Chiral Carboxylic Acid Assisted Ir(III)-Catalyzed Asymmetric C-H Activation/Desymmetrization of Sulfoximines.

The development of privileged chiral carboxylic acids is crucial for enabling asymmetric C-H activation catalyzed by achiral high-valent d6 transition metals. We report the synthesis of a new chiral carboxylic acid that enables Ir(III)-catalyzed asymmetric C-H activation/desymmetrization of sulfoximines with α-bromo ketones. A diverse range of sulfur-stereogenic sulfoximines were synthesized with high yields (up to 90%) and excellent enantioselectivity (up to 97:3 er). The reaction maintained its efficiency upon scale-up, and one of the products 6aa could be readily transformed into the five-membered chiral cyclic sulfoximine derivative. Detailed mechanistic studies establish C-H bond cleavage as the rate-determining step. Furthermore, the alkylated reaction intermediate was successfully isolated and demonstrated complete retention of enantioselectivity upon conversion to the corresponding product.