Asymmetric synthesis of bicyclic dihydropyrans via organocatalytic inverse-electron-demand oxo-Diels–Alder reactions of enolizable aliphatic aldehydes

Abstract

A highly enantioselective organocatalytic inverse-electron-demand oxo-Diels–Alder reaction involving aqueous acetaldehyde has been discovered. The reaction, in which cyclic enones serve as dienes in the presence of readily available secondary amine catalysts, allows facile construction of optically active bicyclic dihydropyrans. Other typical enolizable aliphatic aldehydes can also serve as competent dienophiles in the reaction.