The First Gold(III) Formate: Evidence for β‐Hydride Elimination

Abstract

The first stable gold(III) formate and experimental evidence for its β-hydride elimination are described. A catalytic dehydrogenation of formic acid together with mechanistic studies shed light on potential pathways operating in fundamental gold-catalyzed transformations.

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

“…[117][118][119][120] Migratory insertion and b-hydride elimination are other major pathways that mayb ei nvolved in ac onventional coupling reaction. [122][123][124][125] Based on all the earlyr esults and hypotheses, achieving Au-catalyzed selective cross-coupling reactions was considered an ontrivial task. Althoughb oth Pd 0 and Au I complexes have ad 10 electronic configuration, they have very different redox potentials.…”

“…For Au catalysis, b-hydridee liminationh as only rarely been reported. [122][123][124][125] Based on all the earlyr esults and hypotheses, achieving Au-catalyzed selective cross-coupling reactions was considered an ontrivial task.…”

The First Gold(III) Formate: Evidence for β‐Hydride Elimination

“…This result suggested the possible formation of ah ighly reactive gold(III) hydride species.I nterestingly,t he reaction of formate 2 in the presence of di-tert-butyl acetylenedicarboxylate (3,5equiv) in 1,2-DCE at 100 8 8Ca fforded (Z)-gold(III) vinyl complex 4 in 64 %i solated yield (Scheme 2). [16]). In solution, (Z)-4 slowly isomerized to the E isomer, [19] which could be characterized by X-ray diffraction analysis,r evealing an elongated Au1ÀC33 bond of 2.083 (9) and asmall C33-Au1-C13 angle of 95.68 8 (Table 1a nd Ref.…”

“…Cognizant of the basic nature of [(N^C^C)Au III F] species, [15] we envisioned their potential use as precursors of gold(III) formates.Indeed, after preliminary experiments,the reaction of gold(III) fluoride 1 in the presence of formic acid in CH 2 Cl 2 at room temperature furnished the corresponding formate 2 in quantitative yield (Scheme 2). [16] Gold(III) formate 2 is stable under ambient conditions as as olid but decomposes in solution over prolonged periods of time (days). 1 HNMR analysis of 2 in CD 2 Cl 2 showed as harp singlet resonance at d = 9.46 ppm, characteristic of the formate moiety.F urthermore,asingle crystal was grown by slow diffusion of MeOH into ac oncentrated solution of 2 in CH 2 Cl 2 ,a nd the proposed structure was confirmed by X-ray diffraction analysis (Table 1).…”

“…In solution, (Z)-4 slowly isomerized to the E isomer, [19] which could be characterized by X-ray diffraction analysis,r evealing an elongated Au1ÀC33 bond of 2.083 (9) and asmall C33-Au1-C13 angle of 95.68 8 (Table 1a nd Ref. [16]).…”