Aminoarenethiolato-copper(I) as (pre-)catalyst for the synthesis of diaryl ethers from aryl bromides and sequential C-O/C-S and C-N/C-S cross coupling reactions

Abstract

A small library of 2-aminoarenethiolato-copper(I) (CuSAr) complexes was tested as (pre-)catalysts in the arylation reaction of phenols with aryl bromides. These copper(I) (pre-)catalysts are thermally stable, soluble in common organic solvents, and allow reactions of 6 h at 160 °C with low catalyst loadings of 2.5 mol %. Among the (pre-)catalysts screened, 2-[(dimethylamino)methyl]benzenethiolato-copper(I) (1c) led to the best results and provided good to excellent yields of various substituted diaryl ethers. Mechanistic studies showed that at early stages of the C-O coupling reaction the CuSAr complex is converted into CuBr(PhSAr) via selective coupling of the monoanionic arenethiolato ligand with phenyl bromide with formation of CuBr. In addition, the first results are shown involving a multi-component reaction (MCR) protocol for the in situ synthesis of propargylamines and their subsequent conversion involving a C-O cross coupling reaction. Furthermore, two examples of sequential C-O/C-S and C-N/ C—S cross coupling reactions have been carried out on the same dihalo-pyridine substrate in a one-pot process with the same (CuSAr) (pre-)catalyst (overall yields 40-80%).