Enzyme-Catalyzed Nucleophilic Ring Opening of Epoxides for the Preparation of Enantiopure Tertiary Alcohols

The halohydrin dehalogenase from Agrobacterium radiobacter AD1 (HheC) catalyzes nucleophilic ring opening of epoxides with cyanide and azide. In the case of 2,2-disubstituted epoxides, this reaction proceeds with excellent enantioselectivity (E values up to >200), which gives, by kinetic resolution, access to various enantiopure epoxides and β-substituted tertiary alcohols (ee up to 99%). Since the enzyme has a broad substrate range and because these tertiary alcohols are difficult to prepare in other ways, HheC is an attractive biocatalyst for the production of β-cyano and β-azido tertiary alcohols.