Base-Promoted SNAr Reactions of Fluoro- and Chloroarenes as a Route to N-Aryl Indoles and Carbazoles

Abstract

KOH/DMSO-promoted C-N bond formation via nucleophilic aromatic substitution (SNAr) between chloroarenes or fluoroarenes with indoles and carbazole under transition metal-free conditions affording the corresponding N-arylated indoles and carbazoles has been developed.

Recent Progress Concerning the N-Arylation of Indoles

“…This conclusion was confirmed by the work of Zhang [ 45 ], who prepared a series of tetrafluorophenylbenzenes through the reaction of indoles with pentafluorobenzenes in the presence of sodium hydroxide under mild reaction conditions ( Scheme 5 , Zhang’s N -arylation of indoles). Similar reaction conditions (KOH, DMSO, 100 °C, 24 h) were used by Hua to prepare a series of N -arylated indoles (23 compounds, 24–87% isolated yields) [ 46 ].…”

Synthesis of 7-Amido Indolines by Cp*Co(III)-Catalyzed C–H Bond Amidation

“…Unless otherwise mentioned, all materials were commercially available and used without further purification. Indolines 1a – 1r , 9-(pyrimidin-2-yl)-9 H -carbazole 1s , N -methyl- N -phenylpyrimidin-2-amine 1t – 1v , [Cp*Co­(MeCN) 3 ]­(SbF 6 ) 2 , 1-(pyrimidin-2-yl)-1,2,3,4-tetrahydroquinoline 1w , and dioxazolones 2 are known compounds and synthesized according to previous reported methods. All of the procedures were performed under ambient air.…”

Base-Promoted Annulation of Amidoximes with Alkynes: Simple Access to 2,4-Disubstituted Imidazoles

“…It is readily apparent to find that, in addition to the requirement of CuCl 2 •2H 2 O and/or ligand (pyridine and 2,2 -bipyridine), in both cases, inorganic bases were used as the additives, indicating that base is the key promoter to realize the formation of imidazoles. Therefore, in continuation of our interest in developing alkyne annulation in the synthesis of nitrogen-heterocyclic compounds [27][28][29][30] and base/DMSO-promoted C-N bond formation [31][32][33][34], we decided to explore the possibility of constructing an imidazole ring with the use of inorganic bases as the promoters, without the use of ligands under transition-metal-free conditions. In this paper, we would like to report a new, simple and efficient procedure to afford a variety of 2,4-disubstituted imidazoles starting with amidoximes and terminal alkynes in the presence of Cs 2 CO 3 in DMSO (Equation (4)) [35].…”