Imine Anions Derived from 2° Allylic Amines

Abstract

The application of allylic carbanions to organic synthesis is extensive^2,3 and among the numerous variations are the generation and use of heteroallylic dianions. Noteworthy in this useful option is the ability of sulfide (−S^θ) to stabilize a developing adjacent carbanion,^4,5 while alkoxide (−0^θ) uniquely directs carbanion formation to a distal allylic position (Scheme I).^6,7 We now wish to report that under conditions typically used for hetero allylic dianion formation 2° allylic amides provide a third reaction pathway for this structural entity by isomerizing to the resonance-stabilized imine anions (Scheme I).^8,9 This overall conversion (presumably through an intermediate dianion) represents a heretofore unknown isomerization process that provides an alternative method for the generation of synthetically useful enolate equivalents.¹⁰