Asymmetric Transfer Hydrogenation of 2,3-Disubstituted Flavanones through Dynamic Kinetic Resolution Enabled by Retro-Oxa-Michael Addition: Construction of Three Contiguous Stereogenic Centers

J Org Chem. 2022 Jun 3;87(11):7521-7530. doi: 10.1021/acs.joc.2c00418. Epub 2022 May 23.

Abstract

A ruthenium-catalyzed asymmetric transfer hydrogenation of 2,3-disubstituted flavanones was developed for the construction of three contiguous stereocenters under basic conditions through a combination of dynamic kinetic resolution and retro-oxa-Michael addition, giving chiral flavanols with excellent enantioselectivities and diastereoselectivities. The reaction proceeded via a base-catalyzed retro-oxa-Michael addition to racemize two stereogenic centers simultaneously in concert with a highly enantioselective ketone transfer hydrogenation step. The asymmetric transfer hydrogenation could be achieved at gram scale without loss of the activity and enantioselectivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Flavanones*
  • Hydrogenation
  • Kinetics
  • Stereoisomerism

Substances

  • Flavanones