Dimerization of Oxazolones by Copper-Catalyzed Cross-Dehydrogenative Coupling Reactions

A convenient and efficient cross-dehydrogenative coupling reaction by using readily available and inexpensive copper catalyst was reported. Several oxazolone derivatives underwent dimerization via the formation of Csp3-Csp3 bond under oxidative conditions in the presence of copper(II) acetate as a catalyst, di-tert-butyl peroxide as an oxidant, potassium carbonate as a base, and at high temperature. The dimerized products containing two quaternary centres were obtained in moderate to good yields, suggesting an approach to the synthesis of non-proteinogenic amino acids.