Ethers aryl, formation

Very early reports on these systems described them as polycondensates, consisting of broad molar-mass distributions with randomly branched topologies. The methods of synthesis included Friedel-Crafts coupling of benzyl alcohols [108] and the polymerization of 2,5,6-tribromophenol involving aryl ether formation [109], In addition, hyperbranched natural carbohydrate polymers, such as amylopectin, dextrin, and glycogen have been extensively studied [73-75]. 

FIGURE 1.6 Copper-catalyzed aryl ether formation... 

Arylbismuth 671, 673 Arylboronic acid 671, 673 Arylbutenes, formation of 613 Aryl-2-cyclohexenones 653 Aryl ethers—see also AUyl aryl ethers. Diaryl ethers. Phenyl ethers, Propargyl aryl ethers formation from calixarenes 1387 Aryl haUdes, as phenol precursors 396, 397 Ai-Arylhydroxylamines, isomerization of 801-805 oxidation of 419 3-Arylindoles, synthesis of 1236 Aryl ketones, oxidation of 424, 425 Aryloxylium cations 179 Asatone, synthesis of 1178, 1179 Ash, from incineration of municipal waste, phenoUc compounds in 938 Aspersitin, synthesis of 1327, 1328 Aspirin 10, 11... 

Treatment of oestrone with tetraphenylbismuth monotrifluoroacetate gave oestrone phenyl ether and exemplified, in part, a new procedure for aryl ether formation.31 A detailed study was reported of the formation of benzyl ethers by sequential reaction of alcohols with chloro(phenylmethylene)dimethylammonium chloride and sodium hydrogen telluride.32 Steroidal alcohols, inter alia, were converted into hydrolytically stable silyl ethers by reaction with B N Sil or BulPh2I which were generated in situ from the selenosilane and iodine.33 The 5a-hydroxycholestane (21) was protected in this way. 

Kato, N. Shimamura, S. Khan, S. Takeda, F. Kikai, Y. Hirama, M. Convergent approach to the maduropeptin chromophore aryl ether formation of (R)-3-aryl-3-hydroxypropanamide and cyclization of macrolactam. Tetrahedron 2004, 60, 3161-3172. 

Amines, polymeric, immobilization of the Cu(II) complexes, 134 Arsonic acid, polymer-bound, generated, 139 Aryl ethers, formation with Nafion, 51t... 

Ring arylation of phenols with aryl halides to produce arylphenols is competitive with aryl ether formation. As discussed in Chapter 3.3.2, it is known that the ring arylation proceeds with Pd(0)-PPh3 catalyst. 

Table 1 shows the experimental conditions for the synthesis of azocellulose polymers through alkyl aryl ether formation via Mitsunobu reaction (Scheme 1). Samples AZOEST21 and AZOEST49 were prepared from ESTERCELL cellulose, and Sample AZOVIS69 was prepared from VISCOCELL cellulose. The degrees of substitution (DS) for these samples are 0.21, 0.49 and 0.69, respectively. 

Copper-catalyzed Aryl Ether Formation. Traditional methods for formation of aryl ethers involve stoichiometric Ullmann couplings. A new system was developed exploiting catalytic CuCl and NMI as a ligand. The title compound was chosen due to its similarities to histidine, a common amino acid for binding metals. This methodology was applied to the synthesis of the insecticide diafenthiuron that produced the desired aryl ether in greater than 98% yield compared to 39% reported in current patents (eq 32). ... 

The aryl ether formation was, until the late 1990s, the domain of copper-catalyzed processes, namely the Ullmann reaction. Around 15 years ago, Hartwig and Buchwald independently discovered the palladium-catalyzed alkoxylation of aryl halides with phenols. Later, these reactions were extended to aliphatic alcohols and to hydroxide as nucleophiles (vide infra. Scheme 5-159). The mechanism of the reductive elimination has been elucidated on isolated complexes. ... 

For alkyl aryl ether formation without allylic rearrangement, see, for example Pirrung, M. C. Brown, W. L. Rege, S. Laughton, P. JACS 1991,113,8561. 

For alkyl aryl ether formation with allylic rearrangement, see, for example Danishefsky, S. Berman, E. M. Ciufolini, M. Etheredge, S. J. Segmuller, B. E. JACS 1985,107, 3891. 

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