title: The Janus Face of the X Ligand in the Copper-Catalyzed Azide-Alkyne Cycloaddition.
abstract: To understand the effect of the anion (X) in the copper-catalyzed azide-alkyne cycloaddition (CuAAC) catalytic process, the kinetic profiles of the successive steps of the catalytic cycle have been studied by performing stoichiometric reactions using copper complexes LCuX in which L is a cyclic (alkyl)(amino)carbene (CAAC) ligand and X = OTf, Cl, OAc, OPh, or OtBu. Basic ligands favor the metalation step but disfavor the formation of the catalytically active σ,π-bis(copper) acetylide, whereas non-nucleophilic ligands favor the latter but slowly promote the former. We show that acetate is a good compromise, and in addition, it is very efficient in the proto-demetalation step.
authors.affiliation: UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0358, United States.
authors.forename: Liqun
authors.initials: L
authors.lastname: Jin
authors.affiliation: UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0358, United States.
authors.forename: Erik A
authors.initials: EA
authors.lastname: Romero
authors.affiliation: UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0358, United States.
authors.forename: Mohand
authors.initials: M
authors.lastname: Melaimi
authors.affiliation: UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0358, United States.
authors.forename: Guy
authors.initials: G
authors.lastname: Bertrand