SYNTHESIS OF NEW CHIRAL P,S HYBRID LIGANDS AND THEIR USE IN ASYMMETRIC HYDROSILYLATION OF KETONES

Novel chiral P,S-hybrid Ligands bearing 1,2-cis phosphinomethyl (or th iomethyl) and thio (or phosphino) groups on a cyclopentane skeleton we re prepared by using borane as a protecting group for the phosphino gr oup. Asymmetric hydrosilylation of acetophenone with 1 mol% of rhodium complex catalysts prepared in situ from [Rh(COD)Cl](2) and P,S ligand s, iphenylphosphino)methyl-1-(phenylthio)cyclopentane (TPCP) and pheny lphosphino-2-[(phenylthio)methyl]cyclopentane (PTCP) gave the correspo nding alcohols. The asymmetric hydrosilylation with the ligand TPCP sh elved higher enantioselectivity than that with PTCP or a diphosphine l igand osphino)-2-[(diphenylphosphino)methyl]cyclopentane (PPCP).