Catalytic enantioselective allyl- and crotylboration of aldehydes using chiral diol.Sn[Cl.sub.4] complexes: optimization, substrate scope and mechanistic investigations

The mechanisms and the optimization of the catalytic enantioselective allyl- and crotylboration of aldehydes using chiral diol.Sn[Cl.sub.4] complexes are explained. Bronsted acid held in a highly dissymmetrical environment is shown to act as an efficient catalyst in the system.