Diastereoselective Conjugate Addition of Organocuprates to Chiral <i>N</i>-Enoyl Oxazolidinethiones

Addition of organocuprates, generated in situ using an excess of a 1:2 mixture of CuI·DMS and Grignard reagent, to <i>N</i>-enoyl oxazolidinethiones in the presence of excess TMSI gave preferentially the <i>anti</i> diastereomer where the addition took place when the conformation of the substrate was <i>syn</i>-s-<i>cis</i>. The reaction was investigated with indene-based and three different phenyl glycine derived oxazolidinethiones.