Hemilabile MIC^N ligands allow oxidant-free Au(i)/Au(iii) arylation-lactonization of γ-alkenoic acids

Abstract

Oxidant-free Au-catalyzed reactions are emerging as a new synthetic tool for innovative organic transformations. Still, a deeper mechanistic understanding is needed for a rational design of these processes. Here we...

A Hemilabile NHC‐Gold Complex and its Application to the Redox Neutral 1,2‐Oxyarylation of Feedstock Alkenes

“…This shows that the second donor atom has an influence on both the barrier and the overall thermodynamics of the process. Indeed, the results mirror previous studies where oxidative addition requires a second donor to provide a small bite angle (here, ∠C NHC −Au−N=68.3° and 79.3° for the transition state and Au III product, respectively) [8–10, 14] …”

“…Bourissou and co‐workers reported Au I complexes modified with mesoionic carbene ligands bearing hemilabile N ‐groups (MIC^N); however, these systems were not effective for oxidative addition of iodobenzene [13] . Recently, Valdés, Guisado‐Barrios, Ribas and co‐workers reported two new (MIC^N)Au(I) complexes bearing hemilabile (pyridine or pyrimidine) groups [14] . The viability of oxidative addition of aryl iodides was demonstrated and applied to catalytic arylation‐lactonization reactions of γ‐alkenoic acids.…”

Heart of gold: enabling ligands for oxidative addition of haloorganics in Au(i)/Au(iii) catalysed cross-coupling reactions

“…It should be noted that Font et al reported studies towards a related Au(I)/Au(III) catalysed intramolecular addition of a carboxylic acid to form the corresponding lactone in modest yields using a bidentate C,N-ligand strategy in 2022. 37 Apart from heteroatom-based nucleophiles, pendant electron-rich arenes (33) have been utilized by Chintawar et al in 2020 as intramolecular nucleophiles towards the Au-catalysed Lewis acid alkene activation for the 1,2-alkene diarylation reaction in the synthesis of 34, Fig. 14A.…”

“…It should be noted that Font et al reported studies towards a related Au( i )/Au( iii ) catalysed intramolecular addition of a carboxylic acid to form the corresponding lactone in modest yields using a bidentate C , N -ligand strategy in 2022. 37…”

Migratory Insertion of CO into a Au–C Bond

“…Bourissou, Amgoune and co-workers reported that a Au­(I) center ligated by a rigid, narrow bite-angle carboranyl diphosphine ligand reacts with biphenylene to give a Au­(III) metallacycle ( vide infra ) . Related processes have been described using other LAu­(I) moieties, including L = NHC, cyclic (alkyl)­(amino)­carbene (CAAC), hemilabile P , N (MeDalPhos), and C , N -ligands . These auracycles are readily accessible compounds containing Au­(III)–C bonds, which we suspected might serve as excellent model systems for studying migratory insertion of CO (Scheme B).…”