136660-99-6Relevant articles and documents
Modified Paal-Knorr synthesis of novel and known pyrroles using tungstate sulfuric acid as a recyclable catalyst
Karami, Bahador,Jamshidi, Masih,Khodabakhshi, Saeed
, p. 12 - 16 (2013)
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.
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
Veisi, Hojat,Mohammadi, Pourya,Gholami, Javad
, p. 868 - 873 (2014)
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.
An EPR analysis of β-dimerization in α-blocked pyrroles in oxidant conditions
Julia, Luis,Rius, Jordi,Torrelles, Xavier
, p. 164 - 167 (2011)
Electron paramagnetic resonance (EPR) analysis of neutral and acidic solutions of 2,5-dimethyl-1-phenylpyrrol (1) and meta-, para-, and ortho-bis(2,5-dimethylpyrrol-1-yl)benzenes (4-6) in the presence of Tl(III) trifluoroacetate as oxidant reveals the poor stability of their generated monomeric radical cations which dimerize through C(β) i￡C(β) bond formation. EPR spectra of the monomeric radical cations 4?+, 5?+, and 6 ?+ coincide with that of 1?+, suggesting that the unpaired electron in these charged species is confined in one of the pyrrolic rings. The very twisted angles between pyrrolic and phenyl planes due to steric hindrance in the X-ray analysis of the molecular structure of 4 confirm the absence of extended conjugation in the π-system. Copyright
Nanomagnetically modified sulfuric acid (γ-Fe2O 3@SiO2-OSO3H): An efficient, fast, and reusable catalyst for greener Paal-Knorr pyrrole synthesis
Cheraghi, Samaneh,Saberi, Dariush,Heydari, Akbar
, p. 1339 - 1343 (2014)
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).
An expeditious and highly efficient synthesis of substituted pyrroles using a low melting deep eutectic mixture
Alvi, Shakeel,Ali, Rashid
, p. 9732 - 9745 (2021/12/01)
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.
Efficient synthesis of substituted pyrroles through Pd(OCOCF3)2-catalyzed reaction of 5-hexen-2-one with primary amines
Chen, Xi,Yang, Meng,Zhou, Min
supporting information, p. 5215 - 5218 (2016/11/11)
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.
Indium-Catalyzed Formal N-Arylation and N-Alkylation of Pyrroles with Amines
Yonekura, Kyohei,Oki, Kenji,Tsuchimoto, Teruhisa
, p. 2895 - 2902 (2016/09/16)
Under indium Lewis acid catalysis, a nitrogen atom of N-unsubstituted pyrroles was replaced with a nitrogen atom of primary amines, thereby producing N-aryl- and N-alkylpyrroles. This system formally introducing such carbon frameworks to the pyrrole nitrogen atom shows unique selectivity: only the H?N(pyrrolyl) unit undergoes the N-arylation and N-alkylation even in the coexistence of a similar H?N(indolyl) part; and an aryl–halogen bond remains intact. These are clearly different from the typical method depending on the C?N(pyrrolyl) bond-forming reaction with organic halides as substrates. From a viewpoint of pyrrole N-protection–deprotection chemistry, worth noting is that a methyl group on the pyrrole nitrogen atom can be removed, albeit in a formal way. (Figure presented.).
Greener Paal-Knorr Pyrrole Synthesis by Mechanical Activation
Akelis, Liudvikas,Rousseau, Jolanta,Juskenas, Robertas,Dodonova, Jelena,Rousseau, Cyril,Menuel, Stphane,Prevost, Dominique,Tumkeviius, Sigitas,Monflier, Eric,Hapiot, Frdric
, p. 31 - 35 (2016/01/20)
A straightforward and solventless synthesis of pyrroles was developed by using mechanochemical activation and a biosourced organic acid as the catalyst. Relative to traditional Paal-Knorr methodologies, various N-substituted pyrroles were obtained in very short reaction times. By reaction with unreactive diketones, desymmetrized aliphatic and aromatic compounds were also synthesized.
Synthesis of two distinct pyrrole moiety-containing arenes from nitroanilines using Paal-Knorr followed by an indium-mediated reaction
Kim, Byeong Hyo,Bae, Seolhee,Go, Ahra,Lee, Hyunseung,Gong, Cheoloh,Lee, Byung Min
, p. 265 - 276 (2015/12/30)
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.
Green and rapid strategy for synthesis of novel and known pyrroles by the use of molybdate sulfuric acid
Karami, Bahado,Khodabakhshi, Saeed,Jamshidi, Masih
, p. 1103 - 1106 (2013/10/22)
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.
