Disulfoninnide-Catalyzed Asymmetric Synthesis of β3-Amino Esters Directly from N-Boc-Amino Sulfones

An asymmetric Mannich reaction of silyl ketene acetals with N-Boc-amino sulfones has been developed. A chiral disulfonirnide efficiently catalyzes both the in situ generation of the corresponding N-Boc imines and the asymmetric Mannich reaction with excellent yields and enantioselectivities. Kinetic studies confirm a proposed stepwise mechanism.