19933-24-5Relevant academic research and scientific papers
Ruthenium, rhodium and iridium complexes containing pyrimidine based thienyl pyrazoles: Synthesis and antibacterial studies
Lapasam, Agreeda,Mawnai, Ibaniewkor L.,Banothu, Venkanna,Kaminsky, Werner,Kollipara, Mohan Rao
, (2020)
The reaction of pyrimidine based electron-rich heterocyclic thiophene pyrazoles and halide bridged arene d6 metal precursors yielded a series of mononuclear and dinuclear half sandwich d6 metal complexes. Mononuclear and dinuclear complexes formed by the ratio-based reaction between ligand and metal precursor. All these cationic complexes have been characterized by IR, UV–Vis, 1H NMR, 13C NMR spectroscopic techniques. Complex 5 has been established by single-crystal analysis. X-ray diffraction studies revealed the formation of mononuclear and dinuclear complexes and suggest that the vicinity around the metal atom is distorted octahedral. An in vitro study to screen the antibacterial potential of these complexes against pathogenic bacteria, S. aureus, K. pneumoniae, and E. coli was addressed. All the complexes display a better zone of inhibitions for both Gram-positive (S. aureus) and Gram-negative strains (K. pneumoniae, and E. coli). The minimum inhibitory concentrations (MICs) for the most active complex ranged from 0.125 to 0.25 mg/ml for S. aureus and Klebsiella Pneumoniae and 0.25–0.5 mg/ml for E. coli.
Tris(pyrazolyl)methanides of the alkaline earth metals: Influence of the substitution pattern on stability and degradation
Müller, Christoph,Koch, Alexander,G?rls, Helmar,Krieck, Sven,Westerhausen, Matthias
, p. 635 - 645 (2015)
Trispyrazolylmethanides commonly act as strong tridentate bases toward metal ions. This expected coordination behavior has been observed for tris(3,4,5-trimethylpyrazolyl)methane (1a), which yields the alkaline-earth-metal bis[tris(3,4,5-trimethylpyrazolyl)methanides] of magnesium (1b), calcium (1c), strontium (1d), and barium (1e) via deprotonation of 1a with dibutylmagnesium and [Ae{N(SiMe3)2}2] (Ae = Mg, Ca, Sr, and Ba, respectively). Barium complex 1e degrades during recrystallization that was attempted from aromatic hydrocarbons and ethers. In these scorpionate complexes, the metal ions are embedded in distorted octahedral coordination spheres. Contrarily, tris(3-thienylpyrazolyl)methane (2a) exhibits a strikingly different reactivity. Dibutylmagnesium is unable to deprotonate 2a, whereas [Ae{N(SiMe3)2}2] (Ae = Ca, Sr, and Ba) smoothly metalates 2a. However, the primary alkaline-earth-metal bis[tris(3-thienylpyrazolyl)methanides] of Ca (2c), Sr (2d), and Ba (2e) represent intermediates and degrade under the formation of the alkaline-earth-metal bis(3-thienylpyrazolates) of calcium (3c), strontium (3d), and barium (3e) and the elimination of tetrakis(3-thienylpyrazolyl)ethene (4). To isolate crystalline compounds, 3-thienylpyrazole has been metalated, and the corresponding derivatives [(HPzTp)4Mg(PzTp)2] (3b), dinuclear [(tmeda)Ca(PzTp)2]2 (3c), mononuclear [(pmdeta)Sr(PzTp)2] (3d), and [(hmteta)Ba(PzTp)2] (3e) have been structurally characterized. Regardless of the applied stoichiometry, magnesiation of thienylpyrazole 3a with dibutylmagnesium yields [(HPzTp)4Mg(PzTp)2] (3b), which is stabilized in the solid state by intramolecular N-H···N···H-N hydrogen bridges. The degradation of [Ae{C(PzR)3}2] (R = Ph and Tp) has been studied by quantum chemical methods, the results of which propose an intermediate complex of the nature [{(PzR)2C}2Ca{PzR}2]; thereafter, the singlet carbenes ([:C(PzR)2]) dimerize in the vicinity of the alkaline earth metal to tetrapyrazolylethene, which is liberated from the coordination sphere as a result of it being a very poor ligand for an s-block metal ion.
Studies on diazepines. VIII. Syntheses and rearrangements of 3H-1,2-pyrido- and 3H-1,2-thieno-diazepines
Tsuchiya,Enkaku,Sawanishi
, p. 2188 - 2193 (1979)
The previously unknown 3H-1,2-pyrido- and 3H-1,2-thieno- diazepines (3a:3H-1,2 pyrido [2,3-c] diazepine; 3b:3H-1,2 pyrido [3,2-c] diazepine; 3c:3H-1,2 thieno [2,3-c] diazepine; 3d:3H-1,2 thieno [3,2-c] diazepine) were prepared from the corresponding 1H-isomers. Treatment of 3 (the parent 3H-diazepine) with bases or acids resulted in tautomerization to give the 1H-diazepines 1 (the parent 1H-1,2 diazepine), and photolysis of 3 afforded the condensed 3-vinylpyrazoles 4 (the parent 3-vinylpyrazole). However, thermolysis of the pyridodiazepines (3a,3b) gave 4a(3-vinyl-1H-pyrido[2,3-c]pyrazole), 4b(3-vinyl-1H-pyrido[3,2-c]pyrazole), whereas the thieno-diazepines (3c,3d) gave the corresponding thienylpyrazoles (5) on irradiation via a [1,5] hydrogen shift in the diazepine ring; this mechanism was confirmed by a deuterium-labelling experiment. The 3-acetoxy-(13a) and 3-methoxy (13b) 3H-1,2-thienodiazepines were also prepared, and their photolysis afforded corresponding 3-vinylpyrazoles (14). However, thermolysis or base treatment of 13 resulted in loss of nitrogen to give the corresponding cyclopentenothiophene (15) and acetal (16).
Molybdenum-silver co-catalyzed cycloaddition of alkynes with: N -isocyanoiminotriphenylphosphorane (NIITP): An efficient strategy for the synthesis of monosubstituted pyrazoles
Mi, Pengbing,Lang, Jiajia,Lin, Shaojian
supporting information, p. 7986 - 7989 (2019/07/10)
A new molybdenum-silver co-catalyzed [3+2] cycloaddition of alkynes with N-isocyanoiminotriphenylphosphorane (NIITP) has been described. The NIITP serves as a non-toxic, facile "CNN" source. Over 30 substrates were successfully converted to the desired compounds in good to excellent yields.
Calcium carbide as the acetylide source: Transition-metal-free synthesis of substituted pyrazoles via [1,5]-sigmatropic rearrangements
Yu, Yue,Huang, Wei,Chen, Yang,Gao, Bingjie,Wu, Wanqing,Jiang, Huanfeng
supporting information, p. 6445 - 6449 (2018/06/08)
Under transition-metal-free conditions, calcium carbide was used as the acetylide source to react with a wide range of N-tosylhydrazones derived from aldehydes or ketones, affording various substituted pyrazoles in good yields with high regioselectivities. The transformations go through [3 + 2] cycloadditions followed by [1,5]-sigmatropic rearrangements, which are supported by deuterium-labeling experiments.
Consecutive three-component synthesis of 3-(hetero)aryl-1H-pyrazoles with propynal diethylacetal as a three-carbon building block
Levi, Lucilla,Boersch, Christina,Gers, Charlotte F.,Merkul, Eugen,Mueller, Thomas J. J.
scheme or table, p. 9340 - 9356 (2012/01/04)
A novel consecutive three-component synthesis of 3-(hetero)aryl-1H- pyrazoles via room temperature Sonogashira arylation of propynal diethylacetal used as a propargyl aldehyde synthetic equivalent has been disclosed. The final acetal cleavage-cyclocondensation with hydrazine hydrochloride at 80 °C rapidly furnishes the title compounds in a one-pot fashion.
An efficient solvent-free synthesis of NH-pyrazoles from β-dimethylaminovinylketones and hydrazine on grinding
Longhi, Kelvis,Moreira, Dayse N.,Marzari, Mara R.B.,Floss, Vagner M.,Bonacorso, Helio G.,Zanatta, Nilo,Martins, Marcos A.P.
supporting information; experimental part, p. 3193 - 3196 (2010/08/05)
A series of NH-pyrazoles was efficiently synthesized from the reaction of β-dimethylaminovinylketones ([R1C(O)C(R2){double bond, long}CHN(Me2)], where R1 = Me, Ph, 3-MeO-Ph, 4-Me-Ph, 4-MeO-Ph, 4-F-Ph, 4-Cl-Ph, 4
Regioselective three-component synthesis of highly fluorescent 1,3,5-trisubstituted pyrazoles
Willy, Benjamin,Mueller, Thomas J. J.
experimental part, p. 4157 - 4168 (2009/05/11)
3,5-Disubstituted and 1,3,5-trisubstituted pyrazoles are readily synthesized from acyl chlorides, terminal alkynes, and hydrazines by a consecutive one-pot three-component Sonogashira coupling/Michael addition/cyclocondensation sequence in good to excelle
A novel one-pot method for the preparation of pyrazoles by 1,3-dipolar cycloadditions of diazo compounds generated in situ
Aggarwal, Varinder K.,De Vicente, Javier,Bonnert, Roger V.
, p. 5381 - 5383 (2007/10/03)
A convenient one-pot procedure for the preparation of pyrazoles by 1,3-dipolar cycloaddition of diazo compounds generated in situ has been developed. Diazo compounds derived from aldehydes were reacted with terminal alkynes to furnish regioselectively 3,5-disubstituted pyrazoles. Furthermore, the reaction of N-vinylimidazole and diazo compounds derived from aldehydes gave exclusively 3-substituted pyrazoles in a one-pot process.
Novel C-Alkylation Reaction of Condensed Thiophenes with Enaminones, Enaminonitriles, Ethoxymethylenemalonitrile, Aryl Vinyl Ketones and ω-Nitrostyrenes
Al-Etabi, Alya,Al-Awadi, Nouria,Al-Omran, Fatima,Abdel-Khalik, Mervat Mohammed,Elnagdi, Mohamed Hilmy
, p. 151 - 163 (2007/10/03)
The reaction of 1 with enaminones (3a-c) affords either the enaminones 4a-c or a mixture of 4a-c and the α,β-unsaturated ketones 9a-c depending on applied reaction conditions. Compounds 4a-c rearranged into 9a-c on long reflux in dioxane solution in prese
