Catalytic Asymmetric C–H Activation/Cyclization of Sulfoximines with Sulfoxonium Ylides by a Chiral η6-Benzene Ruthenium(II) Catalyst

Chiral η6-benzene ruthenium(II) (BenRuII)-catalyzed asymmetric C–H activations are challenging and rarely seen in the literature. Herein, the asymmetric C–H activation/cyclization of sulfoximines with sulfoxonium ylides catalyzed by the chiral BenRuII catalyst derived from (S)-H8–BINOL is described. It provides efficient access to various sulfur-chiral 1,2-benzothiazine 1-oxides in high yields with high enantioselectivities (up to 99% yield and 98% ee). Kinetic resolution of racemic sulfoximines was also feasible. The reaction mechanism was studied by the tool of H/D exchange and the kinetic isotope effect. The metallacycle revealing the origin of chiral induction was prepared, characterized, and proved effective for the model reaction. This work demonstrates the great potential of chiral BenRuII catalysts for asymmetric C–H activation.