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This report details a decarboxylative cross-coupling of (hetero)aryl carboxylates with iodoarenes in the presence of a gold catalyst (>25 examples, up to 96% yield). Generating an aryl nucleophile via decarboxylation obviates problems associated with transmetalation at a putative gold(III) complex. This reaction is site specific, which overcomes prior limitations associated with gold catalyzed oxidative coupling reactions. The reactivity of the (hetero)aryl carboxylate correlates qualitatively to the field effect parameter (Fortho). Furthermore, each step in a proposed mechanism was observed from isolated gold complexes, supporting a gold catalyzed mechanism. ASSOCIATED CONTENT Supporting InformationThe Supporting Information is available free of charge on the ACS Publications website at DOI: XX. Experimental procedures and data (PDF)

Palladium-catalyzed cross-couplings and related reactions have enabled many transformations essential to the synthesis of pharmaceuticals, agrochemicals, and organic materials. A related family of reactions that have received less attention are decarboxylative functionalization reactions. These reactions replace the preformed organometallic precursor (e.g., boronic acid or organostannane) with inexpensive and readily available carboxylic acids for many palladium-catalyzed reactions. This review focuses on catalyzed reactions where the elementary decarboxylation step is thought to occur at a palladium center. This review does not include decarboxylative reactions where decarboxylation is thought to be facilitated by a second metal (copper or silver) and is specifically limited to (hetero)arenecarboxylic acids. This review includes a discussion of oxidative Heck reactions, protodecarboxylation reactions, and cross-coupling reactions among others.1 Introduction2 Oxidative Heck Reactions3 Protodecarboxylation Reactions4 Cross-Coupling Reactions5 Other Reactions6 Conclusion

The cross-coupling of sodium (hetero)aryl carboxylates with (hetero)aryl chlorides proceeds with 1 mol % palladium catalyst and does not require inorganic base, silver salts, or copper salts. This coupling uses two low energy partners, and the only stoichiometric byproducts are carbon dioxide and sodium chloride. The substrate scope includes less activated aryl chlorides and carboxylates (>25 examples). The palladium loading could be reduced to 0.1 mol %, and Buchwald-style precatalysts could be used.

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 –.