Kinetic Resolution of cis-Vinyl Epoxide Containing Electron Withdrawing α-Substituent

Abstract

Vinyl epoxides have rich chemistry which come from alkene and epoxide. This combination of two moieties can also provide additional reactivities. However, enantioselective synthesis of vinyl epoxide has been mostly dependent on enantioselective epoxidations which limited the substrate scope. When general enantio selective synthetic methods were not available, kinetic resolution can be utilized as an efficient alternative. On the basis of the previous research on kinetic resolution of α,β-dichloro cis-vinyl epoxide, the current research aims to expand the substrate scope of the kinetic resolution to more general cis-vinyl epoxides. α-Primary aliphatic cis-vinyl epoxide and α-secondary aliphatic cis-vinyl epoxide were examined under the optimized conditions, but poor enantioselectivities were observed. In consideration of high selectivity with α,β-dichloro-cis-vinyl epoxide, electron withdrawing α-substituents were introduced to improve enantioselectivity. Among α-halo-cis-vinyl epoxides, the highest, though moderate, enantioselectivity was observed from the kinetic resolution of α-fluoro cis-vinyl epoxide which has the most electron withdrawing α-substituent. α,α-Dihalo-cis-vinyl epoxide and α-trifluoromethyl-cis-vinyl epoxide will be employed to examine the relationship between electron withdrawing α-substituents and enantioselectivity