Ionization of gold (γ-methoxy)vinyl complexes generates reactive gold vinyl carbene complexes.

Journal Article (Journal Article)

Cationic gold vinyl carbene/allylic cation complexes of the form (E )-[(L)AuC(H)C(H)CAr2 ]+ OTf- {L = IPr, Ar = Ph [(E )-5a ], L = IPr, Ar = 4-C6 H4 OMe [(E )-5b ], L = P(t -Bu)2 o -biphenyl, Ar = 4-C6 H4 OMe [(E )-5c ]} were generated in solution via Lewis acid-mediated ionization of the corresponding gold (γ-methoxy)vinyl complexes (E )-(L)AuC(H)C(H)C(OMe)Ar2 at or below -95 °C. Complexes (E )-5b and (E )-5c were fully characterized in solution employing multinuclear NMR spectroscopy, which established the predominant contribution of the aurated allylic cation resonance structure and the significant distribution of positive charge into the γ-anisyl rings. Complex (E )-5b reacted rapidly at -95 °C with neutral two-electron, hydride, and oxygen atom donors exclusively at the C1 position of the vinyl carbene moiety and with p -methoxystyrene to form the corresponding vinylcyclopropane. In the absence of nucleophile (E )-5a decomposed predominantly via intermolecular carbene dimerization whereas formation of 1-aryl-5-methoxy indene upon ionization of (Z )-(IPr)AuC(H)C(H)C(OMe)(4-C6 H4 OMe)2 [(Z )-6b ] implicated an intramolecular Friedel-Crafts or electrocyclic Nazarov pathway for the decomposition of the unobserved vinyl carbene complex (Z )-[(IPr)AuC(H)C(H)C(4-C6 H4 OMe)2 ]+ OTf- [(Z )-5b ].

Full Text

Duke Authors

Cited Authors

  • Kim, N; Widenhoefer, RA

Published Date

  • June 2019

Published In

Volume / Issue

  • 10 / 24

Start / End Page

  • 6149 - 6156

PubMed ID

  • 31360421

Pubmed Central ID

  • PMC6585879

Electronic International Standard Serial Number (EISSN)

  • 2041-6539

International Standard Serial Number (ISSN)

  • 2041-6520

Digital Object Identifier (DOI)

  • 10.1039/c9sc01574d

Language

  • eng