Enantiopure Guanidine Bases For Enantioselective Enone Epoxidations: 1, Acyclic Guanidines

A range of structurally and functionally varied enantiopure guanidines has been prepared and evaluated in the enantioselective epoxidation of 3-tert-butoxycarbonylamino-4,4-dimethoxycyclohexa-2,5-dien-1-one 1 using tert-butylhydroperoxide. Successful enantioselective epoxidations were observed and useful structure-activity data obtained, but the reactions were slow and the maximum ee observed was 30%.