Trans-selective Asymmetric Aziridination Of Diazoacetamides And N-boc Imines Catalyzed By Axially Chiral Dicarboxylic Acid

摘要

Enantiomerically pure aziridines constitute an important class of chiral synthons, since they can be easily converted to various types of important building blocks, such as functionalized a- or β-amino acid derivatives. Hence, catalytic asymmetric aziridina-tions have drawn attention as a means to access these valuable compounds in a straightforward manner. One prevailing strategy for this purpose is the asymmetric nitrogen transfer to alkene by transition-metal catalysis or organocatalysis. Another attractive but less-studied approach to this end is the use of chiral Lewis acid-catalyzed asymmetric aziridination using imine and diazoac-etate pioneered by Wulff et al. It is well-known that this sort of aziridination including achiral acid catalysis almost has always dominantly provided cis aziridine. In this context, we report herein that axially chiral dicarboxylic acid-catalyzed reaction of N-Boc imines and diazoacetamides offers a novel organocatalytic way for the asymmetric aziridination with remarkably high enantioselectivity and unique trans selectivity, hitherto unattainable using this strategy.