摘要:

AbstractA convenient method to convert homoallyl or homopropargyl ketones or alcohols into 4‐oxo carboxylic acids or γ‐lactones is the oxidative cleavage of the multiple bond with potassium permanganate in diluted sulfuric acid. This is exemplified by the preparation of intermediates for the synthesis of 8‐methylprostaglandin C2. The oxidation of the allylic compounds with permanganate is compared with the oxidative cleavage by ozone/hydrogen peroxide, ozone/chromic acid or sodium periodate/potassium perman

ISSN:0021-8383    

DOI:10.1002/prac.19853270112

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19853270113

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Photochemistry of Diarylsubstituted 2H‐Tetrazoles. II. The Influence of the Substituents on the Absorption Properties of Diarylsubstituted NitriliminesIrradation of 2,5‐diaryl‐2H‐tetrazoles in an EPA‐glass (ether: i‐pentan: ethanol=5:5:2) or in an i‐pentan glass at 77‐80 K with UV‐light of wavelength 290 nm yields diarylnitrilimines by the extrusion of nitrogen. The photoreactions investigated show spectroscopic unity. 22 diarylnitrilimines are included in the discussion with regards to the influence of substituents on the absorption maxima. The influence of substituents is interpreted by a LFE‐relationship. An intramolecular charge transfer as the reason for the relatively strong dependence of ν a∼max‐values on

ISSN:0021-8383    

DOI:10.1002/prac.19853270114

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

13C and15N N.M.R. Spectroscopic Investigations on Push‐pull Butadienes13C and15N n.m.r. spectroscopic investigations show the push‐pull‐character of the investigated butadienes1and2. Linear correlations exist between13C and15N chemical shifts and σp‐constants of substituents on the phenyl ring, and between13C chemical shifts and ΔG≠values of the C1C2rotation process in1,

ISSN:0021-8383    

DOI:10.1002/prac.19853270115

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Preparation of 1,3,4,‐Oxadiazol‐2‐carboxylic Acid DerivativesThe synthesis of 5‐substituted‐1,2,4‐oxadiazol‐2‐carboxylic acid derivatives3a‐gand4a‐gby cyclodehydratation of diacylhydrazines1a‐gand2a‐gare described. Further derivatives6to9are obtained from 1,3,4‐oxadia

ISSN:0021-8383    

DOI:10.1002/prac.19853270116

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

EPR Investigations of Ring Chlorinated 4‐DimethylaminophenylcationsThe influence of the position and the number of chlorine atoms in the ring of 4‐dimethylaminophenylcations on the zero‐field‐splitting(zfs) parameter Dis investigated. It was found that the π‐donor ability of the chlorine atom(s) ind 2(6)‐position(s) increases the zfs parameter D. In the case of 3(5)‐substitution the value of D decreases because of the steric hindrance of the dimet

ISSN:0021-8383    

DOI:10.1002/prac.19853270117

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Studies on UV/Vis Absorption Spectra of Azo Dyes. XII. An Analysis of the Correlations between Absorption Maxima and Hammett‐σ‐Constants for the SubstituentsPreviously claimed relationships between wavelength shifts and Hammett‐σ‐constants for the substituents are mostly unfounded. In certain cases, good linear correlations are found, but in other cases the plots deviate appreciably from linearity.We have examined such correlations on the basis of the classification scheme of organic dyes suggested by Fabian (charge transfer‐(CT)‐chromophores, locally excited‐(LE)‐chromophores) respectively Griffiths (donor‐acceptor chromogens, cyanine‐type chromogens).It was shown that good linear correlations should be obtained by LE‐chromophores (cyanine‐type chromogens). In CT‐chromophores (donor‐acceptor chromogens) however, an electron withdrawing substituent in the acceptor fragment causes a bathochromic displacement of the absorption maxima, and in the donor fragment it has little influence. A reversed behaviour was assumed for electron releasing substituents. Thus in CT‐chromophores V‐type correlations should be obtained.These rules are equally applieable to interpret the linear relationships between σ‐constants and the difference between the absorption maxima of

ISSN:0021-8383    

DOI:10.1002/prac.19853270118

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Formation of Ethoxyhydroquinazolinone by Attack of an Estercarbonyloxygen at a Cyano GroupBy the reaction of ethyl‐2‐oxo‐cyclohexanecarboxylate with cyan amide 4‐ethoxyhexahydroquinazolin‐2‐one(12)is formed. Butyl‐2‐oxo‐cyclopentanecarboxylate and cyan amide yield butyl‐3‐cyanamino‐cyclopent‐1‐en‐carboxylate(14). 2‐Oxocyclohexane‐carboxamide(1)and ethyl‐cyanoacetate form with sodiumhydroxide 4‐cyano‐octahydroisoquinolin‐1, 3‐dione(17)and with ammonium acetate ethyl cyclohexylidene‐cyanoacetate‐2‐carboxamide(18).18and ammonia, hydrazine, or cyclohexylamine form the salt

ISSN:0021-8383    

DOI:10.1002/prac.19853270119

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

Substituent Effects in13C‐ N. M. R. Spectra of Diastereomeric Chalcone Dihalogenides. V. Synthesis, Stereochemistry and Spectroscopy of Chalcone FluorohydrinesChalcone fluorohydrins1and diastereomeric pairs of chalcone chlorohydrins2as standards are investigated in the i.r.,1H,19F, and13C n m. r. spectroscopy field. The substituent dependence of the spectral parameters is discussed.The assignment of conformation and configuration on the basis of vicinal1H1H,1H19F, and1H13C coupling constants is det

ISSN:0021-8383    

DOI:10.1002/prac.19853270120

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

ISSN:0021-8383    

DOI:10.1002/prac.19853270121

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY