Enantioselective N-H Insertion of Sulfonamides: Access to Chiral α-Aminoesters.

We report the first highly enantioselective carbene insertion into the N-H bonds of sulfonamides, affording α-amino esters in moderate to good yields with excellent enantioselectivity (up to 98% ee). The success of this transformation relies on the synergistic effect between a ruthenium carbene intermediate and a chiral phosphoric acid. Slight modification of the reaction conditions further enables the use of carbamates as N-nucleophiles, achieving exceptional enantiocontrol (up to 99% ee). Additionally, this catalytic system facilitates an asymmetric three-component reaction involving sulfonamides, α-aryldiazoacetates, and imines, expanding the synthetic utility of this methodology.