CATALYTIC ASYMMETRIC HYDROSILYLATION OF OLEFINS. III. CHIRAL PHOSPHINE-PALLADIUM(II) COMPLEXES AS HYDROSILYLATION CATALYSTS

Article abstract of DOI:10.1016/S0022-328X(00)86640-1

A palladium(II) complex of menthyldiphenylphosphine (MDPP) or epimeric neomenthyldiphenylphosphine (NMDPP) was used as an effective catalyst for the asymmetric hydrosilylation of styrene and some cyclic conjugated dienes, such as cyclopentadiene; the reaction giving optically active 1-phenylethyl-silane and 2-cycloalkenylsilane derivatives, respectively.MDPP and NMDPP, as ligands which have configurations opposite to each other only at the chiral C(3) center adjacent to the diphenylphosphino group, gave enantiomeric (S)-(-)- and (R)-(+)-1-phenylethyltrichlorosilane, respectively, in the hydrosilylation of styrene with trichlorosilane.However, this is not the case for 2-cycloalkenylsilane formation.Intervention of a ?-allylic palladium is suggested to account for the observed enantioselectivity as well as regioselectivity in the palladium complex-catalyzed addition of trichlorosilane to these olefins.