Catalytic Asymmetric Conjugate Addition of Simple Alkyl Thiols to α,β-Unsaturated N-Acylated Oxazolidin-2-ones with Bifunctional Catalysts

In this communication, we describe an unprecedented highly enantioselective catalytic conjugate addition of simple alkyl thiols to α,β-unsaturated N-acylated oxazolidin-2-ones catalyzed by acid−base bifunctional catalysis. This reaction provides a useful catalytic method for the synthesis of optically active chiral sulfur compounds that are otherwise difficult to prepare by asymmetric catalysis. The successful development of this reaction resulted from a discovery that, upon proper modification, a cinchona alkaloid bearing a thiourea functionality at 6′ position can afford highly efficient catalysis for asymmetric conjugate additions.