Enantioselective olefin epoxidation using homologous amine and iminium catalysts-a direct comparison

Homologous biphenyl and (diastereomeric) binaphthyl tertiary azepines and quaternary iminium salts were prepared from (+)-(S,S)-l-acetonamine. Both the amines and iminium ions behave as effective catalysts for the enantioselective epoxidation of unfunctionalized olefins (ee up to 83%).