Transition metal catalyzed asymmetric reactions represent one of the most important synthetic strategies for the access of chiral compounds. Throughout the development of asymmetric catalysis, chiral ligands have played a vital role, not only in modulating catalytic activity but also in controlling stereochemical induction. Among numerous chiral ligands, chiral bisphosphine monoxide ligand has attracted increasing attention owing to their unique hemilabile coordination properties, which can facilitate efficient transition metal catalysis under mild reaction conditions. Herein, we report the synthesis and application of SPSiOL-derived bisphosphine monoxide ligands SPSiP(O)s. These ligands can be readily prepared in three steps through a Pd-catalyzed cross-coupling of (S)-SPSiOL triflate with diarylphosphine oxide, reduction of the phosphine oxide moiety, and a subsequent Pd-catalyzed coupling reaction with another diarylphosphine oxide, enabling the modular synthesis of SPSiP(O) ligands with diverse electronic and steric variations on both the phosphine and phosphine oxide units. The catalytic potential of SPSiP(O)s was evaluated in a Pd-catalyzed asymmetric Heck-type reaction between 1-aryl-2,6-dibromides and alkenes. After optimization, axially chiral biaryl products were obtained in up to 67% yield and 82% ee using Pd(dba)₂/SPSiP(O). Ligand screening revealed that SPSiP(O) ligands were uniquely effective, with both the electronic and steric properties of the phosphine moiety significantly influencing catalytic efficiency and enantioselectivity. The substrate scope of this asymmetric Heck reaction was subsequently examined, demonstrating broad functional group tolerance and the general applicability. Notably, this reaction represents the first asymmetric Heck desymmetrization of prochiral biphenyl dibromides for the synthesis of axially chiral biphenyl frameworks, highlighting the potential of SPSiP(O)s as versatile ligands for asymmetric catalysis.

Key words: bisphosphine monoxide ligand, SPSiOL, SPSiP(O), Heck reaction, asymmetric catalysis