One-Pot Three-Component Synthesis of Enamine-Functionalized 1,2,3-Triazoles via Cu-Catalytic Azide–Alkyne Click (CuAAC) and Cu‑Catalyzed Vinyl Nitrene Transfer Sequence

A number of enamine-functionalized
1,2,3-triazole derivatives have
been prepared via the Cu-catalyzed three-component reaction of terminal
alkyne, azide, and 2H-azirine. The reaction proceeds
through insertion of vinyl nitrene into the C–Cu bond of the
triazolyl-Cu species, providing an efficient and step- and atom-economic
approach to the enamine-bearing polysubstituted 1,2,3-triazoles. The
resulting triazoles were easily transformed to trisubstituted pyrazoles
in the presence of a Rh catalyst.