title: Mechanistic study of gold(I)-catalyzed intermolecular hydroamination of allenes.
abstract: The intermolecular hydroamination of allenes occurs readily with hydrazide nucleophiles, in the presence of 3-12% Ph(3)PAuNTf(2). Mechanistic studies have been conducted to establish the resting state of the gold catalyst, the kinetic order of the reaction, the effect of ligand electronics on the overall rate, and the reversibility of the last steps in the catalytic cycle. We have found the overall reaction to be first order in gold and allene and zero order in nucleophile. Our studies suggest that the rate-limiting transition state for the reaction does not involve the nucleophile and that the active catalyst is monomeric in gold(I). Computational studies support an "outersphere" mechanism and predict that a two-step, no intermediate mechanism may be operative. In accord with this mechanistic proposal, the reaction can be accelerated with the use of more electron-deficient phosphine ligands on the gold(I) catalyst.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Z Jane
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Diego
authors.initials: D
authors.lastname: Benitez
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Tkatchouk
authors.forename: William A
authors.initials: WA
authors.lastname: Goddard
authors.forename: F Dean
authors.initials: FD
authors.lastname: Toste
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D000586:Amination; D002384:Catalysis; D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D000466:Alkadienes; C025947:propadiene; D006046:Gold