Studies on Rhizopus arrhizus mediated enantioselective reduction of arylalkanones

The effect of substitution on the biotransformation of various arylalkanones using Rhizopus arrhizus was investigated. The organism was found to be promising for the reduction of phenylalkanones and arylethanones with good to excellent enantioselectivity. The reduction followed Prelogʹs rule giving the (S)-carbinols in all the cases. The enantioselectivity of the reaction improved with increasing size of the groups flanking the carbonyl function and the electron withdrawing capacity of the substituents in the aromatic ring. However, the yield was dramatically affected with increased hydrophobicity of the substrates.