The preference for dual-gold(i) catalysis in the hydro(alkoxylation vs. phenoxylation) of alkynes

Abstract

This version is available at https://strathprints.strath.ac.uk/61289/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Herein we study the hydroalkoxylation and hydrophenoxylation of alkynes using density functional theory calculations, and compare two possible mechanisms that have been proposed previously on the basis of theoretical and experimental studies, which unravel different preferences because of both the nature of the alkyne and alcohol, as well as the non-innocent role of the counter-anion of the dual gold based catalyst. Entropy is found to have a significant effect, rendering the nucleophilic attack of the monoaurated intermediate [Au(L)(η 2 -alkyne)] + difficult both kinetically and thermodynamically; this mechanism cannot easily form only the trans-alkene product that is observed experimentally. Instead, reaction via a dual gold catalysed mechanism presents much lower barriers. In addition, for the sake of direct comparison with recent results by Belanzoni, Zuccaccia, oversimplification of the Nheterocyclic carbene (NHC) ligand in the calculations might decrease the enthalpy barrier and lead to results that are not directly applicable to experiment. Moreover, the alkylic or arylic nature of the alkyne and/or alcohol is also tested. ORGANIC & BIOMOLECULAR CHEMISTRY ARTICLE

Gold‐Catalyzed Cross‐Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications

“…[69,70,[79][80][81][82][71][72][73][74][75][76][77][78] In the majority of homogeneous Au catalysts, Au exists in the + 1 oxidation state. [103][104][105][106][107] In the past, the applications of Au I in enantioselectiver eactions have been considered challenging. The relativistic effects cause the contraction of 6s and 6p orbitals andt he expansion of 5d orbitals in Au I .…”

Hydroalkoxylation of Terminal and Internal Alkynes Catalyzed by Dinuclear Gold(I) Complexes with Bridging Di(N-Heterocyclic Carbene) Ligands

“…In this frame, a case that partially deviates from this general trend, is represented by the hydrophenoxylation of diphenylacetylene catalyzed by the dinuclear gold(I) complex [{Au(IPr)} 2 (µ-OH)][BF 4 ], studied in detail by Nolan and coworkers [14][15][16]. In this reaction, the gold catalyst is not only involved in the alkyne activation by forming the A-type π-complex (Scheme 1), but also reacts at the first stage of the reaction with phenol, forming the species [{Au(IPr)} 2 (µ-OPh)] + , thus also activating the nucleophile [15].…”

Phenoxylation of Alkynes through Mono‐ and Dual Activation Using Group 11 (Cu, Ag, Au) Catalysts

“…For the sake of consistency, single point energy calculations on the Gaussian09 optimised structures have been undertaken for the ADF calculations. Part of the geometry optimisations is extracted from past work of Poater and co‐workers , …”

“…Note that [Au] = Au(IMe). [23] Heterobimetallic complexes have been also matter of study due to the fact that the bifunctionality of different metals can lead to unique reactivity. Recent work by Cazin et al reported the hydrophenoxylation of internal alkynes with heterobimetallic Cu-NHC/Au-NHC systems, [35] in line with previous works on two metal moieties bearing different metal nature.…”