CO Extrusion in Homogeneous Gold Catalysis: Reactivity of Gold Acyl Species Generated through Water Addition to Gold Vinylidenes

Abstract

Herein, we describe a new gold-catalyzed decarbonylative indene synthesis. Synergistic σ,π-activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.

Integrated Microdroplets Array for Intelligent Electrochemical Fabrication

“…The gold nanostructures have attracted sustained attention in catalysis, sensing, and electronic field due to the diversified nanostructures 28–31. Electrochemical deposition is a traditional technique for fabricating gold nanostructures (e.g., nanoparticle, nanowires, nanoflowers, nanodendrites) 32–35.…”

Methyl‐, Ethenyl‐, and Ethynyl‐Bridged Cationic Digold Complexes Stabilized by Coordination to a Bulky Terphenylphosphine Ligand

“…[6][7][8] Furthermore,a dvances have also been made in the important fields of gold carbonyls [9] and hydrides. [11,12] Tw oc omprehensive review articles on organometallic intermediates in gold catalysis were published in 2014. [11,12] Tw oc omprehensive review articles on organometallic intermediates in gold catalysis were published in 2014.…”

Gold Acyl Complex Formation and Decarbonylation during Indene Synthesis from Catalytically Active Vinylidene Complexes

“…[6] In a significant advance based on chemical intuition, precedent and serendipity, Hashmi and coworkers have now established that selected diyne systems in the presence of a gold catalyst can be converted directly into a variety of indenes (Scheme 1) simply by nucleophilic reaction with water. [7] In the proposed catalytic cycle, the first important new transformation occurs between intermediate, catalytically active gold vinylidenes, initially conjugated to a vinyl gold substructure, and acyl complexes of gold, as summarized in Scheme 2. Related conversions are known for vinylidene catalytic systems with other metals and have been studied in detail.…”

“…Such reactions were employed successfully in targeted syntheses by Trost. Hashmi and coworkers, [7] when studying the trapping of intermediate vinylidene complexes by water, found that aldehydes were not formed from the acyl intermediates. In the first examples for gold chemistry, also unprecedented in vinylidene-mediated catalysis, decarbonylations occurred consistently allowing subsequent protonations and affording the indene products (Scheme 4).…”

“…Notably, these authors as well as Trost and others (on the basis of indirect evidence), [1,12] prefer to include unstable hydroxycarbene intermediates as preliminaries to acyl formation. Such complexes are mentioned in the introduction to the current paper by Hashmi and coworkers, [7] but they are not included in the final catalytic cycle.…”