title: A highly active and magnetically recoverable tris(triazolyl)-Cu(I) catalyst for alkyne-azide cycloaddition reactions.
abstract: Nanoparticle-supported tris(triazolyl)-CuBr, with a diameter of approximately 25 nm measured by TEM spectroscopy, has been easily prepared, and its catalytic activity was evaluated in the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. In initial experiments, 0.5 mol % loading successfully promoted the CuAAC reaction between benzyl azide and phenylacetylene, in water at room temperature (25 °C). During this process, the iron oxide nanoparticle-supported tris(triazolyl)-CuBr displayed good monodispersity, excellent recoverability, and outstanding reusability. Indeed, it was simply collected and separated from the reaction medium by using an external magnet, then used for another five catalytic cycles without significant loss of catalytic activity. Inductively coupled plasma (ICP) analysis for the first cycle revealed that the amount of copper leached from the catalyst into the reaction medium is negligible (1.5 ppm). The substrate scope has been examined, and it was found that the procedure can be successfully extended to various organic azides and alkynes and can also be applied to the one-pot synthesis of triazoles, through a cascade reaction involving benzyl bromides, alkynes, and sodium azide. In addition, the catalyst was shown to be an efficient CuAAC catalyst for the synthesis of allyl- and TEG-ended (TEG=triethylene glycol) 27-branch dendrimers.
authors.affiliation: ISM, Université Bordeaux, 351 Cours de la Libération, 33405 Talence Cedex (France).
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Laetitia
authors.initials: L
authors.lastname: Etienne
authors.forename: María
authors.initials: M
authors.lastname: Echeverria
authors.forename: Sergio
authors.initials: S
authors.lastname: Moya
authors.forename: Didier
authors.initials: D
authors.lastname: Astruc
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D061565:Cycloaddition Reaction; D015394:Molecular Structure; D014230:Triazoles / Q000737:chemistry*
chemical_list: D000480:Alkynes; D001386:Azides; D014230:Triazoles
keywords: click chemistry; copper; green chemistry; magnetic nanoparticles