Cost Efficient Synthesis of Diaryl Ethers Catalysed by CuI, Imidazolium Chloride and Cs₂CO₃

Abstract

Synthetically versatile imidazolium chlorides, especially 1,3‐bis‐(2,6‐diisopropylphenyl)‐imidazolium chloride (IPrHCl) along with copper (I) iodide and cesium carbonate, were found to be useful to form C−O bonds via coupling of phenols and aryl/heteroaryl bromides. In this catalysis, the metal:ligand (Cu:IPr) loading was optimised to 1.0 mol%, making it an inexpensive and a simple one pot catalytic route for synthesising a variety of diaryl ethers. The catalytic cycle was probed by UV‐Vis, FT‐IR and HRMS techniques confirming involvement of a copper‐imidazolium‐carbonate complex.

Copper‐NHC Based Ullmann Catalysis in Water for Selective N‐Arylation of 3‐Aminophenols

“…The results suggesting that the catalytic process is facilitated by IHPHCl and CuI. The catalytic intermediates which were involved in the reaction between iodobenzene ( 1 a ), 3‐aminophenol ( 2 a ) and the catalytic system were studied using HRMS technique [22] …”

“…The catalytic intermediates which were involved in the reaction between iodobenzene (1 a), 3aminophenol (2 a) and the catalytic system were studied using HRMS technique. [22] Based on the peaks observed in the spectra, the intermediates of the catalytic cycle was postulated ( Figure 6). The peak at m/z = 440.31, suggested the presence of IHP-Cu-I peak, which may be the active catalyst in the reaction.…”

Mechanochemical synthesis of Cu(i)-N-heterocyclic carbene complexes

“…(S)IPr•HCl, (S)IMes•HCl, IPr*•HCl, I t Bu•HCl and MIC•HCl were synthesized following literature procedures. [1][2][3][4][5] Silica gel P60 (230-400 mesh) was used for chromatography.…”

Recent Advancement of Ullmann Condensation Coupling Reaction in the Formation of Aryl-Oxygen (C-O) Bonding by Copper-Mediated Catalyst

“…The aryl bromide/heteroaryl bromide coupled with phenol to give corresponding biaryl ethers with excellent yield; however, highly substituted phenols gave a comparatively low yield of biaryl produces. The electron-withdrawing substituted aryl bromide gave a better results (Scheme 45) [124]. In the Sudeep study, the mechanical aspect of the catalyst was studied using high resolution mass spectrometry (HRMS) techniques systematically.…”

“…The catalysis reaction was proceeded through NHC-copper carbonate species (d) and followed by a bis-µ-oxo NHCcopper complex (e) formation. These intermediates play a critical part in the catalysis and produce the nucleophile incorporated complex (d), which undergoes the addition of aryl halide, followed by a final reductive elimination step yielding the desired biaryl ether and regenerate the intermediate (c) (see Figure 14) [124]. In the Sudeep study, the mechanical aspect of the catalyst was studied using high resolution mass spectrometry (HRMS) techniques systematically.…”