Lipase Catalyzed Kinetic Resolution of rac-2-(3-Methoxy-4-methylphenyl) propan-1-ol and rac-2-(3-Hydroxy-4-methylphenyl)propyl propanoate for S-(+)-Xanthorrhizol

Abstract

E-mail: c2496@kist.re.krReceived November 1, 2011, Accepted November 23, 2011Xanthorrhizol is a bisabolane type of natural sesquiterpene, the major component of essential oils of Curcumaxanthorrhiza. 2-(3-Methoxy-4-methylphenyl)propan-1-ol and 2-(3-hydroxy-4-methyl phenyl)propan-1-olcould be essential building block for enantioselective synthesis of xanthorrhizol. Enantioselective ( c = 53%, E= 80 ± 3) for R-(+)-2-(3-hydroxy-4-methylphenyl) propan-1-ol and (c = 58%, E = 27 ± 1) for R-(+)-2-(3-methoxy-4-methylphenyl) propan-1-ol resolution processes were developed via lipase-catalyzed reaction. Wefound lipase Aspergillus oryzae (AOL) and Porcine pancreas (PPL) are selective to transesterification andhydrolysis in organic and aqueous phase. Modified demethylated substrate is appropriate for enantioselectivehydrolysis reaction without any additives. Enantiopure chiral alcohol was crystallized from ethyl acetate/n-hexane co-solvent system. Gram scale resolved chiral intermediate will facilitate the synthesis of theunnatural S-(+)-xanthorrhizol, the corresponding isomer of the natural one.Key Words : Lipase, Sesquiterpene, Xanthorrhizol, Transesterification, HydrolysisIntroductionR-(−)-Xanthorrhizol is a bisabolane type of natural ses-quiterpene containing a stereogenic centre at the benzylicposition. R-(−)-Enantiomer was isolated from the naturalsources, as constituent of rhizomes of Curcuma xanthorrhiza,