text: Dialkyl (E)-enones have been most commonly epoxidized using either lanthanide/BINOL systems or a magnesium tartrate catalyst.
  For alkyl aryl (E)-enones, both polypeptides and lanthanide/BINOL catalysts give good yields and enantioselectivities. The most common polypeptide employed is poly-L-leucine.
  Aryl alkyl (E)-enones have been epoxidized with high enantioselectivity using stoichiometric zinc peroxide systems. Polyleucine may be used with these substrates as well; when an existing stereocenter in the substrate biases the sense of selectivity of the epoxidation, polyleucine is able to overcome this bias.
  Phase-transfer catalysis has been applied successfully to epoxidations of diaryl (E)-enones (chalcones). Lanthanide/BINOL is effective for this class of substrates as well.
  (Z)-Enones are difficult to epoxidize without intermediate bond rotation to afford trans-epoxides. Lanthanide catalysts do effectively prevent bond rotation, however, and provide access to cis epoxide products.
  With the lone exception of methylidene tetralone substrates, no general methods are available for the asymmetric nucleophilic epoxidation of trisubstituted double bonds.