title: Dissecting Anion Effects in Gold(I)-Catalyzed Intermolecular Cycloadditions.
abstract: From a series of gold complexes of the type [t-BuXPhosAu(MeCN)]X (X=anion), the best results in intermolecular gold(I)-catalyzed reactions are obtained with the complex with the bulky and soft anion BAr4F-[BAr4F-=3,5-bis(trifluoromethyl)phenylborate] improving the original protocols by 10-30% yield. A kinetic study on the [2+2] cycloaddition reaction of alkynes with alkenes is consistent with an scenario in which the rate-determining step is the ligand exchange to generate the (η2-phenylacetylene)gold(I) complex. We have studied in detail the subtle differences that can be attributed to the anion in this formation, which result in a substantial decrease in the formation of unproductive σ,π-(alkyne)digold(I) complexes by destabilizing the conjugated acid formed.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16 43007 Tarragona, Spain, ; e-mail: aechavarren@iciq.es.
authors.forename: Anna
authors.initials: A
authors.lastname: Homs
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16 43007 Tarragona, Spain, ; e-mail: aechavarren@iciq.es.
authors.forename: Carla
authors.initials: C
authors.lastname: Obradors
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16 43007 Tarragona, Spain, ; e-mail: aechavarren@iciq.es.
authors.forename: David
authors.initials: D
authors.lastname: Lebœuf
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16 43007 Tarragona, Spain, ; e-mail: aechavarren@iciq.es ; Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili C/Marcel⋅li Domingo s/n, 43007 Tarragona, Spain.
authors.forename: Antonio M
authors.initials: AM
authors.lastname: Echavarren
keywords: cycloaddition; cyclobutenes; gold catalysis; mechanistic study