Phenols copper-catalyzed coupling with aryl

Copper-catalyzed couplings of phenols with aryl halides. 2-(3 ,4 -Dimethyl-phenoxy)benzoic acid ... 

Examples of the coupling of aryl iodides and bromides with phenols in the presence of catalytic amounts of copper are shown in Equations 19.107-19.113. The reactions of aryl iodides and bromides with a variety of phenols occur in the presence of (CuOTf), PhH as catalyst and CSjCOj as base (Equation 19.107). The air-stable [Cu(MeCN)JPF (5 mol %) also was shown to catalyze the formation of biaryl ethers. As shown in Equation 19.108, o-halo tertiary and secondary benzamides and.sulfonamides that were prepared by ortho-metallation procedures were suitable coupling partners. ... 

Copper catalysts for the formation of biaryl ethers have also been developed that contain diketonate ligands. Researchers at Merck Laboratories reported the coupling of aryl halides with phenols catalyzed by the combination of CuCl and 2,2,6,6-tetramethylhep-tane-3,5-dione (TMHD), which generates a copper diketonate catalyst (Equation 19.111). Catalysts containing related O-donor ligands have also been used. Two examples of reactions conducted with a polyol and with a phosphonic acid as ligand are shown in Equation 19.112 and Equation 19.113. ... 

Some of these drawbacks have been overcome by the recent developments in copper-catalyzed cross-coupling reactions. Buchwald and coworkers reported the coupling of variety of phenols with aryl bromides in the presence of Cs COj (Scheme 20.34) [89]. The less reactive phenols required an equivalent amount of 1-naphthoic acid and molecular sieves to facilitate the transformation. Under these conditions, the reaction of unactivated aryl halides and less reactive or hindered phenols can be achieved. 

C-0 Bond Formation. A simple and mild method for the coupling of aryl iodides and aliphatic alcohols catalyzed by copper iodide which does not require the use of aUcoxide bases has been described. The reaction can be performed in neat alcohol or in toluene as solvent with catalytic quantities of Cul and 1,10-phenanthrohne, and 2 equiv of CS2CO3. This methodology was successfully applied to the formation of allyl vinyl ethers with tetramethyl-l,10-phenanthroline as the ligand. iVAl-Dimethyl glycine is also a good ligand for this copper iodide-catalyzed Ullmann-type diaryl ether synthesis between phenols... 

It is worth noting that the Ullmann-Goldberg condensation of aryl halides with phenols and anilines worked efficiently in the presence of copper in water.50 For example, the coupling of 2-chlorobenzoic acid with 4-chlorophenol (K2C03/pyridine/copper powder) gave 2-(4-chlorophenoxy)carboxylic acid (Eq. 6.23).51 The Cu(I)-catalyzed transformation of 2-bromobenzoic acid into salicylic acid has also been studied in aqueous media (Eq. 6.24).52... 

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