Stereoselective synthesis of 2-aryl-4-en-1-ols, promising synthons for the preparation of oxygen heterocycles

Abstract

Reactions of arylacetic acids with N-methoxymethanamine afford corresponding Weinreb amides which at alkenylation with methallyl and prenyl bromides in the presence of (Me3Si)2N–Na+ form unsaturated amides ArCHRCONMe(OMe) (R = CH2CMe=CH2, CH2C=CMe2). Amides readily react with BuLi and BnMgCl to give ketones ArCHRCOR' (R' = Bu, Bn). A stereoselective reduction of the latter with LiBH(s-Bu)3 leads to a quantitative formation of syn-isomers of 2-aryl-4-en-1-ols.