text: Unsaturated esters may be epoxidized using either electrophilic or nucleophilic methods. Lanthanide-mediated epoxidation has been successfully applied to cinnamates and β-heteroaryl unsaturated esters. Amides are also epoxidized under lanthanide-mediated conditions.
  Epoxidations of other electron-deficient double bonds (substituted by electron-withdrawing groups other than carbonyls) are limited in scope, although a few examples have been reported. The ability of the carbonyl group to coordinate Lewis acidic functionality is critical for most existing methods.