N-Substituted Ephedrines as Chiral Auxiliaries in Enantioselective Alkylation Reactions of Carbonyl Compounds

The synthesis of high optical purity chiral compounds is of current importance in organic and organometallic areas of the chemistry with further boost. Chiral compounds are important because of wide use in many areas such as pharmacy and food industry, etc. Reagents, catalysts or chiral auxiliaries that can control the stereochemistry of the products are required for the synthesis of chiral compounds. Furthermore, the reagents used must be able to be recycled. In recent decades, Ephedra derivative compounds have been widely used as catalyst chiral ligands or chiral inductors in asymmetric synthesis. To our knowledge, no review about Ephedra derivative compounds as chiral auxiliaries used with organometallics in alkylation reactions to carbonyl compounds, has been published. In this paper, the use of N-substituted and N-disubstituted ephedra compounds as chiral auxiliary ligands in alkylation, alkenylation and alquinilation reactions of carbonyl and imine compounds is summarized.