engleski

Enzyme catalysed ring-opening of epoxides

Halohydrin dehalogenase catalyses the ring-closure of halohydrins, as well as the ring-opening of epoxides with both halide and non-natural ionic nucleophiles, such as cyanide, azide and nitrite. What makes this enzyme attractive for synthetic purposes is the fact that ring opening reactions are irreversible and highly b-regioselective. Moreover, reactions can proceed with high enantioselectivity with a wide variety of synthetic substrates. In our screening among wild-type halohydrin dehalogenases, we have identified enzyme from Agrobacterium radiobacter as the most enantioselective in the cyanide-mediated ring opening reaction of epoxides. The enantioselectivity toward monosubstituted epoxides varies from moderate to high (E = 2-106), while resolution of 2, 2-disubstituted epoxides proceeds with excellent enantioselectivity (E ~ 200). This allows preparation of optically pure tertiary alcohols under mild conditions (room temperature and aqueous medium).

kinetic resolution; epoxides; cyanides; azides

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