Backbone-Modified <i>C</i>₂-Symmetrical Chiral Bisphosphine TMS-QuinoxP*: Asymmetric Borylation of Racemic Allyl Electrophiles

A new C2-symmetrical P-chirogenic bisphosphine ligand with silyl substituents on the backbone, (R,R)-5,8-TMS-QuinoxP*, has been developed. This showed higher reactivity and enantioselectivity for direct enantioconvergent borylation of cyclic allyl electrophiles than its parent ligand, (R,R)-QuinoxP* (e.g., a piperidine-type substrate: 95% ee vs 76% ee). The borylative kinetic resolution linear was also achieved using (R,R)-5,8-TMS-QuinoxP* (up to 90% ee, s = 46.4). An investigation into role groups backbone X-ray crystallography computational studies displayed interlocking structures between phosphine moieties (R,R)-5,8-TMS-QuinoxP*. results DFT calculations revealed that entropy effect thermodynamically destabilizes dormant dimer species in catalytic cycle improve reactivity. Furthermore, case, detailed indicated pronounced enantioselective recognition carbon-carbon double bonds, which is virtually unaffected by chirality at allylic position, as key from both enantiomers racemic electrophiles.