Ethers Ullmann synthesis

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. ... 

The syntheses of 1 utilized the Ullmann ether synthesis.13 Reaction of 2 mol of 1-bromonaphthalene with 4,4-(hexafluoroisopropylidiene)diphenol afforded the desired product 1. The reaction was carried out in DM Ac at 160°C in the presence of potassium carbonate as the base and copper (I) iodine as the reaction catalyst to yield 1, as depicted in Scheme 1. The reaction proceeded slowly but in good yield with easy isolation of the desired compound. Acylation of 1 with 4-fluorobenzoyl chloride to prepare 2 was carried out under modified Friedel-Crafts reaction conditions14 using dimethyl-sulfone as catalyst moderator. Both 1 and 2 were easily recrystallized to yield high-purity monomers suitable for polymerizations. 

All of the sulfone diols were able to form oligomers in the second step of the reaction sequence, the Ullmann ether synthesis. As with the synthesis of the mono(bromophenoxy)phenol products, two methods were used to form the dibromo materials. Method A used pyridine, potassium carbonate and cuprous iodide, while Method B employed collidine and cuprous oxide with the dibromobenzene and higher molecular weight diol (IV). The major difference between the syntheses of the mono(bromophenoxy)phenols described earlier and these lies in the stoichiometry of the reactions. In order to... 

Linear annulated dioxins synthesis were reported by analogy with that of the 1,4-benzodioxin series <2002T1533> or in a modification of the Ullmann ether synthesis <2004T8899>. 

For a review of copper-assisted aromatic nucleophilic substitution, sec Lindley Tetrahedron 1984, 40. 1433-1456. "For a review of the Ullmann ether synthesis, see Moroz Shvartsbcrg Russ. Chem. Rev. 1974, 43. 679-689. Wcingarten J. Org. Chem. 1964, 29. 977. 3624. 

Ullmann ether synthesis Tris[2-(2-methoxyethoxy)ethyl]amine, 336... 

Ullmann ether synthesis, 1, 361 for enantioselective reactions characteristics, 1, 366 hydroformylation, 1, 371 hydrogenation, 1, 368 hydrosilylation, 1, 371... 

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

Substitution between various nucleophiles (e.g. substituted phenoxides) with aryl halides. The most common of these is the Ullmann Ether Synthesis. 

Polyarylene ethers were prepared using the Ullmann ether synthesis and had s in air of at least 310°C. 

Coupling reactions. Nanosized copper is a good catalyst for Ullmann ether synthesis, using CS2CO3 as base in MeCN at 50-60°. Carbon-supported copper in the presence of 1,10-phenanthroline shows similar activities with the aid of microwave irradiation. A -Arylation of A-heterocycles (benzimidazole, triazole,...) by ArSi(OR)3 is mediated by Cu-FeCls and TBAF in the air. ... 

The Ullmann ether synthesis also benefits from the presence of A -methylprolinamide/... 

Halophenols without 2,6-disubstitution do not pol5unerize imder oxidative displacement conditions. Oxidative side reactions at the ortho position may consume the initiator or interrupt the propagation step of the chain process. To prepare polyCphenylene oxide)s from unsubstituted 4-halophenols, it is necessary to employ the more drastic conditions of the Ullmann ether synthesis. A cuprous chloride-pyridine complex in 1,4-dimethoxybenzene at 200° C converts the sodium salt of 4-bromophenol to poly(phenylene oxide) (1) ... 

More recent studies have been concerned with the utilization of acetylene functionality and designing a system which would have all the processing criteria of an epoxide system. Materials which process analogously to the state-of-the-art epoxides require a very flexible backbone which will exhibit a low Tg before cure. The study provided a flexible aryl-ether system which Incorporates a phenylsul-fone backbone and has been referred to as ATS. The initial synthesis of ATS Involved the nucleophilic displacement reaction of various leaving groups in the 4,4 positions of diphenylsulfone with the metallic salt of m-hydroxyphenylacetylene. Research in our laboratory for lower cost precursors to ATS has led to the synthesis of bromo end-capped phenylsulfone oligomers via the Ullmann ether synthesis. 

The benzophenone system was also prepared by the reaction of m-hydroxyphenylacetylene with 4,4 -difluorobenzophenone. The S3nithe-sis allowed an independent method of obtaining pure monomer which could be compared with the monomer obtained from the Ullmann ether synthesis. 

A series of acetylene-terminated, aryl-ether thermoset systems were prepared by an Ullmann ether synthesis involving the condensation of various salts of aromatic bis—diols with m—dibromobenzene. The bromo end-capped oligomers were converted to the acetylene-terminated systems by the catalytically-induced, bromo-displacement reaction with 2-methyl-3-but3m-2-ol, followed by base hydrolysis. 

The Ullmann reaction can be taken to refer to two different transformations. The first is the copper mediated coupling of two aryl groups to give a biaryl compound this is the classic Ullmann reaction. The second, the Ullmann-type reaction, is the nucleophilic aromatic substitution between aryl nucleophiles and aryl halides, the most common of which is the Ullmann ether synthesis. The classic Ullmann reaction will be reviewed in this chapter the reader is refered to several excellent reviews for details on the Ullmann-type reaction. " ... 

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