Syntheses of Triangular Gold Complexes and Their Applications in Hydroamination Reaction

Abstract

Triangular all‐metal complexes have aroused our research interest due to their unique structural and properties. Herein, through the facile reduction of μ3‐oxo complex [μ3‐O(PPh3Au)3]+BF4− (1), we synthesized and isolated the triphenylphosphine stabilized triangular tri‐gold complex [(PPh3Au)3]+BF4− (2) for the first time (yield=90 %). Both complexes showed interesting photochemical sensitivity to temperatures and solvents. The cyclic voltammetry of these complexes showed one single oxidation process in CH3CN. These tri‐gold complexes (2 mol % based on the complex itself) were further applied in the catalytic hydroaminations for substituted phenylacetylenes with anilines and gave the corresponding imine products with great catalytic reactivity and regioselectivity without aiding any promoters or additives. When the loading of the tri‐gold complexes was decreased to 1.0 mol%, 95 % and 97 % of conversions were obtained using 1 and 2, respectively. When further decreased the catalyst loading to 0.5 mol% in preparative scale, 83 % and 80 % of isolated yields were achieved, respectively. This method presented great significance for the syntheses of a series of imine‐containing pharmaceutical intermediates even in preparative scale. Moreover, the investigations of catalytic mechanisms of this reaction indicated that these tri‐gold complexes played important roles as efficient pre‐catalysts in hydroaminations.

Advances for Triangular and Sandwich-Shaped All-Metal Aromatics

“…Based on the above work on gold clusters, our group synthesized the first triphenylphosphine stabilized triangular tri-gold complex [(PPh 3 Au) 3 ] + BF 4 − through the facile reduction of μ 3 -oxo complex [μ 3 -O(PPh 3 Au) 3 ] + BF 4 − ( Figure 23 ) [ 127 ]. The cyclic voltammetry of [(PPh 3 Au) 3 ] + BF 4 − showed one single oxidation process.…”

“…Reprinted with permission from ref. [ 127 ] Copyright © 2024 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany.…”

Aryl sulfonate anion stabilized aromatic triangular cation [Pd3]+: syntheses, structures and properties

“…3a). 33,34 For example, 4-methylbenzenesulfonate paired complex 3 presented the maximum absorption at the wavelength of 399 nm. While, the presence of N]N group and the enlarged conjugation area in the methyl orange anion stabilized complex 7 caused red shi (to 404 nm), and the absorption intensity became much stronger than complex 3 (increased about 30%).…”

Evolution of Triangular All-Metal Aromatic Complexes from Bonding Quandaries to Powerful Catalytic Platforms

“…Recently, an interesting development was reported showing that the hydroamination of terminal alkynes could be accomplished using trigold clusters (Scheme b) . The active complex is isolobal to I , and it has triphenylphosphine as the ligand instead of a carbene.…”

“…Recently, an interesting development was reported showing that the hydroamination of terminal alkynes could be accomplished using trigold clusters ( Scheme 4 b). 74 The active complex is isolobal to I , and it has triphenylphosphine as the ligand instead of a carbene. This species could be prepared by CO-mediated reduction of its parent oxo complex, through a strategy that is reminiscent to that adopted by Sadighi for the synthesis of I .…”