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. A chiral dipeptidic proline-derived thiourea organocatalyst was rationally designed and facilely prepared from dipeptidic proline, a chiral diamine as a linker, and isothiocyanate. This asymmetric 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. image