Immobilized CuO Hollow Nanospheres Catalyzed Alkyne-Azide Cycloadditions

An approach for gram-scale synthesis of uniform Cu₂O nanocubes by a one-pot polyol process was used. The CuO hollow nanostructures were prepared by adding aqueous ammonia solutions with Cu₂O nanocube colloidal solutions. CuO hollow nanospheres on acetylene black (CuO/AB), were synthesized and used for the catalytic [3+2] cycloaddition of azides with terminal alkynes to provide products in good yields with high regioselectivity. The CuO/AB was readily separated by centrifugation and could be reused ten times under the present reaction conditions without any loss of catalytic activity. Transition metals loaded onto acetylene black are useful reagents for a wide variety of organic transformations. Moreover, these heterogeneous systems are promising industrial catalysts.