Enantiomerically pure cyclobutane derivatives and their use in organic synthesis

The importance of cyclobutanes as intermediates in organic synthesis has been recognized in the last 30 years. The availability of enantiomerically enriched derivatives for their use in chiral synthesis has spurred new methods for their preparation. Most of these developments occurred in the last 15 years. Effective methods include photochemical and catalyzed [2+2] cycloadditions with alkenes possessing chiral auxiliary groups which are either covalently or noncovalently bonded to the reacting partners. Many of these approaches are in their infancy and require further exploitation.