Benzotriazole: an excellent ligand for Cu-catalyzed N-arylation of imidazoles with aryl and heteroaryl halides (original) (raw)
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An efficient copper-catalyzed coupling of aryl halides with imidazoles
Tetrahedron Letters, 1999
Copper-catalyzed N-arylation of imidazoles can be accomplished using (CuOTf)2°benzene as a copper source and Cs2CO3 as a base in xylenes at 110-125 °C. Addition of 1,10-phenanthroline (phen) and trans, trans-dibenzylideneacetone (dba) was crucial to the success of the process. The products, N-arylimidazoles, were isolated in high yields.
ChemInform, 2007
CuOAc-Mediated N-arylation of 1H-indole derivatives and 1H-carbazole with aryl iodides under base-free and ligandless conditions provides the required N-arylazoles with complete N-selectivity and in moderate to good yields. The experimental conditions for this new version of the Ullmann Introduction 1-Arylindoles are central structural elements in many pharmacologically important and bioactive compounds. In fact, these arylazoles are of interest as angiotensin II antagonists, melatonin receptor MT 1 agonists, antiallergic and antipsychotic agents, COX-2 inhibitors and herbicides, and also as synthetic intermediates used to prepare other biologically active compounds. Moreover, numerous N-arylindoles bearing 4-fluorophenyl groups are to be found among the most selective ligands with high affinities for the G 2 binding site. On the other hand, 9-arylcarbazoles have attracted attention because of their luminescent properties and as discotic molecules. Much consideration has thus been directed towards the preparation of such N-arylazoles. Methods developed for the synthesis of 1-arylindoles include the Fischer synthesis, Ullmann-type couplings between aryl halides and indoles, nucleophilic aromatic substitution, intramolecular Pd-catalysed annulation of didehydrophenylalanine derivatives, Pd-catalysed N-arylation of indoles with aryl halides [8c,15] and Cu-catalysed N-arylation of indoles variously with diaryliodonium salts, with aryl iodides or bromides in the presence of a suitable ligand or with zeolite NaY. On the other hand, 9-arylcarbazoles have been prepared by Ullmann N-arylation of 9H-carbazoles with aryl halides, Pd/P(tBu) 3 -catalysed coupling of aryl bromides with carbazole, [15c] or Pd-catalysed double N-aryl- [a]
Catalysis Letters, 2014
A highly porous metal-organic framework (Cu 2 (BDC) 2 (DABCO)) was synthesized and used as an efficient and recyclable heterogeneous catalyst for the Ullmann-type N-arylation of aryl halides with imidazoles. The Cu 2 (BDC) 2 (DABCO) was characterized by several techniques, including X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen physisorption measurements. The catalyst offered high activity under mild conditions, confirming outstanding advantages when employing the Cu 2 (BDC) 2 (DABCO) as catalyst for Ullmann-type N-arylation reaction. The catalyst could be separated from the reaction mixture by simple filtration, and could be reused without a significant degradation in catalytic activity. Keywords Cu 2 (BDC) 2 (DABCO) Á N-arylation Á Coupling reaction, imidazoles Á Metal-organic frameworks Electronic supplementary material The online version of this article (
Tetrahedron, 2008
Highly selective, practical, and efficient protocols for the preparation of 4(5)-aryl-1H-imidazoles 2, 2,4(5)-diaryl-1H-imidazoles 3, and 4,5diaryl-1H-imidazoles 1 are described. A key step of these protocols is the regioselective synthesis of 5-aryl-1-benzyl-1H-imidazoles 9 by Pd-catalyzed direct C-5 arylation of commercially available 1-benzyl-1H-imidazole (8) with aryl halides. The three-step synthesis of compounds 3 from 8 also involves the Pd-catalyzed and Cu-mediated direct C-2 arylation of imidazoles 9 with aryl halides under base-free and ligandless conditions. On the other hand, the four-step synthesis of imidazoles 1 from 8 also involves the regioselective bromination of compounds 9 and a Suzuki reaction of the resulting 5-aryl-1-benzyl-4-bromo-1H-imidazoles 11 with arylboronic acids 5 under phase-transfer conditions, followed by N-debenzylation.
Tetrahedron Letters, 2011
Substituted 2-mercaptobenzimidazoles (MBI) are an important class of bio-active and industrially important organic compounds. In this Letter, a new synthetic method is presented for the selective S-arylation of MBI with substituted aryl iodides using low cost copper (I) iodide and 1,10-phenanthroline as a catalytic system. The selective formation of S-arylated product was confirmed by several spectroscopic techniques and the vibrational spectrum was found to be in very good agreement with the theoretical spectrum calculated by density functional theory.
A PRELIMINARY STUDY ON THE REGIOSELECTIVE C-H ARYLATION OF IMIDAZO[2,1-b]THIAZOLE
2019
Recently, the transition metal-catalyzed direct arylation reactions of azoles with aryl halides have emerged as an attractive strategy for the effective construction of aromatic Csp2–Csp2 bonds. These reactions, unlike the traditional metal-catalyzed crosscoupling protocols involving the use of preformed organometallics, enable the direct elaboration of heteroaromatic cores without the pre-activation of both the coupling partners.
Copper-Catalyzed One-Pot Synthesis of Substituted Benzimidazoles
Advanced Synthesis & Catalysis, 2010
A copper-catalyzed one-pot synthesis of functionalized benzimidazoles has been developed. The procedure combines the copper-catalyzed three-component cascade reaction of sulfonyl azides, alkynes and 2-bromoaniline and the coppercatalyzed intramolecular N-arylation of sulfon