Mechanochemical Synthesis of 1,2,4-Triazoles via a [3+2] Cycloaddition of Azinium-N-Imines and Nitriles

We report here a mechanochemical Cu-catalyzed [3 + 2] cycloaddition of azinium-N-imines with nitriles under solventless grinding conditions. Various 1,2,4-triazolos derivatives were obtained in 51-80% yields. The developed protocol offers advantages in functional-group compatibility, scalability, no use of solvents, shorter reaction time, and without external heating. In addition, heterocyclic N-imines such as quinolinium and isoquinolinium salts are also suitable substrates, resulting in the production of 1,2,4-triazolo[1,5-a]quinoline and 1,2,4-triazolo [5, 1-a]isoquinoline derivatives under mechanochemical conditions.

Automated summary

A mechanochemical Cu-catalyzed [3 + 2] cycloaddition of azinium-N-imines with nitriles was reported under solventless grinding conditions. Various 1,2,4-triazolos derivatives were obtained in high yields. The developed protocol offers advantages in functional-group compatibility, scalability, and shorter reaction time.