- 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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- 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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- 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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- An expeditious and highly efficient synthesis of substituted pyrroles using a low melting deep eutectic mixture
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An expeditious green method for the synthesis of diverse valued substituted pyrroles through a Paal-Knorr condensation reaction, using a variety of amines and 2,5-hexanedione/2,5-dimethoxytetrahydrofuran in the presence of a low melting mixture ofN,N’-dimethylurea andL-(+)-tartaric acid (which acts as a dual catalyst/solvent system), has fruitfully been revealed. Herein, we have disclosed the applicability of this simple yet effective strategy for the generation of mono- and dipyrroles in good to excellent yields. Moreover,C3-symmetric tripyrrolo-truxene derivatives have also been assembled by means of cyclotrimerization, Paal-Knorr and Clauson-Kaas reactions as crucial steps. Interestingly, the melting mixture was recovered and reused with only a gradual decrease in the catalytic activity (over four cycles) without any significant drop in the yield of the product. This particular methodology is simple, rapid, environmental friendly, and high yielding for the generation of a variety of pyrroles. To the best of our knowledge, the present work reveals the fastest greener method reported up to this date for the construction of substituted pyrroles by utilizing the Paal-Knorr synthetic protocol, achieving impressive yields under operationally simple reaction conditions without involving any precarious/dangerous catalysts or unsafe volatile organic solvents.
- Alvi, Shakeel,Ali, Rashid
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p. 9732 - 9745
(2021/12/01)
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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
-
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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- 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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- 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)
-
- Naturally occurring organic acids for organocatalytic synthesis of pyrroles via Paal–Knorr reaction
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Abstract: In this study, common naturally occurring organic acids, namely oxalic, malonic, succinic, tartaric and citric acid (as safe, inexpensive, and biodegradable organocatalysts), have been employed for Paal–Knorr pyrrole synthesis. The organocatalyzed reaction proved to be effective in ethanol at 60?°C. However, the reaction rate is mainly dominated by the nature and position of functional groups on the aromatic ring of substrate. This metal-free procedure tolerates a series of functional groups and should be considered as an asset to the pharmaceutical industry since no metal contamination could take place during the synthesis of pyrrole scaffolds. Graphic abstract: [Figure not available: see fulltext.].
- Mohsenzadeh, Farshid,Darabi, Hossein Reza,Alivand, Mahsa,Aghapoor, Kioumars,Balavar, Yadollah
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p. 5255 - 5262
(2020/09/09)
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- A mild and efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst under solvent-free sonication
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A highly efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst has been developed under solvent-free sonication. This reaction has a broad substrate scope and high yields were obtained within a short reaction time. Remarkably, no additional additives and volatile organic solvent are required for this method and the MIL-53(Al) could be recovered and reused several times without significant drop-off in catalytic activity.
- Nguyen, Hai Truong,Thuy Nguyen, Linh Ho,Le Hoang Doan, Tan,Tran, Phuong Hoang
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p. 9093 - 9098
(2019/03/28)
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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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- 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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- 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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- 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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- New nano-Fe3O4-supported Lewis acidic ionic liquid as a highly effective and recyclable catalyst for the preparation of benzoxanthenes and pyrroles under solvent-free sonication
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A novel magnetic nanomaterial-immobilized Lewis acidic ionic liquid was successfully synthesized by the covalent embedding of 3-(3-(trimethoxysilyl)propyl)-1H-imidazol-3-ium chlorozincate (ii) ionic liquid to the surface of Fe3O4 nanoparticles. The material was then characterized by FT-IR, SEM, TEM, TGA, ICP-OES, Raman, and EDS. Its performance as a new-generation Lewis acidic catalyst was also examined on the ultrasound-mediated synthesis of benzoxanthenes and pyrroles. Upon completion, the catalyst was simply recovered by an external magnet for multiple reuses without significant lessening of catalytic performance.
- Nguyen, Hai Truong,Thi Le, Ngoc-Phuong,Nguyen Chau, Duy-Khiem,Tran, Phuong Hoang
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p. 35681 - 35688
(2018/10/31)
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- Direct Synthesis of Pyrroles via Heterogeneous Catalytic Condensation of Anilines with Bioderived Furans
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Given the wide applications of pyrroles in agriculture, pharmaceuticals, and supramolecular and materials chemistry, a mild and eco-friendly route to produce functionalized pyrroles from bioderived feedstocks is highly desirable. Described herein is a mild and convenient synthesis of pyrroles via direct condensation of an equimolar amount of structurally diverse anilines with biobased furans catalyzed by a simple and efficient solid acid H form zeolite Y catalyst. The protocol tolerates a large variety of functional groups and offers a general and versatile method for scale-up synthesis of a variety of N-substituted pyrrole compounds. Most importantly, the bioactive pyrrole-derived drug pyrvinium, which has lately been confirmed as highly effective in curing colon cancer, can be obtained by this method.
- Tao, Lei,Wang, Zi-Jian,Yan, Tian-Hao,Liu, Yong-Mei,He, He-Yong,Cao, Yong
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p. 959 - 964
(2017/08/09)
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- A green and efficient method for the synthesis of pyrroles using a deep eutectic solvent ([CholineCl][ZnCl2]3) under solvent-free sonication
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An efficient deep eutectic solvent-based synthesis of pyrroles under ultrasound irradiation has been developed to provide a significant improvement of the yield up to 99% in a short reaction time. The synthesis of pyrroles is highly atom-economical, producing water as the sole byproduct. In addition, [CholineCl][ZnCl2]3 is easily synthesized from commercially available choline chloride and zinc chloride via a cost-effective and environmentally benign pathway. The obtained [CholineCl][ZnCl2]3 has been characterized by FT-IR, 1H-NMR, 13C-NMR, HRMS (ESI), Raman, and TGA. Five new pyrroles are synthesized by the current method. Moreover, [CholineCl][ZnCl2]3 could be reused up to four times without significant loss of catalytic activity.
- Truong Nguyen, Hai,Nguyen Chau, Duy-Khiem,Tran, Phuong Hoang
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p. 12481 - 12489
(2017/11/06)
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- L-Tryptophan-catalyzed Paal-Knorr pyrrole cyclocondensation: An efficient, clean and recyclable organocatalyst
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A simple, clean, and efficient solvent-free protocol is introduced for Paal-Knorr pyrrole synthesis catalyzed by l-tryptophan as a thermally resistant, natural primary amino acid. The products were obtained mostly in excellent yields through the reaction of hexane-2,5-dione with aromatic primary amines bearing a variety of substituents. The catalyst could be easily isolated from the reaction mixture and recycled at least six times without significant loss of activity. The procedure has an environmentally benign nature in agreement with the concepts of green chemistry.
- Aghapoor, Kioumars,Mohsenzadeh, Farshid,Darabi, Hossein Reza,Sayahi, Hani,Balavar, Yadollah
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p. 407 - 415
(2016/04/26)
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- Design and development of pyrrole carbaldehyde: An effective pharmacophore for enoyl-ACP reductase
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Enoyl-ACP reductase is the key enzyme involved in FAS-II synthesis of mycolic acid in bacterial cell wall and is a promising target for discovering new chemical entity. The designed pharmacophores are the possible better tools to combat mutation in enoyl-ACP enzyme, which leads to a decrease in volume of triclosan binding site. Compound 3a showed H-bonding interactions similar to that of triclosan with enoyl-ACP enzyme and with a better docking score (C score 8.81), while the compound 3f showed additional interaction with MET98.H amino acid residue. The 3D-QSAR computations also support the docking study to develop novel pyrrole-based derivatives. Graphical abstract: Molecular docking 3D-QSAR studies and synthesis of active analogs of pyrrole carbaldehyde as better receptor fit pharmacophore for enoyl-ACP reductase along with in vitro antitubercular activity. (Figure Presented).
- Joshi, Shrinivas D.,Kumar, Devendra,More, Uttam A.,Yang, Kap Seung,Aminabhavi, Tejraj M.
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p. 672 - 689
(2016/03/08)
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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
-
supporting information
p. 5215 - 5218
(2016/11/11)
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- Synthesis of two distinct pyrrole moiety-containing arenes from nitroanilines using Paal-Knorr followed by an indium-mediated reaction
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Synthesis of arenes substituted with two differently substituted-pyrrole moieties was investigated. A Paal-Knorr condensation reaction of nitroanilines with 1,4-diketone to nitrophenyl-1H-pyrroles followed by an indium-mediated reduction-triggered coupling reaction with another kind of 1,4-diketone resulted in two distinct pyrrole-containing arenes, variously substituted 1-((1H-pyrrol-1-yl)phenyl)-1H-pyrroles, in reasonable yield.
- Kim, Byeong Hyo,Bae, Seolhee,Go, Ahra,Lee, Hyunseung,Gong, Cheoloh,Lee, Byung Min
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p. 265 - 276
(2015/12/30)
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- 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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p. 475 - 481
(2015/08/06)
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- A convenient one-pot synthesis of polysubstituted pyrroles from N-protected succinimides
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The dienamine products formed by the reaction between polysubstituted succinimides and the Petasis reagent were subjected to isomerization under mild acidic conditions to give polysubstituted pyrroles in excellent yields (85-95%). The scope and limitations of this methodology are explored.
- Kobeissi, Marwan,Yazbeck, Ogaritte,Chreim, Yamama
-
supporting information
p. 2523 - 2526
(2014/05/06)
-
- An efficient synthesis of N-substituted pyrroles catalyzed by MgI2 etherate
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We describe a convenient and useful procedure for the synthesis of various 2,5-dimethyl-N-substituted pyrrole derivatives by the addition of 2,5-hexadione with aromatic amines, heteroaromatic amines and aliphatic amines catalyzed by MgI2 etherate (MgI2·(OEt2)n) in good to excellent yields.
- Zhang, Yongdong,Weng, Guodong,Chen, Jingyan,Ma, Danting,Zhang, Xingxian
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p. 131 - 135
(2015/02/19)
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- Organic synthesis in deep eutectic solvents: Paal-Knorr reactions
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Deep eutectic solvents (the combination of either urea or glycerol with choline chloride) are effective solvents/catalysts for Paal-Knorr reactions to form pyrroles of furans. The reaction conditions are quite mild and do not require the addition of an additional Bronsted or Lewis acid catalyst. Given the inexpensive, non-toxic, and recyclable nature of the DES, these reaction conditions are simple and highly environmentally friendly.
- Handy, Scott,Lavender, Kevin
-
supporting information
p. 4377 - 4379
(2013/07/26)
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- 1-Methylimidazolium hydrogen sulfate catalyzed convenient synthesis of 2,5-dimethyl-N-substituted pyrroles under ultrasonic irradiation
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Ionic liquid [HMIM]HSO4 was found to be an efficient catalyst for the synthesis of N-substituted pyrroles through the reaction of 2,5-hexanedione with amines under ultrasonic irradiation at room temperature. These reactions proceed with good yields under short reaction time. Furthermore, the green catalytic system can be recycled specific times with no decreases in yields and reaction rates.
- Li, Daqing,Zang, Hongjun,Wu, Changchun,Yu, Nianqin
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p. 1144 - 1148
(2013/06/27)
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- Modified Paal-Knorr synthesis of novel and known pyrroles using tungstate sulfuric acid as a recyclable catalyst
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Tungstate sulfuric acid (TSA) as a solid acid catalyst has been synthesized and used in Paal-Knorr synthesis of some novel and known pyrroles under solvent-free conditions. Catalyst loadings can be as low as 1 mol percent to give high yields of the corresponding pyrroles at 60 °C. To make the catalyst, sodium tungstic reacted with chlorosulfonic acid in nhexane.
- Karami, Bahador,Jamshidi, Masih,Khodabakhshi, Saeed
-
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- Green and rapid strategy for synthesis of novel and known pyrroles by the use of molybdate sulfuric acid
-
Molybdate sulfuric acid as a highly efficient catalyst has been employed for the modified Paal-Knorr synthesis of some novel and known pyrroles under solvent-free conditions. Catalyst loads as low as 1 mol % could be used leading to high yields of pure pyrrole derivatives at an oil bath temperature of 60 oC. This method has advantages such as the use of very low amounts of a recyclable catalyst, avoidance of organic solvents, and high product yields.
- Karami, Bahado,Khodabakhshi, Saeed,Jamshidi, Masih
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p. 1103 - 1106
(2013/10/22)
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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
-
-
- One-pot green synthesis of pyrrole derivatives catalyzed by nano sulfated zirconia as a solid acid catalyst
-
A new and efficient method for the preparation of N-substituted pyrroles from one-pot Paal-Knorr condensation has been accomplished using nano-crystalline sulfated zirconia (SZ) as the catalyst in ethanol at moderate temperature. This new protocol has the advantages of easy availability, stability, reusability and eco-friendliness of the catalyst, high to excellent yields, simple experimental and work-up procedure. The synthesized compounds were confirmed through spectral characterization using IR, 1H NMR, 13C NMR and mass spectra. A new and efficient method for the preparation of N-substituted pyrroles from one-pot Paal-Knorr condensation has been accomplished using nano-crystalline sulfated zirconia (SZ) as the catalyst in ethanol at moderate temperature. This new protocol has the advantages of easy availability, stability, reusability and eco-friendliness of the catalyst, high to excellent yields, simple experimental and work-up procedure. Copyright
- Teimouri, Abbas,Chermahini, Alireza Najafi
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experimental part
p. 372 - 376
(2012/04/23)
-
- 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
-
experimental part
p. 491 - 495
(2012/06/16)
-
- 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
-
experimental part
p. 15 - 19
(2012/07/03)
-
- Silica-supported bismuth(III) chloride as a new recyclable heterogeneous catalyst for the Paal-Knorr pyrrole synthesis
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Silica-supported bismuth(III) chloride (BiCl3/SiO2) acts as as a highly efficient heterogeneous Lewis acid catalyst for the Paal-Knorr pyrrole synthesis in hexane at room temperature. The catalyst exhibited remarkable reusable activity and higher catalytic performance than homogeneous BiCl3. A plausible mechanism for the catalytic action of BiCl3/SiO2 has been introduced.
- Aghapoor, Kioumars,Ebadi-Nia, Leila,Mohsenzadeh, Farshid,Mohebi Morad, Mina,Balavar, Yadollah,Darabi, Hossein Reza
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experimental part
p. 25 - 30
(2012/05/20)
-
- Ultrasound-assisted synthesis of 2,5-dimethyl-N-substituted pyrroles catalyzed by uranyl nitrate hexahydrate
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An efficient synthesis of different novel 2,5-dimethyl-N-substituted pyrrole derivatives by the Paal-Knorr condensation has been accomplished using uranyl nitrate hexahydrate as catalyst under soft conditions and ultrasonic irradiation. The synthesized compounds were confirmed through spectral characterization using IR, 1H NMR, 13C NMR and mass spectra.
- Satyanarayana,Sivakumar
-
experimental part
p. 917 - 922
(2012/03/08)
-
- 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
-
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
-
experimental part
p. 585 - 590
(2011/10/18)
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- Catalytic applications of nano β-PbO in Paal-Knorr reaction
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Several 2,5-dimethyl-N-substituted pyrroles were prepared by the condensation of different substituted anilines with 2,5-hexanedione using nano lead oxide as an efficient and recyclable catalyst. All the synthesized compounds are confirmed through IR, 1H NMR, 13C NMR and mass spectral data. Nano lead oxide β-PbO (P85) was prepared by dissolving lead acetate dihydrate in 1-propanol at a pH 9.0 under stirring at 85 °C. The structural study and surface morphology of the lead oxide (PbO) were characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM) and the functional groups of the PbO sample were investigated using infrared spectrophotometer.
- Pasha, Sk. Khadeer,Satyanarayana,Sivakumar,Chidambaram,Kennedy, L. John
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experimental part
p. 891 - 894
(2012/01/07)
-
- 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
-
experimental part
p. 80 - 83
(2012/01/12)
-
- One-pot synthesis of N-substituted pyrroles catalyzed by polystyrene-supported aluminum chloride as a reusable heterogeneous Lewis acid catalyst
-
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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- Approach to synthesis of Β-enamino ketones and pyrroles catalyzed by gallium(III) triflate under solvent-free conditions
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Metal triflates have been used to catalyze synthesis of-enamino ketones or pyrroles from amines and 1,3-dicarbonyl or 1,4-dicarbonyl compounds under solvent-free conditions, respectively. Among different metal triflates screened, 0.5mol% Ga(OTf)3 efficiently promoted the reactions to give excellent yields. In addition, the catalyst could be recovered easily after the reactions and reused without evident loss in activity.
- Chen, Jiuxi,Yang, Xiaoliang,Liu, Miaochang,Wu, Huayue,Ding, Jinchang,Su, Weike
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experimental part
p. 4180 - 4198
(2010/01/15)
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- Cobalt(ll) chloride as a novel and efficient catalyst for the synthesis of 1,2,5-trisubstituted pyrroles under solvent-free conditions
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CoCl2 is used as an efficient catalyst in the Paal-Knorr condensation of 2,5-hexadione with primary amines under solvent-free conditions, leading to the formation of pyrrole derivatives in excellent yield. This method is very easy, rapid, and high yielding reaction for the synthesis N-substituted pyrrole derivatives.
- De, Surya K.
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p. 592 - 595
(2008/12/22)
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- Sulfamic acid as a novel, efficient, cost-effective, and reusable solid acid catalyst for the synthesis of pyrroles under solvent-free conditions
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Paal-Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of sulfamic acid under solvent-free conditions has been accomplished with an excellent yield. This is a very easy, rapid, and high-yielding reaction for the synthesis N-substituted pyrrole derivatives. Copyright Taylor & Francis Group, LLC.
- De, Surya K.
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p. 803 - 809
(2008/09/16)
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- Simple synthesis of pyrroles under solvent-free conditions
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Paal-Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of praseodymium(III) trifluoromethanesulfonate under solvent-free conditions has been accomplished with an excellent yield. This method is a very easy, rapid, and high-yielding reaction for the synthesis of N-substituted pyrrole derivatives. Copyright Taylor & Francis Group, LLC.
- De, Surya K.
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scheme or table
p. 2768 - 2774
(2009/04/11)
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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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- An approach to the Paal-Knorr pyrroles synthesis catalyzed by Sc(OTf)3 under solvent-free conditions
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A facile synthesis of N-substituted pyrroles by the Paal-Knorr condensation has been accomplished using a simple procedure. Among different metal triflates screened, 1 mol % Sc(OTf)3 efficiently promoted the reaction to give excellent yield (89-98%) under mild reaction conditions. Additionally, Sc(OTf)3 could be recovered easily after the reactions and reused without evident loss in activity.
- Chen, Jiuxi,Wu, Huayue,Zheng, Zhiguo,Jin, Can,Zhang, Xingxian,Su, Weike
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p. 5383 - 5387
(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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