Regiodivergent Ring Opening of Chiral Aziridines

Kinetic resolution of strained three-membered rings has proven broadly useful for the generation of enantiopure organic intermediates. Herein we demonstrate a complementary approach whereby a single catalyst transforms a racemic mixture of aziridines to a pair of regioisomeric products, each in good yield with exceptionally high enantioselectivity. Specifically, the dimeric yttrium salen catalyst accelerates the ring opening of aliphatic aziridines by trimethylsilylazide, inducing nucleophilic attack at the primary position of one enantiomer and the secondary position of the other. Both rate and selectivity are highly sensitive to the catalyst structure.