The Betti reaction is one of the best-known multicomponent reactions, leading to the production of Betti bases. This kind of chiral ligand, due to its special structure, can chelate with metals, providing useful catalysts for a wide range of asymmetric syntheses [1-6]. Given the biological and chemical importance of chiral Betti bases, accurate methods for their separation are of great significance. Diastereomeric crystallization is a simple, scalable, and efficient method that typically uses natural (L)-tartaric acid as a chiral resolving reagent to prepare chiral Betti bases [1-6]. The oxidation of allylic C-H bonds in olefins with an oxidant in the presence of copper salts and chiral ligands, known as the enantioselective Kharasch-Sosnovsky reaction, is a powerful tool for the synthesis of chiral allylic esters [6, 7]. A mixture of an acyclic Schiff base and two C-3 epimeric 1,3-naphthoxazine that are in equilibrium with each other was prepared by a three-component reaction of β-naphthol, 4-chlorobenzaldehyde, and ammonium acetate in ethanol at room temperature. Analyzing this mixture by 1HNMR spectroscopy, revealed that the population of the trans isomer is higher than both the imine and cis forms, and also the ratio of the imine is more than the cis isomer. Then by acidic hydrolysis, all the isomers were converted into a stable racemic Betti base salt. The resulting salt was then neutralized with an alkali solution to give the racemic-free Betti base. Then, its enantiomers were separated by the diastereomeric crystallization method using (L)- tartaric acid. Finally, the copper complexes of the synthesized chiral Betti bases were used in the enantioselective Kharasch-Sosnovsky reaction, resulting in good yields of chiral allylic esters with moderate enantioselectivity.
