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Regioselective alcoholysis of silychristin acetates catalyzed by lipases.

International journal of molecular sciences (2015-05-29)
Eva Vavříková, Paolo Gavezzotti, Kateřina Purchartová, Kateřina Fuksová, David Biedermann, Marek Kuzma, Sergio Riva, Vladimír Křen
ABSTRACT

A panel of lipases was screened for the selective acetylation and alcoholysis of silychristin and silychristin peracetate, respectively. Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/ n-butanol. Both of these reactions occurred without diastereomeric discrimination of silychristin A and B. Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule.

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