PHOTOINDUCED ELECTRON TRANSFER-INITIATED ENANTIOSELECTIVE CYCLIZATION OF N-BENZOYL-alpha-DEHYDROARYLALANINE tert-BUTYL ESTERS IN THE PRESENCE OF CHIRAL AMINE

摘要

The asymmetric photocyclization of the title compounds in 1,2-dichloroethane was found to proceed cleanly in the presence of primary,secondary,or tertiary chiral amine to give the corresponding cis- and trans-3,4-dihydrooxazole derivatives in enantiomeric excess (ee) of 11-38% and 6-33%,respectively,depending on the steric factor of the aryl substituent as well as on the hydrogen-bonding ability of the chiral amine.