Regioselective Synthesis of <i>N</i>²‑Alkylated-1,2,3 Triazoles and <i>N</i>¹‑Alkylated Benzotriazoles: Cu₂S as a Recyclable Nanocatalyst for Oxidative Amination of <i>N</i>,<i>N</i>‑Dimethylbenzylamines

Copper chalcogenide nanoparticles (Cu2S) synthesized for the first time from a single-source precursor, CuSPh, act as highly efficient and reusable heterogeneous catalyst for regioselective amination of N,N-dimethylbenzylamines with various azoles. The reaction involves N–H/C–H cross-dehydrogenative coupling (CDC) and demonstrates wide functional group tolerance. It provides highly selective access to N1-alkylated benzotriazoles, N2-alkylated 1,2,3-triazoles and 4-phenyl-1,2,3-triazoles, and N-alkylated carbazoles in 70–89% yields under solvent-free conditions. The Cu2S nanocatalyst has been characterized by PXRD, XPS, SEM–EDX, and HR–TEM analysis. Mechanistic studies suggest that the reaction follows a radical pathway and involves an iminium ion intermediate.