Ruthenium-Catalyzed Formal Asymmetric Reductive Isomerization of α-Hydroxyenones

The isomerization of α-hydroxyketones (acyloins) is a fundamental transformation in carbohydrate chemistry. It has been found to play important roles in the metabolic processes of living organisms and organic synthesis. However, catalytic asymmetric acyloin isomerization remains a formidable challenge and has not been addressed. In this work, we report the unprecedented ruthenium-catalyzed formal asymmetric reductive isomerization of α-hydroxyenones. The protocol affords a variety of enantioenriched acyloins with a high level of enantioselectivities, and systematic mechanistic studies demonstrate a transformation involving the isomerization of α-hydroxyenones and ruthenium-catalyzed asymmetric transfer hydrogenation. The work provides an alternative approach to realizing the challenging catalytic asymmetric acyloin isomerization.