Novel biphenyl organocatalysts for iminium ion-catalyzed asymmetric epoxidation

Two novel chiral biphenyl iminium salts derived from l-acetonamine, containing electron-withdrawing 3,3′-substituents on the biphenyl unit, have been prepared and tested as asymmetric catalysts for epoxidation of prochiral alkenes. The results are compared with those achieved using the corresponding unsubstituted system.