Despite their promising properties, 6 azetidines are underrepresented relative to closely related nitrogen-containing heterocycles: this is due to a lack of robust synthetic methods to access these species 7-8 , especially using asymmetric catalysis. Application of a ring-expansion strategy for the asymmetric, one-carbon homologation of readily prepared aziridines via carbene insertion would be an attractive new entry towards the enantioselective synthesis of azetidines (Figure ). However, this approach comes with two major selectivity challenges. The first is the innate reactivity of the intermediate aziridinium ylides, which undergo highly favorable cheletropic extrusion of olefins in many contexts. Schomaker and others have demonstrated that these reactive intermediates can be harnessed in [2,3]-Stevens rearrangements and other ring-opening reactions. 12 However, we are unaware of any examples of a one-carbon ring expansion of aziridines through a [1,2]-Stevens rearrangement strategy. Secondly, the diradical mechanism of the [1,2]-Stevens rearrangement 13 has made it a challenging reaction class for asymmetric catalysis: few asymmetric variations have been reported. Enantiopure quaternary ammonium salts can undergo [1,2]-Stevens rearrangements with N-to-C chirality transfer; 15 however, escape of the radical pair from the solvent cage is often competitive with radical recombination, and erosion of enantiopurity is often observed. General strategies for stereocontrol over these rearrangements are an unmet challenge facing the field of asymmetric catalysis.