RuPHOX‐Ru Catalyzed Asymmetric Cascade Hydrogenation of 3‐Substituted Chromones for the Synthesis of Corresponding Chiral Chromanols

Abstract

AbstractAn efficient RuPHOX−Ru catalyzed asymmetric cascade hydrogenation of 3‐substituted chromones has been achieved under mild reaction conditions, affording the corresponding chiral 3‐substituted chromanols in high yields with excellent enantio‐ and diastereoselectivities (up to 99 % yield, >99 % ee and >20 : 1 dr). Control reactions and deuterium labelling experiments revealed that a dynamic kinetic resolution process occurs during the subsequent hydrogenation of the C=O double bond, which is responsible for the high performance of the asymmetric cascade hydrogenation. The resulting products allow for several transformations and it was shown that the protocol provides a practical and alternative strategy for the synthesis of chiral 3‐substituted chromanols and their derivatives.