Chemoenzymatic synthesis of (2S)-2-arylpropanols through a dynamic kinetic resolution of 2-arylpropanals with alcohol dehydrogenasesElectronic supplementary information (ESI) available: Synthesis and spectroscopic data of 2-arylpropanals 1b-f, HPLC analyses and procedure for oxidation of (2S)-arylpropanols 2c and 2d to (2S)-2-arylpropionic acids. See DOI: 10.1039/c005098a

We applied Horse Liver Alcohol Dehydrogenase (HLADH) to the enantioselective synthesis of six (2 S )-2-arylpropanols, useful intermediates in the synthesis of Profens. The influence of substrate structure and reaction conditions on yields and enantioselectivity were investigated. The high yields and high enantioselectivity towards the ( S )-enantiomer obtained in the bioreduction of 2-arylpropionic aldehydes, clearly indicate the achievement of a DKR process through a combination of an enzyme-catalyzed kinetic reduction with a chemical base-catalyzed racemization of the unreacted aldehydes. The racemization step is represented by the keto-enol equilibrium of the aldehyde and can be controlled by modulating pH and reaction conditions. (2 S )-2-Arylpropanols, useful intermediates in the synthesis of Profens, were obtained by means of a dynamic kinetic resolution (DKR) of racemic 2-arylpropanals. The DKR process combines an enzymatic reduction with a chemical base-racemization of the unreacted aldehyde.