New transformations from a 3-silyloxy 2-aza-1,3-diene: Consecutive Zr-mediated retro-Brook rearrangement and reactions with electrophiles

摘要

A one-pot procedure for the transformation of the title compound to alpha-functionalized (silylated) and alpha,beta-unsaturated secondary amides was described. The following steps were involved: a Zr-mediated retro-Brook rearrangement, selective deprotonation with n-BuLi on the organometallic intermediate, and trapping with electrophiles including alkyl and acyl halides and aldehydes. The electrophilic addition step occurred at a stabilized m-silyl carbanion center without affecting the near transition metal residue. In the case of aldehydes, the Peterson alkenation reaction took place on the transition metal complex in a highly stereoselective way. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 34]