Ullmann Condensation Reactions

Cl Reactive Blue 19 (9) is prepared by the reaction of bromamine acid (8) with y -aminophenyl-P-hydroxyethylsulfone [5246-57-1] (76) ia water ia the presence of an acid-hinding agent such as sodium bicarbonate and a copper catalyst (Ullmann condensation reaction) and subsequent esterification to form the sulfuric ester. 

The same group of authors has recently reported a combination of various palladium- and copper-catalyzed Suzuki, cyanation, and Ullmann condensation reactions for the synthesis of thiophene-based selective angiotensin II AT2 receptor antagonists (Scheme 6.24) [55],... 

Ukraine, titanium production in, 24 847 UL 94 flame testing, 19 588 UL94 flammability test, 10 175-176 Ulexite (boronatrocalcite cottonball), 4 133t, 241, 243t, 245, 5 785t Ullmann condensation reaction, 9 309, 310, 444... 

The novel indolo[3,2-/ ]carbazole compound 58 has been prepared in good yield by an Ullmann condensation reaction of 5,ll-dihydroindolo[3,2-/ ]carbazole with 1-iodonaphthalene. The product was found to exist in two isomeric forms, cis and trans, attributable to the hindered rotation of the bonds binding the naphthyl groups <1999JA5097>. 

Tomita, M., Fumitani, K., Aoyagi, Y. Cupric oxide as an efficient catalyst in Ullmann condensation reaction. Chem. Pharm. Bull. 1965, 13, 1341-1345. 

Little information is available on the mechanism of the traditional Ullmann condensation reactions. The difficulties in drawing mechanistic conclusions arise from the reactions being conducted at high temperatures (>150 °C) and the typically heterogeneous reaction conditions. Because the mechanism is not yet known in detail, improvements in this reaction have been gained empirically, instead of from theory. The mechanistic proposals for these reactions remain speculative. 

The Ullmann coupling [30] involves treatment of aryl halides with stoichiometric copper at high temperatures to yield biaryl compounds. Considerable effort has been made to lower the temperature necessary for initiation of the reaction, as well as decrease the required amount of copper salts. These advances served as the basis for extending this method for the synthesis of aryl heteroatom bonds, known as the Ullmann Condensation Reaction [22, 31, 32]. After several reports for C-O and C-N bond formation, methods for C-S bond formation began to emerge. 

In a synthesis of decinine, a phenol was protected as a methanesulfonate that was stable during an Ullmann coupling reaction and during condensation, catalyzed by calcium hydroxide, of an amine with an aldehyde. Aryl methanesulfonates are cleaved by warm sodium hydroxide solution. 

Ullmann condensation of the sodium salt of p-chlorothiophe-nol (31) with 2-iodobenzoic (32) acid gives 33. Cyclization by means of sulfuric acid affords the thioxanthone, 34. Reaction with the Grignard reagent from 3-dimethylaminopropyl chloride affords the tertiary carbinol (35). Dehydration by means of acetic anhydride affords chlorprothixene as a mixture of geometric isomers, 36. (Subsequent work showed the Z isomer-chlorine and amine on the same side—to be the more potent compound.) Chlorprothixene is said to cause less sedation than the phenothiazines. ... 

Additional studies showed that iodoferrocene was approximately as reactive as l-iodo-2-nitrobenzene under Ullmann conditions. A mixed Ullmann reaction involving these two reactive aryl halides produced 2-nitrophenylferrocene. Ullmann condensations of iodoferrocene with various sodium phenoxides and sodium arenethiolates likewise led to ferrocenyl aryl ethers and sulfides, respectively (84, 85). 

Low molecular weight aromatic ethers have been prepared principally by the condensation of phenolate salts with aromatic halides 82). The Ullmann condensation (81), which employs copper or its salts as catalysts has been used in most cases in the laboratory. Recently a modification of the Ullmann condensation which consists of heating copper (1) oxide, the free phenol, and the aromatic halide in s-collidine has been reported (3). This method is recommended for alkali-sensitive aromatic compounds. In addition, reaction of phenolate salts with copper (1) oxide and the aromatic halide in boiling N,N-dimethyl formamide is described. When the halogen is activated by electronegative groups as in -chloroni-... 

Unlike thioindoxyl (Section VI, 1,2), 4-hydroxybenzo[6]thiophene will not condense with aniline, nor will it undergo a Ullmann-Fetvadjian reaction with 1-naphthylamine.554... 

Like thioindoxyl (Section VI, 1,2) and 2-naphthol, but unlike thiooxindole (Section VI, 1,1) and 4-hydroxybenzo[6]thiophene (Section VI, 1,3), 5-hydroxybenzo[6]thiophene condenses readily with aromatic amines.558 It undergoes a normal Ullmann-Fetvadjian reaction with 1-naphthylamine to give l-methylthieno[3,2-u]benz[fe]-acridine, but with 2-naphthylamine an inseparable mixture of 1-methylthieno[3,2-u]benz[j]acridine and dibenz[u,j]acridine is obtained.558... 

Sulfar fibers are extruded from polyphenylene sulfide) or PPS by the melt-spinning process. The first PPS polymer was made in 1897 by the Friedel-Crafts reaction of sulfur and benzene. Researchers at Dow Chemical, in the early 1950s, succeeded in producing high-molecular weight linear PPS by means of the Ullmann condensation of alkali metal salts of p-bromothiophenol. 

Important vat dyes containing a carbazole moiety include C.I. Vat Brown 3 and Vat Black 27. These dyes are made according to the method shown in Fig. 13.126 for Vat Brown 3. The synthesis employs an Ullmann-type condensation reaction between compounds... 

A synthetic route to ( )-0,f>-dimethyltubocurarine iodide (CXXV), via the racemate of 0,0-dimethylbebeerine (CXXIII), was announced in 1959 by Tolkachev and his collaborators (94). It started by the condensation of 3-methoxy-4-hydroxyphenethylamine with 4-benzyloxy-phenylacetic acid to give the amide CXXVI. Reaction of the potassium salt of the latter with the methyl ester of 3-bromo-4-methoxyphenyl-acetic acid in the presence of copper powder gave compound CXXVII. This on condensation with 3-methoxy-4-hydroxy-5-bromophenethyl-amine afforded compound CXXVIII, which was methylated to CXXIX. The latter compound was cyclized with phosphorous oxychloride to the dihydroisoquinoline derivative CXXX. Debenzylation of CXXX followed by intramolecular Ullmann condensation yielded compound CXXXI. The latter was converted to racemic dimethylbebeerine (CXXIII) by reduction with zinc dust in acetic acid followed by methyla-tion. Finally, treatment of ( + )-CXXIII with methyl iodide furnished the dimethyl ether of ( + )-tubocurarine iodide, identified by comparison of its UV-spectrum with that of the dimethyl ether of natural tubo-curarine iodide and by melting-point determination of a mixture of the two specimens. 

In a synthesis of decinine, a phenol was protected as a methanesulfonate that was stable during an Ullmann coupling reaction and during a condensation, catalyzed by calcium hydroxide, of an amine with an aldehyde. Aryl methanesulfonates are cleaved by warm sodium hydroxide solution, with LDA (THF, -78°C to rt, 57-95% yield) or with TMSOK/CH3CN. An aryl methanesulfonate was cleaved to a phenol by phenyllithium or phenylmagnesium bromide it was reduced to an aromatic hydrocarbon by sodium in liquid ammonia. ... 

A conventional synthesis of tecleanthine (50) has been executed. Ullmann reaction of 2-amino-3-methoxybenzoic acid with 3-methoxy-4,5-methylene-dioxyiodobenzene gave the diphenylamine (49). Compound (49) was converted by cyclization (POCI3), hydrolysis (HCl), and methylation into tecleanthine (50). The Ullmann condensation was also used to prepare the natural acridones (48 R = R = R = R = OMe) and xanthoxoline (48 R = OH, R = R = R = H, iV-demethyl). The corresponding 9-thioketones were also synthesized. 

Even though the Jourdan-Ullmann condensation has been known for more than a century, the mechanism is still not quite clear. On the one hand, the reaction may proceed via a free-radical mechanism, pertaining to the reductive dehalogenation of aryl halides and the acceleration of the reaction rate by ultraviolet irradiation, as outlined in Scheme 1. On the other hand, the reaction may involve halonium and proceed as a simple aromatic nucleophilic substitution, as displayed in Scheme 2. However, for the reaction of 6>-halobenzoic acid, it is believed that the copper ion coordinates with both carboxyl and... 

Both ultrasound and microwave have been applied to accelerate the reaction the Jourdan-Ullmann condensation under microwave irradiation can be carried out in... 

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