- 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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- 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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- Spectroscopic Study of Some New N-Aryl Pyrroles
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A series of new 2,5-dimethyl-N-substituted pyrroles (I) were obtained by condensation of 2,5-hexanedione with different amines.The UV data show that about 11.7percent of the total electronic density of the nitrogen of pyrrole ring is conjugated with the aryl group.A correlation between the UV and NMR results has been established, and the mass spectra of these derivatives have also been measured and discussed.
- Saeed, Ali A. H.
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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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- 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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- 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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- Grinding solvent-free paal-knorr pyrrole synthesis on smectites as recyclable and green catalysts
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An environmentally benign method for the synthesis of N-substituted pyrroles from one-pot solvent-free condensation reaction of 2,5-hexanedione with various primary amines (Paal-Knorr pyrrole synthesis) on smectite clays as green and reusable heterogeneous Lewis acid catalysts is presented. The use of nontoxic, inexpensive, easily available and reusable catalysts under solvent-free conditions make this protocol practical, environmentally friendly and economically attractive.
- Marvi, Omid,Nahzomi, Hossein Taherpour
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p. 139 - 147
(2018/04/23)
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- Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium
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The synthesis of N-heteroaromatic compounds via an acceptorless dehydrogenative coupling process involving direct use of ammonia as the nitrogen source was explored. We report the synthesis of pyrazine derivatives from 1,2-diols and the synthesis of N-substituted pyrroles by a multicomponent dehydrogenative coupling of 1,4-diols and primary alcohols with ammonia. The acridine-based Ru-pincer complex 1 is an effective catalyst for these transformations, in which the acridine backbone is converted to an anionic dearomatized PNP-pincer ligand framework.
- Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 11931 - 11934
(2018/09/27)
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- One-pot synthesis of: N -substituted pyrroles from nitro compounds and 2,5-hexadione over a heterogeneous cobalt catalyst
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In this study, the one-pot heterocyclization of nitro compounds with 2,5-hexadione was studied for the synthesis of N-substituted pyrroles via a Paal-Knorr condensation process. The heterogeneous cobalt-nitrogen catalyst (Co-Nx/C-800-AT) was found to be active for this reaction with formic acid. Formic acid served as a hydrogen donor for the transfer hydrogenation, and also acted as an acid catalyst. More importantly, this method was tolerant of other functional groups, and hence various N-substituted pyrroles were produced with good to excellent yields. The Co-Nx/C-800-AT catalyst was highly stable, and could be reused several times without loss of its catalytic activity.
- Gong, Zheng,Lei, Yu,Zhou, Peng,Zhang, Zehui
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p. 10613 - 10618
(2017/10/05)
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- Efficient synthesis of substituted pyrroles through Pd(OCOCF3)2-catalyzed reaction of 5-hexen-2-one with primary amines
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An efficient and facile Pd(OCOCF3)2-catalyzed one-pot cascade protocol has been developed for the synthesis of multiple substituted pyrroles in good to excellent yields. Unlike the reported method starting from the 2-alkenal-1,3-carbonyl compounds, the process utilizes the less reactive 5-hexen-2-one and the method has great potential as a complement to the current developed methods.
- Chen, Xi,Yang, Meng,Zhou, Min
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supporting information
p. 5215 - 5218
(2016/11/11)
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- Paal-knorr pyrrole synthesis in water
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Water was a suitable medium for Paal-Knorr pyrrole cyclocondensation. Hexa-2,5-dione was reacted with several aliphatic and aromatic primary amines, affording N-substituted 2,5-dimethyl pyrrole derivatives in good to excellent yields. An efficient, green method using water either as environmentally friendly solvent or catalyst was presented.
- Akbaslar, Dilek,Demirkol, Onur,Giray, Sultan
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supporting information
p. 1323 - 1332
(2014/04/17)
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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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- 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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- Simple, efficient and convenient synthesis of pyrroles and pyrazoles using zeolites
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A convenient heterogeneous catalytic methodology for the synthesis of Pyrroles and Pyrazoles by an intermolecular reaction of γ or β-diketones with primary amines or hydrazine derivatives over zeolites are described.
- Sreekumar,Padmakumar, Raghavakaimal
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p. 1661 - 1665
(2007/10/03)
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- Pyrrole and Pyrazole Ring Closure in Heterogeneous Media
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Pyrroles and pyrazoles may be conveniently prepared by dispersing primary amines or hydrazines and 1,4- or 1,3-diketones, respectively, on alumina or clay (montmorillonite K 10) without solvent, keeping the mixture at 20 deg C or higher temperatures for 1-26 h, and then eluting the product with dichloromethane.
- Texier-Boullet, F.,Klein, B.,Hamelin, J.
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p. 409 - 411
(2007/10/02)
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- Conformational Effects in Fluorescent Excited Charge-transfer Complex Formation
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From a study if the variation in fluorescence quantum yield and lifetime with change in solvent polarity for some ω-(1-naphthyl)-N-alkylpyrroles it is concluded that the conformation of the excited complex has little effect upon the wavelength of fluorescence but does have an effect upon the relative efficiencies of the radiative and non-radiative decay processes.
- Luo, Xiu-Jin,Beddard, Godfrey S.,Porter, George,Davidson, R. Stephen,Whelan, Terence D.
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p. 3467 - 3476
(2007/10/02)
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