Arylamines copper-catalyzed

Reaction of Arylamines Copper-catalyzed C—N coupling affords powerful tool for the synthesis of nitrogenated compounds [33]. In 1987, Paine reported soluble cuprous ion as the active catalytic species in Ullmann coupling [34]. Soluble air-stable copper(I) complex, Cu(PPh3)jBr, has been used for the synthesis of functionalized diaryl and triaryl amines (Scheme 20.17) [35]. Copper(I) complexes 7-8 and CuI-PBu have been employed for the coupling of aryl halides with aiyl amines [36, 37]. The catalyst with PBu could be used for the coupling of less reactive aiyl chlorides in the presence of KOTlu. 

General procedure for the copper-catalyzed synthesis of primary arylamines via amidation/hydrolysis ... 

In addition to the work using palladium catalysts, a wide array of copper catalysts have been developed for the synthesis of arylamines. Some of the earliest examples of the copper-catalyzed coupling chemistry used simple copper salts such as copper acetate... 

Arylations. Copper(II) acetate catalyzes the reaction of arylboronic acids with phenols and amines (including imidazole and amides) to provide diaryl ethers (e.g., for synthesis of thyroxine) and arylamines, respectively. The reactions are quite erratic, although some preparatively useful cases have been found. 

Palladium(0)-catalyzed coupling of iodobenzene (153) and the commercial arylamine 154 afforded quantitatively the diarylamine 156 (Scheme 34) [178]. The oxidative cyclization of the diarylamine 156 to clausine L (148) is catalytic in palladium(II) and copper(II) acetate (or manganese(lll) acetate, respectively). Thus, air is the actual oxidizing agent in this process. For example, employing only... 

A construction of the carbazole framework involving copper(ll)-catalyzed aryla-mine arylation and palladium(ll)-mediated oxidative cyclization has been reported by Menendez et al. (Scheme 41) [190, 191]. The diarylamines 95 were obtained by copper(ll) acetate-catalyzed N-arylation of arylamines 31 with phe-nyllead triacetate (183) using Barton s conditions [192]. Subsequent oxidative cyclization using palladium(ll) acetate under microwave irradiation afforded the carbazoles 32. This procedure was applied to the synthesis of murrayafoline A (188) [190]. 

Some of the optimized procedures for Stille and Sonogashira reactions involve the addition of copper cocatalysts to accelerate the cross-coupling procedures. A word of caution should be provided on the role of these additives in Pd-catalyzed amination procedures. Beletskaya and Davydov have reported the arylation of benzotriazole and of diary-lamines in polar organic or aqueous organic solvents using a combination of palladium and copper as catalyst.The arylation of amino acids has been reported under similar conditions.However, these reaction conditions are similar to classic Ullmann procedures for the synthesis of arylamines, except for the addition of palladium to the reaction mixture. In one case, subsequent work showed that the palladium species was not an essential component and that copper alone was the true catalyst in their reactions. An unusual accelerating effect of amino acid coordination to copper was used to explain the low-temperature Ullmann conditions. Beletskaya, however, showed that lower yields and a mixture of N1 and N2 arylation products were observed from the reactions of benzotriazole in the absence of copper and no reaction was observed in the absence of palladium. The conditions for this chemistry are, however, distinct enough from those of the majority of the aryl halide aminations to support the idea that a different mechanism may operate. 

This multicomponent reaction gives rise to a variety of ortho-functionalized arylamines 315 and thioethers 316 in good overall yields. The reaction can be extended to functionalized benzynes. Thus, the sulfonate 317 readily provides the expected aryne that adds regioselectively magnesium thiolate 318 providing the magnesium derivative 319. Its copper(I)-catalyzed trapping furnishes the tetrasub-stituted benzene 320 in 72% yield (Scheme 4.71) 171]. 

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