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Pure Appl. Chem., 2001, Vol. 73, No. 1, pp. 167-174

Selective biotransformation reactions on (±)-aryl alkyl ketones, (±)-benzoxazines, and d-arabino- and d-threo-hydroxyalkyltriazoles

Raunak, Ashok K. Prasad, Najam A. Shakil, Himanshu and Virinder S. Parmar

Department of Chemistry, University of Delhi, Delhi-110 007, India

Abstract: The capabilities of porcine pancreatic lipase (PPL), Candida antarctica lipase (CAL), and Candida rugosa lipase (CRL) were evaluated for enantio- and/or regioselective acetylation/deacetylation of (±)-2,4-diacetoxyphenyl alkyl ketones, (±)-4-alkyl-3,4-dihydro-3-hydroxyalkyl-2H-1,3-benzoxazines, and d-arabino and d-threo-polyhydroxyalkyltriazoles in organic solvents. PPL in tetrahydrofuran (THF) exhibited high to moderate enantioselectivity during the deacetylation of (±)-2,4-diacetoxyaryl alkyl ketones and acetylation of (±)-3-hydroxyalkyl-2H-1,3-benzoxazines. Together with enantioselectivity, PPL in THF also showed exclusive regioselectivity for the deacetylation of para-acetoxy over the ortho-acetoxy function, with respect to the nuclear carbonyl group in 2,4-diacetoxyphenyl alkyl ketones. CAL in diisopropyl ether (DIPE) and PPL in THF exhibited exclusive selectivity for the acetylation of primary hydroxyl over secondary hydroxyl group(s) of d-arabino- and d-threo-polyhydroxyalkyltriazoles.