- A detective story in drug discovery: Elucidation of a screening artifact reveals polymeric carboxylic acids as potent inhibitors of RNA polymerase
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Chasing the active impurity: In the validation of a screening hit it was discovered that a polymeric trace impurity was responsible for the biological activity. Such a side product can be formed with similar compounds. During the investigations it was discovered that the negatively charged macromolecule interacts very efficiently with the protein surface of E. coli RNAP via electrostatic interactions. Copyright
- Zhu, Weixing,Groh, Matthias,Haupenthal, J?rg,Hartmann, Rolf W.
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Read Online
- 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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Read Online
- 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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- 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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- 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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- Synthesis and antimicrobial activity of novel 2,5-dimethyl pyrrolyl benzamide derivatives
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A new series of substituted 4-(2,5-dimethyl-1H-pyrrol-1-yl)-N-phenyl benzamides (3a-j) has been synthesized by reacting 4-(2,5-dimethyl-1H-pyrrol-1-yl) benzoic acid (2) with substituted primary aromatic amines in presence of HBTU and DIEA in dry DMF. The purity of the compounds was confirmed by melting point and TLC. The structures of the newly synthesized compounds were confirmed by analytical and spectral data such as FTIR, 1H NMR, 13C NMR and Mass spectroscopy. These compounds were screened for their antimicrobial and antitubercular activities using broth microdilution and MABA methods respectively.
- Hallikeri,Joshi, Shrinivas D.,Kumar, Devendra,Kulkarni
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- Sulfamic acid heterogenized on functionalized magnetic Fe3O4 nanoparticles with diaminoglyoxime as a green, efficient and reusable catalyst for one-pot synthesis of substituted pyrroles in aqueous phase
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Surface functionalization of magnetic nanoparticles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. We have conveniently loaded sulfonic acid groups on amino-functionalized Fe3O4 nanoparticles affording sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (MNPs/DAG-SO3H) as an active and stable magnetically separable acidic nanocatalyst, which was characterized using X-ray diffraction, Fourier transform infrared and energy-dispersive X-ray spectroscopies, scanning and transmission electron microscopies, vibrating sample magnetometry and elemental analysis. The catalytic activity of MNPs/DAG-SO3H was probed through one-pot synthesis of N-substituted pyrroles from γ-diketones and primary amines in aqueous phase at room temperature. The heterogeneous catalyst could be recovered easily by applying an external magnet device and reused many times without significant loss of its catalytic activity.
- Veisi, Hojat,Mohammadi, Pourya,Gholami, Javad
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p. 868 - 873
(2015/02/19)
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- An efficient and green procedure for synthesis of pyrrole derivatives by Paal-Knorr condensation using sodium dodecyl sulfate in aqueous micellar
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A simple, economical, and green approach to the synthesis of N-substituted pyrroles using sodium dodecyl sulfate as surfactant in water is described. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (60-98%).
- Veisi, Hojat,Azadbakht, Reza,Ezadifar, Mehdi,Hemmati, Saba
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p. E241-E246
(2013/06/04)
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- One-pot tandem reactions for direct conversion of thiols and disulfides to sulfonic esters, alcohols to bis(indolyl)methanes and synthesis of pyrroles catalyzed by N-chloro reagents
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A convenient synthesis of sulfonic esters from thiols and disulfides has been described. In situ preparation of sulfonyl chlorides from thiols is accomplished by oxidation with Chloramin-T, tetra-butylammonium chloride (t-Bu4NCl) and water. The sulfonyl chlorides are then further allowed to react with phenol derivatives in the same reaction vessel. Also, a facile synthesis of bis(indolyl)methanes from alcohols using TCCA/KBr/wet-SiO2, and N-substituted pyrroles by reaction of hexane-2,5-dione with primary amines has been accomplished under mild condition with excellent yields.
- Veisi, Hojat,Ataee, Meral,Fatolahi, Leila,Lotfi, Shahram
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p. 111 - 117
(2013/07/26)
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- One-pot tandem reactions for direct conversion of thiols and disulfides to sulfonic esters, and Paal-Knorr synthesis of pyrrole derivatives catalyzed by TCCA
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A convenient synthesis of sulfonic esters from thiols and disulfides is described. In situ preparation of sulfonyl chlorides from thiols is accomplished by oxidation with trichloroisocyanuric acid (TCCA), tetra-butylammonium chloride (t-Bu4NCl), and water. The sulfonyl chlorides are then further allowed to react with phenol derivatives in the same reaction vessel. Also, a facile synthesis of N-substituted pyrroles by the reaction of hexane-2,5-dione with primary amines has been accomplished using TCCA as a catalyst under mild condition with excellent yields.
- Hemmati, Saba,Mojtahedi, Mohammad Majid,Abaee, Mohammad Saeed,Vafajoo, Zahra,Saremi, Shokufe Ghahri,Noroozi, Mohammad,Sedrpoushan, Alireza,Ataee, Meral
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p. 347 - 357
(2013/09/23)
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- Silica sulfuric acid (SSA) as a solid acid heterogeneous catalyst for one-pot synthesis of substituted pyrroles under solvent-free conditions at room temperature
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A variety of N-substituted pyrroles have been synthesized by reacting γ-diketones with amines, diamines or triamine in the presence of silica sulfuric acid (SSA) at room temperature under solvent-free conditions. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (70-98%).
- Veisi, Hojat
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scheme or table
p. 2109 - 2114
(2010/06/14)
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- One-pot synthesis of substituted pyrroles with N, N, N', N' -tetrachlorobenzene-1, 3-disulphonamide and N, N'-diiodo-N, N' -1, 2-ethanediylbis(p-toluenesulphonamide) as novel catalytic reagents
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In this research, N, N, N'N'-tetrachlorobenzene-1, 3-disulphonamide as novel catalytic reagent and 2V,2V'-diiodo-2V,2V'-1, 2-ethane- diylfeis(p-toluenesulphonamide) as new catalyst were used for the synthesis of V-substituted pyrroles in good to excellent yields under mild conditions. These reusable reagents were compared with existing reagents and it is clear that this study is a welcome addition in the field of pyrrole synthesis.
- Ghorbani-Vaghei, Ramin,Veisi, Hojat
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experimental part
p. 33 - 38
(2010/08/07)
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- Design, synthesis, and biological evaluation of N-carboxyphenylpyrrole derivatives as potent HIV fusion inhibitors targeting gp41
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On the basis of the structures of small-molecule hits targeting the HIV-1 gp41, N-(4-carboxy-3-hydroxy)phenyl-2,5-dimethylpyrrole (2, NB-2), and N-(3-carboxy-4-chloro)phenylpyrrole (A1, NB-64), 42 N-carboxyphenylpyrrole derivatives in two categories (A and B series) were designed and synthesized. We found that 11 compounds exhibited promising anti-HIV-1 activity at micromolar level and their antiviral activity was correlated with their inhibitory activity on gp41 six-helix bundle formation, suggesting that these compounds block HIV fusion and entry by disrupting gp41 core formation. The structure-activity relationship and molecular docking analysis revealed that the carboxyl group could interact with either Arg579 or Lys574 to form salt bridges and two methyl groups on the pyrrole ring were favorable for interaction with the residues in gp41 pocket. The most active compound, N-(3-carboxy-4-hydroxy)phenyl-2,5-dimethylpyrrole (A12), partially occupied the deep hydrophobic pocket, suggesting that enlarging the molecular size of A12 could improve its binding affinity and anti-HIV-1 activity for further development as a small-molecule HIV fusion and entry inhibitor.
- Liu, Kun,Lu, Hong,Hou, Ling,Qi, Zhi,Teixeira, Cátia,Barbault, Florent,Fan, Bo-Tao,Liu, Shuwen,Jiang, Shibo,Xie, Lan
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experimental part
p. 7843 - 7854
(2009/11/30)
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- Zinc tetrafluoroborate-catalysed synthesis of highly substituted pyrroles by a solvent-free reaction
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A simple and highly efficient synthesis of penta- and tri-substituted pyrroles has been developed using the Paal-Knorr reaction catalysed by aqueous zinc tetrafluoroborate at room temperature under solvent-free conditions.
- Ranu, Brindaban C.,Ghosh, Sudip,Das, Arijit
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p. 220 - 221
(2007/10/03)
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- INHIBITORS OF HISTONE DEACETYLASE
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The invention relates to the inhibition of histone deacetylase. The invention provides compounds and methods for inhibiting histone deacetylase enzymatic activity. The invention also provides compositions and methods for treating cell proliferative diseases and conditions.
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Page/Page column 230-231
(2010/02/11)
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