Nanoscrystalline CuO: Synthesis and application as an efficient catalyst for the preparation of 1,2,3-triazole acyclic nucleosides via 1,3-dipolar cycloaddition

Nanowire CuO particles with an average diameter range of 2.5-3.7 nm were examined as catalysts for the 1,3-dipolar cycloadditions of organic azides to terminal alkynes. The material was successfully synthesized at room temperature from metallic copper powder by a facile solution-phase method in the presence of nitric acid, sodium hydroxide (NaOH) and ethylene glycol (EG) as growth-directing agent. The crystallinity, purity, morphology, specific surface areas and structural features of the as-prepared nanowires were characterized by powder X-ray diffraction, Bninauer-Emmett-Teller (BET) method and high-Transmission Electron Microscopy. Under mild reaction conditions, the addition of organic azides to terminal alkynes gives 1,4-disubstituted 1,2,3-triazole as a single regioisomer in good yields with reusability of the catalyst. The present click reaction protocol of terminal alkynes, via 1,3-dipolar cycloaddition with various organic azides allows the regioselective synthesis of 1,2,3-triazole acyclic nucleosides in good yields. We have then initiated the one-pot tandem [3 + 2] cycloaddition where benzylchloride was reacted with propargyl derivatives and sodium azide in the presence of CuO nanoparticles as catalyst. (C) 2012 Elsevier B.V. All rights reserved.