Ullmann 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). 

Ullmann diaryl ether synthesis.2 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. 

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

Ullmann diaryl ether synthesis ArHal + HOAr ArOAr ... 

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

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... 

A variant for the synthesis of diaryl ethers—e.g. diphenyl ether 9, where an aryl halide and a phenoxide are reacted in the presence of copper or a copper-(I) salt, is called the Ullmann ether synthesis. ... 

Sawyer and coworkers have developed an efficient alternative Ullmann synthesis of diaryl ethers, diaryl thioethers, and diarylamines using the SNAr reaction. Phenol, thiophenol, or aniline reacts with an appropriate aryl halide, in the presence of KF-alumina and 18-crown-6 in acetonitrile or DMSO to give the corresponding diaryl ether or diaryl thioether as shown in Eqs. 9.6 and 9.7.9a... 

A useful reaction for investigation is the Ullmann synthesis of diaryl ethers, which has potential importance for synthesis of a number of commercial products in the agrochemical and pharmaceutical fields, but which suffers from serious drawbacks, particularly high temperatures... 

The synthesis of aryl ethers and especially diaryl ethers has recently received much attention as an alternative to the Ullmann Ether Synthesis. 

Snieckus, V. The directed ortho metalation— Ullmann connection. A new Cu(I (-catalyzed 231 variant for the synthesis of substituted diaryl ethers. J. Org. Chem. 1999, 64, 2986—2987. 

The name Ullmann is not only associated with the biaryl synthesis (Figure 16.4, 16.5), but is also known from the synthesis of diaryl ethers (Ullmann synthesis of diaryl ethers). An example is given in the topmost reaction of Figure 16.6. Remember Side Note 5.6, where we asked the following question How can diphenyl ethers be prepared Now you are ready to give a correct answer, which is By way of Ullmann synthesis. ... 

ULLMANN GOLDBERG Aromatic substitution Cu catalyzed substitution of aromatic halides in the synthesis of disryls, diaryl ethers, diaryl... 

Cristau, H.-J., Cellier, P. P., Hamada, S., Spindler, J.-F., Taillefer, M. A General and Mild Ullmann-Type Synthesis of Diaryl Ethers. Org. Lett. 2004, 6, 913-916. 

Ullmann ether reaction The synthesis of diaryl ethers by the coupling of an aroxide anion with an aryl halide in the presence of copper. 

Various synthetic approaches have been demonstrated for the synthesis of PAEs since early days [35 0], PAEs were synthesized by Ullmann condensation between bisphenols and aryl fcis-halide monomers using Cu(I) salt/pyridine as catalyst [36], General Electric developed the first commercially successful PAE poly(2,6-dimethyl phenylene oxide) (PPO) [38], It was prepared by oxidative coupling of 2,6-dimethyI phenol. However, this process has its own restrictions, because it does not allow much structural variation or inclusion of any electron-withdrawing group into the polymer main chain. First attempts to synthesize polysulfones (PSF) were successfully done by Friedel-Crafts sulfonylation reaction of arylenedisulfonyl chlorides, for example, diphenyl ether-4,4 -disulfonyl chloride with diaryl ethers, for example, diphenyl ether, or by self-condensation of 4-phenoxy benzene sulfonyl chloride in the presence of FeCls [41], Whereas the former reaction involves side reactions (sulfonylation not only in the para- but also in the ort/io-position), the latter produces only the desired linear all-para products. 

Synthetic Methodology Derived from the DoM-Cross-Coupling Nexus 11099 Table 14.19 The DoM-Ullmann synthesis of diaryl ethers [12]. 

Elix, Musidlak, Sala and Sargent 128) have reported a novel synthetic route to xanthones which used an Ullmann reaction to produce a diaryl ether and its subsequent condensation to yield the xanthones (route C). This route is exemplified by the synthesis of thiophaninic acid (136) (Scheme 16). 

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