Arylation of aromatic compounds

Arylation of Aromatic Compounds. In contrast to Friedel-Crafts alkylations, arylations of aromatics are not as well known, and usually require drastic conditions. They iaclude (/) dehydrogenating condensation (SchoU reaction) (2) arylation with aryl haUdes and (J) arylation with dia2onium hahdes. 

Phenyl radicals can be generated by the thermal decomposition of lead tctrabcnzoate, phenyl iodosobenzoate, and diphenyliodonium hydroxide,- - and by the electrolysis of benzoic acid.- These methods have been employed in the arylation of aromatic compounds, including heterocycles. A method of promise which has not been applied to the arylation of heterocycles is the formation of aryl radicals by the photolysis of aromatic iodides at 2537... 

Arylation of Aromatic Compounds The Gomberg-Bachmann and Related Reactions 253... 

The Gomberg-Bachmann reaction is a method for arylation of aromatic compounds and quinones (Gomberg and Bachmann, 1924). Originally this reaction involved adding aqueous sodium hydroxide slowly to an intimate mixture of an aqueous solu-... 

A bond between carbon and halogen can be cleaved quite easily with light221 One of the few synthetic applications of this reaction is the photo-arylation of aromatic compounds, a sequence employed in the synthesis of alkaloids222,223) as shown for the key step in the synthesis of boldine (2.13) 223>. 

Arylation of Aromatic Compounds by Diazonium Salts Arylation or Aryl-de-hydrogenation... 

Dickerman, S.C., Weiss, K. (1957) Arylation of aromatic compounds by the Meerwein reaction. Evidence for aryl radicals from orientation studies. J. Org. Chem. 22, 1070. 

During their work on the arylation of aromatic compounds by substitution, Fujiwara, et al. observed biaryl formation when aromatic compounds were placed in the presence of olefin-palladium complexes and silver nitrate.80 Developing this reaction as a method for biphenyl synthesis, these authors showed that the more stable the olefin-palladium complex was, the lower the yield. Ethylene dichloropalladium proved to be the best choice, when used with silver nitrate. However, the reaction required stoichiometric amounts of both catalysts (Scheme 10.47). Benzene derivatives substituted by electron-donating or -withdrawing groups reacted as well, but a mixture of regioisomers was produced, except for nitrobenzene, which only gave m,m -dinitrobiphenyl. 

Kakiuchi F, Kan S, Igi K, Chatani N, Murai S (2003) A ruthenium-catalyzed reaction of aromatic ketones with arylboronates a new method for the arylation of aromatic compounds via C-H bond cleavage. 1 Am Chem Soc 125 1698-1699... 

Isotope Effects (knjk, ) in Arylations of Aromatic Compounds (Eliel et cd., 1962)... 

Direct arylation of aromatic compounds by C-H activation with aryl halides by transition metal catalysis has become an important synthetic process. However until recently the reported procedures were limited to only electron-rich aromatic rings and heteroaromatic compounds. Biaryl compounds containing pyrazine were isolated in moderate to high yields when potassium... 

The arylation of aromatic compounds with aryldiazonium salts (III) in the presence of base affording biaiyls (II) is called the Gomberg-Bachmann-Hey (GBH) reaction [46]. First observations were published by Bamberger [47] and Kuhling [48] more than a century ago. However, the first practical synthesis of biaryls was discovered by the former authors, and was further developed by Hey. The original... 

The use of dry aryldiazonium salts of naphthalene-1-sulfonic [70], naphthalene-1,5-disulfonic [70], ZnCl2 complex [70], hexafluorophosphoric or tetrafluoroboric acid [61] in non-aqueous medium under as mild as possible reaction conditions is substantial to reach higher yields of biaryls. An alternative method for non-aqueous GBH reaction is the aprotic diazotation of aromatic amines with alkyl nitrites such as butyl or pentyl nitrite with subsequent arylation of aromatic compound, as demonstrated by Cadogan [71,72]. This method is realized by simple heating the mixture of aromatic amine, alkyl nitrite and liquid arene at an elevated temperature. When a mixture of 3-aminopyridine (46), benzene and pentyl nitrite is heated at reflux, 3-phenylpyridine (47) is obtained with a 55% yield [71], Scheme 16. 

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