Mechanochemical\nActivation of Aryl Diazonium Salts:\nSynthesis of Polycyclic (Hetero)Aromatics

Although the synthesis of polycyclic (hetero)aromatics\nvia the\n[4 + 2] benzannulation process has been thoroughly explored, the restricted\navailability of energy sources (including thermal, light, and electrical\nenergy) mandates the utilization of substantial quantities of organic\nsolvents, inevitably leading to environmental pollution, resource\nwastage, and low reaction efficiency. Herein, we report a new method\nfor the synthesis of polycyclic (hetero)aromatics from diazonium salts\nand alkynes under ball-milling conditions. This mechanochemical approach\nrequires only substoichiometric amounts of DMSO as a liquid-assisted\ngrinding additive and furnishes the desired product in a short time.