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 b s t r a c tA 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 CeO 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 CeO cross coupling reaction. Furthermore, two examples of sequential CeO/CeS and CeN/ CeS 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 40e80%).

Trimethoxyphenyl (TMP) as a Useful Auxiliary for in situ Formation and Reaction of Aryl(TMP)iodonium Salts: Synthesis of Diaryl Ethers

“…We have also demonstrated that the use of aryl(TMP)iodonium tosylates is compatible with a combination of both sterically encumbered aryl electrophile and phenol nucleophile. The symmetrical, and highly sterically congested, 2,2′,6,6′‐tetramethyldiphenyl ether ( 2 ri ) has only been described in the literature on one other occasion, and in ∼2% yield by GCMS (Scheme ). The coupling of 1 r and 2 i proceeded in 52% isolated yield under our standard conditions to deliver 3 ri (Scheme ).…”

“…The symmetrical, and highly sterically congested, 2,2',6,6'-tetramethyldiphenyl ether (2 ri) has only been described in the literature on one other occasion, [13] and in~2% yield by GCMS (Scheme 2). The symmetrical, and highly sterically congested, 2,2',6,6'-tetramethyldiphenyl ether (2 ri) has only been described in the literature on one other occasion, [13] and in~2% yield by GCMS (Scheme 2).…”

Efficient Pyrazole Moiety‐Containing Ligands for Cu‐Catalyzed O‐Arylation of Phenols

“…For these reaction, many mechanisms are proposed and it is recognized that they are categorized into four classes . By examining the various reaction systems that have been developed so far, we can see that reaction products vary greatly depending on ligands, solvents, bases, and so on . Therefore the mechanistic discussion is still controversial even for the same experimental data …”

Palladium‐Catalyzed O‐Arylation Reaction Using Different Heterogeneous Catalyst Systems: The Role of Support

“…Transition metal‐catalyzed C−O bond formation with aryl halides and aromatic phenols is a powerful tool to prepare diarylethers ,. These products are commonly found in a variety of important compounds including a number of pharmaceuticals, agrochemicals, polymers, and life science . Therefore, the development of efficient methods for the synthesis of these essential compounds has achieved considerable attention in synthetic chemistry.…”