Asymmetric hydrosilylation of olefins catalyzed by MOP-palladium complexes

Axially chiral monophosphines, 2-(diphenylphosphino)-2'-methoxy-1,1'-binaphthyl (MeO-MOP, 1a) and its biphenanthryl analog 5, were prepared starting with homochiral 2,2'-dihydroxy-1,1'-binaphthyl and 3,3'-dihydroxy-4,4'-biphenanthryl, respectively. The palladium complexes coordinated with the MOP ligands are highly effective catalysts for several types of catalytic asymmetric reaction where chelating bisphosphine ligands cannot be used because of their low catalytic activity or low selectivity towards the desired reaction pathway. Palladium-catalyzed hydrosilylation of olefins is one of the typical examples. High enantioselectivity was observed in the asymmetric hydrosilylation of alkyl-substituted terminal olefins (92-97% ee), bicyclo[2.2.1]heptene derivatives (92-96% ee), styrene derivatives (89-96% ee), and cyclic 1,3-dienes (80% ee). The hydrosilylation products were efficiently converted into optically active alcohols by oxidation of the carbon-silicon bond.