Stereoselective reduction of ethyl 4-chloro-3-oxobutanoate by fungi

The enantioselectivity of ECAA to ECHB by eight fungi of four genus was eva luated. All strains showed (S)-selectivity, and Cylindrocarpon sclerotigenu m IFO 31855 gave the highest yield and good optical purity (e.e.; >99%). Ce ll-free extract and acetone-dried cells of C. sclerotigenum IFO 31855 reduc ed ECAA to (S)ECHB in the presence of NADPH (e.e.;>99%) and the e.e. was no t decreased by heat treatment of the cell-free extract or the acetone-dried cells. The active fractions shown by two peaks on a DEAE-Toyopearl 650 M c olumn gave preferentially (S)-ECHB (e.e.; > 99%).