Direct access to stabilized CuI using cuttlebone as a natural-reducing support for efficient CuAAC click reactions in water

Abstract

Cuttlebone@CuCl₂ has efficiently catalyzed the one-pot azidonation of organic bromides, followed by a regioselective azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reaction to produce the corresponding 1,4-disubstituted 1,2,3-triazole derivatives in excellent yields, in water. Importantly, cuttlebone is not only used for successful immobilization of CuCl₂ in order for its heterogenation, but it is also utilized as a natural-reducing platform which can reduce Cu^II to the click-active stabilized Cu^I. This mild three component synthetic approach avoids handling of hazardous and toxic azides, because of their in situ generation. Moreover, the catalyst has the advantages of being ligand-free, leaching-free, thermally stable, easy to synthesize from inexpensive commercially available precursors, environmentally friendly and recyclable for at least seven times without a significant decrease in its activity and selectivity.