Catalyst- and Additive-Free Chemoselective Transfer Hydrogenation of α-Keto Amides to α-Hydroxy Amides by Sodium Formate

A catalyst- and additive-free chemoselective transfer hydrogenation of alpha-keto amides to alpha-hydroxy amides is easily achieved by using sodium formate as a hydrogen source. The utility of this method is demonstrated by gram-scale synthesis and transformation of the resultant alpha-hydroxy amides into polysubstituted acetamides and 2-arylindole derivatives. Control experiments suggest that the NH group of alpha-keto amides is crucial for the chemoselective reduction through the formation of hydrogen bonds.