N-aryl-, reactions

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-... 

N-Arylpiperazin-2-ones, N-arylpiperazin-2,5-diones and N-aryl-3,4-dihydro-quinolin-2(lff)-ones have been synthesized via a microwave-enhanced Goldberg reaction [105]. N-arylation reactions with 4-benzylpiperazin-2-one and 4-benzylpiperazin-2,5-dione performed in the microwave (reflux conditions) were tremendously accelerated in comparison with the same transformations performed under classical heating at reflux (Schemes 103 and 104). The phenylation of 3,4-dihydroquinolin-2(lH)-one under microwave irradiation was also faster but less pronounced. 

Dibromonaphthalene 274 undergoes a Pd(0)-BINAP [3+3] coupling reaction, believed to involve an initial N-arylation reaction and subsequent C-C bond formation of product 275 (Equation 37) <2004OL3293>. Bis(sulfonamide) 276 (formed in 56% yield in the presence of Cul and CsOAc in dimethyl sulfoxide (DMSO)) is not observed under the palladium-catalyzed conditions. 

At intramolecular variant of the N-arylation reaction has led to the pentacyclic compound (38) (Cu2 Cl2, K2C03, diglyme). 

The initial observation indicating that such C-arylation was indeed feasible stemmed from an attempted palladium-catalyzed double N-arylation reaction (for details of this type of coupling reaction, see below). With the objective of preparing C2-symmetric bissulfoximine 28, dibromonaphthalene 29 was treated with an excess of sulfoximine 9 under standard coupling conditions using [Pd2dba3]/ BINAP as a catalyst in the presence of a base and, to our surprise, cyclic sulf-oximine 30 was obtained in excellent yield (Scheme 2.1.1.8) [30]. 

Benzimidazole, N-aryl-reactions, 5, 448-449 Benzimidazole, 2-aryl-l-methyl-reactions,... 

The N-arylation reactions are investigated more seldom than the N-alkylation ones. N-Arylation of 5-phenylte-trazole with bis-(4-methoxyphenyl)iodonium bromide in MeOH in the presence of Et3N yielded only the N2-isomer 260 (Equation 42) <2001CHE372>. 

A microwave-assisted one-pot two-step approach towards 1-arylindazoles relied on a copper-catalyzed intramolecular N-arylation-cyclization of in situ formed arylhydrazones [72], Traditionally, the Cul-diamine-complex catalyzed N-arylation reactions occurred at elevated temperatures (up to 110 °C) and required prolonged time (up to 24 h) to go to completion [73]. The com-... 

It was found that N-arylation reactions could be carried out in solventless conditions with all the six catalysts 222-227. However, with the presence of a little NMP (1 ml at a 5 mmol scale), reaction yields were higher in all cases. In the presence of NMP, the yields were 77-100%, wheareas for the neat case, the yields were 56-68% (Scheme 54). 

The arylation of nucleophiles by reaction with diaryliodonium salts can be greatly facilitated by copper catalysis. This effect was observed by Beringer et al in the thermal decomposition of diaryliodonium halides as well as by Caserio et al in the hydrolysis of diaryliodonium salts. 2 jhe thermal decomposition of diphenyliodonium chloride shows a reduced activation energy upon copper catalysis Ea = 19 kcal/mole in Methylene glycol in the presence of CuCl instead of 31 kcal/mole in the absence of catalyst.From the synthetic point of view, the copper-catalysed arylation with diaryliodonium salts has been particularly useful in the case of a number of reactions involving heteroatomic nucleophiles, in particular for 5-, 5e-, O- and N-arylation reactions. 

N-Arylation. Reaction of R2NH with Arl is completed at room temperature using the BINOL-CuBr complex as catalyst. ... 

A copper-catalyzed A-alkynylation reaction developed for amides was also applied to pyrroles. Therefore, treatment of pyrrole 55 with bromoalkyne 56 in the presence of copper sulfate and 1,10-phenanthroline gave A-alkynylpyrrole 57 <04OLl 151>. A copper catalyzed N-arylation reaction of indoles has also been demonstrated with pyrroles and other ji-excessive nitrogen heterocycles <04JOC5578>. 

An SN2-type ring-opening of N-activated aziridines 105 with a 2-bromobenzyl alcohol/thiol 106, followed by a copper-catalyzed intramolecular N-arylation reaction, afforded the corresponding tetrahydrobenzox(thi)azepines 107 in good yields (14JOC6468). 

Suramwar et al. (2012) used predominant (111) facet CuO nanoparticles as heterogenous catalysts for the N-arylation reactions of indoles using indoacyl derivatives (Scheme 2.16). The nanoparticle catalysts were recycled and reused for further catalytic reactions with minimal loss in activity. 

Intramolecular Pd-catalyzed or -mediated N-arylation reactions have been employed in the synthesis of several natural products [5]. For example, pyrroloindoline 4,... 

The Hartwig-Buchwald arylation of amines can also be favorably combined with the Heck reaction [383, 384]. For example, the intramolecular palladium-catalyzed N-arylation of immobilized dehydro(halophenyl)alaninate was found to proceed smoothly to form indolecarboxylates. The method was successfully combined with the Heck reaction to constitute a one-pot indole synthesis in the form of a palladium-catalyzed cascade C,N-arylation reaction (Scheme 8.58) [383, 384]. 

Conversely, in the synthesis of Tumor Necrosis Factor-a Converting Enzyme (TACE) inhibitors, Chemey et al. [40] found that O-arylation occurred in the presence of the more hindered secondary aniline (Scheme 5.23). Arylation of secondary aniline, if it occurred, would have been <5%. This is another example of the copper-promoted N-arylation reaction being very sensitive to steric effects. 

Scheme 9.2 Synthesis of diazaacenes by Pd-catalyzed N-arylation reaction.

More complex cascade processes involving this type of three-component couphng include the Cu(I)-catalyzed cascade coupling/cyclization reaction for the synthesis of 2-(aminomethyl) indoles 104 (Scheme 5.69) [72] and 105 (Scheme 5.70) [73], and the Cu(I)-catalyzed domino three-component coupling/cyclization/N-arylation reaction, which provided a concise synthesis of indole-fused 1,4-diazepines 106 (Scheme 5.71) [74]. 

SCHEME 5.71 Cu(I)-catalyzed cascade couphng/cyclization/N-arylation reaction for the synthesis of indole-fused 1,4-diazepines 106. 

Scheme 1 In Situ Generation of Aminostannanes for Pd-Catalyzed N-Arylation Reactions...

Fig. 4 Hemilabile biaryl phosphine ligands for Pd-catalyzed N-arylation reactions...

Carreira has recently described Pd-catalyzed N-arylation reactions of N-Boc-2,6-diazaspiro[3.3]heptane [240]. For example, the coupling of this nucleophile with 2-bromotoluene proceeded in 97% yield using the Pd2(dba)3/BINAP catalyst system (Eq. 43). This core may serve as a useful structural analog to the piperazine ring, which is a common moiety in many biologically active molecules and pharmaceuticals. A number of studies have examined Pd-catalyzed N-arylation reactions of piperazine derivatives [217, 241, 242] and other rigid cyclic diamine... 

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