N-Heterocyclic carbenes (NHCs) were demonstrated to be efficient catalysts for the Staudinger reaction of ketenes with N-tosyl, N-benzyloxycarbonyl, or N-tert-butoxycarbonyl imines. Chiral NHC 8b, conveniently prepared from L-pyroglutamic acid, catalyzed the reactions of arylalkylketenes with a variety of N-tert-butoxycarbonyl arylimines to give the corresponding cis-beta-lactams in good yields with good diastereoselectivities and excellent enantioselectivities (up to 99% ee). Two possible catalytic pathways, initiated by the addition of NHC to ketenes or imines, were discussed.
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