Organocatalytic asymmetric cyclization of aminochalcones and azlactones: Synthesis of 3,4-dihydroquinolinones

A novel and efficient reaction of aminochalcones and azlactones has been developed under the catalysis of bifunctional organocatalysts. The corresponding enantioenriched 3,4-dihydroquinolinones were efficiently assembled in moderate to excellent yield with excellent enantioselectivitiy. In this work, the synthons with tosylaminochalcones in an asymmetric approach were not confined to traditional unsaturated compounds via the aza-Michael/Michael addition pathway. Azlactones with highly nucleophilicity under a chiral base could promote the Michael addition to substituted 2-aminochalcones, followed by amide formation to deliver dihydroquinolinones in high enantiocontrol. A novel and efficient enantioselective cyclization protocol of aminochalcones with azlactones has been developed for the construction of enantioenriched 3,4-dihydroquinolinones.