Dipeptidic Proline‐Derived Thiourea Organocatalysts for Asymmetric Michael addition Reactions between Aldehydes and Nitroolefins

The enantiodivergent synthesis of syn ‐Michael adducts can be easily achieved by switching the terminal proline in dipeptidic proline‐thiourea catalysts. In this study, a dipeptidic proline‐derived thiourea organocatalyst was rationally designed and facilely prepared from dipeptidic proline, a chiral diamine as a linker, and isothiocyanate. This asymmetric bifunctional catalyst for Michael addition between aldehydes and nitroolefins provided chiral 4‐nitro aldehyde adducts with yields of up to 99 %, 92 : 8 syn ‐diastereoselectivity, and 97 % enantiomeric excess at room temperature.