Metal- and Azide-Free Synthesis of 1,2,3-Triazoles

Metal- and Azide-Free Synthesis of 1,2,3-Triazoles

Author: Asian Journal of Organic Chemistry

1,2,3-Triazoles have applications in chemistry, biology, and materials sciences. Cu(I)-catalyzed azide-alkyne cycloadditions have been the preferred method to synthesize these compounds. However, reactions that provide access to 1,2,3-triazoles under metal-free, oxidant-free, and azide-free conditions are rare.

Jianbo Wang and colleagues, Peking University, Beijing, China, have developed an efficient method for the synthesis of poly-substituted 1,2,3-triazoles from α,α-difluoro-N-tosylhydrazones and amines. The α,α-difluoro-N-tosylhydrazones, which can be readily prepared, react with a variety of amines in the presence of LiOt-Bu as a base to give 1,2,3-triazoles (reaction pictured). The reaction proceeds via the cleavage of two C(sp3)–F bonds.

The reaction conditions are mild and the approach has a broad substrate scope. Some of the products are obtained in nearly quantitative yield. The proposed mechanism involves the generation of an azoalkene by releasing a fluoride anion, an azo-Michael addition of aniline, a C–F cleavage, an intramolecular cyclization, and a final aromatization.


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