The synthesis of a novel non- C2 symmetric H 4-BINOL ligand and its application to titanium-catalyzed enantioselective addition of diethylzinc to aldehydes

Abstract

The synthesis of the novel non- C 2 symmetric ligand ( R)-5,6,7,8-tetrahydro-1,1′-binaphthol has been achieved via partial reduction of 2,2′-bis(methoxymethoxy)-1,1′-binaphthyl with Raney NiAl alloy in dilute aqueous NaOH solution followed by hydrolysis with HCl. Its titanium complex was found to be an effective catalyst in the asymmetric addition of diethylzinc to a variety of aldehydes, leading to the formation of secondary alcohols in high yields with good to excellent enantioselectivities.