Carbonium ion rearrangements: competitive migration of the electronically constrasted groups methyl and diphenylphosphinyl

Abstract

Carbonium ion rearrangements are described in which either a methyl group or the electronegative diphenylphosphinyl group can migrate. When a very careful balance between electronic effects is made, the two groups migrate competitively with the Ph₂PO migration slightly predominating. It is suggested that it is the ability of the group which stays behind to support the positive charge rather than ‘migratory aptitude’ which is important in these reactions.