Reactivity of allyl anions of allylphosphine-boranes towards electrophiles

Abstract

The reactivity of mesomeric carbanions derived from allylphosphine-boranes varies as a function of electrophile. Small sp3-electrophiles react predominantly at the α carbon atom whereas bulky sp3- electrophiles and carbonyl compounds react mainly at the γ carbon. In the case of electron-deficient aldehydes reduction of carbonyl group and formation of the corresponding alcohols is observed. This is attributed to the weakly reducing properties of carbanions derived from allylphosphine-boranes, whose mesomeric form resembles the structure of a modified borohydride. © ARKAT-USA, Inc.