title: Phosphonium Formation by Facile Carbon-Phosphorus Reductive Elimination from Gold(III).
abstract: A recent trend in homogeneous gold catalysis has been the development of oxidative transformations relying on Au(I)/Au(III) redox cycling. Typically, phosphine-supported Au(I) precatalysts are used in the presence of strong oxidants to presumably generate phosphine Au(III) intermediates. Herein, we disclose that such Au(III) complexes can undergo facile C(aryl)-P reductive elimination to afford phosphonium salts, which have been spectroscopically and crystallographically characterized. Mechanistic studies indicate that this process occurs from cationic species at temperatures as low as -20 °C but can be accelerated in the presence of nucleophiles, such as acetonitrile and phosphines, via a five-coordinate intermediate. Importantly, this study highlights that irreversible C(aryl)-P reductive elimination is a feasible decomposition or activation pathway for phosphine-supported Au(III) catalysts and should not be ignored in future reaction development.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawai
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: William J
authors.initials: WJ
authors.lastname: Wolf
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Antonio G
authors.initials: AG
authors.lastname: DiPasquale
authors.affiliation: Los Alamos National Laboratory , Chemistry Division, Los Alamos, New Mexico 87545, United States.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Winston
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: F Dean
authors.initials: FD
authors.lastname: Toste
mesh_terms: D002244:Carbon / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000737:chemistry*
chemical_list: D010758:Phosphorus; D002244:Carbon; D006046:Gold