Yeast‐mediated preparation of l ‐PAC in an organic solvent

The yeast‐mediated acyloin condensation of benzaldehyde and pyruvic acid to form l ‐PAC occurs in a petroleum spirit solvent system at room temperature with moderate conversion (30%) and high enantioselectivity (86%ee) after 24 h. The addition of a small amount of ethanol (0.5% mL) to the reaction mixture inhibits the formation of the side product benzyl alcohol and increases the conversion to l ‐PAC. Conducting the reaction using 13 C‐labeled pyruvate indicated that the pyruvate was incorporated into the l ‐PAC and that the excess pyruvate was converted into ethanol. Conducting the reaction at 5°C results in similar conversion but higher enantioselectivity. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 827–831, 2002; DOI 10.1002/bit.10117