摘要:

AbstractOxidative cyclization ofD‐galactose (p‐chlorophenyl)thiosemicarbazone gave 2‐(p‐chloroanilino)‐5‐(D‐galacto‐1,2,3,4,5‐pentahydroxypentyl)‐1,3,4‐thiadiazole (1), whose acetylation afforded 2‐[N‐acetyl‐N‐(p‐chlorophenyl)]‐amino‐5‐(D‐galacto‐1,2,3,4,5‐pentacetoxypentyl)‐ 1,3,4‐thiadiazole (3). Its periodate oxidation of the glycol groups gave 2‐(p‐chloroanilino)‐1,3,4‐thiadiazole‐5‐carboxaldehyde (4), which can be transformed into 1,2‐[2‐(p‐chloroanilino)‐1,3,4‐thiadiazol‐5‐yl]‐1‐hydroxy‐2‐oxoethane. A number of hydrazones of the formyl thiadiazole was prepared and its reduction with sodium borohydride gave 2‐(p‐chloroanilino)‐5‐hydroxymethyl‐1,3,4‐thiadiazole (6), whose acetylation gave a mono‐O‐acetyl derivative (7). Oxidation of the formyl thiadiazole

ISSN:0021-8383    

DOI:10.1002/prac.19863280102

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Electrochemical Reductive Alkylation of Azomethines with 1‐Bromadamantane and 9‐Bromo‐tetrahydro‐exo‐dicyclopentadieneElectrochemically generated radical anions of Schiffbases1a—11react in DMF and in the presence of bridgeheadhalogenides as 1‐bromoadamantane and 9‐bromo‐tetrahydro‐exo‐dicyclopentadiene to 1‐[α‐(aryl‐ or alkylamino)‐α‐arylmethyl]‐adamantanes and the correspondent 9‐tetrahydro‐exo‐dicyclopentadienes. In the course of SET‐mechanism originating bridgehead radicals couple with the azomethine‐radicalanions at the position of the highest unpaired electron density, which is predominantly the carbon of the C,N‐double bond. Only in cases when this density at the N‐atom is relatively high, or steric hindrance impedes C‐alkylation, N‐hydroalkylated products as N,N‐disubstituted 1‐aminoadamantanes and 9‐amino‐tetrahydro‐exo‐dicyclopentadienes are formed. Product distribution, cyclic‐voltammetric r

ISSN:0021-8383    

DOI:10.1002/prac.19863280103

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Syntheses of C‐Nucleosides and Analogs of C‐Nucleosides. IV. Preparation and Characterization of 5(S)‐ and 5(R)‐Tetrahydroxybutyl‐3‐methyl‐1,3‐oxazolidines1‐Deoxy‐1‐methylamino‐D‐hexitols1,2,3react with ketendithioacetals4to give the acyclic C‐nucleosides5,6and7. The structure of the compounds were verified by means of periodate oxidation and spectroscopic investigations. Some properties of the acyclic C‐nucleosides were investigated by acetalation reactions o

ISSN:0021-8383    

DOI:10.1002/prac.19863280104

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Studies on the Autoxidation of 1‐Phenylbuta‐1,3‐diene and 2‐Phenylbuta‐1,3‐dieneHydrogenation of the polymeric peroxides formed during the autoxidation of 1‐phenylbuta‐1,3‐diene (1) and 2‐phenylbuta‐1,3‐diene (10) at 50°C in an autoclave yielded 1‐phenylbutane‐3,4‐diol (5) and 2‐phenylbutane‐1,4‐diol (12), respectively.The LiAlH4reduction of 1‐phenylbuta‐1,3‐diene oxidate (50°C) yielded cinnamyl alcohols (4) as a major product.The oxygen‐containing polymeric products formed along with Diels‐Alder dimers during the oxidation of the title substances at 140°C showed no degradation after subjecting to hydrogen

ISSN:0021-8383    

DOI:10.1002/prac.19863280105

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractThe reaction of different 2‐amino‐4H‐pyrans (1, 10) with guanidine affords 2,6‐diaminopyrimidine derivatives (3). Treatment of the pyrans mentioned or their acetylated derivatives with trityl tetrafluoroborate does not yield pyrylium salts, and pyrid‐2‐one systems (8, 11, 14) are obtained from the 2‐amino‐4H‐pyrans (1, 10, 13) on treatment w

ISSN:0021-8383    

DOI:10.1002/prac.19863280106

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Stereochemistry of the 2‐Aryl‐cyclohexanones. I. Analysis of the Configuration and Conformation of the cis‐trans‐Isomeric 2,6‐Dimethyl‐2‐aryl‐cyclohexan‐1‐ones by the Aid of their OximesDesulfurization of the n‐butylthiomethylene ketone6with Raney nickel yields a mixture of trans‐ and cis‐stereoisomers7and8, the conformations of which are7Aand8B, respectively. While the ketone7gives rapidly and quantitatively the oxime9, the isomer8reacts much more slowly to a mixture of9and10. A detailed analysis of the configuration and conformation of the ketones7and8as well as

ISSN:0021-8383    

DOI:10.1002/prac.19863280107

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Synthesis, Reactivity and1H‐NMR‐Spectroscopy of 14,15‐Methylene Derivatives of the Androstane and Estratriene SeriesUnder the activating and syn‐directing effect of the 17‐hydroxy group the Simmons Smith cyclopropanation of 14,15‐unsaturated 17‐hydroxy steroids of the androstane and estratriene series1a, 5and9affords the 14,15‐methylene steroids2a, 6and10with cis position of the 14,15‐methylene and 17‐hydroxy groups in a stereospecific reaction. Oxidation of these compounds yields the 17‐keto derivatives3, 7and11, which were reduced to the compounds4a, 8and12with trans position of the 14,15‐methylene and 17‐hydroxy groups by complex hydrides or diborane. In a phase transfer catalyzed reaction dichloro‐ or dibromocarbene was added to 3β, 17β‐diacetoxy‐5α‐androst‐14‐ene1bforming the 14β, 15β‐dihalogenmethylene steroids13and14. The 17‐keto steroids7and11were transformed into 17‐methyl and 17‐ethynyl derivatives15–20. Cleavage of the cyclopropane ring of2a, 2band3by catalytic hydrogenation affords the 14β‐methyl derivatives21–23, the acid catalyzed ring opening with hydrogen chloride yields the 14β‐chloro, 15β‐methyl derivatives24–29. Structure elucidation has been established by1H n.m.r. and mass spectroscopy. The configuration at C17, C14 and C15 was also determined by means of1H n.m.r. spectroscopy, using the chemical shifts of the 18‐protons, the coupling constants and the chemical shifts of the 17‐protons. The configuration of the 17‐disubstit

ISSN:0021-8383    

DOI:10.1002/prac.19863280108

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Radical Reactions of N‐Heterocyclic Compounds. IV. ESR Investigation of H‐Transfer between Aminic Antioxydants and Peroxy RadicalsThe N‐radicals of pyrazole‐, imidazole‐ and indole‐derivatives were prepared in comparatively high concentrations at room temperature in benzene or toluene and their e.s.r. signals were interpreted. In H‐abstraction by free or to Co(III)‐coordinated tert.‐butylperoxy radicals from bifunctional heterocyclic substituted amines2–9, 11the following efficiency was ascertained: unhindered OH>aniline‐NH>heterocyclic‐NH, hindered OH‐groups. No radical attack on the exocyclic NH2‐group took place.The splitting constant concerning the heterocyclic nitrogen of nitroxyl radicals5a, 10awas in the range aNendo= 0.7 to 0.85 mT in contrast to exocyclic nitroxyls6a, 8a, 9a, 11apossessing aNexo= 1.0 to 1.1 mT. The interruption of the π‐conjugation between the heterocyclic and the aniline groups by insertion of a CH2‐group led to the decrease of the stability of the generated N‐radicals. In the case of anilinebenzimidazole9the Co(III)‐complexed endocyclic aminyl radical9bwas observed simultaneo

ISSN:0021-8383    

DOI:10.1002/prac.19863280109

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Photochemical Primary Processes of Xanthene Dyes. V. Investigations of the Influence of Micelles on the Photochemical Primary Processes of ErythrosineThe triplet state of erythrosine decays in water solution mono‐ and bimolecularly (k1= 0,85 · 104s−1; kbi= 7,6 · 108l/mol s). As results of the bimolecular triplet decay a half‐reduced and a half‐oxidized form of the dye are observed. The dye ions are localized in the Stern layer of cationic micelles. The triplet state of those dye ions, which are localized individually at micelles, decays only monomolecularly (k 1kM= 2,1 · 103s−1). If two or more dye ions are localized at a micelle, the bimolecular triplet decay takes place during the flash. Anionic micelles have no influence on the triplet decay processes

ISSN:0021-8383    

DOI:10.1002/prac.19863280110

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Picosecond Spectroscopic Investigations of 1‐Phenylazo‐2‐naphtholsThe photoisomerization of substituted 1‐phenylazo‐2‐naphthols is studied in fluid solution and in polymer film (cellulose acetate). With the help of picosecond spectroscopy the absorption from an excited state, bleaching, and time resolved fluorescence were measured. The results can be interpreted by the assumption that during periods of less than 10 ps, the S1‐state of the azo form is changed to the S1‐state of the hydrazone form by proton transfer. This S1‐state relaxes by internal conversion and by diabatic isomerization with a time constant of 20 to 60 ps, depending on substituent and solvent. By exciting the substances solved in polymer film, we observed a relatively strong fluorescence, which is found to be amplified spontaneous emission (s

ISSN:0021-8383    

DOI:10.1002/prac.19863280111

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY