Ligand-free copper(I) catalyzed N- and O-arylation of aryl halides

Abstract

Abstract-A simple and industrially viable protocol for C-N and C-O coupling is reported here. Arylation of phenol, benzylamine and imidazole with aryl bromides is achieved using ligand-free Cu(I) halide salts in low catalytic amount (2.5 mol %).

Highly Practical “Ligand‐Free‐Like” Copper‐Catalyzed N‐Arylation of Azoles in Lower Nitrile Solvents

“…The results clearly implied that a "ligand-free-like" N-arylation may be expected by using a suitable monodentate ligand as solvent. Recently, several such procedures were achieved using DMF, [12] DMP, [13] or TEOS [14] as monodentate ligand solvents. To develop a more convenient and milder procedure for this purpose, we herein report the first nitrile-type of monodentate ligand-mediated, highly practical "ligand-free-like" copper-catalyzed Narylation procedure, which was achieved by using lower nitriles as solvent without any additional ligands.…”

Ullmann reaction through ecocatalysis: insights from bioresource and synthetic potential

“…), as a base, and 10 mol% of copper source were still necessary, TBAB (0.3 equiv.) Importantly, examples involving "ligand-free" coupling of aryl halides with phenols are scarcely described in the literature and they usually require extreme reaction conditions (temperatures of 150-160 o C) 91,92 . The loading of copper could be reduced to 5 mol%.…”

Development of Methodologies for Copper-Catalyzed C–O Bond Formation and Direct Cyanation of Aryl Iodides

“…However, no product was obtained ( Table 1, entry 1). Literature suggests that cesium carbonate can serve as a base for C-O bond forming reactions [62,63]. Changing from K 3 PO 4 to Cs 2 CO 3 we were able to obtain a 97% yield of the desired product when performing the reaction at 170°C for 30 min using 20 mol% Cu 2 O and a 1:2 ratio of aryl iodide to phenol (Table 1, entry 2).…”