Nucleophilic substitutions usingO‐alkyl‐N,N′‐dialkylisoureas. Applications to ephedrines
作者:
Martin A. Poelert,
Richard M. Kellogg,
L. A. Hulshof,
期刊:
Recueil des Travaux Chimiques des Pays‐Bas
(WILEY Available online 1994)
卷期:
Volume 113,
issue 7‐8
页码: 365-368
ISSN:0165-0513
年代: 1994
DOI:10.1002/recl.19941130705
出版商: WILEY‐VCH Verlag
数据来源: WILEY
摘要:
AbstractDialkylcarbodiimides in the presence of a Cu1catalyst react cleanly with the hydroxyl group of N‐methylated (1R,2S)‐ephedrine and (1S,2S)‐pseudoephedrine. These adducts react with nucleophiles like alkyl and aryl thiols as well as thioic acids and phthalimide to form the substitution products with overall retention of configuration. It is postulated that intramolecular participation of the amino group via anSN2 reaction leads to aziridium salts, which are subsequently opened by the nucleophiles via a secondSN2 reaction. This synthetic approach is also useful for the inversion of simple secondary alcohols; on treatment with dicyclohexylcarbodiimide followed by benzothioic acid and treatment with LiAlH4, menthol was converted in good yield to neomenthane
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