- Catalytic activity of the nanoporous MCM-41 surface for the Paal-Knorr pyrrole cyclocondensation
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The investigation of different oxide surfaces revealed that nanoporous silica (MCM-41) had the best catalytic activity for Paal-Knorr pyrrole synthesis. Despite the same composition, MCM-41 proved to be more effective than SiO2 itself, probably due to a significantly higher surface area of the SiO2 nanopores. The important features of this "clean" solvent-free protocol are the ease of recovery and the reuse of the catalyst for several cycles, operational simplicity, and easy product isolation and purification.
- Aghapoor, Kioumars,Amini, Mostafa M.,Jadidi, Khosrow,Mohsenzadeh, Farshid,Darabi, Hossein Reza
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Read Online
- Hexafluoroisopropanol as solvent and promotor in the Paal-Knorr synthesis of N-substituted diaryl pyrroles
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An additive-free synthesis of challenging N-substituted aryl pyrroles from the often poorly soluble corresponding 1,4-diketones by means of the Paal-Knorr pyrrole synthesis is reported, which makes use of the unique properties of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a solvent and reaction promotor. Our procedure offers simple execution and purification as well as easy scale-up and can be applied in the Paal-Knorr synthesis of a large number of structurally diverse pyrroles including the synthetically challenging tetra- and penta-substituted pyrroles in moderate to excellent yields. HFIP can also be used as solvent in the Paal-Knorr synthesis of furans and thiophenes; however, the solvent effect is more pronounced in synthesis of pyrroles.
- Schirmacher, Robert H.E.,R?sch, Daniel,Thomas, Franziska
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- Synthesis of Fe3O4@L-proline@SO3H as a novel and reusable acidic magnetic nanocatalyst and its application for the synthesis of N-substituted pyrroles at room temperature under ultrasonic irradiation and without solvent
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N-Substituted pyrroles have been prepared in high isolated yields (65–90%) by the reaction of hexane-2,5-dione with amines or diamines in the presence of Fe3O4@L-proline@SO3H at ambient temperature under ultrasonic irradiation and without solvent. The experimental procedure involves simple operations, and the products are readily separated by external magnet. The same reaction of hexane-2,5-dione with amines containing electron-acceptor substituents, such as 4-nitroaniline, resulted in fair yields of pyrrole derivatives.
- Behbahani, Farahnaz K.,Shokri, Fatemeh
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- Amidosulfonic acid supported on graphitic carbon nitride: novel and straightforward catalyst for Paal–Knorr pyrrole reaction under mild conditions
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A novel heterogeneous acidic catalyst was prepared by in situ immobilization of amidosulfonic acid (NH2SO3H) on graphitic carbon nitride (g-C3N4) under hydrothermal conditions. The textural morphology of NH2SO3H/g-C3N4 nanocomposite was characterized via powder X-ray diffraction, FT-IR, TGA, EDX, and scanning electron microscopy. The spatial arrangement of the amidosulfonic acid on the surface of g-C3N4 leads to the construction of a unique solid acid structure, resulting in a substantial enhancement of catalytic activity toward a high efficient preparation of pyrroles by Paal–Knorr reaction. The reactions undergo completion readily with good to excellent yields, with simple purification in an environmentally friendly manner. The NH2SO3H/g-C3N4 nanocomposite can be readily recycled, and no noteworthy reduction in the catalytic activity detected after four runs. Graphic abstract: [Figure not available: see fulltext.]
- Azhdari, Asieh,Azizi, Najmedin,Sanaeishoar, Haleh,Tahanpesar, Elham
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p. 625 - 634
(2021/05/12)
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- Facile fabrication of porous magnetic covalent organic frameworks as robust platform for multicomponent reaction
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The design of cheap yet efficient nanoporous magnetic catalysts for the environmentally benign process's widespread application is an extremely attractive, challenging chemical research field. A novel porous magnetic covalent organic framework was prepared by the condensation reaction of melamine and terephthaladehyde on the surface of 3,4-dihydroxybenzaldehyde coated magnetic Fe3O4 nanoparticles COF@Fe3O4 under hydrothermal conditions for the first time. The high surface area magnetic COF could exhibit superior catalytic activity for sustainable synthesis of trisubstituted and tetrasubstituted imidazoles and pyrroles in good to excellent yields in PEG as solvent under environmentally friendly, ambient conditions and making the overall process economical, efficient, and green. The retrievable catalyst in PEG is general and applicable to a broad substrate scope and functional group compatibility. The structure and morphology of the COF@Fe3O4 were characterized by FTIR, XRD, EDX, and SEM spectroscopy. The COF@Fe3O4 magnetic catalyst was recovered by an external magnet and used for several cycles without significant catalytic activity loss.
- Azizi, Najmedin,Heidarzadeh, Fatemeh,Farzaneh, Fezeh
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- Crystalline salicylic acid as an efficient catalyst for ultrafast Paal–Knorr pyrrole synthesis under microwave induction
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Abstract: In this study, the viability of a wide range of crystalline aromatic and aliphatic carboxylic acids as organocatalysts has been investigated for solvent-free Paal–Knorr pyrrole synthesis under microwave activation. Among these potential catalysts, crystalline salicylic acid proved to be a remarkable catalyst because its efficiency remained high even under low microwave power irradiation or a shorter reaction time for the model reaction. The outstanding catalytic activity of salicylic acid allowed the Paal–Knorr cyclocondensation with a turnover frequency up to 1472?h?1 which is unique in the context of a metal-free homogeneous catalysis. The attractive feature of this organocatalyst is its assistance in ultrafast pyrrole synthesis with no risk of metal contamination. Graphic abstract: [Figure not available: see fulltext.] Synopsis: A green and expeditious protocol for the synthesis of 2,5-dimethylpyrroles via combination of salicylic acid as catalyst (in its solid state) and microwaves has been introduced.
- Aghapoor, Kioumars,Mohsenzadeh, Farshid,Darabi, Hossein Reza,Sayahi, Hani
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- Fe3O4@SiO2-PTMS-Guanidine-SA nanoparticles as an effective and reusable catalyst for the synthesis of N-substituted pyrroles
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Fe3O4@SiO2-PTMS-Guanidine-SA nanoparticles used as an effective catalyst for the synthesis of N-substituted pyrroles. Pyrroles were synthesized from the reaction between primary amine derivatives and 2,5-hexanedione with high to excellent yields under mild reaction conditions. After completion of the reaction, Fe3O4@SiO2-PTMS-Guanidine-SA magnetic nanoparticles could be recovered easily from the reaction mixture by an external magnet and reused. This catalyst was characterized by FT-IR spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis and vibrating-sample magnetometry techniques.
- Rostami, Hedieh,Shiri, Lotfi
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p. 1329 - 1335
(2020/01/28)
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- Synthesis, structure and in vitro anti-trypanosomal activity of non-toxic arylpyrrole-based chalcone derivatives
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With an intention of identifying chalcone derivatives exhibiting anti-protozoal activity, a cohort of relatively unexplored arylpyrrole-based chalcone derivatives were synthesized in moderate to good yields. The resultant compounds were evaluated in vitro for their potential activity against a cultured Trypanosoma brucei brucei 427 strain. Several compounds displayed mostly modest in vitro anti-trypanosomal activity with compounds 10e and 10h emerging as active candidates with IC50 values of 4.09 and 5.11 μM, respectively. More importantly, a concomitant assessment of their activity against a human cervix adenocarcinoma (HeLa) cell line revealed that these compounds are non-toxic.
- Hoppe, Heinrich C.,Isaacs, Michelle,Khanye, Setshaba D.,Kruger, Cuan,Oderinlo, Ogunyemi O.,Smith, Vincent J.,Veale, Clinton G. L.,Zulu, Ayanda I.
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supporting information
(2020/04/10)
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- Copper-Catalyzed Selective Pyrrole Functionalization by Carbene Transfer Reaction
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1H-Pyrroles can be directly functionalized by means of the incorporation of carbene groups from diazo compounds, in a process catalyzed by TpxCu complexes (Tpx=hydrotrispyrazolylborate ligand). The reactions take place with a complete selectivity toward the formal insertion of the carbene into the Cα?H bond, leading to alkylated pyrroles, with no modification of the Cβ?H, N?H or C=C bonds of the pyrrole unit. Alkyl substituents at C-ring as well as alkyl, aryl, allyl or alkyne substitution at N atom are tolerated, the strategy affording 20 new pyrrole derivatives. The observance of partial deuteration at the methylene group when the reaction is carried out with added D2O serves to discard the direct insertion of the carbene group into the Csp2?H bond, the alternative electrophilic attack to the pyrrole ring being feasible. (Figure presented.).
- Rodríguez, Anabel M.,Molina, Francisco,Díaz-Requejo, M. Mar,Pérez, Pedro J.
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supporting information
p. 1998 - 2004
(2020/03/04)
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- Synthesis of Pyrrole Derivatives Promoted by Fe(ClO4)3/SiO2 as an Environmentally Friendly Catalyst
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N-Substituted pyrroles have been prepared in high isolated yields (702-99%) by the reaction of hexane-2,5-dione with amines or diamines in the presence of Fe(ClO4)3/SiO2 at ambient temperature under solvent-free conditions. The experimental procedure involves simple operations, and the products are readily separated by short column chromatography. The same reaction of hexane-2,5-dione with amines containing electron-acceptor substituents, such as 4-nitroaniline, resulted in fair yields of pyrrole derivatives.
- Arabpourian,Behbahani
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p. 682 - 685
(2019/07/19)
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- ANDROGEN RECEPTOR ANTAGONISTS
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Compounds that inhibit the androgen receptor, pharmaceutical compositions comprising one or more of the compounds, as well as methods of treating cancer using such compounds are described.
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Paragraph 0566-0568
(2019/08/26)
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- Sustainable Manganese-Catalyzed Solvent-Free Synthesis of Pyrroles from 1,4-Diols and Primary Amines
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A general and selective metal-catalyzed conversion of biomass-derived primary diols and amines to the highly valuable 2,5-unsubstituted pyrroles has been developed. The reaction is catalyzed by a stable nonprecious manganese complex (1 mol %) in the absence of organic solvents whereby water and molecular hydrogen are the only side products. The manganese catalyst shows unprecedented selectivity, avoiding the formation of pyrrolidines, cyclic imides, and lactones.
- Borghs, Jannik C.,Lebedev, Yury,Rueping, Magnus,El-Sepelgy, Osama
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supporting information
p. 70 - 74
(2019/01/11)
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- A New Green and Efficient Br?nsted: Lewis Acidic DES for Pyrrole Synthesis
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Abstract: Deep eutectic solvents (DESs) are fluids composed of different Lewis or Br?nsted acids and bases, generally acknowledged as new analogues to ionic liquids (ILs), because of their similar characteristics, but with more advantages related to preparation cost, environmental impact etc. Their preparation involve the simple mixing of two components generally with moderate heating that are inexpensive, non-toxic, biodegradable and the resulting mixture is capable to overcome the drawbacks of conventional organic solvents and ILs. Chemical reactions with these materials are significantly less hazardous and they can act as catalysts as well as reaction media. Here, three new DESs based on ZrOCl2·8H2O in combination with urea, ethylene glycol and glycerol are introduced. Physicochemical properties like phase behaviour, Freezing point, density, viscosity, thermal stability and miscibility properties in common solvents are determined. In addition, a new method for the determination of acidity of DESs having both Br?nsted and Lewis sites is also introduced in this work. A convenient synthesis of pyrrole through Paal–Knorr reaction is reported using a variety of amines which are used to establish the importance of this catalyst in organic reactions. The products are analysed by GC–MS, 1H NMR and 13C NMR. By comparing the three DESs, DES 1 (formed from ZrOCl2·8H2O with urea) has the lowest density, viscosity, highest acidity and thermal stability. It was shown to be an excellent green catalyst for Paal–Knorr reaction. Reusability of the catalyst was also achieved up to 4 runs, without significant loss in its catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]
- Shaibuna,Theresa, Letcy V.,Sreekumar
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p. 2359 - 2372
(2018/06/20)
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- Bio-based material as medium, mild and reusable catalyst for paal–knorr pyrrole synthesis with and without ultrasonic irradiation
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Background: Pyrrole moiety is found in naturally occurring compounds such as chlorophyll, haem, and vitamin B12 and present in a number of drugs for example atorvastatin, ketorolac, elopiprazole, tolmetin and sunitinib. Various methods have been used for the synthesis of pyrrole derivatives; however, still there is a need for environmentally benign and economic protocol. Method: We have reported a simple, mild and speedy synthesis of N-substituted 2,5-dimethyl pyrrole derivatives in ‘’GAAS’’ as medium and catalyst at room temperature and under ultrasound irradiation. Results: This protocol was employed for the synthesis of various 2,5-dimethyl-N-substituted pyrrole-derivatives using both aliphatic as well as aromatic amines in short time (2 to 10 minutes)with excellent yield (84-95%) at room temperature and under ultrasonic irradiation. The catalytic system “GAAS’’ was regenerated and reused five times effectively without major loss of activity. Conclusion: In conclusion, we have developed an eco-friendly, simple, faster, reusable, mild, and efficient protocol for the synthesis of N-substituted pyrrole derivatives. This bio-based protocol is cost-effective and greener methodology for the synthesis of biologically active N-substituted pyrrole derivatives.
- Sharma, Abha,Kalyani, Illa Siva,Fatima, Anam
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supporting information
p. 226 - 232
(2018/03/09)
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- Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr pyrrole synthesis: a safe, expeditious, and sustainable protocol
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Abstract: Among various alkali (Na, K) and alkaline-earth (Ca, Mg, Sr, Ba) chlorides, calcium(II) chloride was found to be a cost-effective Lewis acid catalyst for solvent-free synthesis of pyrroles from primary aromatic and aliphatic amines under open-vessel focused microwave irradiation. The salient features of this environmentally benign method are high to quantitative conversion, short reaction time, safe and clean reaction profile, possibility of scale-up to multigram quantities, and use of a low-cost, widely available, nontoxic catalyst.
- Aghapoor, Kioumars,Mohsenzadeh, Farshid,Darabi, Hossein Reza,Rastgar, Saeed
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p. 4063 - 4072
(2018/06/19)
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- Direct Synthesis of Pyrroles by Dehydrogenative Coupling of Diols and Amines Catalyzed by Cobalt Pincer Complexes
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Herein, the first example of base-metal-catalyzed dehydrogenative coupling of diols and amines to selectively form functionalized 1,2,5-substituted pyrroles liberating water and hydrogen gas as the sole by-products is presented. The reaction is catalyzed
- Daw, Prosenjit,Chakraborty, Subrata,Garg, Jai Anand,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 14373 - 14377
(2016/11/11)
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- The Paal-Knorr reaction revisited. A catalyst and solvent-free synthesis of underivatized and N-substituted pyrroles
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A new, modified synthesis of pyrroles is described. The reaction of 2,5-hexandione with a variety of amines yielded the expected pyrrole analogues in excellent yields. The reactions were carried out under the ultimate green conditions excluding both catalyst and solvent applying simple stirring at room temperature. The variety of amines include aqueous ammonium hydroxide for the synthesis of pyrroles with a free NH group, and benzylamines, anilines and phenylene-diamines for the synthesis of several N-derivatized pyrroles. The reaction also occurs efficiently with a variety of 1,4-diketones, although the reaction rates and yields are lower for the diketones that do not possess terminal methyl group(s). This journal is
- Cho, Hyejin,Madden, Richard,Nisanci, Bilal,T?r?k, Bla
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p. 1088 - 1099
(2015/03/04)
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- Sulfamic acid heterogenized on functionalized magnetic Fe3O4 nanoparticles with diaminoglyoxime as a green, efficient and reusable catalyst for one-pot synthesis of substituted pyrroles in aqueous phase
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Surface functionalization of magnetic nanoparticles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. We have conveniently loaded sulfonic acid groups on amino-functionalized Fe3O4 nanoparticles affording sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (MNPs/DAG-SO3H) as an active and stable magnetically separable acidic nanocatalyst, which was characterized using X-ray diffraction, Fourier transform infrared and energy-dispersive X-ray spectroscopies, scanning and transmission electron microscopies, vibrating sample magnetometry and elemental analysis. The catalytic activity of MNPs/DAG-SO3H was probed through one-pot synthesis of N-substituted pyrroles from γ-diketones and primary amines in aqueous phase at room temperature. The heterogeneous catalyst could be recovered easily by applying an external magnet device and reused many times without significant loss of its catalytic activity.
- Veisi, Hojat,Mohammadi, Pourya,Gholami, Javad
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p. 868 - 873
(2015/02/19)
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- Hexaalkylguanidinium salts as ionic liquids - Applications in titanium and aluminium alcoholate assisted synthesis
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The solubility of titanium and aluminium alcoholates and of titanium tetrakis(trimethylsilanolate) in several hexaalkylguanidinium-based room temperature ionic liquids was screened. The solvent/solute combinations which displayed the highest alcoholate solubility and stability were applied as Lewis-acidic catalytic media for several dehydrating cyclocondensations: lactamisation of ω-aminocarboxylic acids, direct amidation of carboxylic acids, synthesis of oxazolines from carboxylic acids and 2-aminoethanol, lactonisation of 6-hydroxyhexanoic acid, and Paal-Knorr synthesis of pyrroles.
- Arkhipova, Maria,Eichel, Svetlana,Maas, Gerhard
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p. 56506 - 56517
(2015/02/05)
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- An expeditious and solvent-free synthesis of substituted pyrroles using sulfated anatase-titania as a solid acid catalyst
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Sulfated anatase-titania (TiO2S4 21) has been used as a solid acid catalyst for the synthesis of substituted pyrroles from diketone and aromatic/aliphatic (acyclic and cyclic) primary amines by simple physical grinding. This sulfated titania gives an excellent yield with less reaction time and is an inexpensive, easily recyclable nanocatalytic material for this reaction. Higher catalytic activity of TiO2S 4 21 is due to its increased Broonsted acidity.
- Ravi, Krishnaswamy,Krishnakumar, Balu,Swaminathan, Meenakshisundaram
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p. 370 - 375
(2013/05/08)
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- Efficient synthesis of N-substituted pyrroles catalyzed by a novel an organic-inorganic hybrid solid acid catalyst
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A novel organic-inorganic hybrid solid acid [MIMBS]3PW 12O40 has been successfully prepared. It showed high catalytic activity for N-substituted pyrroles through the cyclocondensation of primary amines with 1,4-dicarbonyl compounds. The solid acid catalyst is stable and can be easily recovered and reused without losing its activity in its efficiency. In addition, a plausible mechanism for the catalytic action of [MIMBS]3PW12O40 has been introduced.
- Gao, Lanchang,Bing, Liu,Zhang, Zehui,Kecheng, Huang,Xiaoyun, Hu,Deng, Kejian
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- Xanthan sulfuric acid as an efficient, green, biodegradable, and recyclable solid acid catalyst for one-pot synthesis of N-substituted pyrroles under solvent-free conditions at room temperature
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A new, green, and efficient method for synthesis of a variety of N-substituted pyrroles from condensation reactions of 2,5-hexanedione with amines or diamines using xanthan sulfuric acid as a biosupported and reusable ecofriendly catalyst under solvent-free conditions at room temperature is described. The use of a nontoxic, inexpensive, easily available, and reusable biosupported proton source catalyst under solvent-free conditions makes this protocol practical, environmentally friendly, and economically attractive.
- Rahmatpour, Ali
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experimental part
p. 491 - 495
(2012/06/16)
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- Polystyrene-supported GaCl3 as a highly efficient and recyclable heterogeneous Lewis acid catalyst for one-pot synthesis of N-substituted pyrroles
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A new and environmentally benign method for the preparation of N-substituted pyrroles from one-pot condensation reaction of 2,5-hexanedione with amines and diamines in the presence of polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid catalyst is presented. This new protocol has the advantages of easy availability, stability, reusability and eco-friendly of the catalyst, high to excellent yields, simple experimental and work-up procedure.
- Rahmatpour, Ali
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experimental part
p. 15 - 19
(2012/07/03)
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- Cellulose sulfuric acid as a biodegradable and recoverable solid acid catalyst for one pot synthesis of substituted pyrroles under solvent-free conditions at room temperature
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A new and efficient method for the preparation of N-substituted pyrroles from one-pot condensation reaction of 2,5-hexandione with amines and diamines in the presence of cellulose sulfuric acid (CSA) as a bio-supported catalyst at room temperature under solvent-free conditions is presented. This new protocol has the advantages of easy availability, stability, reusability and eco-friendly of the catalyst, high to excellent yields, simple experimental and work-up procedure.
- Rahmatpour, Ali
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experimental part
p. 80 - 83
(2012/01/12)
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- ZrOCl2·8H2O as a highly efficient, eco-friendly and recyclable Lewis acid catalyst for one-pot synthesis of N-substituted pyrroles under solvent-free conditions at room temperature
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A new and efficient method for the synthesis of a variety of N-substituted pyrroles from condensation reactions of 2,5-hexanedione with amines or diamines using ZrOCl2·8H2O as a water-tolerant Lewis acid catalyst at room temperature is described.The use of nontoxic, inexpensive, easily available and reusable catalyst under solvent-free conditions make this protocol practical, environmentally friendly and economically attractive.
- Rahmatpour, Ali
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experimental part
p. 585 - 590
(2011/10/18)
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- One-pot synthesis of N-substituted pyrroles catalyzed by polystyrene-supported aluminum chloride as a reusable heterogeneous Lewis acid catalyst
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A convenient and efficient procedure is presented for the one-pot synthesis of N-substituted pyrroles by condensation of 2,5-hexandione and amines or diamines in the presence of cross-linked polystyrene-supported aluminum chloride (PS/AlCl3) as a highly active and reusable heterogeneous Lewis acid catalyst. This polymeric solid acid catalyst is stable and can be easily recovered and reused without appreciable change in its efficiency.
- Rahmatpour, Ali,Aalaie, Jamal
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experimental part
p. 85 - 90
(2011/10/09)
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- Sulfamic acid as efficient and reusable catalytic system for the synthesis of pyrrole, furan, and thiophene derivatives
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Sulfamic acid has been utilized for the first time as an efficient and reusable catalytic system for the synthesis of heteroaromatics such as pyrrole, furan, and thiophene derivatives from 1,4-diketones. This new procedure offers significant improvements in the reaction rates and yields in a shorter reaction time and a lower reaction temperature contrasted with the reported results. The recovered catalyst can be reused for subsequent runs with only a gradual decrease in activity. The most important feature is that the reaction process is homogeneous whereas the separation process is heterogeneous, which is often seen in other catalysts, and so it is a good character for technical application.
- Luo, Haitang,Kang, Yuru,Li, Qi,Yang, Liming
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p. 144 - 148
(2008/09/18)
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- Zinc tetrafluoroborate-catalysed synthesis of highly substituted pyrroles by a solvent-free reaction
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A simple and highly efficient synthesis of penta- and tri-substituted pyrroles has been developed using the Paal-Knorr reaction catalysed by aqueous zinc tetrafluoroborate at room temperature under solvent-free conditions.
- Ranu, Brindaban C.,Ghosh, Sudip,Das, Arijit
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p. 220 - 221
(2007/10/03)
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- Fe3+-montmorillonite as effective, recyclable catalyst for Paal-Knorr pyrrole synthesis under mild conditions
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Fe3+-montmorillonite clay catalyst was used for the first time for pyrroles preparation by Paal-Knorr condensation. The features of this catalytic system are improved yields, mild conditions, a simple procedure, and high catalytic efficiency. The catalyst could be easily recycled and reused for three times without visible losing of activity. Copyright Taylor & Francis, Inc.
- Song, Guoyong,Wang, Bo,Wang, Guang,Kang, Yuru,Yang, Tao,Yang, Liming
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p. 1051 - 1057
(2007/10/03)
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- Pyrrole synthesis in ionic liquids by Paal-Knorr condensation under mild conditions
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Paal-Knorr condensation of 2,5-hexandione with primary amines was successfully carried out in ionic liquids. Through investigating different ionic liquids, different reaction times, the reaction, using ionic liquids as solvent, exhibited simple product isolation procedure, improved yields and exclusive selectivity and the mild conditions and the avoidance of using toxic catalysts are also its special features. Recovery and reuse of ionic liquid are also satisfactory.
- Wang, Bo,Gu, Yanlong,Luo, Cheng,Yang, Tao,Yang, Liming,Suo, Jishuan
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p. 3417 - 3419
(2007/10/03)
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- Layered zirconium phosphate and phosphonate as heterogeneous catalyst in the preparation of pyrroles
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Pyrroles may be prepared by condensation of alkyl and aryl amines and 1,4-diketones (Paal-Knorr reaction) under potassium exchanged layered Zirconium phosphate and zirconium sulfophenyl phosphonate catalyst in solvent free conditions.
- Curini, Massimo,Montanari, Francesca,Rosati, Ornelio,Lioy, Eduardo,Margarita, Roberto
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p. 3923 - 3925
(2007/10/03)
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- Synthesis of alkyl-substituted pyrroles by three-component coupling of carbonyl compound, amine and nitro-alkane/alkene on a solid surface of silica gel/alumina under microwave irradiation
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Efficient synthesis of highly substituted alkylpyrroles and fused pyrroles has been achieved by a three-component coupling of (a) α,β-unsaturated aldehyde/ketone, amine and nitroalkane and (b) α,β-unsaturated nitroalkene, aldehyde/ketone and amine on the surface of silica gel and alumina without any solvent under microwave irradiation.
- Ranu, Brindaban C,Hajra, Alakananda
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p. 4767 - 4773
(2007/10/03)
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- Microwave-assisted synthesis of substituted pyrroles by a three- component coupling of α,β-unsaturated carbonyl compounds, amines and nitroalkanes on the surface of silica gel
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An improved procedure has been developed for the synthesis of highly substituted pyrroles through a simple one-pot reaction of α,β-unsaturated aldehydes/ketones, amines and nitroalkanes on the surface of silica gel without any solvent under microwave irradiation.
- Ranu, Brindaban C.,Hajra, Alakananda,Jana, Umasish
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