Copper(II)-Catalyzed [3+2] Cycloaddition Reactions Of Secondary Amines With α-diazo Compounds

1,2,3-Triazoles are very important five-membered nitrogen heterocycles owing to their distinctive structure and chemical characteristics. They have tremendous applications in various research fields. Therefore, the research on the synthesis and properties of this class of compounds has always been a hot topic of organic chemistry. To this day, Husigen-cycloaddition, Cu-Catalyzed Azide-Alkyne Cycloaddition, enamine’s cycloaddition, diazo compounds’ cycloaddition And other methods have been widely used in the synthesis of 1,2,3-triazole. In view of the important nature and wide range of applications of the 1,2,3-triazole, So the new direct and efficient synthesis of 1,2,3-triazole is still exciting.The cross-dehydrogenative coupling(CDC) reaction can use the simple substrates instead of materials with functional groups, which made the synthetic programs shorter and more efficient, more economical and environmentally friendly. Therefore, the oxidative cross-dehydrogenative coupling(CDC) reaction to be recognized as one of the most effective way to formation of C-C bond and C-heteroatom bonds. In this field, using the α-C(sp3)-H which adjacent to the nitrogen in α-amino acid derivatives to form iminium and reaction with various nucleophilies has been widely reported.In this paper, using α-amino acid derivatives as a starting material, in the presence of Cu Br2 and DBU under oxygen atmosphere at room temperature, a novel [3+2] cycloaddition reaction of secondary amines with α-diazo compounds has been developed for the first time. The reaction involves a sequential aerobic oxidation/[3+2] cycloaddition/oxidative aromatization procedure. The reaction not only to expand the use of α-amino acid derivatives in the cross-dehydrogenative coupling reaction, but also sets up a new simple and efficient method for the synthesis of 1,2,3-triazoles.