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SOLID-PHASE IMMOBILIZED BIOCATALYSTS FOR OPTICAL RESOLUTION OF SECONDARY ALCOHOLS
Abstract:
Chirality emerged as a key issue for the efficiency of many pharmaceutical products. Optical resolution of synthetic racemic intermediates by biocatalysis was intensively studied in the last decades. Secondary alcohols are important intermediates in several pharmaceutical processes and their optical resolution by lipases could be used to introduce chirality in a specific reaction sequence. Immobilization of the enzyme represents an important advantage, allowing multiple use of a robust solid-phase catalyst. We carried out sol-gel entrapment of Candida antarctica B lipase in matrices derived from ternary silane precursor systems and then adsorbed on Celite. Several ionic liquids have been employed as structure-directing additives and stabilizers against lipase inactivation during the sol-gel immobilization process. The obtained biocatalysts were investigated in the kinetic resolution of model secondary alcohols. The addition of an ionic liquid during the immobilization process resulted in preparations with higher activities and better enantioselectivity, compared to the native lipase. The proper selection of the ionic liquid cation and/or anion was essential to obtain robust biocatalysts with adequate properties. Lipase catalysts will be employed for optical resolution of heterocyclic intermediates of pharmacologically active compounds.

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