Ullmann diphenyl ether synthesis

A practical route to aporphine-benzylisoquinoline dimers by an improved Ullmann diphenyl ether synthesis has been worked out. The aromatic halide and the phenolic compound are heated with pentafluorophenyl copper in dry pyridine the average yield of dimer being 50%. ... 

Ullmann diphenyl ether synthesis, 451-452 Ullmann reaction, 130, 132, 184, 363, 654... 

Ullmann diphenyl ether synthesis. Copper or one of its salts or oxides has been used to effect this reaction between an aromatic halide and a phenol. Cava... 

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. ... 

In order to circumvent the problem of low yields in the usual Ullmann reaction, most syntheses of bisbenzylisoquinoline alkaloids have formed the diphenyl ether linkages at an early stage and confronted the problem of isomer separation later. In the case of phaeantharine (18) (Section II,A,3), which has no asymmetric carbons, this approach was clearly preferred. This synthesis exemplifies the use of Reissert alkylation as a key step (9,269). Several analogs of bisbenzylisoquinoline alkaloids were prepared in an analogous manner (270,271). One... 

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. ... 

Another synthesis of vertaline (61) involves an intermolecular [3 + 2] cycloaddition of nitrone 19 as a key step (Scheme 9) (27, 22). Ullmann reaction of bromide 82 with 79 in the presence of a phase-transfer catalyst such as tetra-butylammonium bromide gave the diphenyl ether 83 in about 50% yield. The cycloadduct 84 was prepared in 99% yield by heating 83 with the nitrone 19 in refluxing toluene. Treatment of 84 with methanesulfonyl chloride afforded an in-... 

Synthesis of the alkaloids trilobine and obaberine, containing the diphenyl ether linkages, have been accomplished from (5)-(+)-(0)-benzyl-8-bromo-A -benzoylnorarmepavine (80) by Ullmann condensation with the phenolic amide (81) followed by reductive debenzylation to give the phenolic ether (82). ... 

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. 

The newly described depsidones, their occurrence and synthesis are listed in Table 5. The synthesis of depsidones with a lactole ring like those in norstictic, stictic or salazinic acids have caused considerable difficulties. Hareed (353) tried to prepare a depsidone by a) oxidative coupling, b) by a Smiles rearrangement and c) by an Ullmann reaction of a diphenyl ether, but all three attempts failed (see Scheme 123). Some time later Rama (604) successfully synthesized the lactone depsidone 359 and the lactole depsidone 360 via oxidative coupling of a dibenzophenone (see Scheme 124), The structure of the precursor 358... 

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