 Achiral Lewis acids have been used for decades to promote the synthesis of racemic mixtures in a myriad different reactions.Starting in the 1960s chemists have use the chiral acids to induce the enantioselective reactions.Common reaction types include Diels-Alder reactions, the ene reaction, [2+2] cycloaddition reactions, hydrocyanation of aldehydes, and most notably, Sharpless epoxidations.