Enantioselective Reduction of Aromatic Ketones Using Celeriac as Biocatalyst

The enantioselective reduction of aromatic ketones was investigated by using celeriac chips as biocatalysts under mild and environmentally benign conditions, which afforded corresponding optically active (S)-1-aryl alcohols. The enantioselectivity of products was in accordance with the Prelog's rule. The effects of some factors, including pH, reaction time, reaction temperature, substrate concentration, on the conversion of aromatic ketones and the enantiomeric excesses of (S)-1-aryl alcohols were examined, and these reaction conditions were optimized. The structure-effect relationship of substrates was also studied. The steric factors and electronic effects of substituents linked to carbonyl group have been found to significantly affect the conversion of substrates and the enantiomeric excesses of products. Under appropriate conditions, the conversion of acetophenone could be as high as 100% and the enantiomeric excess of (S)-1-phenylethanol exceeded 99.0%. The conversion of other aromatic ketones, including proplophenone, p-methylacetophenone and p-chloroacetophenone, reached moderate level, but all of the highest enantiomeric excesses of corresponding (S)-1-aryl alcohols exceeded 99.0%.