摘要
A general method for the preparation of dissymmetric olefins has been developed. The anion derived from an enantiomerically enriched P‐(phenylthiomethyl)phosphonamidate(1,3,2‐oxazaphosphorinane2‐oxide) was added to 4‐tert‐butylcyclohexanone with excellent diastereoselectivity. The β‐hydroxyphos‐phonamidate was converted into a (phenylthio)‐methylidene with excellent stereospecificity using a novel electrophile‐promoted olefination that employed trityl triflate and 2,6‐lutidine in warm acetonitrile. The vinyl sulfide underwent nickel‐catalyzed coupling with Grignard and dialkylzinc reagents to produce (S)‐4‐(tert‐butyl)alkylidenecyclohexanes with moderate to high stereospecificity. Copyright © 1995 VCH Publishers, Inc.