- 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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- 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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- 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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- 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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- Method for preparing N-aryl pyrrole compound
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The present invention relates to a method for preparing an N-aryl pyrrole compound. Furan containing different substituents, aromatic amine containing different substituents and a solid Lewis acid catalyst are mixed and placed in a closed reactor, and an N-aryl pyrrole compound with different substituents is prepared under certain catalytic conditions. The reaction temperature of the catalytic reaction condition is 140-210 DEG C. The solid Lewis acid catalyst is prepared by a sol-gel method, Hf is used as a core metal element, and a mesoporous molecular sieve SBA-15 is used as a carrier. According to the method, the catalyst is simple to prepare, low in cost, high in reaction activity, good in water resistance and structural stability and high in catalytic reaction yield; meanwhile, the Lewis acid type catalyst does not generate acid protons, the corrosion of the catalyst to equipment at high temperature is avoided, the post-reaction treatment is convenient, and the catalyst is renewable and environment-friendly.
- -
-
Paragraph 0021-0043; 0045
(2020/09/09)
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- Superbase-promoted multi-molecular acetylene/arylamine self-organization to 1-arylpyrroles
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A new superbase-promoted reaction of acetylene involves self-organization of its three molecules with one molecule of arylamine in KOH/DMSO system to afford 1-aryl-2,5- dimethylpyrroles in up to 63% yields. The key step of this reaction cascade is assumed to be the nucleophilic addition of acetylene to the C = N bond of the intermediate aldimine (aza-Favorsky reaction).
- Schmidt, Elena Yu.,Semenova, Nadezhda V.,Ivanova, Elena V.,Bidusenko, Ivan A.,Trofimov, Boris A.
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p. 109 - 111
(2020/02/29)
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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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- 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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- 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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- 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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- Novel and highly efficient preparation of pyrroles using supported ionic liquid ILCF3SO3@SiO2 as a heterogeneous catalyst
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Abstract: A supported ionic liquid ILCF3SO3@SiO2 was synthesized and used as a highly efficient catalyst in the Paal–Knorr reaction for the preparation of pyrroles. The heterogeneous catalyst could be easily recovered and recycled for five times without noticeable loss of catalytic activity. Also a possible reaction mechanism is provided.
- Liu, Yang,Hu, Yu Lin
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p. 1033 - 1040
(2018/05/22)
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- Synthesis and Properties of N-Arylpyrrole-Functionalized Poly(1-hexene- alt-CO)
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The 1,4-polyketone derived from 1-hexene and carbon monoxide, poly(1-hexene-alt-CO) (1), can undergo Paal-Knorr cyclization with substituted anilines to yield N-pyrrole-functionalized polyketones. A variety of pendant functionalities are introduced to 1,
- Samples, Evan M.,Schuck, Jeremy M.,Joshi, Padmanabh B.,Willets, Katherine A.,Dobereiner, Graham E.
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p. 9323 - 9332
(2018/11/27)
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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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- Design, Synthesis, and Evaluation of Thiazolidine-2,4-dione Derivatives as a Novel Class of Glutaminase Inhibitors
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Humans have two glutaminase genes, GLS (GLS1) and GLS2, each of which has two alternative transcripts: the kidney isoform (KGA) and glutaminase C (GAC) for GLS, and the liver isoform (LGA) and glutaminase B (GAB) for GLS2. Initial hit compound (Z)-5-((1-(
- Yeh, Teng-Kuang,Kuo, Ching-Chuan,Lee, Yue-Zhi,Ke, Yi-Yu,Chu, Kuang-Feng,Hsu, Hsing-Yu,Chang, Hsin-Yu,Liu, Yu-Wei,Song, Jen-Shin,Yang, Cheng-Wei,Lin, Li-Mei,Sun, Manwu,Wu, Szu-Huei,Kuo, Po-Chu,Shih, Chuan,Chen, Chiung-Tong,Tsou, Lun Kelvin,Lee, Shiow-Ju
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p. 5599 - 5612
(2017/07/22)
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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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- 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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- Cyclodextrin-based PNN supramolecular assemblies: a new class of pincer-type ligands for aqueous organometallic catalysis
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Water-soluble cyclodextrins (CDs) bearing two nitrogen atoms as metal coordinating sites have been synthesized. An appropriate phosphane could be included within their cavity through the primary face to form self-assembled PNN supramolecular edifices. Once the PNN ligands were coordinated to platinum, the resulting complexes proved to be very effective as catalysts in a domino reaction, where a Pt-catalyzed reduction of nitrobenzene was followed by a Paal-Knorr pyrrole reaction. In the nitrobenzene reduction, the modified CDs acted both as first- and second-sphere ligands. Contrary to an acyclic glucopyranose-based NN ligand unable to interact with a phosphane ligand, the CD-based PNN ligands stabilized the catalytic species in water by supramolecular means. Interestingly, the product and the water-soluble Pt-catalyst could be recovered in two different phases once the reaction was complete.
- Menuel,Bertaut,Monflier,Hapiot
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p. 13504 - 13512
(2015/08/03)
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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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- The application of iron (III) phosphate in the synthesis of N-substituted pyrroles
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A variety of N-substituted pyrroles have been prepared by reacting 2,5-hexadione with amines or diamines in the presence of iron (III) phosphate at room temperature under solvent-free conditions. The experiment protocol features simple operations, and the products are isolated in high yields (88-99%).
- Samadi, Marjan,Behbahani, Farahnaz K.
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p. 2881 - 2884
(2015/11/03)
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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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- Discovery and optimisation studies of antimalarial phenotypic hits
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There is an urgent need for the development of new antimalarial compounds. As a result of a phenotypic screen, several compounds with potent activity against the parasite Plasmodium falciparum were identified. Characterization of these compounds is discussed, along with approaches to optimise the physicochemical properties. The in vitro antimalarial activity of these compounds against P. falciparum K1 had EC50 values in the range of 0.09e29 mM, and generally good selectivity (typically >100-fold) compared to a mammalian cell line (L6). One example showed no significant activity against a rodent model of malaria, and more work is needed to optimise these compounds.
- Mital, Alka,Murugesan, Dinakaran,Kaiser, Marcel,Yeates, Clive,Gilbert, Ian H.
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supporting information
p. 530 - 538
(2015/10/12)
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- Nanomagnetically modified sulfuric acid (γ-Fe2O 3@SiO2-OSO3H): An efficient, fast, and reusable catalyst for greener Paal-Knorr pyrrole synthesis
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Paal-Knorr pyrrole synthesis was performed in the presence of superparamagnetic nanoparticles of modified sulfuric acid (γ-Fe 2O3@SiO2-OSO3H) as an efficient and magnetically separable catalyst. Recovery of the catalyst was simple using a magnet, allowing its reuse without significant loss of its catalytic activity (over five cycles).
- Cheraghi, Samaneh,Saberi, Dariush,Heydari, Akbar
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p. 1339 - 1343
(2014/07/21)
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- Indium-mediated one-pot pyrrole synthesis from nitrobenzenes and 1,4-diketones
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One-pot reduction-triggered heterocyclizations of nitrobenzene derivatives with 1,4-diketones were investigated. In the presence of indium/AcOH in toluene at 80 C, reaction of nitrobenzenes with 2,5-hexadione produced moderate to excellent yields (40-98%)
- Lee, Hyunseung,Kim, Byeong Hyo
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p. 6698 - 6708
(2013/07/26)
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- Discovery and structure-activity relationships of pyrrolone antimalarials
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In the pursuit of new antimalarial leads, a phenotypic screening of various commercially sourced compound libraries was undertaken by the World Health Organisation Programme for Research and Training in Tropical Diseases (WHO-TDR). We report here the detailed characterization of one of the hits from this process, TDR32750 (8a), which showed potent activity against Plasmodium falciparum K1 (EC50 ~ 9 nM), good selectivity (>2000-fold) compared to a mammalian cell line (L6), and significant activity against a rodent model of malaria when administered intraperitoneally. Structure-activity relationship studies have indicated ways in which the molecule could be optimized. This compound represents an exciting start point for a drug discovery program for the development of a novel antimalarial.
- Murugesan, Dinakaran,Mital, Alka,Kaiser, Marcel,Shackleford, David M.,Morizzi, Julia,Katneni, Kasiram,Campbell, Michael,Hudson, Alan,Charman, Susan A.,Yeates, Clive,Gilbert, Ian H.
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supporting information
p. 2975 - 2990
(2013/05/23)
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- Trifluoroacetic acid: An efficient catalyst for paal-knorr pyrrole synthesis and its deprotection
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In the present work, we demonstrated a simple and an efficient method for the condensation of substituted aryl/heteroaryl amines with acetonylacetone in the presence of trifluoro acetic acid to afford the corresponding 2,5-dimethyl-1-substitued pyrroles using Paal-Knorr synthesis in excellent yields. Trifluoroacetic acid was used under reflux condition for the deprotection of 2,5-dimethyl-1-substitued pyrroles to their corresponding substituted aryl/heteroaryl amines in moderate yields. 2,5-Dimethyl-1-substitued pyrrole were characterized by NMR and LC-MS. The yield of the compounds was found to be excellent.
- Venugopala, K. Narayanaswamy,Prasanna, Renuka T.,Odhav, Bharti
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p. 8685 - 8689
(2013/11/06)
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- Squaric acid catalyzed simple synthesis of N-substituted pyrroles in green reaction media
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An operationally simple and efficient protocol for squaric acid catalyzed synthesis of N-substituted pyrroles via the reaction of 2,5- dimethoxytetrahydrofuran and 2,5-hexandione with aryl amines in green reaction media (water, deep eutectic solvent, and polyethylene glycol) under ultrasound irradiation or thermal conditions in good to excellent yields has been developed.
- Azizi, Najmadin,Davoudpour, Anahita,Eskandari, Farshid,Batebi, Ehlham
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p. 405 - 409
(2013/05/09)
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- 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)
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- Paal-Knorr pyrrole synthesis using recyclable amberlite IR 120 acidic resin: A green approach
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Amberlite IR 120 acidic resin, a polymer matrix, has been demonstrated as a catalyst for Paal-Knorr condensation of 2,5-hexadione with primary amines under solvent-free conditions. This is an efficient, mild, and green methodology for N-substituted pyrrole derivatives. Copyright Taylor & Francis Group, LLC.
- Devi, Aarti,Shallu,Sharma,Singh, Jasvinder
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experimental part
p. 1480 - 1488
(2012/05/05)
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- One-pot green synthesis of pyrrole derivatives catalyzed by nano sulfated zirconia as a solid acid catalyst
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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)
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- 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
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experimental part
p. 917 - 922
(2012/03/08)
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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)
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- Synthesis of phosphane oxide bridged bis- and triscatechol derivatives
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Linear biscatechols and triangular triscatechols possessing spacers containing phosphane oxide were synthesized. For this, the central phosphorus was introduced by the reaction of active organometallic intermediates with either dichlorophenylphosphane or
- Albrecht, Markus,Song, Yun
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p. 3037 - 3042
(2008/02/08)
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- Sulphonamide derivatives
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Glutamate receptor function in a mammal may be potentiated using an effective amount of a compound of formulaR1—L—NHSO2R2??Iin whichR1 represents an unsubstituted or substituted aromatic or heteroaromatic group;R2 represents (1-6C)alkyl, (3-6C)cycloalkyl, (1-6C)fluoroalkyl, (1-6C)chloroalkyl, (2-6C)alkenyl, (1-4C)alkoxy(1-4C)alkyl, phenyl which is unsubstituted or substituted by halogen, (1-4C)alkyl or (1-4C)alkoxy, or a group, of formula R3R4N in which R3 and R4 each independently represents (1-4C)alkyl or, together with the nitrogen atom to which they are attached form an azetidinyl, pyrrolidinyl, piperidinyl, morpholino, piperazinyl, hexahydroazepinyl or octahydroazocinyl group; andL represents a (2-4C)alkylene chain which is unsubstituted or substituted by one or two substituents selected independently from (1-6C)alkyl, aryl(1-6C)alkyl, (2-6C)alkenyl, aryl(2-6C)alkenyl and aryl, or by two substituents which, together with the carbon atom or carbon atoms to which they are attached form a (3-8C)carbocyclic ring;and pharmaceutically acceptable salts thereof.Also disclosed are compounds of formula I, processes for preparing them and pharmaceutical compositions containing them.
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- Protection of Primary Amines as N-Substituted 2,5-Dimethylpyrroles
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Protection of primary amine group is achieved by incorporating it into an N-substituted 2,5-dimethylpyrrole system.The method affords protection against strong bases and nucleophiles, heating with concentrated alkali, standard mineral acid work-up conditions, and various other reagents.Phenyl-, pyridil-, thiazolyl-, and alkyl-amines have been studied.All give trisubstituted pyrroles in high yield (>80percent) by reaction with hexane-2,5-dione.The pyrroles from the first three types are stable to storage; even the N-alkyl compounds can be used without difficulty.Regeneration of the amine group, by treatment with hydrxylamine hydrochloride, is efficient (80percent yield) with the phenyl, pyridyl, and alkyl compounds but less satisfactory (60 - 65percent generally but down to 25percent in two cases) with the thiazolyl derivatives.
- Bruekelman, Stephen P.,Leach, (Miss) Susan E.,Meakins, G. Denis,Tirel, Malcolm D.
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p. 2801 - 2807
(2007/10/02)
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