Diaryl ether, synthesis

Many reactions have been shown to benefit from irradiation with ultrasound (ref. 19). We therefore decided to investigate the effect of ultrasound, different catalysts and the presence of solids on Ullmann diaryl ether synthesis. Indeed, sonication of mixtures of a phenol and a bromoaromatic compound, in the absence of solvent and presence of copper (I) iodide as catalyst and potassium carbonate as base, produces good yields of diaryl ethers at relatively low temperatures (Fig. 10) (ref 20). 

Xing, X. et al.. Utilization of a copper-catalyzed diaryl ether synthesis for the preparation of verbenachalcone. Tetrahedron, 58, 7903, 2002. 

Thiation of aromatic compounds is utilized both for the preparation of aryl sulfides and for the generation of sulfur heteroarenes. The diaryl thioether motif is found in the structure of several approved pharmaceuticals, such as antihistamines. In a recent letter, Wu and He disclosed that Cu(I) catalysis is very efficient for the coupling of thiophenols with aryl iodides (Scheme 39) [ 108]. The procedure is very similiar to the diaryl ether synthesis under microwave irradiation reported by the same authors. 

J. Scott Sawyer, Recent Advances in Diaryl Ether Synthesis, Tetrahedron 2000, 56, 5045- 5065. 

J. A. Lindley, Copper Assisted Nucleophilic Substitution of Aryl Halogen, Tetrahedron 1984, 40, 1433. J. S. Sawyer, Recent Advances in Diaryl Ether Synthesis, Tetrahedron 2000, 56, 5045- 5065. 

Vttmann diaryl ether synthesis. This copper(I) derivative is recommended as the condensing reagent in the Ullmann synthesis of diaryl ethers from phenols and bromoarenes in refluxing pyridine (equation I). 

ULLMANN DIARYL ETHER SYNTHESIS Copper(I) phenylacetylide. 

Buck, E., Song, Z. J., Tschaen, D., et al. (2002) Ullmann diaryl ether synthesis rate acceleration by 2,2,6,6-tetramethylheptane-3,5-dione. Organic letters, 4, 1623-1626. 

The SjvAr reaction is another attractive method for diaryl ether synthesis, and reactions of o-nitro- and o-cyanofluorobenzenes with phenols were reported . 7r-Complexation of aryl halides with transition metals activates the aromatic nuclei toward S fAr. Segal employed a ruthenium chlorobenzene complex in the poly(aryl ether) synthesis , and the methodology was extensively studied by Pearson, Rich and their coworkers using manganese complex and later iron and ruthenium complexes in natural product synthesis " . The intramolecular substitution of an aromatic chloride with a phenylalanine derivative takes place at room temperature without racemization (equation 27). 

Substitution. Ullmann diaryl ether synthesis catalyzed by Cu(OTf)2-BINAMINE occurs at a relatively low temperature (in dioxane, 110°, base Cs2C03). ... 

This reaction is related to the Rosemound-von Braun Nitrile Synthesis, Ullman Diaryl Ether Synthesis, and Ullmann Acridine Synthesis. 

Ullmann diaryl ether synthesis ArHal + HOAr ArOAr ... 

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... 

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