cas 43067-01-2, Dimethyl 4-(2-Chlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate

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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
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
p. 1551 - 1566
(2017/05/17)

Novel Magnetically Separable Sulfated Boric Acid Functionalized Nanoparticles for Hantzsch Ester Synthesis
A novel, separable, solid-acid catalyst consisting of sulfated boric acid nanoparticles immobilized on a silica-coated magnetite support was prepared. This catalyst permits the preparation of dihydropyridine derivatives (Hantzsch esters) by condensation of an aldehyde with two equivalents of a β-keto ester in the presence of ammonium acetate. The catalyst can be recovered and recycled.
Azizi, Kobra,Azarnia, Jamshid,Karimi, Meghdad,Yazdani, Elahe,Heydari, Akbar
p. 1810 - 1813
(2016/07/16)

A Simple and Efficient One-pot Synthesis of 1,4-dihydropyridines Using Nano-WO3-supported Sulfonic Acid as an Heterogeneous Catalyst under Solvent-free Conditions
Nano-tungsten trioxide-supported sulfonic acid (n-WSA) was found to be an effective heterogeneous catalyst for the one-pot reaction of aromatic aldehydes, β-dicarbonyl compounds and ammonium acetate to afford 1,4-dihydropyridine derivatives in good to excellent yields. The other main advantages of the present method are short reaction times, simple workup, ease in purification and environmentally benign methodology. The reaction conditions were optimized employing Response Surface Method technique (Central Composite Design (CCD)) which is economically considerable because of the minimum number of experiments required to evaluate the effects of multiple parameters on the response.
Bitaraf, Mehrnoosh,Amoozadeh, Ali,Otokesh, Somayeh
p. 336 - 344
(2016/05/09)

Synthesis, evaluation of pharmacological activity, and molecular docking of 1,4-dihydropyridines as calcium antagonists
1,4-Dihydropyridine (DHP) is an important class of calcium antagonist. It inhibits the influx of extracellular Ca2+ through L-type voltage-dependent calcium channels. Two series of nifedipine analogues were synthesized and evaluated as calcium
Shaldam, Moataz Ahmed,El-Hamamsy, Mervat Hamed,Saleh, Dalia Osama,El-Moselhyb, Tarek Fathy
p. 297 - 304
(2016/05/19)

Study of temperature dependent three component dynamic covalent assembly VIa Hantzsch reaction catalyzed by dioxido- and oxidoperoxidomolybdenum(VI) complexes under solvent free conditions
Tridentate ONO donor ligands derived from heterocyclic compound 4-acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one (Hap) and aromatic hydrazides {benzoyl hydrazide (Hbhz), isonicotinoyl hydrazide (Hinh), nicotinoyl hydrazide (Hnah) and furoyl hydrazide (Hfah)} react with [MoVIO2(acac)2] (Hacac = acetylacetone) in equimolar ratio in methanol to give dioxidomolybdenum(vi) complexes, [MoO2(ap-bhz)(MeOH)] 1, [MoO2(ap-inh)(MeOH)] 2, [MoO2(ap-nah)(MeOH)] 3 and [MoO2(ap-fah)(MeOH)] 4. Reaction of these ligands with in situ generated oxidoperoxidomolybdenum(vi) precursor results in the formation of oxidoperoxidomolybdenum(vi) complexes, [MoO(O2)(ap-bhz)(MeOH)] 5, MoO(O2)(ap-inh)(MeOH)] 6, MoO(O2)(ap-nah)(MeOH)] 7 and MoO(O2)(ap-fah)(MeOH)] 8. These complexes have been characterized by elemental analysis, spectroscopic techniques (infrared, UV-vis, 1H and 13C NMR) and thermogravemetric analysis. The structures of complexes [MoVIO2(ap-bhz)(H2O)] 1a (water coordinated), [MoVIO2(ap-bhz)(DMSO)] 1b (DMSO coordinated), [MoVIO2(ap-nah)(DMF)] 3a (DMF coordinated), [MoVIO(O2)(ap-bhz)(MeOH)] 5 (methanol coordinated) and [MoVIO(O2)(Hap-nah)(OMe)]·MeOH 7a (methoxy coordinated) have been confirmed by single crystal X-ray studies. X-ray diffraction study also reveals that tridentate ligands bind to the metal center through enolic oxygen (of pyrazolol), azomethine nitrogen and enolic oxygen (of hydrazide) atoms. In complex 7a, pyridinic nitrogen is protonated. These complexes [dioxidomolybdenum(vi) as well as oxidoperoxidomolybdenum(vi)] have been tested as catalysts for temperature dependent one pot three component (methylacetoacetate, benzaldehyde and ammonium acetate) dynamic covalent assembly, via Hantzsch reaction, using 30% H2O2 as a green oxidant under solvent free conditions. Various parameters such as the amount of catalyst, oxidant and temperature of the reaction mixture have been taken into consideration to optimize the reaction conditions. In the Hantzsch reaction, the temperature and oxidant control the conversion and selectivity of the desired product.
Maurya, Mannar R.,Saini, Neeraj,Avecilla, Fernando
p. 12993 - 13009
(2016/02/12)

Ultrasound-mediated, uranyl nitrate hexahydrate-catalyzed synthesis of 1,4-dihydropyridines under mild conditions
Abstract Synthesis of 1,4-dihydropyridines by three-component condensation reaction of aldehyde, 1,3-dicarbonyl compounds, and ammonium acetate have been found to be efficiently catalyzed by uranyl nitrate hexahydrate [UO2(NO3)2 ·6H2O] at room temperature under ultrasound irradiation. This novel synthetic method offers the advantages of high yields, short reaction times, simplicity, and easy workup compared to the conventional methods reported in the literature.
Palakshi Reddy,Sarveswari,Vijayakumar
p. 6877 - 6883
(2015/08/18)

Alginic acid: A highly efficient renewable and heterogeneous biopolymeric catalyst for one-pot synthesis of the Hantzsch 1,4-dihydropyridines
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
p. 56658 - 56664
(2015/02/02)

A magnetic particle-supported sulfonic acid catalyst: Tuning catalytic activity between homogeneous and heterogeneous catalysis
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
experimental part
p. 2001 - 2008
(2012/10/08)

PEG400-lithium carbonate catalyzed synthesis of 1,4-dihydropyridines under solvent-free conditions
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Reddy, B. Palakshi,Rajesh,Vijayakumar
experimental part
p. 153 - 158
(2012/05/20)

Hantzsch reaction on free nano-Fe2O3 catalyst: Excellent reactivity combined with facile catalyst recovery and recyclability
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
experimental part
p. 9230 - 9232
(2011/10/03)

Bismuth trichloride - A clean, green catalyst for the synthesis of Hantzsch 1,4-dihydropyridines (DHPs)
Hantzsch 1,4-dihydropyridines (DHPs) are synthesized in good to excellent yields from aldehydes, 1,3-dicarbonyl compounds and ammonium acetate using bismuth trichloride which acts as mild Lewis acid promoter and 10 mol% is enough for this protocol under solvent free conditions.
Bhatti, Ravinder S.,Krishan, Pawan,Suresh,Sandhu, Jagir S.
experimental part
p. 707 - 710
(2011/08/06)

Gallium(III) chloride as an efficient new catalyst for the production of Hantzsch 1,4-dihydropyridines
Hantzsch 1,4-dihydropyridines (DHPs) are synthesized in good to excellent yields from aldehydes, 1,3-dicarbonyl compounds and ammonium acetate using gallium(III) chloride which acts as dehydrating agents and 5 mol% is enough for this protocol under solvent free conditions.
Kumar, Dhruva,Saini, Anil,Suresh,Sandhu, Jagir S.
experimental part
p. 996 - 1000
(2010/07/09)

New efficient protocol for the production of hantzsch 1,4-dihydropyridines using RuCl3
Hantzsch 1,4-dihydropyridines are synthesized in a few minutes and in good to excellent yields from aldehydes, 1,3-dicarbonyl compounds, and ammonium acetate. The reaction is performed in solvent-free conditions, and 5mol% of RuCl3 is enough for this protocol.
Kumar, Dhruva,Sandhu, Jagir S.
experimental part
p. 1957 - 1965
(2009/10/09)

Hantzsch synthesis of polyhydroquinolines - A simple, efficient and neat protocol
A variety of polyhydroquinolines have been synthesized under eco-benign conditions. The reaction proceeds smoothly without any catalyst at room temperature in short reaction time. The yields and purity are excellent.
Arumugam, Pandurangan,Perumal, Paramasivan T.
p. 1084 - 1090
(2008/12/23)

COMPOUNDS AND COMBINATIONS THEREOF FOR INHIBITING BETA-AMYLOID PRODUCTION AND METHODS OF USE THEREOF
Provided are compounds which can be used in combination for treating diseases associated with a condition associated with cerebral accumulation of Alzheimer’s amyloid, such as Alzheimer’s disease. Also provided are methods of treating or reducing the risk of developing β-amyloid production, β-amyloid deposition, β-amyloid neurotoxicity (including abnormal hyperphosphorylation of tau) and microgliosis associated with cerebral accumulation of Alzheimer’s amyloid by administering therapeutically effective amounts of compounds which in combination can decrease β-amyloid production and capacitative calcium entry in cells. Further provided are methods for diagnosing diseases associated with cerebral accumulation of Alzheimer’s amyloid in animals or humans by administering diagnostically effective amounts of the compounds.
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Page/Page column 119-120

(2010/11/29)

An efficient, metal-free, room temperature aromatization of Hantzsch-1,4-dihydropyridines with urea-hydrogen peroxide adduct, catalyzed by molecular iodine
A mild, highly efficient and metal-free synthetic method for aromatization of 1,4-dihydropyridines employing urea-hydrogen peroxide adduct as oxidant catalyzed by 20 mol % of molecular iodine was developed. The reaction was carried out in ethyl acetate at room temperature and the products were isolated in high to excellent yields. A plausible free-radical mechanism is proposed based on results obtained with derivatives having alkyl and aryl substituents in the 1,4-dihydropyridine ring.
Filipan-Litvi?, Mirela,Litvi?, Mladen,Vinkovi?, Vladimir
p. 5649 - 5656
(2008/09/21)

Synthesis of substituted 1,4-dihydropyridines in water using phase-transfer catalyst under microwave irradiation
The synthesis of various substituted 1,4-dihydropyridines has been achieved by the reaction of aldehydes, ethyl/methyl acetoacetates, and ammonium acetate in water using phase-transfer catalyst under microwave irradiation. Compared to the classical Hantzsch's reaction conditions, this new method consistently has the advantage of good yields and short reaction times. Bifunctional compounds containing two units have been synthesized using dialdehyde as precursor in good yields.
Salehi, Hojatollah,Guo, Qing-Xiang
p. 4349 - 4357
(2007/10/03)

Synthesis of hantzsch 1,4-dihydropyridines under microwave irradiation
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.
p. 659 - 663
(2007/10/03)

Scaling up of dihydropyridine ester synthesis by using aqueous hydrotrope solutions in a continuous microwave reactor
We report here the scaling up of clinically important dihydropyridine by using a continuous microwave reactor (CMR). We also report the use of aqueous hydrotrope solution as a cheap, safe and "green" alternative to organic solvent to carry out homogeneous reactions under microwave heating. We have studied different aqueous hydrotrope solutions for the reaction in batch as well as continuous-flow process.
Khadilkar, Bhushan M.,Madyar, Virendra R.
p. 452 - 455
(2013/09/07)

Synthesis and radioprotective effects of adamantyl substituted 1,4-dihydropyridine derivatives
A series of 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic acid diesters substituted at the N-1 and/or C-4 positions of the dihydropyridine ring was synthesized. The in vitro cytotoxicity and in vitro and in vivo radioprotective efficacy of these agents were evaluated in Chinese hamster (V-79) cells and CD2F1 male mice, respectively. Compounds with at least one adamantyl substituent afforded better radioprotection than those without this substituent. Substitution of an aromatic ring at the C-4 position of the dihydropyridine ring did not enhance the radioprotectant action of the compounds. Copyright (C) 1998 Elsevier Science Ltd.
Donkor, Isaac O.,Zhou, Xiaoxin,Schmidt, Jeffery,Agrawal, Krishna C.,Kishore, Vimal
p. 563 - 568
(2007/10/03)

Aqueous hydrotrope solution as a safer medium for microwave enhanced Hantzsch dihydropyridine ester synthesis
Hantzsch esters are prepared for the first time, by condensing alkyl β-aminocrotonate, aldehyde and alkyl acetoacetate in aqueous sodium butylmonoglycosulphate (NaBMGS) as a safe reaction medium in an unmodified domestic microwave oven.
Khadilkar, Bhushan M.,Gaikar, Vilas G.,Chitnavis, Ashish A.
p. 8083 - 8086
(2007/10/02)

Synthesis of 1,4-dihydropyridines and their hypotensive activity
1,4-Dihydropyridines (1-35) have been synthesised by treating different aldehydes with dicarbonyl compounds and ammonium hydroxide and are found to possess hypotensive activity.
Shinde, D. B.,Shinde, N. D.,Shingare, M. S.,Dubey, M. P.,Patnaik, G. K.
p. 920 - 922
(2007/10/03)

1,4-Dihydropyridine antagonist activities at the calcium channel: A quantitative structure-activity relationship approach
The effect of 46 1,4-dihydropyridine-type calcium channel antagonists on the tonic contractile response of longitudinal muscle strips of guinea pig ileum was determined. 2,6-Dimethyl-3,5-dicarbomethoxy-4-phenyl-1,4-dihydropyridine (13) and 13 ortho-, 15 meta-, and seven para-monosubstituted and 10 polysubstituted aromatic derivatives of 13 were studied. The pharmacological activities of the monosubstituted derivatives were best correlated by eq 10, log 1/C = 0.68π + 2.50σ(m) - 0.47L(meta) - 3.40B1(para) + 11.31, which had a correlation coefficient of 0.89. The full data set was best correlated by eq 11, log 1/C = 0.62π + 1.96σ(m) - 0.44L(meta) - 3.26B1(para) - 1.51L(meta) + 14.23, which had a correlation coefficient of 0.90. Equations of similar form but involving an ortho steric term were found to correlate the radioligand binding data for this class of compounds.
Coburn,Wierzba,Suto,Solo,Triggle,Triggle
p. 2103 - 2107
(2007/10/02)

Studies directed toward ascertaining the active conformation of 1,4-dihydropyridine calcium entry blockers
A series of unsymmetrically substituted 4-phenyl-1,4-dihydropyridine calcium entry blockers were investigated for their ability to relax potassium-contracted rabbit aortic smooth muscle and to competitively displace [3H][nitrendipine from its specific binding sites on guinea pig myocardial membranes in order to delineate the pharmacologically active conformer with respect to the position of the aromatic substituents (synperiplanar or antiperiplanar). The data show that the 1,4-dihydropyridine receptor distinguishes between 2',3'-disubstituted phenyldihydropyridines and 2',5'-disubstituted analogues as measured by changes of vasodilation and receptor affinity in vitro. The IC50 values for vasorelaxation by the analogues presented here correlate best with the K(d) values for binding to the predominant receptor of two coexisting dihydropyridine binding sites in the guinea pig myocardium. We report the first observation of an antiperiplaner orientation of an o-phenyl substituent in the X-ray structure of 2-chlorophenyl analogue 3. Using nuclear Overhauser enhancement, we have developed a method that also demonstrates that an ortho (chloro or nitro) substituent on the phenyl ring does not preclude the presence of either synperiplanar or antiperiplanar phenyl rotamer in solution. These experimental findings contrast with the accepted belief that o-phenyl substituents essentially force these 1,4-dihydropyridines into the synperiplanar conformation exclusively.
Rovnyak,Andersen,Gougoutas,Hedberg,Kimball,Malley,Moreland,Porubcan,Pudzianowski
p. 936 - 944
(2007/10/02)