Showing papers on "Pyrazole published in 2009"
TL;DR: The antiviral activity for such novel compounds against a broad panel of viruses in different cell cultures revealed that N-acetyl 4,5-dihydropyrazole 7 was the only active one at subtoxic concentrations against vaccinia virus (Lederle strain) in HEL cell cultures with a 50% effective concentration (EC(50) value of 7 microg/ml.
289 citations
TL;DR: A five-membered, two-nitrogen-containing heterocycle ring is widely found as the core structure in a large variety of compounds that possess important agrochemical and pharmacological properties as mentioned in this paper.
186 citations
TL;DR: The catalytic C-H arylation combined with the protecting group transposition and N-alkylation provides a rapid route to fully substituted pyrazoles with complete regiocontrol of all substituents.
Abstract: Pyrazoles are important azole heteroarenes frequently found in pharmaceuticals and protein ligands, and there has been a growing interest in new synthetic methods for their preparation. We report the first catalytic intermolecular C-H arylation of pyrazoles, namely SEM-protected pyrazoles and N-alkylpyrazoles, which lays the foundation for a new approach to the synthesis of complex arylated pyrazoles, where new arene rings are directly attached to predetermined positions of the heteroarene nucleus ("topologically obvious synthesis"). Through a systematic search, we identified a palladium-pivalate catalytic system as the most effective protocol and mapped the reactivity of all three C-H bonds of the pyrazole (C-5 > C-4 >> C-3). To circumvent the low reactivity of the C-3 position, we developed a "SEM switch", which transposes the SEM-protecting group from one nitrogen to the other in one step, and in the process transforms the unreactive C-3 position to the reactive C-5 position. The SEM switch thus enables sequential arylation of C-5 and C-3 position, providing rapid access to protected or free 3,4,5-triarylpyrazoles (the C-4 arene ring is readily introduced by bromination and Suzuki coupling). Furthermore, N-alkylation of SEM-protected pyrazoles allows for regioselective introduction of the amine substituent, addressing the low regioselectivity of N-alkylation of pyrazoles lacking sufficient steric bias. Thus, the catalytic C-H arylation combined with the protecting group transposition and N-alkylation provides a rapid route to fully substituted pyrazoles with complete regiocontrol of all substituents. The particular strength of this strategy is the ability to commence the synthesis from either the parent pyrazole or practically any pyrazole intermediate.
170 citations
TL;DR: Two series of novel rigid pyrazolone derivatives were synthesized and evaluated as inhibitors of Mycobacterium tuberculosis and confirm the fundamental role of the p-chlorophenyl moiety at C4 in the antimycobacterial activity.
140 citations
TL;DR: A series of novel 3-aryl-1-(4- tert -butylbenzyl) -1 H -pyrazole-5-carbohydrazide hydrazone derivatives were synthesized and the effects of all the compounds on A549 cell growth were investigated as mentioned in this paper.
133 citations
TL;DR: A series of new imines and amines have been synthesized by condensation of 1H-3-ferrocenyl-1-phenylpyrazole-4-carboxaldehyde with the corresponding amines, followed by reduction with sodium borohydride, showing a wide range of activities.
111 citations
TL;DR: In this article, 4-cyanobenzylideneamino antipyrine (CBAP) has been synthesized and characterized by elemental analysis, FT-IR, UV-VIS and X-ray single crystal diffraction techniques.
Abstract: 4-(4-cyanobenzylideneamino)antipyrine (CBAP) has been synthesized and characterized by elemental analysis, FT-IR, UV-VIS and X-ray single crystal diffraction techniques. Crystallographic study reveals that the compound adopts trans configuration about the Schiff base imine double bond. The substituted p-cyanophenyl ring indirectly linked to the pyrazoline ring by the C=N double bond is almost coplanar with the pyrazole ring, whereas the phenyl ring directly attached to the pyrazoline ring forms an effective dihedral angle. Density functional calculations have been carried out to optimize and to characterize the title compound by using B3LYP method at 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structural parameters and the theoretical vibrational frequencies show good agreement with experimental values. On the basis of theoretical vibrational analyses, the thermodynamic properties (standard heat capacities, standard entropies, and standard ent...
108 citations
TL;DR: Some of the compounds showed promising antioxidant activity in vitro and cytotoxic activity against DLA cells and EAC cells.
Abstract: The aim of the present work was to synthesise coumarinyl heterocycles and to elucidate the potential role of these compounds as antioxidants and cytotoxic agents against Dalton's lymphoma ascites tumour cells (DLA) and Ehrlich ascites carcinoma cells (EAC). The synthesis of coumarin derivatives containing pyrazole, pyrazolone, thiazolidin-4-one, 5-carboxymethyl-4-thiazolidinone and 3-acetyl-1,3,4-oxadiazole ring is reported. 4-Methylcoumarinyl-7-oxyacetic acid hydrazide (1) reacted with arylazopropanes or hydrazono-3-oxobutyrate derivatives to form pyrazole (3a-c) and pyrazolone derivatives (5a-c). Heterocyclisation of Schiff's bases of 1 with thioglycolic acid, thiomalic acid or acetic anhydride afforded novel heterocyclic derivatives 4-thiazolidinones (7a-c), 5-carboxymethyl-4-thiazolidinones (8a-c) and oxadiazoles (9a-c), respectively. Some of the compounds showed promising antioxidant activity in vitro and cytotoxic activity against DLA cells and EAC cells.
107 citations
TL;DR: In this article, the most pertinent general features of pyrazoles, in comparison with other heterocycles that are also popular ligands, and some aspects of the supramolecular chemistry of free pyrazole are also included.
Abstract: This Microreview deals with the supramolecular chemistry of pyrazole metal complexes, in particular, complexes of pyrazoles with a nonsubstituted N–H group, which are able to engage in hydrogen bonding. The most pertinent general features of pyrazoles, in comparison with other heterocycles that are also popular ligands, and some aspects of the supramolecular chemistry of free pyrazoles are also included. In addition to the general supramolecular chemistry of pyrazole complexes, sections of this Microreview are devoted to liquid crystals, self-assembled species, and hosts for anions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
99 citations
TL;DR: Efficient synthetic routes to pyrazolo[3,4-b]indoles and pyrazol[1,5-a]benzimidazoles via intramolecular palladium- and copper-catalyzed cyclization of 1-aryl/1-unsubstituted 5-(2-bromoanilino)pyrazole precursors via intramsolecular C-C and C-N bond formation have been reported.
Abstract: Efficient synthetic routes to pyrazolo[3,4-b]indoles and pyrazolo[1,5-a]benzimidazoles via intramolecular palladium- and copper-catalyzed cyclization of 1-aryl/1-unsubstituted 5-(2-bromoanilino)pyrazole precursors via intramolecular C-C and C-N bond formation have been reported.
94 citations
TL;DR: In this article, the synthesis of pyrazoles via 1,3-dipolar cycloaddition of diazo compounds to alkynes proceeds easily by heating and is conducted under solvent-free conditions affording the pyrazole products in high yields without any work up or purification.
TL;DR: The full functionalization of the pyrazole ring was achieved by successive regioselective metalations using TMPMgCl x LiCl and TMP(2)Mg x 2 LiCl.
TL;DR: Enaminonitrile 2 was used as key intermediate for the synthesis of polyfunctionally substituted heterocycles incorporating benzothiazole moiety via its reactions with some N-nucleophiles.
TL;DR: Design, synthesis, and SAR development led to the identification of the potent, novel, and selective pyrazole based inhibitor (7f) of Coactivator Associated Arginine Methyltransferase (CARM1).
TL;DR: A series of N-benzyl-1-heteroaryl-3-(trifluoromethyl)-1H-pyrazole-5-carboxamides targeting co-activator associated arginine methyltransferase 1 (CARM1) have been designed and synthesized with the thiophene analogues being superior to thiazole, pyridine, isoindoline and benzofuran based inhibitors.
TL;DR: Preparation of some novel substituted pyrazole and pyrazolo[3,4-d]pyrimidine derivatives revealed promising antiviral activity against herpes simplex virus type-1 in comparison to Acyclovir as a control.
TL;DR: In this article, the titanium-catalyzed 3-component coupling of an alkyne, isonitrile, and amine can be used to generate tautomers of 1,3-diimines.
Abstract: The titanium-catalyzed 3-component coupling of an alkyne, isonitrile, and amine can be used to generate tautomers of 1,3-diimines. These diimines produced in situ undergo cyclization with hydrazine and hydrazine derivatives in a one-pot procedure to provide pyrazoles. Seventeen examples of pyrazoles are provided using this one-pot, 4-component procedure from simple starting materials. The regioselectivity of the alkyne addition can be controlled in some cases with catalyst architecture, and regioselectivity of monosubsituted hydrazines to unsymmetrical 1,3-diimines is discussed. This multicomponent coupling strategy was applied to the synthesis of withasomnine in an efficient procedure, which gave the natural product in 24% overall yield from 4-pentyn-1-ol.
TL;DR: Several compounds are identified that exhibit low micromolar to mid nanomolar anti-proliferative activity based on its presumably promiscuous scaffold, or if it results from the Michael acceptor properties of the alpha,beta-unsaturated 1,3-diketone moiety central to its structure.
TL;DR: A facile and practical strategy catalyzed by CoCl( 2)6 H(2)O has been developed for the N-arylation of nitrogen nucleophiles with substituted aryl halides in water, which requires only mild conditions.
Abstract: Cobalt 'n' cross-coupling! A facile and practical strategy catalyzed by CoCl(2)6 H(2)O has been developed for the N-arylation of nitrogen nucleophiles with substituted aryl halides in water. The protocol is very simple and requires only mild conditions. A variety of nitrogen nucleophiles, including pyrazole, indole, and 7-azaindole, undergo catalysis to afford N-arylated products in moderate to good yields (up to 86 %; see scheme).
TL;DR: It was found that dipole moment, excitation energy, the energy value of LUMO, solvent accessible surface area, and heat of formation were the key molecular descriptors in descriping the cytotoxic effect of those compounds against EAC.
TL;DR: Trans-N,N'-bis(1-Ethyl-2-benzimidazolyl-imine-1,2-diimine is the best accelerating ligand in this series that supports the Cu(I)-catalyzed Ullmann N-arylation and the direct three-component azide-alkyne cycloaddition reaction to give the corresponding substituted imidazole, pyrazole, and triazole in high yields.
Abstract: Five new tetradentate ligands [NNNN] with benzimidazolyl-imine or amine nitrogen donors have been synthesized in good yields under mild conditions from easily available substrates. trans-N,N'-bis(1-Ethyl-2-benzimidazolylmethylene)cyclohexane-1,2-diimine is the best accelerating ligand in this series that supports the Cu(I)-catalyzed Ullmann N-arylation and the direct three-component azide-alkyne cycloaddition reaction to give the corresponding substituted imidazole, pyrazole, and triazole in high yields. Single-crystal X-ray diffraction analysis of its complex with CuI reveals a novel one-dimensional coordination polymer of the metal chain bridged alternately by the [NNNN] ligand and diiodides.
TL;DR: The three-component reaction of the zwitterions generated from dialkyl acetylenedicarboxylate and isocyanides with 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one is described in this article.
TL;DR: In this article, the synthesis of planar chiral P,N-ligands based on 3,4-dimethylphosphaferrocene and either pyrazole or 1-methylimidazole is described.
TL;DR: In this paper, three 4-iodopyrazolium salts with 3,5-dimethyl (3a), 3-5-diphenyl (3b), and 3, 5-diisopropyl substituents, respectively, were synthesized using a modular approach.
TL;DR: Tryptophan derivative 1l exhibited the highest cytotoxic activity in the cell growth inhibition of all three types of cell lines and in the in vitro antitumor activity of all synthesized compounds.
TL;DR: A series of novel 3-aryl-1-arylmethyl-1H-pyrazole-5-carbohydrazide N-beta-glycoside derivatives was synthesized by the reaction of substituted 1H- pyrazoles with d-sugar and all compounds had inhibitory effects on the growth of A549 lung cancer cells.
TL;DR: The one-pot synthesis of multisubstituted pyrazole derivatives was achieved via catalyst-free 1,3-dipolar cycloaddition of ethyl diazoacetate and nitroalkenes as the key step and elimination of the leaving group followed by intramolecular proton transfer with satisfactory yields.
Abstract: The one-pot synthesis of multisubstituted pyrazole derivatives was achieved viacatalyst-free 1,3-dipolar cycloaddition of ethyl diazoacetate and nitroalkenes as the key step and elimination of the leaving group (NO2 or Br) followed by intramolecular proton transfer with satisfactory yields.
TL;DR: The 3-pyrazolyl-4,5-dicarbethoxy isoxazoles (9a-c) exhibited the maximum antinociceptive activity.
TL;DR: The developed efficient electrocatalytic approach to medicinally relevant spirocyclic [indole-3,4′-pyrano[2,3-c]pyrazoles] is beneficial from the viewpoint of diversity-oriented large-scale processes and represents a novel example of facile environmentally benign synthetic concept for electrocatalysttic multicomponent reaction strategy.
Abstract: Electrochemically induced catalytic multicomponent transformation of isatins, 3-methyl-2-pyrazolin-5-ones and malononitrile in ethanol in an undivided cell in the presence of sodium bromide as an electrolyte results in the formation of spirooxindoles with fused functionalized pyrano[2,3-c]pyrazole system in 78–99} yields. The developed efficient electrocatalytic approach to medicinally relevant spirocyclic [indole-3,4′-pyrano[2,3-c]pyrazoles] is beneficial from the viewpoint of diversity-oriented large-scale processes and represents a novel example of facile environmentally benign synthetic concept for electrocatalytic multicomponent reaction strategy.
TL;DR: It was found that ultrasound irradiations enable some reactions to occur which could not be carried out under silent condition in addition to improvement in reaction times.