“…Mechanochemistry is mainly promoted by either hand grinding or ball-milling under the solvent-free condition. Indeedly, ball-milling has already been applied for the grinding of minerals into fine particles and the preparation and modification of inorganic solids [26][27][28][29] , but more recently it has rapidly developed in the areas of organic synthesis, e.g., Suzuki [30][31][32] , Sonogashira [33][34][35] , Michael [36][37][38] , aldol reaction [39][40][41][42] , Diels-Alder reaction [43,44] , and so on. Among these, only one recent report by Stolle and co-workers [45] has addressed 1,3-dipolar cycloaddition reaction of azides with alkynes by means of ball-milling, which was named "solvent-free click reaction".…”