Enzyme-Catalyzed Chemoselective Transesterification Reactions on Hydroxymethylated Phenolic Compounds

The chemoselective capabilities of porcine pancreatic lipase (PPL) in tetrahydrofuran andCandida rugosalipase (CRL) in diisopropyl ether have been investigated for selective acetylation and deacetylation of hydroxymethylated phenols and hydroxyaryl alkyl ketones and their peracetylated derivatives. Both PPL and CRL exhibited exclusive selectivity for the acetylation of alcoholic hydroxyl group over the phenolic hydroxyl group(s) of the hydroxymethylated phenols1–5and aryl alkyl ketones6–9, and for the deacetylation of ester group involving the phenolic hydroxyl group over the ester group involving alcoholic hydroxyl of the peracetates19–24. The preliminary results indicate that this strategy of chemoselective acetylation can also be used in the enantiomeric resolution of racemic ketones6–9. Single crystal X-ray diffraction studies have confirmed the structures of compounds4, 15, and17.