Highly Diastereo‐ and Enantioselective Aza‐Mannich Addition of Oxazolones toN‐Boc Protected α‐Amido Sulfones Catalyzed by Bifunctional Thiourea‐modified Cinchona Alkaloid

Abstract A diastereo‐ and enantioselective aza‐Mannich addition of oxazolones to α‐amino sulfones catalyzed by tertiary amine‐1‐phenylethyl thiourea based on cinchona structure has been developed. The reaction afforded the azlactone adducts bearing quaternary and tertiary stereogenic centers with high yields (up to 98 %) and moderate to excellent diastereo‐ and enantioselectivities (up to >99 : 1 dr and 96 % ee). The absolute configuration of a product was assigned by X‐ray crystal structural analyses and a plausible reaction mechanism was proposed.