Triazole−Au(I) Complexes: A New Class of Catalysts with Improved Thermal Stability and Reactivity for Intermolecular Alkyne Hydroamination

Abstract

I. General Methods and materials: Unless otherwise noted, all commercial reagents and solvents were obtained from the commercial provider and used without further purification. Anhydrous toluene was distilled from sodium benzophenone ketyl. 1 H-NMR and 13 C-NMR spectra were recorded on Joel 270 and Varian 600 MHz spectrometers. Chemical shifts were reported relative to internal tetramethysilane (δ 0.00 ppm) or CDCl 3 (δ 7.26 ppm) for 1 H and CDCl 3 (δ 77.0 ppm) for 13 C. 31 P-NMR was recorded on Varian 600 MHz spectrometer operating at 242.88 MHz for 31 P. Chemical shifts were reported in ppm down field from internal Me 4 Si and external 85% H 3 PO 4 , respectively. Flash column chromatography was performed on 230-430 mesh silica gel. Melting points were measured on a Mel-Temp 1001D apparatus and uncorrected. HRMS were recorded on LTQ-FTUHRA spectrometer. PPh 3 AuCl 1 , PPh 3 AuNTf 2 2 , IPrAuNTf 2 2 were prepared according to the reported procedure Procedure for synthesis of Triazole-Gold complex 2a, 2b NaOH 1.0 eq., PPh 3 AuCl 1.0 eq. MeOH, rt,

Synthesis and application of a novel bis-1,2,3-triazole ligand containing a 2,2'-bipyrrolidine core

“…Additionally, the difference in © ARKAT USA, Inc chemical shift (δ 25.8 ppm) observed in the 31 P NMR signal relative to pure Ph 3 PAuCl (δ 34.3 ppm) and Ph 3 PAuOTf (δ 28.8 ppm) is a compelling result that strongly supports complex formation. 10 At this point though, it is difficult to determine any specific binding motif in solution. It is also important to note here that the complex generated when using only one equivalent of Ph 3 PAuCl was quite unstable and clearly started to decompose upon work up and solvent removal.…”

“…[5][6][7][8][9] In the case of Au(I), neutral TA ligands can dramatically enhance the thermal stability and chemoselectivity of the Au-cation. 10,11 In the absence of neutral secondary ligands or strong sigma-donating spectator ligands, Au-cation often decomposes to a metallic form through external reduction or disproportionation pathways. 12 By harnessing the productive partnership between Au(I) and TA, we have broadened the scope of Au-catalysis by generating new catalyst libraries that offer broad electronic and structural range.…”

Expanding the frontier of gold-catalyzed cyclizations and rational ligand design.

“…328 Shi and coworkers reported an even higher turnover using a Ph3PAuOTf/benzotriazole/H3PW12O40 system (Scheme 37-a). 348 When we used Tanaka's acidic promoter with our L1-AuCl precatalyst and the alkali salt of the bulky counterion CTf3 -, we found that the catalytic loading could be reduced to 0.0025% (25 ppm) and the reaction reached an impressive TON of 31200. To the best of our knowledge, no other catalyst system has matched this prowess at such low temperature (50 o C).…”

Synthesis of N-heterocycles through cyclization-triggered tandem additions to alkynes and the study of promoters in ionic reactions.

“…Our new gold catalyst system not only has shown superior reactivity in all major types of gold-catalyzed reactions but also is devoid of the drawbacks of silver-gold interactions. We used the hydroamination of alkynes 11,114 as a model system to evaluate the response of our imido gold precatalyst to Brønsted acids, and found that acid strength correlated with performance. This procedure was superior to the traditional silver halide removal protocol ( Figure 6).…”