Highly Diastereoselective and Enantioselective Michael Addition of 5H-Oxazol-4-ones to α,β-Unsaturated Ketones Catalyzed by a New Bifunctional Organocatalyst with Broad Substrate Scope and Applicability.

A new thiourea-tertiary amine bifunctional catalyst derived from L-tert-leucine was developed and provides excellent stereocontrol in a novel and direct Michael addition of 5H-oxazol-4-ones to α,β-unsaturated ketones with much broad substrate scope. The conjugate addition products with chiral vicinal quaternary and tertiary stereocenters can be easily transformed to structurally interesting compounds or building blocks.