Arenes diaryl ethers

The coordination of Cr(CO)3 does not activate aryl chloride sufficiently for Williamson diaryl ether formation to occur. Smooth formation of aryl ether 222 proceeds by reacting the easily prepared arene-Ru complex 220 of the highly functionalized aryl chloride with phenol 219. Decomplexation of 221 by irradiation gives 222, and the product is used for the synthesis of the BCF rings of ristocetin A [57],... 

The reaction of nucleophiles with chloroarene-Mn(CO)3 and fluoro arene-Cr(CO)3 complexes has been employed for the synthesis of diaryl ethers and has been particularly applied (ref. 55) to the selective arylation of polyfunctional phenols by reaction of the phenoxide formed from NaH in dimethylformamide with the 4-chlorotoluene-manganese tricarbonyl cation (as the hexafluorophosphate) in acetonitrile at ambient temperature over 18 hours. 

Thiation of arenes is used both for preparation of aryl sulfides and for generation of heteroqfdic sulfur aromatic compounds. The diatyl thioether group is found in the structure of several approved pharmaceuticals, for example antihistamines. In a recent letter Wu and He disclosed that Cu(I) catalysis is very efficient for coupling of aryl thiols with aryl iodides (Scheme 15.69) [135], The procedure is very similar to that reported by the same authors for diaryl ether synthesis under the action of microwave irradiation (Scheme 15.65). 

Sodium/liq, ammonia Arenes from diaryl ethers... 

Arenes from phenols via diaryl ethers ArOH ArH... 

Intramolecular displacement of a fluoride in an electron-deficient arene by a phenohc oxygen is a reliable method for the construction of macrocychc diaryl ethers (66 67) and a useful alternative to the... 

In synthetic contexts, thiyl radicals are known to engage in a number of useful reactions [191-198], including C-H bond abstraction [197, 199-203]. Recently, MacMillan has demonstrated the capacity of catalytically generated thiyl radicals to cleave the C-H bond of benzylic ethers for radical coupling reactions (Fig. 27) to form diaryl methanols (a) [204] or p-amino ethers (b) [205]. The light source is either a Blue LED or a Compact fluorescent lamp (CFL), as designated above. In both reactions, a wide variety of arene components and ether substitutions are tolerated to furnish a diverse set of products and only a catalytic amount of methyl thioglycolate is necessary to affect the desired C-H HAT event. In the formation of diaryl ethers (Fig. 27a), phosphate serves as the base, whereas the P-amino ether... 

The free amino group of 4-0-methyldopamine and 4-0-methyltyramine react as nucleophiles in a chemoselective manner with [RuCp] -complexed p-substituted chloro-arenes. As a consequence, it is not necessary to use protecting groups for the synthesis of peptides with alternating amide and diaryl ether bonds. 

Diary,I sulfones. Sulfuric acid and trifluoroacetic anhydride (1 2 equivalents) form bis(trifluoroacetyl) sulfate (1). which converts arenes and phenol ethers into diaryl sulfones in 70-99% yield. 

The reactivity of cycloaliphatic epoxy monomers with cations is higher than that of glycidyl ether monomers. For this reason, cycloaliphatic epoxies are used for UV-cure coatings. The most efficient initiators are complex aromatic salts of Lewis acids such as diaryl iodonium, triarylsul-fonium, or arene diazonium (Table 2.23) (Crivello, 1999). 

Whereas the torsion angle across the central arene C=C bond is small (< 6°) for 5,11-dialkyl substitution, it increases with diaryl substitution and terminal Cr(CO)3 coordination to > 30° for 5,ll-diphenylchrysene-6,12-dione, obtained from 98a upon careful ether cleavage and oxidation. 

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