title: Metal-Free Intermolecular Azide-Alkyne Cycloaddition Promoted by Glycerol.
abstract: Metal-free intermolecular Huisgen cycloadditions using nonactivated internal alkynes have been successfully performed in neat glycerol, both under thermal and microwave dielectric heating. In sharp contrast, no reaction occurs in other protic solvents, such as water, ethanol, or diols. DFT calculations have shown that the BnN3/glycerol adduct promotes a more important stabilization of the corresponding LUMO than that produced in the analogous BnN3/alcohol adducts, favoring the reactivity with the alkyne in the first case. The presence of copper salts in the medium did not change the reaction pathway (Cu(I) acts as spectator), except for disubstituted silylalkynes, for which desilylation takes place in contrast to the metal-free system.
authors.affiliation: Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université de Toulouse, UPS and CNRS UMR 5069, 118, route de Narbonne, 31062 Toulouse cedex 9 (France).|Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avda. Països Catalans, 16, 43007 Tarragona (Spain).
authors.forename: Marta
authors.initials: M
authors.lastname: Rodríguez-Rodríguez
authors.affiliation: Laboratoire de Chimie de Coordination (LCC), Centre National de la Recherche Scientifique (CNRS), 205, route de Narbonne, 31077 Toulouse cedex 4 (France).
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gras
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avda. Països Catalans, 16, 43007 Tarragona (Spain). mapericas@iciq.es.
authors.forename: Miquel A
authors.initials: MA
authors.lastname: Pericàs
authors.affiliation: Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université de Toulouse, UPS and CNRS UMR 5069, 118, route de Narbonne, 31062 Toulouse cedex 9 (France). gomez@chimie.ups-tlse.fr.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Gómez
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D002384:Catalysis; D003300:Copper; D061565:Cycloaddition Reaction; D005990:Glycerol / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D008872:Microwaves; D012997:Solvents
chemical_list: D000480:Alkynes; D001386:Azides; D008670:Metals; D012997:Solvents; D003300:Copper; D005990:Glycerol
keywords: azide-alkyne cycloaddition; density functional calculations; glycerol; metal-free reactions; microwave activation