Synthesis of 3-Aza-bicyclo[3.1.0]hexan-2-one Derivatives via Gold-Catalyzed Oxidative Cyclopropanation of N-Allylynamides

N-allylynamides with various functional groups and different substitution patterns can be converted into 3-aza-bicyclo[3.1.0]hexan-2-one derivatives in moderate to high yield using IMesAuCl/AgBF4 as the catalyst and pyridine N-oxide as the oxidant. A noncarbene mediated approach is proposed as the mechanism.