The influence of microwave irradiation on lipase-catalyzed kinetic resolution of racemic secondary alcohols

The influence of microwave irradiation on the Novozyme 4350 (Candida antarctica lipase) catalyzed kinetic resolution of secondary alcohols with different functional groups was studied in comparison to the use of conventional heating at 60 degrees C. p-Chlorophenyl acetate was used as an acyl donor and toluene as the solvent. (+/-)-1-Phenyl-1-propanol 1, (+/-)-1-(4-bromophenyl)-propan-1-ol 3, (+/-)-1-phenylbut-3-en-1-ol 5 and (+/-)-3-bromo-2-(2-hydroxypropyl)-1,4-dimethoxynaphthalene 7 were successfully resolved into their (S)-alcohols and (R)-esters, respectively, in good enantiomeric excess. Resolution of (+/-)-ethyl-5-(4-methoxybenyloxy)-3-hydroxypentanoate 9 afforded its (R)-alcohol and (S)-ester using this method. In addition, microwave-assisted lipase transesterification of meso-symmetric diol 11 effected desymmetrization to ester 12 with high enantiomeric excess. In all cases studied, the conversion value for the microwave-assisted lipase kinetic resolution of secondary alcohols was higher than that obtained using conventional heating. (C) 2007 Elsevier Ltd. All rights reserved.