title: Kinetic resolution of alpha-lipoic acid via enzymatic differentiation of a remote stereocenter.
abstract: Kinetic resolution of alpha-lipoic acid, a case of remote stereocenter discrimination, was accomplished using lipase from Aspergillus oryzae WZ007. Performance of this lipase was investigated for enantioselective esterification of (S)-alpha-lipoic acid, leaving the target product (R)-alpha-lipoic acid in unreacted form. The effects of chain length of alcohol, type of solvent, molar ratio of alcohol:acid, and reaction temperature were studied. The optimum reaction conditions were found to be esterification with n-octanol at 50 degrees C in heptane with an alcohol:acid molar ratio of 5:1. The conversion rate of alpha-lipoic acid was 75.2%, with an enantiomeric excess of 92.5% towards unreacted substrate in a reaction time of 48 h.
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou, People's Republic of China.
authors.forename: Hong-de
authors.initials: HD
authors.lastname: Yan
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wang
authors.forename: Ling-jie
authors.initials: LJ
authors.lastname: Chen
mesh_terms: D001236:Aspergillus oryzae / Q000737:chemistry / Q000201:enzymology*; D002384:Catalysis; D004951:Esterification; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism; D008063:Thioctic Acid / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D008063:Thioctic Acid; D008049:Lipase