Organocatalyzed Michael–Michael Cascade Reaction: Asymmetric Synthesis of Polysubstituted Chromans

An enantioselective cascade Michael–Michael reaction between chalcones enolates and nitromethane catalyzed by a bifunctional thiourea is developed. This reaction provides a mild but efficient approach to chiral benzopyrans bearing three consecutive stereocenters in high yields with excellent stereoselectivities, and the benzopyrans can be easily transformed to the corresponding tricyclic product

Organocatalyzed Michael–Michael Cascade Reaction: Asymmetric Synthesis of Polysubstituted Chromans

An enantioselective cascade Michael–Michael reaction between chalcones enolates and nitromethane catalyzed by a bifunctional thiourea is developed. This reaction provides a mild but efficient approach to chiral benzopyrans bearing three consecutive stereocenters in high yields with excellent stereoselectivities, and the benzopyrans can be easily transformed to the corresponding tricyclic product