5044-20-2Relevant academic research and scientific papers
One-pot green synthesis of pyrrole derivatives catalyzed by nano sulfated zirconia as a solid acid catalyst
Teimouri, Abbas,Chermahini, Alireza Najafi
, p. 372 - 376 (2012)
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
Pyrrole syntheses based on titanium-catalyzed hydroamination of diynes
Ramanathan, Balasubramanian,Keith, Adam J.,Armstrong, Douglas,Odom, Aaron L.
, p. 2957 - 2960 (2004)
(Equation Presented) Titanium-catalyzed hydroamination of 1,4- and 1,5-diynes by primary amines leads to imino-alkynes that undergo in situ 5-endo dig and 5-exo dig cyclization reactions, respectively. The products are 1,2,5-trisubsituted pyrroles accesse
Quararibea metabolites. 3. Total synthesis of (±) - Funebral, a rotationally restricted pyrrole alkaloid, using a novel Paal-Knorr reaction
Yu, Shao-Xia,Le Quesne, Philip W.
, p. 6205 - 6208 (1995)
The total synthesis of (±) - funebral 5, a sterically crowded, rotationally restricted pyrrole alkaloid, has been achieved by means of a new variation of the Paal-Knorr synthesis, employing titanium isopropoxide.
Paal-Knorr reaction catalyzed by metal-organic framework IRMOF-3 as an efficient and reusable heterogeneous catalyst
Phan, Nam T. S.,Nguyen, Tung T.,Luu, Quang H.,Nguyen, Lien T. L.
, p. 178 - 185,8 (2012)
A highly porous metal-organic framework (IRMOF-3) was synthesized from the reaction of zinc nitrate hexahydrate and 2-amino-1,4-benzenedicarboxylic acid by solvothermal method. Physical characterizations of the material were achieved by using a variety of different techniques, including X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. The IRMOF-3 was used as an efficient heterogeneous catalyst for the Paal-Knorr reaction of benzyl amine with 2,5-hexanedione. Excellent conversions were obtained under mild conditions in the presence of 3 mol% catalyst. The IRMOF-3 catalyst could be reused several times without a significant degradation in catalytic activity.
Hexafluoroisopropanol as solvent and promotor in the Paal-Knorr synthesis of N-substituted diaryl pyrroles
Schirmacher, Robert H.E.,R?sch, Daniel,Thomas, Franziska
, (2021/02/20)
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.
Amidosulfonic acid supported on graphitic carbon nitride: novel and straightforward catalyst for Paal–Knorr pyrrole reaction under mild conditions
Azhdari, Asieh,Azizi, Najmedin,Sanaeishoar, Haleh,Tahanpesar, Elham
, p. 625 - 634 (2021/05/12)
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.]
Crystalline salicylic acid as an efficient catalyst for ultrafast Paal–Knorr pyrrole synthesis under microwave induction
Aghapoor, Kioumars,Mohsenzadeh, Farshid,Darabi, Hossein Reza,Sayahi, Hani
, (2021/04/19)
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.
Facile fabrication of porous magnetic covalent organic frameworks as robust platform for multicomponent reaction
Azizi, Najmedin,Heidarzadeh, Fatemeh,Farzaneh, Fezeh
, (2021/07/26)
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.
Fe3O4@SiO2-PTMS-Guanidine-SA nanoparticles as an effective and reusable catalyst for the synthesis of N-substituted pyrroles
Rostami, Hedieh,Shiri, Lotfi
, p. 1329 - 1335 (2020/01/28)
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.
Naturally occurring organic acids for organocatalytic synthesis of pyrroles via Paal–Knorr reaction
Mohsenzadeh, Farshid,Darabi, Hossein Reza,Alivand, Mahsa,Aghapoor, Kioumars,Balavar, Yadollah
, p. 5255 - 5262 (2020/09/09)
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.].
