Ba-Catalyzed Direct Mannich-Type Reactions of a β,γ-Unsaturated Ester Providing β-Methyl <i>aza</i>-Morita−Baylis−Hillman-Type Products

Abstract

Barium-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester are described. The Ba-catalyst not only promoted the Mannich-type reactions, but also isomerized Mannich adducts to afford beta-methyl aza-Morita-Baylis-Hillman-type products in 61-88% yield from various aryl, heteroaryl, and alkyl imines. Preliminary trials on enantioselective variants with a chiral biaryldiol ligand gave products in up to 80% ee.