title: Isolation of bis(copper) key intermediates in Cu-catalyzed azide-alkyne "click reaction".
abstract: The copper-catalyzed 1,3-dipolar cycloaddition of an azide to a terminal alkyne (CuAAC) is one of the most popular chemical transformations, with applications ranging from material to life sciences. However, despite many mechanistic studies, direct observation of key components of the catalytic cycle is still missing. Initially, mononuclear species were thought to be the active catalysts, but later on, dinuclear complexes came to the front. We report the isolation of both a previously postulated π,σ-bis(copper) acetylide and a hitherto never-mentioned bis(metallated) triazole complex. We also demonstrate that although mono- and bis-copper complexes promote the CuAAC reaction, the dinuclear species are involved in the kinetically favored pathway.
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry, University of California San Diego, La Jolla, CA 92093-0343, USA.
authors.forename: Liqun
authors.initials: L
authors.lastname: Jin
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry, University of California San Diego, La Jolla, CA 92093-0343, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Tolentino
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry, University of California San Diego, La Jolla, CA 92093-0343, USA.
authors.forename: Mohand
authors.initials: M
authors.lastname: Melaimi
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry, University of California San Diego, La Jolla, CA 92093-0343, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Bertrand
keywords: Catalysis; Mechanism; carbene