A New Synthesis of Pyrrolidines by Way of an Enantioselective Mannich/Diastereoselective Hydroamination Reaction Sequence
摘要:
A new two-step synthesis of highly substituted pyrrolidines has been developed. Chiral silane Lewis acid promoted enantioselective Mannich reactions of silyl ketene imines with acylhydrazones may be used to access bishomoallylic benzoic hydrazides that In turn may be cyclized to pyrrolidines by way of the thermal hydroamination reaction reported recently by Beauchemin. Importantly, excellent diastereoselectivity may be realized in the hydroamination reactions.
A New Silicon Lewis Acid for Highly Enantioselective Mannich Reactions of Aliphatic Ketone-Derived Hydrazones
作者:Gregory T. Notte、James L. Leighton
DOI:10.1021/ja800830h
日期:2008.5.1
The first general method for the highly enantioselective Mannich reaction of aliphatic ketimines is reported. A new, second generation chiral silane Lewisacid has been developed that promotes the reaction between ketone-derived hydrazones and silyl ketene acetals, providing the beta,beta-disubstituted beta-amino esters with good enantioselectivity even for the hydrazone derived from 2-butanone (methyl