Structural models for lithium intermediates during carboxamide-directed metallations

Abstract

Structural models for Li intermediates during metallations of two different organic precursors having –NH–CO units are isolated and structurally characterised, and shown to be complexed mono- and di-meric azaenolates with (–NC–OLi·xB)_n(B = Lewis base) groupings; contrary to earlier assumptions, the structures imply that the N-(rather than the O-) centres of these species would direct second lithiations to nearby C–H bonds although it has proved impossible thus far to detect the proposed dilithiated systems.