Stereoselective Synthesis of Optically Active α-Hydroxy Ketones and anti-1,2-Diols via Asymmetric Transfer Hydrogenation of Unsymmetrically Substituted 1,2-Diketones

Abstract
A well-defined chiral Ru catalyst RuCl(N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine)(η6-arene) effectively promotes asymmetric transfer hydrogenation of 1-aryl-1,2-propanedione with HCOOH/N(C2H5)3, leading preferentially to optically active 1-aryl-2-hydroxy-1-propanone with up to 99% ee and 89% yield at 10 °C. The reaction at 40 °C gives anti-1-aryl-1,2-propanediol with up to 95% ee and 78% yield. This is a highly efficient procedure for the synthesis of optically active anti-diols.