Enantio-, regio-, and chemoselective reduction of aromatic a-diketones by baker's yeast in diverse organic-water solvent systems

The enantio- and regioselective reduction of several symmetric and nonsymmetrical parasubstituted benzil derivatives was achieved utilizing Saccharomyces cerevisiae ( baker's yeast) in solvents such as EtOAc, Et2O, n-hexane, n-pentane and toluene in the presence of 14-33% of water. For compounds (1c) and (3b) using organic solvents gave significantly better yields. However, (1a), (1b) and (3a) give comparable yields, regardless of solvent. In most cases the reduction in organic-water solvent systems gave higher ee.