- The mechanism of the reaction of hydrazines with α,β-unsaturated carbonyl compounds to afford hydrazones and 2-pyrazolines (4,5-dihydro-1H-pyrazoles): Experimental and theoretical results
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The reaction of hydrazines with α,β-unsaturated carbonyl compounds to afford 2-pyrazolines was studied using a dissymmetric chalcone (phenyl/p-tolyl) and three hydrazines, hydrazine itself, phenylhydrazine and thiosemicarbazide. Several products were iden
- Alkorta, Ibon,Elguero, José,Hoz, Antonio de la
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- 13C NMR spectroscopy of heterocycles: 1-phenyl-3-aryl/t-butyl-5-arylpyrazoles
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A series of chalcones 1-12 were converted to pyrazolines (1Pi-12Pi) by reaction with phenylhydrazine followed by DDQ oxidation to produce the corresponding pyrazoles (1Pz-12Pz). Three 1-phenyl-3-t-butyl-5-arylpyrazoles (13Pz-15Pz) were synthesized using an analogous approach. Molecular modeling studies predicted the 5-aryl group of the pyrazoles for both series to have a torsion angle of 52°-54° whereas the 1-phenyl group was predicted to have 35°-37° torsion angles. The 3-aryl group was predicted to be essentially coplanar (-3°) with the pyrazole system in the first series. 13C NMR data for both series, 1Pz-12Pz and 13Pz-15Pz, were collected in DMSO-d6 at 50°C. A plot of the C4 chemical shifts for 1Pz-12Pz versus Hammet constants for 5-aryl substituents yielded a very good linear correlation (R2=0.96) with a slope of 1.5. The chemical shift data for C4 showed little or no dependence on 3-aryl substituents. The result for 13Pz-15Pz, despite only three points, was consistent with the first series results and yielded a ρ value of 2.0. Distal transmission of substituent effects (5-aryl groups) to C4 of the pyrazole system was reduced by roughly 50-60% of that of the analogous planar isoxazole system, but are not consistent with results for the similarly twisted 4-bromoisoxazoles.
- Hockstedler, Amy N.,Edjah, Beatrice A.,Azhar, Saajid Z.,Mendoza, Hadrian,Brown, Nicole A.,Arrowood, Hayley B.,Clay, Andrew C.,Shah, Anand B.,Duffek, Glenda M.,Cui, Jianmei,Baumstark, Alfons L.
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p. 125 - 131
(2017/04/14)
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- An eco-friendly synthesis of 2-pyrazoline derivatives catalysed by CeCl 3· 7 H 2O
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Abstract: 1,3,5-triaryl-2-pyrazoline derivatives were synthesised by a condensation reaction between chalcones and phenyl hydrazine using cerium chloride heptahydrate as a catalyst. All these reactions were carried out in ethyl lactate (70%) as a green solvent. Easy and efficient work up, recyclability of solvent and catalyst are the key merits of this protocol. Graphical Abstract:: SYNOPSIS A facile protocol for the synthesis of 1,3,5-triaryl-2-pyrazolines is described. The solvent ethyl lactate, obtained from renewable sources, is biodegradable. The catalyst CeCl 3· 7 H 2O is a water-tolerant Lewis acid with low toxicity. Easy and clean work up, recyclable solvent and catalyst are merits of the protocol. The reaction works well for all systems giving good yields of the desired products.[Figure not available: see fulltext.].
- Bhat, Prabhat,Shridhar, Gomathi,Ladage, Savita,Ravishankar, Lakshmy
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p. 1441 - 1448
(2017/09/25)
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- Synthesis and anticancer activity of 1,3,5-triaryl-1H-pyrazole
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Previous studies demonstrated that some pyrazole derivatives could be considered as potential anticancer agents. A series of 1,3,5-triaryl-1H-pyrazole derivatives were prepared by the reaction of phenylhydrazin and different chalcones. The previous classi
- Ghadbeigi, Sajad,Ostad, Seyed Nasser,Shafiee, Abbas,Amini, Mohsen
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p. 754 - 759
(2015/10/05)
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- SAR studies of differently functionalized chalcones based hydrazones and their cyclized derivatives as inhibitors of mammalian cathepsin B and cathepsin H
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Cathepsins have emerged as potential drug targets for melanoma therapy and engrossed attention of researchers for development and evaluation of cysteine cathepsin inhibitors as cancer therapeutics. In this direction, we have designed, synthesized, and ass
- Raghav, Neera,Singh, Mamta
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supporting information
p. 4233 - 4245
(2014/08/18)
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- Nanocasting, Template Synthesis, and Structural Studies on Cesium Salt of Phosphotungstic Acid for the Synthesis of Novel 1,3,5-Triaryl-pyrazoline Derivatives
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The elimination of the silica matrix of composites by HF occurred by a two-step reaction deposition of a Cs2.5H0.5PW12O40 (CsHPW) salt nanocrystal. We used 2D hexagonal SBA-15 silica as a template for the nanofabrication of CsHPW nanoparticles. Nanocast CsHPW materials are stable against leaching and colloidization in polar solvents. The catalytic performance of the nanocast CsHPW materials exceeded that of bulk Cs2.5H0.5PW12O40, which is the most active among the acidic HPW salts. A series of novel 1,3,5-triaryl-pyrazoline derivatives were synthesized by the reaction between chalcone and phenylhydrazine in high yield in the presence of CsHPW salt nanocrystals.
- Fazaeli, Razieh,Aliyan, Hamid,Tangestaninejad, Shahram,Mohammadi, Esmaeel,Bordbar, Maryam
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p. 237 - 246
(2016/04/19)
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- A convenient and efficient protocol for the synthesis of 1,3,5-triaryl-2-pyrazolines in acetic acid under ultrasound irradiation
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1,3,5-Triaryl-2-pyrazolines were synthesized in acetic acid in high yields within 60-180 min under ultrasound irradiation at room temperature.
- Lin, Zhi-Ping,Li, Ji-Tai
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experimental part
p. 267 - 271
(2012/06/18)
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- Nanocasting, template synthesis, and structural studies on cesium salt of phosphotungstic acid for the synthesis of novel 1,3,5-triaryl-pyrazoline derivatives
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The elimination of the silica matrix of composites by HF occurred by a two-step reaction deposition of a Cs2.5H0.5PW 12O40 (CsHPW) salt nanocrystal. We used 2D hexagonal SBA-15 silica as a template for the nanof
- Fazaeli, Razieh,Aliyan, Hamid,Tangestaninejad, Shahram,Mohammadi, Esmaeel,Bordbar, Maryam
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experimental part
p. 237 - 246
(2012/06/30)
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- Synthesis of some new bioactive 1-N-subtituted 3,5-diaryl-2-pyrazolines
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A group of four series (A-D) of 22 new bioactive 1-N-acid substituted 3, 5-diphenyl-2-pyrazolines were synthesized by cyclization of variably substituted chalcones and simple or substituted phenyl hydrazine and / or semicarbazide, using acetic acid as a s
- Khan, Sadaf Sadiq,Hasan, Aurangzeb
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p. 131 - 138
(2008/02/12)
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- A modified and convenient method for the preparation of N-phenylpyrazoline derivatives
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Ten new N-phenylpyrazoline derivatives have been synthesized in high yields by condensation of chalcones with phenylhydrazine in the presence of potassium carbonate in reflux conditions. The workup is simple and involves treatment with ice-cold water. As compared with the previous method a considerable increase in the reaction rate with better yields has been observed.
- Safaei-Ghomi,Bamoniri,Soltanian-Telkabadi
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p. 892 - 896
(2008/02/10)
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- REACTION OF SINGLET OXYGEN WITH 2-PYRAZOLINE: IMPLICATION FOR CATION RADICAL - SUPEROXIDE ION PAIR INTERMEDIATE
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Kinetic studies on photosensitized oxygenation of 1,3,5-triaryl-2-pyrazolines show that an electron-transfer from the pyrazoline to singlet oxygen may take place to give a cation radical and superoxide ion pair.The reaction of pyrazoline cation radicals with superoxide ion shows the same product distribution with singlet oxygenation.
- Akasaka, Takeshi,Nakagawa, Masaru,Nomura, Yuko,Sato, Rikiya,Someno, Kazuo,Ando, Wataru
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p. 3807 - 3812
(2007/10/02)
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- ACTIVATED Ba(OH)2 AS CATALYST IN ORGANIC SYNTHESIS
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Several barium hydroxide catalysts have been prepared.Of these, the one called C-200 has been shown to be the most active.It has been used in several organic reactions: aldol and Claisen-Schmidt condensations, ester hydrolysis, esterification of acid chlorides, Williamson's ether synthesis, benzil-benzilic acid rearrangement and the synthesis of Δ2-pyrazolines.
- Garcia-Raso, Angel,Sinisterra, Jose V.,Marinas, Jose M.
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p. 1435 - 1445
(2007/10/02)
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