Copper-Catalyzed Dynamic Kinetic Asymmetric Arylation of Secondary Phosphine-Boranes for the Synthesis of P(III)-Stereogenic Centers

Transition-metal-catalyzed asymmetric C-P(III) bond formation is a direct method for the construction of P(III)-stereogenic centers; however, achieving high enantioselectivity remains a challenge. Herein, an unprecedented Cu-catalyzed dynamic kinetic resolution of secondary phosphine-boranes was successfully developed. This asymmetric C-P(BH3) coupling reaction provided the direct and highly enantioselective synthesis of P(III)-stereogenic centers, enabling the formation of chiral medium-sized benzophosphine-boranes (7-10-membered cycles). A mechanism of dynamic kinetic resolution involving the unusual rapid racemization of secondary phosphine-boranes has been proposed.