom {{{\rm k}_{\rm p} } {\sqrt {2{\rm k}_{\rm t} } }}} \right.\kern-\nulldelimiterspace} {\sqrt {2{\rm k}_{\rm t} } }} $\end{document}at 50°C were determined for 37 olefins, using chlorobenzene as the solvent and azodiisobutyronitril as the initiator. In the group of acyclic aliphatic olefins the oxidability rises with increasing number of alkyl groups bound to the double bond. This is also true for cyclic olefins, but in this case the ring size has also a great influence on the oxidability. So the oxidability decreases from five‐ring to eight‐ring cycloolefins. Particularly high oxidabilities are found in the case of olefins in which a phenyl group is attached directly to the CC‐dou

ISSN:0021-8383    

DOI:10.1002/prac.19833250404

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

3‐α‐Bromacetyl‐coumarines as Synthones for Heterocyclic Substituted Coumarines3‐α‐Bromacetyl‐coumarines2react easily and in high yields with thiourea and thioamide derivatives3and5, resp., to 4‐coumar‐3′‐yl‐thiazoles4and6, resp., as well as with N,N‐disubstituted thioamides11and N,N,N′,N′‐tetraalkylthiourea12to 5‐coumar‐3′‐yl‐oxathioliumsalts13and14, respectively. In a two‐step reaction2can be transformed by reaction with aniline17to 4‐coumar‐3′‐yl‐imidazoles21and 5‐coumar‐3′

ISSN:0021-8383    

DOI:10.1002/prac.19833250405

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Determination of Configurations by the Aid of Sterically Corresponding Epoxides. VIII. Glycidic Nitriles. I. Synthesis of 4‐Aryl‐1‐oxaspiro(2,5)octane‐2‐nitriles and 4‐Aryl‐1‐oxaspiro(2,5)octane‐2‐carboxylic Acid Methyl EstersThe condensation of 2‐aryl‐cyclohexan‐1‐ones (1–5) with ClCH2CN or ClCH2CO2CH3at 80°C in the presence of NaH and in dimethoxyethane yields the corresponding glycidic nitriles and the glycidic esters, respectively. The configuration and the preferred conformation of the two isomeric 1‐oxaspiro‐[2,5]octane derivatives (12 Aand12 B) formed have been determined by1H‐n.m.r. spectroscopy. Some earlier results from BOEKELHEIDEand SCHILLINGand from SCH

ISSN:0021-8383    

DOI:10.1002/prac.19833250406

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Partial Syntheses of Cardenolides and Cardenolide Analogues. VI. (20R)‐ and (20S)‐Cardanolides(20R)‐Dihydrodigitoxigenin (2) and (20S)‐dihydrodigitoxigenin (4) as well as their 3‐acetates3and5, respectively, were synthesized by catalytic hydrogenation of the appropriate cardenolides and separation by column chromatography on silica of the mixtures of stereoisomers. Hydroxymethylation of3and5followed by selective elimination yielded (20S)‐ and (20R)‐14‐hydroxy‐22‐methylene‐5β,14β‐cardanolide 3‐acetate (10and16), respectively.The biological activities of the synthesized 20‐stereoisomeric cardanolides are investigated and discussed. Cardanolides10and16have a strong inhibitory activity on the proliferation of Ehrlich ascites carcinom

ISSN:0021-8383    

DOI:10.1002/prac.19833250407

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Partial Syntheses of Cardenolides and Cardenolide Analogues. VII. Synthesis of A/B‐cis‐ and C/D‐cis‐linked Steroidal Mono‐ and Bis (α‐methylene‐γ‐butyrolactones)The synthesis of A/B‐cis‐ and C/D‐cis‐linked steroidal mono‐ and bis(α‐methylene‐γ‐butyrolactones)10–13,18and24by Reformatsky‐type reaction of 3β‐acetoxy‐14‐hydroxy‐5β, 14β‐androstan‐17‐one(6), 14‐hydroxy‐5β, 14β‐androstane‐3,17‐dione (8), 3β‐acetoxy‐14‐hydroxy‐5β,14β‐pregnan‐20‐one (17) and 14‐hydroxy‐5β,14β‐pregnane‐3,20‐dione (23), respectively, with ethyl α‐(bromomethyl)acrylate is described. All steroidal lactones exhibit strong inhibitory activity on the proliferation of Ehrlich ascites carcinoma cells in suspension culture. For inhibitory activity the lactone moiety at

ISSN:0021-8383    

DOI:10.1002/prac.19833250408

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Partial Syntheses of Cardenolides and Cardenolide Analogues. VIII. Lactone Ring‐Alkylated CardenolidesBase‐catalyzed alkylation of digitoxigenin (1), digitoxin (2), digoxigenin (3), and gitoxigenin‐3,16‐diacetate (4) with allyl bromide, allyl chloride or n‐propyl bromide in DMF resulted in the formation of the 22‐allyl‐, 21ξ,22‐diallyl‐, 22‐propyl‐, and 21ξ,22‐dipropyl‐derivatives5–14, respectively.The determination of the molecular biological activity of the derivatives

ISSN:0021-8383    

DOI:10.1002/prac.19833250409

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Partial Syntheses of Cardenolides and Cardenolide Analogues. IX. Cardenolide Derivatives with an Unsaturated Aldehyde Function at the Lactone RingOxidation of 22‐allyl‐digitoxigenin‐3‐acetate [1] and 22‐allyl‐digitoxin (4) with selenium dioxide resulted in the introduction of an oxygen function into the unsaturated C‐22 substituent of the cardenolide molecule. The isolated compounds were the 22‐(3′‐oxo‐prop‐1′‐en‐1′‐yl)‐derivatives3and6of1and4, respectively. The molecular biological activity of3was estimated to be about six times highe

ISSN:0021-8383    

DOI:10.1002/prac.19833250410

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Electrochemical Oxidation of Organic Compounds in Fluorosulfuric Acid. V. Anodic Behaviour of Aromatic Nitrocompounds, Nitriles, Amines, Acetamides, and OximesThe anodic behaviour of a series of methyl substituted nitrobenzenes, benzonitriles, aniline derivatives, acetanilides and acetophenone oximes was investigated by cyclic voltammetry at platinum electrodes in HSO3F at −76°C. With the exception of the parent compounds and partly of the monomethyl derivatives relatively stable cation radicals could be detected. In a second anodic wave in many cases the functionalization of a CH3‐group to CH2‐OSO2F took place. From a comparison of the peak potentials and from the dependence of the voltammetric curves on the scan rate follows that the aniline derivatives are oxidized without deprotonation of the −NH3+group, whereas for the nitrocompounds, nitriles and acetanilides a deprotonation of the functional group is coupled with the oxidation, and the cation radicals are stable onyl in the deprotonated state. A kinetic study of the subsequent reaction of some nitrocompounds was made and the deviating behavior of some acetanilides was found to be due to the anodic dimerization to benzidine der

ISSN:0021-8383    

DOI:10.1002/prac.19833250411

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY