Aryl electrophile

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-... 

A novel method has been developed for the selective N-arylation of indoles with aryl electrophiles in the presence of potassium fluoride adsorbed onto basic alumina <96TL299>. 

The reaction of aryl electrophiles with organomagnesium compounds is known as Kumada or Kumada-Tamao-Corriu reaction. The most common leaving groups in the electrophile are halogen atoms and, among them, chlorine is the most wanted due to the good availability and the low price of aryl or heteroaryl chlorides. Unfortunately, the oxidative addition of a metal center to an aryl chloride is a difficult reaction and many efforts have been made to overcome existing limitations. 

SCHEME 83. Pd-catalyzed cyanation of aryl electrophiles with Zn(CN)2... 

Table 5.4 Reactivity profile of aryl electrophiles in iron-catalyzed cross-coupling reactions.

Scheme 30. Coupling of aryl electrophiles with aryl Grignard reagents Meyer s coupling [115] a) MeOTf,b) NaBH4,c) (COOH)2 Fuson s procedure [116b] d) Et20, C6H6...

Since the initial report from Migita [77,78] Pd-catalyzed cross-coupling to generate aryl and alkyl sulfides has been studied extensively [14, 15, 17, 18, 28, 77-111]. The large majority of this work is dedicated to developing synthetically useful protocols for the coupling of various thiols with an appropriate vinyl or aryl electrophile. 

Through a survey of a number of Pd/ligand combinations, Pd/NHC-based systems were found to possess the desired activity. Interestingly, organic bases such as NEt3, which are commonly used in Sonogashira reactions of aryl electrophiles, were ineffective under the conditions described in Eq. 14. 

Terminal alkynes may be deprotonated with LDA and transmet-allated with zinc to undergo palladium-catalyzed cross-couplings with aryl electrophiles (Scheme O... 

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