Selective Bioreduction Of 2'-chloro-acetophenone By Yeast In Ionic Liquids/water Biphasic System

With the progress in pharmacology of chiral pharmaceuticals and the strict regulation in the application of new drug in recent years, the research and development of chiral pharmaceuticals has become the new direction internationally. Many researchers are applying themselves to develop new processes for chiral compound synthesis with high conversion ratio and high stereo-selectivity, in which, biotransformation is attracted interests because of mild reaction condition and high stereo-selectivity.Ionic liquids (ILs) have been vigorously investigated as possible replacements for volatile organic solvents. This work presents the use of imidazolium Ionic Liquids ([C_nmim][PF₆]) in biphasic system in the asymmetric reduction of 2'-chloro-acetophenone(2'-Cl-AP) to (S)-1-(2-chloro-phenyl)ethanol((S)-1-2-Cl-PE) catalyzed by Candida Pseudotropicalis A. The biocompatibility of imidazolium ionic liquids is carefully assayed before using. The results suggest that an increase in alkyl group chain substituted on the cation ring correspond with an increase in toxicity. It is also found that the ratio of ILs in the biphasic system influence the performance of the reaction distinctly. Under the optimal conditions, the maximum yield and product e.e. were 85% and >99.9%. Additionally, immobilized yeast cells exhibits greater biocompatibility with ionic liquids, and could be used repeatedly in biphasic system in whole cell biocatalytic process.