Stereoselective oxidation and reduction by immobilized Geotrichum candidum in an organic solvent

Cells of the fungus, Geotrichum candidum, were immobilized on a water-absorbing polymer and used for stereoselective oxidation and reduction in an organic solvent using cyclohexanone, cyclopentanol or alkan-2-ols as additive. Enantiomerically pure (R)-1-arylethanols were obtained by the stereoselective oxidation of racemic 1-arylethanols, whereas enantiomerically pure (S)-1-arylethanols were obtained by the reduction of the corresponding ketones, in contrast to reduction in water by the free cells in which (R)- or (S)-1-arylethanols were produced in low ee.The reaction mechanism was investigated by measuring the partition of the substrates and products between the organic phase and aqueous phase in the polymer around which the cells were immobilized. Deuterated compounds were used to determine the role of the additives.