The hypothesis that a carbonyl group bonded to a heteroatom can provide dipole stabilization for formation of a carbanion adjacent to the heteroatom has been supported for esters, thioesters, and amides by experiment and the~ ry. l-~ s~+ Both approaches also suggest that complexation of the lithium ion to the carbonyl oxygen is an important factor in the stabilization of these organolithiums. The early cases of self-addition of a-heteroatom ...
