C-3 arylation

The first example of C-arylation with pentavalent bismuth compound is 

Although non-enolizable substrates are not arylated by arylbismuth(V) compounds under neutral conditions, their derived enolate anions react easily with Ph3BiCl2, Ph3BiC03 and tetraphenylbismuth(V) compounds to produce 

C-Arylation of phenols and naphthols with arylbismuth(V) compounds 

AriBiCOi Ar = phenyl, p-tolyl, p-anisyl, P-O2NC6H4 PhiBiCO, 

4-dimethyl-phenyl, mesityl Ar2Bi(OAc)2 Ar = 2-allyloxy-phenyl 

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The Suzuki coupling of arylboronic acids and aryl halides has proven to be a useful method for preparing C-aryl indoles. The indole can be used either as the halide component or as the boronic acid. 6-Bromo and 7-bromoindolc were coupled with arylboronic acids using Pd(PPh3)4[5]. No protection of the indole NH was necessary. 4-Thallated indoles couple with aryl and vinyl boronic acides in the presence of Pd(OAc)j[6]. Stille coupling between an aryl stannane and a haloindole is another option (Entry 5, Table 14.3). 

A combination of Cp nCX —A CXC) (where = cyclopentadienyl) effectively promotes the Friedel-Crafts coupling of glycosyl fluorides with aromatic compounds, such as trimethoxyben2ene or methoxynaphthalenes. The derived C-aryl glycosides are potent antitumor agents (39). 

Another source of C-unsubstituted derivatives are o-aminopyridine aldehydes e.g. 216 - 217) (60JCS1370), and the corresponding ketones may be used to furnish C-aryl compounds (71GEP2051013). 

Isomerism about a formal Csp —Csp double bond Isomensm about a formal (C—C C-aryl and C-acyl derivatives... 

The reaction has been extended to indazole (67BSF2619) from which both isomers have been obtained, and to pyrazolones (68BSF5019). In the latter system N-, O- and C-aryl and even diaryl derivatives have been isolated from the reaction with l-fluoro-2,4-dinitrobenzene. 

X-ray analysis of an optically active oxaziridine substituted at nitrogen with the 1-phenylethyl group of known configuration led to the absolute configuration (+)-(2R,3R)-2-(5-l-phenylethyl)-3-(p-bromophenyl)oxaziridine of the dextrorotatory compound as expected, C-aryl and A-alkyl groups were trans to each other (79MI50800). 

Imidazole, 2-amino-1 -methyl-4,5-diphenyl-tautomerism, 5, 368 Imidazole, 2-aroyl-mass spectra, 5, 360 synthesis, 5, 391, 402 UV spectra, 5, 356 Imidazole, 4-aroyl-synthesis, 5, 474 Imidazole, C-aroyl-UV spectra, 5, 356 Imidazole, aryl-nitration, 5, 396, 433 oxidation, 5, 433 Imidazole, 1-aryl-dipole moments, 5, 351 dearylation, 5, 449 ethylation, 5, 448 H NMR, 5, 353 hydroxymethylation, 5, 404 rearrangement, 5, 108 synthesis, 5, 390 thermal rearrangement, 5, 363 Imidazole, 2-aryl-chlorosulfonation, 5, 397 synthesis, 5, 475 Imidazole, 4-aryl-bromination, 5, 399 Imidazole, C-aryl-electrophilic substitution, 5, 432-433 nitration, 5, 433 Imidazole, N-aryl-reactions, 5, 448-449 structure, 5, 448-449 Imidazole, arylmercapto-... 

THE C-ARYLATION OF g-DICARBONYL COMPOUNDS ETHYL l-(p-METHOXYPHENYL)-2-OXOCYCLOHEXANECARBOXYLATE... 

Aryl lead tncarboxylates have been shown to be intermediates in two new routes to phenols, and to have considerable potential as reagents for the C-arylation of carbon acids which are more acidic than diethyl malonate. A... 

The enamine (28) did not undergo C arylation with p-nitrochlorobenzene under these conditions, and at higher temperatures N arylation and subsequent eleavage with formation of N-(4-nitrophenyl) pyrrolidine takes place (68). 

Low yields of C-arylated ketones have also been obtained by reaction of pyrrolidine enamines with diaryl iodonium salts (68). 

Stereoselective inverse-demand hetero (4 + 2) cycloadditions. A Chiral Template for C-Aryl Glycoside Synthesis. Chiral allenamides2 4 had been used in highly stereoselective inverse-demand hetero (4 + 2) cycloaddition reactions with heterodienes.5 These reactions lead to stereoselective synthesis of highly functionalized pyranyl heterocycles. Further elaboration of these cycloadducts provides a unique entry to C-aryl-glycosides and pyranyl structures that are common in other natural products (Scheme 1). 

This chapter covers recent information on the preparation, physical properties, and reactions of quinoxaline and its C-alkyl, C-aryl, iV-alkyl, and A-aryl derivatives as well as their respective ring-reduced analogs. In addition, it includes methods for introducing alkyl or aryl groups (substituted or otherwise) into quinoxalines already bearing substituents and the reactions specific to the alkyl or aryl groups in such compounds. For simplicity, the term alkylquinoxaline in this chapter is intended to include alkyl-, alkenyl-, alkynyl-, and aralkylquinoxalines likewise, arylquino-xaline includes both aryl- and heteroarylquinoxalines. 

Schemes Sm-promoted reductive coupling of chiral C-aryl imines...

This methodology has been applied to carbohydrate derivatives and provides a route to certain C-aryl glycosides. 

Entry 5 involves metallic copper as a catalyst and is probably a metal-catalyzed reaction (see Section 11.3). The reaction is carried out with excess phenol without solvent. Entries 6 and 7 are cases of C-arylation, both using 2,4-dinitrochlorobenzene. 

Anthryl, 1-naphthyl, mesityl, and 4-quinolyl groups in 37h-k promote C/C aryl shift (see Table 2) their proclivity to migrate is far greater than expected from the electronic influence of the x-systems. This is presumably due to the intermediacy of spiro-linked benzenium betaines 30 31 , occurring in place of the carbenes otherwise encountered. The formation of phosphinic esters 42h-k is partly or completely suppressed 30). 

In recent years, a variety of hypervalent iodine reagents have been available. The versatility of these hypervalent organoiodine reagents in organic synthesis has been well recognized. Diaryliodonium salts constitute an important reagent class for the transfer of aryl groups. These iodonium ion salts have been used effectively in C-arylation of a variety of nucleopohiles.112 The arylation of the anion of nitroalkanes with diaryliodonium salts was already reported in 1963.113... 

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