Formal Diels–Alder Reactions of Chalcones and Formylcyclopropanes Catalyzed by Chiral N-Heterocyclic Carbenes

Highly enantioselective (formal) hetero-Diels–Alder reactions between chalcones and formylcyclopropanes are disclosed. The challenging N-heterocyclic carbene (NHC)-bounded enolate intermediates from formylcyclopropanes were captured for new C–C bond forming reactions. The reaction products were obtained with high diastereo- and enantioselectivities and could be easily transformed to optically pure multisubstituted cyclohexane derivatives.本研究报道了查尔酮与甲酰基环丙烷之间的高对映选择性（形式）杂Diels–Alder反应。由甲酰基环丙烷衍生得到的、极具挑战性的N-杂环卡宾（N-heterocyclic carbene, NHC）配位烯醇中间体被捕获，用于构建新碳-碳键的反应。所得反应产物具有优异的非对映选择性与对映选择性，且可便捷转化为光学纯的多取代环己烷衍生物。