Production of (S)-2-fluorophenylethan-1-ol and (S)-3-fluorophenylethan-1-ol by Alternaria alternata using ram horn peptone in microbial growth medium

Enantiomerically pure, fluorinated compounds have an important role in medicinal chemistry. Alternariaalternata isolates were used for the synthesis of (S)-2 -fluorophenylethan-1-ol 1b and (S)-3 -fluorophenyle than-1-ol 2b.Biocatalytic syntheses of optically active 1b and 2b were achieved by asymmetric reduction of 2 -fluoroacetophenone 1aand 3 -fluoroacetophenone 2a in the batch culture of A. alternata containing ram horn peptone (RHP). The reaction conditions (pH, temperature, and agitation) that improve the conversion of the substrates were studied. The optimalreaction conditions were found as pH 6.0, agitation 250, temperature 32 °C and substrate 3 mmol/100 mL. The gram scale productions of 1b and 2b by the most effective biocatalyst A. alternata EBK-6 using RHP was carried out in a fermenter with 1-L working volume. The results showed that the yields with 99% enantiomeric excess (ee) of both 1b and 2 breached 75% for 1b and 66% for 2b. The concentrations of products 1b and 2b at the end of fermentation were 3.1 g/Land 2.8 g/L, respectively. As a result, 2 important chiral intermediates for the pharmaceutical industry using A. alternataEBK-6 in the submerged culture containing RHP from waste material were scaled up to gram scale with excellent ee.