- First Report About the Use of Micellar Keggin Heteropolyacids as Catalysts in the Green Multicomponent Synthesis of Nifedipine Derivatives
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Abstract: Micellar Keggin heteropolyacid catalysts were prepared using hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide—CTAB), 1-hexadecyl-pyridinium chloride, and Keggin heteropolyacids H3PMo12O40 and H4PMo11VO40 as precursors. Four catalysts were prepared (PMo12C16, PMo11VC16, PMo12C16Py, and PMo11VC16Py) and characterized by 31P NMR, FT-IR, XRD, SEM analysis and textural properties (SBET). The acidic characteristics of the catalysts were determined by potentiometric titration with n-butylamine. A series of bioactive 1,4-dihydropyridine derivatives such as nifedipine and nemadipine B were synthesized using these new materials, in a one-pot procedure in ethanol. This methodology requires a reaction time of 8?h, and a temperature of 78?°C to obtain good to excellent yields of 1,4-dihydropyridine derivatives. The micellar Keggin catalysts are insoluble in polar media, which allows easy removal of the reaction products without affecting their catalytic activity. The leaching test showed that they have an excellent stability and can be used five times as heterogeneous catalysts without appreciable loss of the catalytic activity. Using the same material, unsymmetrical 1,4-dihydropyridines such as nitrendipine can be obtained through a sequence of steps in very good yield (78?%). Graphical Abstract: [Figure not available: see fulltext.]
- Palermo, Valeria,Sathicq, ángel G.,Constantieux, Thierry,Rodríguez, Jean,Vázquez, Patricia G.,Romanelli, Gustavo P.
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Read Online
- Silica functionalized sulphonic acid coated with ionic liquid: An efficient and recyclable heterogeneous catalyst for the one-pot synthesis of 1,4-dihydropyridines under solvent-free conditions
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Silica-supported sulphonic acid catalysts were prepared and coated with ionic liquid, and their catalytic activities were evaluated for the one-pot synthesis of 1,4-dihydropyridines. Different catalysts with an ionic liquid layer (SCILLs) have been prepared with a view to determine the most active catalyst. Silica sulphonic acid coated with [BMIM][PF6] was found to be the most active catalyst and can be recycled for several runs without the loss of significant activity. It was characterized using SEM, TEM, TGA and FTIR.
- Sharma, Pankaj,Gupta, Monika
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Read Online
- Synthesis of hantzsch 1,4-dihydropyridines under microwave irradiation
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Biologically active substituted 1,4-dihydropyridines have been synthesized in excellent yields by the reaction of aldehydes, ethyl or methyl acetoacetic ester and ammonium acetate under microwave irradiation (MWI) within 0.75-3 min.
- Anniyappan, Marimuthu,Muralidharan,Perumal, Paramasivan T.
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Read Online
- One-pot synthesis of 1,4-dihydropyridine derivatives using the Fe2ZnAl2O7 catalyzed Hantzsch three-component reaction
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A facile, low-cost, and effective one-pot method was developed for the synthesis of 1,4-dihydropyridine derivatives with high yields through the three-component reaction of ammonium acetate, ethyl acetoacetate, and aromatic aldehydes using Fe2ZnAl2O7 as catalyst. The reaction was conducted at 70–80°C temperature under solvent free conditions. The developed method had some great advantages, including safe and clean reaction conditions, high to excellent product yields, short reaction time, and a novel and powerful heterogeneous catalyst. The developed heterogeneous solid catalyst had high efficiency and reusability in one-pot multi-component syntheses such that it was easily reused four to five times without significant loss in efficiency and product yield. The catalyst was characterized by scanning Electron Microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction techniques. N2 sorption isotherms of the prepared nanocomposite exhibited surface area 2.1313E+01 m2/g and total pore volume of 3.0957E-02 cm3/g. Substituted dihydropyridine derivatives were characterized and confirmed using 1H NMR and 13C NMR, and elemental spectral data.
- Zargarzadeh, Reza,Akbari Dilmaghani, Karim,Nikoo, Abbas
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p. 1310 - 1316
(2021/02/16)
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- Search for Antimicrobial Activity Among Fifty-Two Natural and Synthetic Compounds Identifies Anthraquinone and Polyacetylene Classes That Inhibit Mycobacterium tuberculosis
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Drug-resistant tuberculosis threatens to undermine global control programs by limiting treatment options. New antimicrobial drugs are required, derived from new chemical classes. Natural products offer extensive chemical diversity and inspiration for synthetic chemistry. Here, we isolate, synthesize and test a library of 52 natural and synthetic compounds for activity against Mycobacterium tuberculosis. We identify seven compounds as antimycobacterial, including the natural products isobavachalcone and isoneorautenol, and a synthetic chromene. The plant-derived secondary metabolite damnacanthal was the most active compound with the lowest minimum inhibitory concentration of 13.07 μg/mL and a favorable selectivity index value. Three synthetic polyacetylene compounds demonstrated antimycobacterial activity, with the lowest MIC of 17.88 μg/mL. These results suggest new avenues for drug discovery, expanding antimicrobial compound chemistries to novel anthraquinone and polyacetylene scaffolds in the search for new drugs to treat drug-resistant bacterial diseases.
- Pollo, Luiz A. E.,Martin, Erlon F.,Machado, Vanessa R.,Cantillon, Daire,Wildner, Leticia Muraro,Bazzo, Maria Luiza,Waddell, Simon J.,Biavatti, Maique W.,Sandjo, Louis P.
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- A New Type of Magnetically-Recoverable Heteropolyacid Nanocatalyst Supported on Zirconia-Encapsulated Fe3O4 Nanoparticles as a Stable and Strong Solid Acid for Multicomponent Reactions
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Abstract: A novel highly efficient magnetically retrievable catalyst was developed by the immobilization of H3PW12O40 (20–60 wt%) on the surface of zirconia-encapsulated Fe3O4 nanoparticles. The prepared HPW supported on nano-Fe3O4@ZrO2 heterogeneous acid catalyst (or n-Fe3O4@ZrO2/HPW) was fully characterized by several physicochemical techniques such as: Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometry and thermogravimetric analysis. The FT-IR spectroscopic data revealed that H3PW12O40 molecules on the nano-Fe3O4@ZrO2 support existed in the Keggin structure. The acidity of the catalyst was measured by the help of a potentiometric titration with n-butylamine. It was surprising that this very strong solid acid catalyst exhibited an excellent acid strength which was as a result of possessing a higher number of surface active sites compared to its homogeneous analogues. The catalytic activity of the as-prepared novel nano-Fe3O4@ZrO2/HPW was explored through the one-pot three-component synthesis of different 3,4-dihydropyrimidin-2(1H)-ones (i.e. Biginelli reaction) and 1,4-dihydropyridines (i.e. Hantzsh reaction) under solvent free condition. The sample of 40 wt% showed higher acidity and activity in the catalytic transformation. After the reaction, the catalyst/product isolation could be easily achieved with an external magnetic field and the catalyst could be easily recycled for at least five times without any decrease in its high catalytic activity. The excellent recyclability was attributed to the strong interaction between the hydroxyl groups of the nano-Fe3O4@ZrO2 support and the HPW species. Graphical Abstract: [Figure not available: see fulltext.].
- Zolfagharinia, Somayeh,Kolvari, Eskandar,Koukabi, Nadiya
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p. 1551 - 1566
(2017/05/17)
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- Fe3O4@SiO2 supported aza-crown ether complex cation ionic liquids: preparation and applications in organic reactions
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A series of aza-crown ether ionic liquids supported on magnetic Fe3O4@SiO2 core-shell particles were designed, synthesized and characterized by elemental analysis, TEM, TG and FT-IR. These new aza-crown ether complex cation ionic liquids were utilized as heterogeneous acidic catalysts in Friedel-Crafts alkylation and Hantzsch reaction in good yields under convenient reaction conditions. Moreover, these magnetic particle supported IL catalysts could be readily recovered by an external magnet and reused five times without obvious loss of activity.
- Li, Dandan,Wang, Jinyuan,Chen, Fengjuan,Jing, Huanwang
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p. 4237 - 4242
(2017/02/05)
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- Synthesis and in vitro evaluation of Ca2 + channel blockers 1,4-dihydropyridines analogues against Trypanosoma cruzi and Leishmania amazonensis: SAR analysis
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Drugs containing the1,4-dihydropyridine (DHP) core have recently attracted attention concerning their antiparasitic effect against various species of Leishmania and Trypanosoma. This approach named drugs repositioning led to interesting results, which have prompted us to prepare 21 DHP's analogues. The 1,4-DHP scaffold was decorated with different function groups at tree points including the nitrogen atom (NH and N-phenyl), the aryl group attached to C-4 (various substituted aryl residues) and the carbon atoms 2 and 6 (bearing Ph or Me groups). Moreover, the products were evaluated for their cytotoxicity on three cancer and a non-tumoral cell lines. Only 6 of them were antiproliferative and their weak effect (CC50 comprised between 27 and 98 μM) suggested these DHPs as good candidates against the intracellular amastigote forms of L. amazonensis and T. cruzi. L. amazonensis was sensitive to DHPs 5, 11 and 15 (IC50 values at 15.11, 45.70 and 53.13 μM, respectively) while 12 of them displayed significant to moderate trypanocidal activities against T. cruzi. The best trypanocidal activities were obtained with compounds 2, 18 and 21 showing IC50 values at 4.95, 5.44, and 6.64 μM, respectively. A part of the N-phenylated DHPs showed a better selectivity than their NH analogues towards THP-1 cells. 4-Chlorophenyl, 4-nitrophenyl and 3-nitrophenyl residues attached to the carbon atom 4 turned to be important sub-structures for the antitrypanosomal activity.
- Pollo, Luiz A.E.,de Moraes, Milene H.,Cisilotto, Júlia,Creczynski-Pasa, Tania B.,Biavatti, Maique W.,Steindel, Mario,Sandjo, Louis P.
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p. 789 - 797
(2017/09/23)
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- Tetraethylammonium 2-(carbamoyl)benzoate as a bifunctional organocatalyst for one-pot synthesis of Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives
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Abstract: A green, convenient, and environment-friendly approach for the synthesis of biologically active Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives in the presence of tetraethylammonium 2-(carbamoyl)benzoate, as an effective bifunctional metal-free catalyst, has been developed via a one-pot multicomponent reaction of various aldehydes, ethyl acetoacetate or cyclic 1,3-dicarbonyl compounds, and ammonium acetate in EtOH under reflux conditions. The proposed methodology is capable of providing the desired products in good to excellent yields and short reaction time with straightforward work-up and a low-cost procedure. Graphical abstract: [Figure not available: see fulltext.]
- Yarhosseini, Mahsa,Javanshir, Shahrzad,Dekamin, Mohammad G.,Farhadnia, Mohammad
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p. 1779 - 1787
(2016/09/28)
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- 2-Hydroxyethylammonium acetate: An efficient and reusable homogeneous catalyst for the synthesis of Hantzsch 1, 4-dihydropyridines
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2-Hydroxyethylammonium acetate ionic liquid was found to be an excellent catalyst for the one-pot synthesis of 1,4-dihydropyridine derivatives via Hantzsch reaction of ethyl acetoacetate or acetoacetanilide, ammonium acetate, and various aromatic aldehyde
- Kang, Li-Qin,Cao, Zhi-Jun,Lei, Ze-Jun
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p. 1125 - 1128
(2016/09/09)
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- Synthesis of 1,4-dihydropyridine esters using low-melting sugar mixtures as green solvents
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Several low-melting sugar mixtures (LMMs) were synthesized and used for preparation of 1,4-dihydropyridines with aldehydes, 1,3-dicarbonyl compounds, and a nitrogen source as starting materials. Good yields, low reaction times, recyclability of LMMs, and catalyst-free methodology are some of the highlights of this new protocol.
- Kumar, J. Ashwin,Shridhar, Gomathi,Ladage, Savita,Ravishankar, Lakshmy
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supporting information
p. 1989 - 1998
(2016/12/09)
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- Hybrid pharmacophore-based drug design, synthesis, and antiproliferative activity of 1,4-dihydropyridines-linked alkylating anticancer agents
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Two series of novel substituted 1,4-dihydropyridine derivatives incorporating nitrogen mustard pharmacophore hybrids without spacer DHP-M (4a-4d) and with ethyl spacer DHP-L-M (8a-8g) were designed and synthesized. They were subjected to in silico ADME prediction study to check their drug-like properties and evaluated for their cytotoxicity against: A 549 (lung), COLO 205 (colon), U 87 (glioblastoma), and IMR-32 (neuroblastoma) human cancer cell lines in vitro using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay against chlorambucil and docetaxel. Majority of the test compounds exhibited moderate to significant cytotoxic activity. The highest activity in all the investigated cancer cells was displayed by DHP-M (4a). This may be due to the less steric hindrance offered by 4a.
- Singh, Rajesh K.,Prasad,Bhardwaj
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p. 1534 - 1545
(2015/04/21)
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- Alginic acid: A highly efficient renewable and heterogeneous biopolymeric catalyst for one-pot synthesis of the Hantzsch 1,4-dihydropyridines
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Alginic acid, a naturally occurring polysaccharide, in its granular form and without any post-modification was found to be an efficient, environmentally benign, easily recoverable and low-cost catalyst for the clean and rapid synthesis of 1,4-dihydropiridine derivatives (DHPs) just based on its polysaccharide architecture. The Hantzsch pseudo-four-component reaction of ethyl or methyl acetoacetate, ammonium acetate and different aldehydes is catalyzed by alginic acid efficiently under mild conditions to afford the desired products in high to quantitative yields and clean reaction profiles. Avoiding the use of any transition metal, the use of a one-pot and multi-component procedure for the synthesis of DHPs, the reusability of the catalyst and operational simplicity are important features of this methodology.
- Dekamin, Mohammad G.,Ilkhanizadeh, Siamand,Latifidoost, Zahra,Daemi, Hamed,Karimi, Zahra,Barikani, Mehdi
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p. 56658 - 56664
(2015/02/02)
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- Synthesis and antimicrobial evaluation of 2-aminobenzophenone linked 1,4-dihydropyridine derivatives
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A series of novel aminobenzophenone linked 1,4-dihydropyridines (1,4-DHPs) hybrids were synthesized by incorporating aminobenzophenone moiety on 1,4-dihydropyridines scaffold (5a-f) and characterized by IR, 1H NMR and CHN elemental analysis. The synthesized compounds were tested for their in vitro antibacterial activity against the Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Among all the synthesized compounds, compounds 5b, 5c and 5e have shown the maximum activity in their group whereas compounds 5a, 5d, 5f have shown the minimum activity.
- Li, Pengying,Sahore, Ketki,Liu, Jianjun,Singh, Rajesh K.
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p. 5291 - 5294
(2014/12/10)
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- A magnetic particle-supported sulfonic acid catalyst: Tuning catalytic activity between homogeneous and heterogeneous catalysis
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Surface functionalization of magnetic particles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. The introduction of magnetic particles (MPs) in a variety of solid matrices allows the combination of well-known procedures for catalyst heterogenization with techniques for magnetic separation. We have conveniently loaded sulfonic acid groups on magnetic particles supports in which chlorosulfonic acid is used as sulfonating agent. The main targets are room temperature, solvent-free conditions, rapid (immediately) and easy immobilization technique, and low cost precursors for the preparation of highly active and stable MPs with high densities of functional groups. The inorganic, magnetic, solid acid catalyst was characterized via Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometer (VSM) and titration. The catalyst is active for the Hantzsch reaction and the products are isolated in high to excellent yields (90-98%). Supporting this acid catalyst on magnetic particles offers a simple and non-energy-intensive method for recovery and reuse of the catalyst by applying an external magnet. Isolated catalysts were reused for new rounds of reactions without significant loss of their catalytic activity. Copyright
- Koukabi, Nadiya,Kolvari, Eskandar,Zolfigol, Mohammad Ali,Khazaei, Ardeshir,Shaghasemi, Behzad Shirmardi,Fasahati, Behzad
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experimental part
p. 2001 - 2008
(2012/10/08)
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- Comparative study of various green chemistry approaches for the efficient synthesis of 1,4-dihydropyridines
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Hantzsch 1,4-dihydropyridine and its derivatives are an important class of bioactive molecules in the pharmaceutical field. The work on this project was started with the objective of synthesizing known 1,4-dihydropyridine by various green chemistry methods like microwave, solvent-free, ultrasonication and compared the results with conventional technique using different aldehydes and 1,3-dicarbonyl compounds as substituents. The twelve known 1,4-dihydropyridines were synthesized and characterized by their TLC, FT-IR and 1H NMR, elemental studies. When all the data cross-examined, it was concluded that microwave, ultrasonic and solvent-free methods were efficient and less time consuming with high yield. At the same time conventional method was time consuming but scalable when compared with other methods.
- Kaur, Prabhjot,Sharma, Heena,Rana, Rekha,Prasad, D. N.,Singh, Rajesh K.
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p. 5649 - 5651,3
(2020/09/15)
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- Design, solvent free synthesis, and antimicrobial evaluation of 1,4 dihydropyridines
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Here in, we report the usage of cellulose sulfuric acid as a heterogeneous eco friendly catalyst for the synthesis of 1,4 dihydropyridines under solvent free conditions via Hantzsch three component reaction of an aldehyde, ethyl acetoacetate and ammonium acetate at 100 °C for 2-5 h. In silico studies were performed on twenty two possible 1,4 dihydropyridines (DHPs) analogues against K+ channel receptor (KcsA). In order to validate in silico studies, thirteen compounds were synthesized and evaluated as antibacterials against twenty seven ESBL isolates of Klebsiella pneumoniae and Escherichia coli.
- Murthy,Rajack, Abdul,Taraka Ramji,Jeson Babu,Praveen, Ch.,Aruna Lakshmi
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p. 6016 - 6023
(2012/11/07)
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- Silica sulfuric acid: An efficient heterogeneous catalyst for the one-pot synthesis of 1,4-dihydropyridines under mild and solvent-free conditions
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A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields, and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.
- Datta, Bandita,Pasha, M. Afzal
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experimental part
p. 1180 - 1184
(2012/06/04)
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- Silica Sulfuric Acid: An Efficient Heterogeneous Catalyst for the One-Pot Synthesis of 1,4-Dihydropyridines under Mild and Solvent-Free Conditions
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A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields, and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.
- Datta, Bandita,Pasha, M. Afzal
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p. 1180 - 1184
(2016/04/10)
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- A simple and efficient one-pot synthesis of Hantzsch 1,4-dihydropyridines using silica sulphuric acid as a heterogeneous and reusable catalyst under solvent-free conditions
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A simple, inexpensive and efficient one-pot synthesis of 1,4-dihydropyridine derivatives under solvent-free conditions using silica sulphuric acid (SSA) as a heterogeneous and recyclable catalyst is reported.
- Kolvari, Eskandar,Zolfigol, Mohammad Ali,Koukabi, Nadiya,Shirmardi-Shaghasemi, Behzad
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experimental part
p. 898 - 902
(2012/03/27)
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- An Efficient Synthesis of 4-Aryl-1,4-dihydropyridines Via VB1 Catalyzed Hantzsch Reaction
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An environmentally rapid and benign protocol for the synthesis of 4-aryl-1,4-dihydropyridines compounds using VB1 as a catalyst under microwave irradiation and solvent-free conditions has been achieved. The procedure is operationally simple, giving good to high product yield.
- Fan, Chuangang,Song, Mingzhi
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scheme or table
p. 707 - 711
(2012/06/01)
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- Hantzsch reaction on free nano-Fe2O3 catalyst: Excellent reactivity combined with facile catalyst recovery and recyclability
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A magnetic nanoparticle catalyst was readily prepared from inexpensive starting materials which catalyzed the Hantzsch reaction. High catalytic activity and ease of recovery from the reaction mixture using an external magnet, and several reuse times without significant losses in performance are additional eco-friendly attributes of this catalytic system.
- Koukabi, Nadiya,Kolvari, Eskandar,Khazaei, Ardeshir,Zolfigol, Mohammad Ali,Shirmardi-Shaghasemi, Behzad,Khavasi, Hamid Reza
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experimental part
p. 9230 - 9232
(2011/10/03)
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- Synthesis and anticancer activity of some new series of 1, 4-dihydropyridine derivatives
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A series of 1,4-dihydropyridine derivatives 1a-c have been prepared from 4-substituted aromatic aldehyde, ethyl acetoacetate and ammonium hydroxide following Hantzsch method. The compounds 1a-c have been reacted with semicarbazide to give the compounds 2a-c. The compounds 1a-c have been reacted with thiosemicarbazide to give the compounds 3a-c. The structures of synthesized compounds are confirmed by IR, 1H and 13C NMR, mass spectrometry and elemental analyses. The newly synthesized compounds have been screened for preliminary anti-cancer activity against HepG2 (Liver), Hela (Cervical) and MCF-7 (Breast) cancer cells. The compound 2a is highly active against HepG2, MCF-7 and 3a is highly active against Hela (Cervical) and these have been selected for advanced preclinical development.
- Surendra Kumar,Idhayadhulla,Jamal Abdul Nasser,Murali
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experimental part
p. 1140 - 1144
(2011/10/05)
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- Synthesis of 1,4-dihydropyridines using Ce(SO4)2-SiO2 as catalyst under solvent-free conditions
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A facile and efficient one-pot synthesis of 1,4-dihydropyridines from aldehyde, 1,3-dicarbonyl compounds and ammonium acetate in the presence of Ce(SO4)2-SiO2 at 80 °C under solvent-free conditions is described. Compared with the classical Hantzsch reaction, this novel method consistently has the advantages of excellent yields and short reaction time.
- Pei, Wen,Wang, Qin,Li, Xiaonian,Sun, Li
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experimental part
p. 483 - 486
(2010/10/02)
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- Synthesis, characterization and anticonvulsant activity evaluation of some 1,4-dihydropyridines and 3,5-(substituted)oxycarbonyl-1,4-dihydro-2,6-dimethyl- n- [2-(4-sulfamoylphenylamino)-acetyl]-4-(substituted)pyridines
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A series of 3,5-(substituted)oxycarbonyl-1,4-dihydro-2,6-dimethyl-4- (substituted)pyridines (1a-j) were synthesized by Hantzsch method for pyridine synthesis. Treatment with chloroacetyl chloride produced N-(2-chloroacetyl)-3,5- (substituted)oxycarbonyl-1,4-dihydro-2,6-dimethyl-4-(substituted)pyridines (2a-e), which on further treatment with sulfanilamide resulted in 3,5-(substituted)oxycarbonyl-1,4-dihydro-2,6- dimethyl-N-[2-(4- sulfamoylphenylamino)-acetyl]-4-(substituted)pyridines (3a-e). The structures has been established on the basis of spectral (IR, 1H-NMR, mass) and elemental analysis. Compounds 1a-j and 3a-e (5 mg/kg and 10 mg/kg) were evaluated for their anticonvulsant effect against pentylenetetrazole-induced convulsions with diazepam (4 mg/kg) as the reference. Compounds 3a-e exhibited significant (p 0.01) anticonvulsant activity compared to the control.
- Subudhi, Bharat Bhusan,Panda, Prasanna K.,Swain, Sarada P.,Sarangi, Priyambada
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experimental part
p. 147 - 153
(2009/06/28)
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- Synthesis and antiulcer activity study of 1,4- Dihydropyridines and their Mannich bases with sulfanilamide
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3,5-Diethoxycarbonyl- I ,4-dihydro-2,6-dimethyl-4-(substituted)- pyridines Ia-c are prepared following Hantzsch pyridine synthesis by condensation of ethyl acetoacetate with different aromatic aldehydes in presence of ammonium hydroxide. Compounds Ia-c on
- Subudhi,Panda,Bhatta
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experimental part
p. 725 - 728
(2009/12/26)
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- Synthesis of some C-3,4,5-substituted 2,6-dimethyl-1,4-dihydropyridines (4-DHPs)
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A series of C-3,4,5-substituted 2,6-dimethyl-1,4-dihydropyridines (1,4-DHPs) with pharmacological properties were prepared by a variation from the classical Hantzsch synthesis. The procedure involves treatment of the respective aldehyde with either ethyl-3-aminocrotonate or 3-aminocrotonitrile in anhydrous acetic acid at temperatures not exceeding 60°C, thus minimizing by-product formation. The structures of title compounds were elucidated by 1H NMR, 13C NMR, FTIR, and elemental analysis. Copyright Taylor & Francis Group, LLC.
- Navarrete-Encina, Patricio A.,Squella, Juan A.,Carbajo,Conde,Nunez-Vergara, Luis J.
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p. 2051 - 2060
(2008/02/04)
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- Synthesis of some new unsymmetrically substituted 1,4-dihydropyridines
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A series of some new 3,5-unsymmetrically substituted 1,4-dihydropyridines have been synthesized, which have ethoxycarbonyl and acetyl groups on 3- and 5-positions, respectively. A three-step procedure has been examined to increase the yield of the desired products, by suppressing the formation of the symmetrically substituted 3,5-diacetyl-1,4-dihydropyridines and 3,5-diethoxycarbonyl-1,4-dihydropyridines.
- Memarian, Hamid R.,Abdoli-Senejani, Masumeh,D?pp, Dietrich
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- Rapid and cleaner synthesis of 1,4-dihydropyridines in aqueous medium
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The present investigation deals with a novel water soluble Lewis acid complex, Zn[(L)proline]2 catalyzed Hantzsch 1,4-dihydropyridine derivatives syntheses in aqueous medium assisted by microwave irradiation. The microwave promoted syntheses in aqueous medium afforded moderate to excellent yield (up to 98%) within short reaction time and allowed the reaction to take place with low microwave power (200 W). This synthetic methodology provides easier separation of products and the catalyst exhibits recycling ability without loss of its catalytic activity up to five reaction cycles.
- Sivamurugan,Vinu,Palanichamy,Murugesan
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p. 267 - 271
(2007/10/03)
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- Microwave-assisted synthesis of antimicrobial dihydropyridines and tetrahydropyrimidin-2-ones: Novel compounds against aspergillosis
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Ten 4-aryl-1,4-dihydropyridine and three 4-aryl-1,2,3,4- tetrahydropyrimidin-2-one derivatives have been synthesized and examined for their activity against pathogenic strains of Aspergillus fumigatus and Candida albicans. Although none of the three compo
- Chhillar, Anil K.,Arya, Pragya,Mukherjee, Chandrani,Kumar, Pankaj,Yadav, Yogesh,Sharma, Ajendra K.,Yadav, Vibha,Gupta, Jyotsana,Dabur, Rajesh,Jha, Hirday N.,Watterson, Arthur C.,Parmar, Virinder S.,Prasad, Ashok K.,Sharma, Gainda L.
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p. 973 - 981
(2007/10/03)
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- Synthesis of Hantzsch 1,4-dihydropyridines under solvent-free condition using Zn[(L)proline]2 as Lewis acid catalyst
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The present short communication describes a Lewis acid (Zn[(L)proline] 2) catalysed one pot synthesis of Hantzsch 1,4-dihydropyridine (DHP) derivatives under solvent-free condition by conventional heating and microwave irradiation. The Lewis acid catalyst Zn[(L)proline]2 used in this reaction afford moderate to good yield. The catalyst is reusable upto five cycles without appreciable loss of its catalytic activity.
- Sivamurugan,Kumar, R. Suresh,Palanichamy,Murugesan
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p. 969 - 974
(2007/10/03)
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- PROCESS FOR THE PREPARATION OF 1,4-DIHYDROPYRIDINES AND NOVEL 1,4-DIHYDROPYRIDINES USEFUL AS THERAPEUTIC AGENTS
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The present invention provides a process for the preparation of 1,4-dihydropyridines of the formula (1), wherein R1 is H, NO2, Cl, OAc, OH, R2 is H, NO2, Cl, -O-CH2-O-, OMe, OAc, OEt, OH, R3 is H, NO2, Cl, N(Me)2, -O- CH2 -O-, OMe, OAc, OH, R4 is H, OMe, OAc, OH, R5 is H, Cl, I, and R6 and R7 are either methyl, ethyl or both by preparing a mixture of an aromatic aldehyde, alkyl acetoacetate and a source of ammonia, adsorbing the prepared mixture and adsorbent till adsorbent becomes free flowing, heating the material so obtained under microwave irradiation, cooling the reaction mixture and recovering the compound of formula (1). The present invention also relates to novel 1,4-dihydropyridines with cardiovascular activity.
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- A convenient ferric chloride catalyzed synthesis of 5-alkoxycarbonyl-4-aryl-3,4-dihydropyrimidin-2(1H)-ones under microwave irradiation
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A series of ethyl 4-aryl-6-methyl-1,2,3,4-tetrahydropyrimidin-2-one-5-carboxylates 4 were synthesized by the condensation of aromatic aldehydes, ethyl acetoacetate and urea in the presence of ferric chloride hexahydrate under microwave irradiation. The reactions were completed in 4-6 min with 87-92% yield.
- Tu, Shu-Jiang,Zhou, Jian-Feng,Cai, Pei-Jun,Wang, Hai,Feng, Jun-Cai
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p. 147 - 151
(2007/10/03)
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