Ligand-assisted rate acceleration in transacylation by a yttrium-salen complex. Demonstration of a conceptually new strategy for metal-catalyzed kinetic resolution of alcohols.

[reaction: see text]. Yttrium-salen complexes effect transacylation between enolesters and chiral secondary alcohols, resulting in varying degrees of kinetic resolution. Even though the enantioselectivity remains modest (k(fast)/k(slow) up to 4.81), these results represent the first demonstration of a conceptually new metal-catalyzed acyl transfer process that results in kinetic resolution. On the basis of the solid-state structure of the catalyst, a novel associative mechanistic pathway is proposed for the reaction.