Merging photoredox and catalysis by transition metals, coined as metallaphotoredox catalysis, has proven to be an excellent new platform for the development of new synthetic strategies for the formation of carbon–carbon and carbon–heteroatom bonds [1]. In this presentation, we will present a dual catalytic system that has been successfully developed for the ligation of azides with alkynes to yield 1,4-disubstituted-1,2,3-triazoles in a resgioselective manner. Our strategy consists of merging decatungstate anion [W₁₀O₃₂]^4- photocatalysis in the presence of a hydrogen donor solvent to reduce the Cu(II) precursor into the catalytically active species Cu(I), consequently starting a copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC).

The resulting bifunctional H⁺[W₁₀O₃₂]⁵⁻/Cu(I) catalytic system operates efficiently in an environmentally benign water–ethanol solvent mixture as a reaction medium, producing only 1,4-disubstituted-1,2,3-triazole derivatives with high yields of up to 99% under mild conditions. This metallaphotoredox approach can be applied to a large range of substrates and large-scale reactions. To prove the sustainability of this dual catalytic process, CuAAC was performed under sunlight exposure too [2].

References

[1] P. J. Sarver, V. Bacauanu, D. M. Schultz, D. A. DiRocco, Y. Lam, E. C. Sherer, D. W. C. MacMillan, Nat. Chem. 2020, 12, 459.

[2] S.-E. Stiriba, N. Aflak, E. M. El Mouchtari, H. Ben El Ayouchia, S. rafqah, H. Anane, M. Julve, Appl Organomet Chem. 2023; 37:e7175.