Elucidating the mechanism, origin of regioselectivity and substrate scope of the synthesis of structurally diverse 1,2,4-triazoles <i>via</i> a rare type of diazo compound reactivity

The 1,2,4-triazole scaffold plays a significant role in drug development, and efficient methods for synthesizing its derivatives are in high demand. In this work, we propose a convenient approach for the synthesis of polysubstituted 1<i>H</i>-1,2,4-triazoles under mild, metal-free conditions in a highly regioselective manner. The reaction proceeds with high yields and demonstrates tolerance towards a broad range of functional groups. Unlike previously reported methods, this approach does not require the prior preparation of azlactones and is effective with a wide variety of diazo reagents. A reaction mechanism supported by DFT calculations is proposed, and pathways for further transformation of functionalized 1,2,4-triazole derivatives are demonstrated.