Stereodivergent Synthesis of Enantioenriched Organoboron Compounds with Carbon/Boron Dual Stereocenters via Rh(I)/Cu(I)-Catalyzed Enantioselective Desymmetrization of B–H Insertions

Despite notable progress in the study of chiral boron compounds, research on tetracoordinate chiral boron species remains limited. Achieving a configurationally stable boron stereocenter typically requires stabilizing the tetrahedral structure of the boron atom with suitable Lewis bases. Moreover, due to the high reactivity of borane complexes and the limited methods for their modification, designing and synthesizing tetracoordinate chiral boron compounds with stable stereocenters presents considerable challenges. Herein, we report the use of prochiral NHC carbene-substituted boranes in rhodium(I)/chiral diene and copper(I)/chiral bisoxazoline-catalyzed systems, achieving the stereodivergent synthesis of organoboron compounds featuring contiguous carbon and boron stereocenters via enantioselective desymmetrization of carbene B-H insertion. Both catalytic systems delivered good yields and high stereoselectivity (up to 99% ee and 93:7 dr), allowing access to the full complement of stereoisomers at will. Structural analysis of the typical product revealed a tetrahedral character of 91.1% for the boron stereocenters, demonstrating their high configurational stability. This work provides a robust approach to accessing structurally diverse and configurationally stable tetracoordinate chiral boron compounds.