Mechanistic Investigation into the Gold-Catalyzed Decarboxylative Cross-Coupling of Iodoarenes

Abstract

While many gold-catalyzed reactions have been thoroughly developed, most are not thought to involve redox events at gold. In contrast, recent advances have demonstrated the feasibility of redox gold catalysis. This report describes a detailed mechanistic investigation of the gold-catalyzed decarboxylative cross-coupling, which likely proceeds via a high-valent Au­(I/III) pathway. This investigation includes a kinetic analysis, stoichiometric experiments with Au­(III) complexes, and density functional theory calculations. These data support a turnover-limiting oxidative addition to form a Au­(III) aryl complex, with an off-cycle resting state. The dominant pathway appears to proceed through a silver-mediated decarboxylation with a subsequent Ag­(I) to Au­(III) transmetalation. These data provide some rationale for the significant counterion effects between SbF6 – and NTf2 –.

Migratory Insertion of CO into a Au–C Bond

“…Exposure of cyclopropanes 2b – e to 1 led to decomposition, with no evidence for the formation of C–C oxidative addition products . Similar results were obtained using MeDalPhosAuCl or IPrAuCl in place of 1 . The contrasting reactivity of 3-membered 2b – e versus 2a was investigated computationally (see Supporting Information (SI)), leading to two key findings.…”

Circular Discovery in Small Molecule and Conjugated Polymer Synthetic Methodology

“…One such example uses stoichiometric Ag in a method of decarboxylative coupling. 73 , 74 Here, a Ag carboxylate is delivered to the Au metal center using Ag(I) to Au(III) transmetalation. Another report, inspired by a Au/Ag dual catalytic system, sought to discover a Pd/Ag system with catalytic amounts of both metals for direct arylation.…”

“…Since these reports of Au/Ag dual catalysis, new methods have been reported drawing insight from the Au/Ag transmetalation step initially discovered in this polymerization study. One such example uses stoichiometric Ag in a method of decarboxylative coupling. , Here, a Ag carboxylate is delivered to the Au metal center using Ag­(I) to Au­(III) transmetalation. Another report, inspired by a Au/Ag dual catalytic system, sought to discover a Pd/Ag system with catalytic amounts of both metals for direct arylation .…”

Mechanistic views and computational studies on transition-metal-catalyzed reductive coupling reactions

“…Over the past decades, transition-metal-catalyzed coupling reactions have undergone revolutionary development and have become one of the most efficient methods for the installation of a wide variety of functional groups. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Coupling reactions are classified into three types: cross-coupling reactions between a nucleophile and an electrophile, [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] oxidative coupling reactions with two nucleophiles, [33][34][35][36][37][38][39] and reductive coupling Fengjiao Xiao was born in Loudi, Hunan, China, in 1998. She received her bachelor's degree from Shaanxi Normal University.…”