For the conversion, a mixture of 1 mL of a buffer (100 mM TEA, pH=7, 10% glycerol, 1 mM ZnCl2), 3 ml 4-methyl-2-pentanol, 1 ml 1-[3,5 bis-(trifluoro-methyl)phenyl]ethane-1-one, 2 mg NAD and 0.7 kU recombinant oxidoreductase from Microbacterium spec. DSMZ 20028 was incubated at room temperature for 24 h with constant thorough mixing. After 24 h, more than 90% of the 1-[3,5 bis-(trifluoro-methyl)phenyl]ethane-1-one used had been reduced to (1S)-1[3,5-bis(trifluoromethyephenyl)ethane-1-ol. Subsequently, the 4-methyl2-pentanol phase containing the product was separated from the aqueous phase, filtered, and the product (1S)-1[3,5-bis(trifluoromethyl)phenyl]ethane-1-ol was obtained by distillation. The crude product (1S)-1-[3,5-bis(trifluoromethyl)phenyl]ethane-1-one obtained in this manner exhibited an enantiomeric excess of >99.5%.
