Catalytic asymmetric synthesis of optically active alcohols via hydrosilylation of olefins by a chiral monophosphine-palladium catalyst

Abstract

Axially chiral monophosphines 1, (S)-2-(diphenylphosphino)-2‘-methoxy- l,l’-binaphthyl (MOP, la) and its analogs substituted with isopropoxy (lb), benzyloxy (lc), and ethyl (Id) at 2' position, were prepared. Reaction of simple terminal alkenes 5 with trichlorosilane at 40 ° in the presence of 0.1 or 0.01 mol % of palladium catalyst prepared in situ from [PdCl(π-C3H5)]2 and (S)-la proceeded with unusual regioselectivity (up to 94%) and with high enantioselectivity to give high yields of 2-(trichlorosilyl)alkanes 6 together with a minor amount of l-(trichloro-silyl)alkanes 6'. Oxidation of the carbon-silicon bond gave optically active alcohols 8 (RCH(OH)CH3), enantiomeric purity ranging between 94% and 97% ee. The high enantioselectivity was also observed in the enantioposition-selective hydrosilylation of norbornene (9) and related meso bicyclic olefins catalyzed by the MOP/palladium, which gave exo-2-norbomanol (11) and related alcohols with up to 96% ee. © 1992, Walter de Gruyter. All rights reserved.