613686-09-2Relevant academic research and scientific papers
Ruthenium-catalyzed C-H/CO/olefin coupling reaction of N-arylpyrazoles. Extraordinary reactivity of N-arylpyrazoles toward carbonylation at C-H bonds
Asaumi, Taku,Chatani, Naoto,Matsuo, Takuya,Kakiuchi, Fumitoshi,Murai, Shinji
, p. 7538 - 7540 (2003)
The reaction of 1-arylpyrazoles with CO and ethylene in the presence of Ru3(CO)12 resulted in regioselective carbonylation at the ortho C-H bonds. While it is found that the pyrazole ring also functions as the directing group for C-H
C?N Cross-Coupling Reactions Under Mild Conditions Using Singlet Di-Radical Nickel(II)-Complexes as Catalyst: N-Arylation and Quinazoline Synthesis
Sikari, Rina,Sinha, Suman,Chakraborty, Gargi,Das, Siuli,van Leest, Nicolaas Petrus,Paul, Nanda D.
supporting information, p. 4342 - 4353 (2019/08/21)
Herein we report a cost-effective synthetic approach for C?N cross-coupling reactions of a broad array of nitrogen nucleophiles and aryl halides under mild conditions. These reactions are catalyzed by an inexpensive, air-stable, earth-abundant and easy-to-prepare singlet di-radical nickel(II)-catalyst containing two antiferromagnetically coupled single-electron oxidized diiminosemiquinonato type ligands. This protocol provides an alternative method for C?N cross-coupling reactions avoiding nickel(0)/nickel(II) or nickel(I)/nickel(III) redox processes via cooperative participation of metal and ligand-centered redox events. Besides a wide range of N-arylation reactions, by judicious choice of aryl halides and nitrogen nucleophiles the synthesis of a variety of polysubstituted quinazolines has been achieved in moderate to good yields under relatively mild reaction conditions. Our catalyst has been found to be almost equally effective in quinazoline synthesis via C?N cross-coupling of (i) 2-bromobenzylamine with benzamide, and (ii) 2-bromobenzylbromide with amidine. Control experiments and DFT studies were performed to improve the understanding of the cooperative participation of ligand and metal (nickel)-centered redox events during oxidative addition/reductive elimination processes of the catalytic cycle and to shed light on the plausible mechanistic pathway of the C?N cross-coupling reactions. (Figure presented.).
Palladium nanoparticles supported on organofunctionalized kaolin as an efficient heterogeneous catalyst for directed C-H functionalization of arylpyrazoles
Yang, Ping,Bao, Yong-Sheng
, p. 53878 - 53886 (2017/12/05)
A heterogeneous catalyst system based on the immobilization of Pd0 nanoparticles onto organofunctionalized kaolin is reported with a view to introducing new synthetic routes of directed C-H functionalization of arylpyrazoles. Various characterization techniques revealed that the functional groups, 3-aminopropyltriethoxysilane (APTES) and phenyltrimethoxysilane, become strongly attached to the kaolin surface through Si-O-Si bonds and 3-6 nm sized Pd0 nanoparticles are uniformly decorated and stabilized through the organic amine moieties. The nano-palladium catalyst is durable, undergoing five times reuse with moderate catalytic activity. The XPS analysis of the catalyst before and after reaction suggested that the reaction might be performed via a catalytic cycle that begins with Pd0.
Ru/C-catalyzed carbonylation at ortho-C-H bonds in 2-phenylpyridines
Imoto, Shinya,Uemura, Takeshi,Kakiuchi, Fumitoshi,Chatani, Naoto
, p. 170 - 172 (2008/03/13)
Ru/C also exhibits catalytic activity for carbonylation at ortho-C-H bonds in 2-phenylpyridines. Georg Thieme Verlag Stuttgart.
Ruthenium- and rhodium-catalyzed direct carbonylation of the ortho C-H bond in the benzene ring of N-arylpyrazoles
Asaumi, Taku,Matsuo, Takuya,Fukuyama, Takahide,Ie, Yutaka,Kakiuchi, Fumitoshi,Chatani, Naoto
, p. 4433 - 4440 (2007/10/03)
The direct carbonylation of C-H bonds in the benzene ring of N-phenylpyrazoles via catalysis by ruthenium or rhodium complexes is described. The reaction of N-phenylpyrazoles with carbon monoxide and ethylene in the presence of Ru3(CO)12 or Rh4(CO)12 resulted in the site-selective carbonylation of the ortho C-H bonds in the benzene ring to give the corresponding ethyl ketones. A variety of functional groups on the benzene ring can be tolerated. N-Phenylpyrazoles have higher reactivities than would be expected, based on the pKa values of the conjugate acid of pyrazole. The choice of solvent for this reaction is significant, and N, N-dimethylacetamide (DMA) gives the best result.
