- Natural Hydroxyapatite: Green Catalyst for the Synthesis of Pyrroles, Inhibitors of Corrosion
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Polysubstituted pyrroles have been synthesized in good yields via a four-component one-pot reaction of 1,3-dicarbonyl compounds, amines, aldehydes, and nitroalkanes using natural hydroxyapatite (HAp) as an efficient green catalyst. This strategy provides advantages such as simple experimental and work-up procedures, mild conditions, high selectivity, low cost, high atom economy, and environmental friendliness; it uses a green commercial catalyst and does not require a solvent. The electrochemical behavior of S300 steel in 1 M hydrochloric acidic was studied in the presence of these heterocyclic compounds. The results showed good inhibition efficiency for steel in acidic media.
- Louroubi, Abdelhadi,Nayad, Abdallah,Hasnaoui, Ali,Idouhli, Rachid,Abouelfida, Abdessalam,El Firdoussi, Larbi,Ait Ali, Mustapha
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- Nenitzescu Synthesis of 5-Hydroxyindoles with Zinc, Iron and Magnesium Salts in Cyclopentyl Methyl Ether
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In this work, mild Lewis acids and low environmental impact solvents were investigated for Nenitzescu synthesis. Cyclopentyl methyl ether can be used at room temperature in substitution of halogenated solvents with zinc, iron and magnesium salts as homogeneous catalysts to give 5-hydroxyindoles in fair to good yields. The reaction features a straightforward workup and excellent solvent recycle.
- Azzena, Ugo,Beccu, Andrea,Carboni, Silvia,Carraro, Massimo,De Luca, Lidia,Gaspa, Silvia,Livesi, Marco,Pira, Giovanni Michele,Pisano, Luisa,R?mer, Melina,Satta, Giuseppe,Solinas, Angelo,Usala, Elena
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supporting information
p. 5835 - 5842
(2021/11/17)
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- Expeditious and eco-friendly synthesis of new multifunctionalized pyrrole derivatives and evaluation of their antioxidant property
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Diminution of oxidative stress-mediated diseases is an essential pharmaceutical objective in modern biomedical research. The present work stresses upon the efficient and eco-friendly synthesis of an array of novel diversely functionalized pyrrole derivatives which are found to be antioxidants with reactive oxygen species (ROS) shielding competency against the deleterious consequence of oxidative stress. The results of the investigation displayed the effect of structural modification of the pyrrole derivatives on their respective antioxidant properties to various ROS. Noteworthy, the pyrrole moiety bearing 4-hydroxycoumarin or 2-hydroxy-1,4-naphthoquinone as substituent showed outstanding defensive potency towards [rad]OH and O2 [rad] ? while, nitrogen atom linked with aliphatic side-chain in the pyrrole scaffold made a strong affirmative impression in DPPH[rad] scavenging assay. More interestingly, an influencing reducing power was observed in pyrrole derivatives carrying cyclohexane 1,3-dione as one of the substituents. To have a comprehensive acuteness into the antioxidant capacity of the synthesized pyrrole derivatives against Trolox as a standard antioxidant, a crucial approach was taken into account by calculating TEAC (Trolox Equivalent Antioxidant Capacity) in case of [rad]OH and DPPH[rad] scavenging activity.
- Kundu, Tania,Pramanik, Animesh
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- β-Enaminone Synthesis from 1,3-Dicarbonyl Compounds and Aliphatic and Aromatic Amines Catalyzed by Iron Complexes of Fused Bicyclic Imidazo[1,5-a]pyridine Derived N-Heterocyclic Carbenes
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A series of Fe–NHC complexes (1–2)c of the fused bicyclic imidazo[1,5-a]pyridine framework of the type [CpFe(2-R-imidazo[1,5-a]pyridin-3-ylidene)(CO)2]BF4 {R = mesityl (1c), nPr (2c)} successfully carried out the synthesis of β-enamino ketones (3–10) and (17–27) and β-enamino esters (11–16) and (28–36) by the condensation of acyclic and cyclic 1,3-dicarbonyl compounds and various aliphatic and aromatic amines in the presence of light irradiation. Quite significantly, the catalytically relevant substrate adduct species of the type [CpFe(NHC)(acac)] (2e) and the product adduct species of the type [CpFe(NHC)(β-enaminone)] (2f) of the Fe–NHC precatalyst (2c) have been detected by mass spectrometry study. The [CpFe(2-R-imidazo[1,5-a]pyridin-3-ylidene)(CO)2]BF4 {R = mesityl (1c), nPr (2c)} complexes were obtained from their respective N–heterocyclic carbene precursors namely, the 2-R-imidazo[1,5-a]pyridin-2-ium chloride {R = mesityl (1a), nPr (2a)} by the reaction with CpFe(CO)2I in the presence of KN(SiMe3)2 followed by the salt metathesis reaction with AgBF4.
- Prakasham,Gangwar, Manoj Kumar,Ghosh, Prasenjit
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p. 295 - 313
(2019/01/24)
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- Citrus juice: Green and natural catalyst for the solvent-free silica supported synthesis of β-enaminones using grindstone technique
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Aim and Objective: Citrus Juice as an efficient, cost-effective and green catalyst employed for one-pot synthesis of various β-substituted enaminones through the reaction of β-dicarbonyl compounds with different primary amines in a solvent-free conditions on silica gel as solid surface using grindstone technique in high yields and short reaction times. The presented procedure is operationally simple, practical and green. Material and Methods: The wide application of this procedure is demonstrated by the use of various substituted amines to react with β-dicarbonyl compounds. The method was successfully applied for primary amines (15 entries) and the related enaminones were well synthesized in good to excellent yields. Melting points were measured on an Electro thermal 9100 apparatus. 1HNMR and 13C NMR spectra were recorded on a FTNMR BRUKER DRX 500 Avence spectrometer. Chemical shifts were given in ppm from TMS as internal references and CDCl3 was used as the solvent as well. The IR spectra were recorded on a Perkin Elmer FT-IR GX instrument. The chemicals used in this work were purchased from Merck and Fluka chemical companies. Results: Grinding synthesis of citrus juice catalyzed enamination of 1,3-dicarbonyls (acetylacetone, methyl and ethyl-3-oxobutanoate) with various primary amines (aromatic and aliphatic) under solvent-free silica supported conditions was examined and studied (15 entries) and the obtained enaminones were well synthesized in good to excellent yields. Furthermore, the effect of various catalysts on the yield and reaction time for grinding synthesis of 3-phenylamino-but-2-enoic acid ethyl ester (1) by this method has evaluated as well. Conclusion: a novel, efficient and green protocol for the grinding synthesis of enaminones using citrus juice as natural catalyst has been presented. This methodology is user friendly, green and low cost procedure under mild reaction condition with faster reaction rates. The citrus juice is inexpensive and non-toxic which makes the process convenient, more economic and benign. Furthermore, applying grindstone technique in solvent-free conditions, use of silica gel as a solid and heterogeneous surface in reaction, high yields of products, cleaner reaction profiles, and availability of the reagents makes this method a better choice for synthetic chemists.
- Marvi, Omid,Fekri, Leila Zare
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- β-Enaminones over recyclable nano-CoFe2O4: a highly efficient solvent-free green protocol
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Abstract: β-Enaminone and its derivatives have emerged among the finest bioactive intermediates. High yields of several β-enaminones (86–97%) are achieved through treatment of substituted aromatic and aliphatic amines with cyclic/acyclic 1,3-diketones, over the magnetically separable cobalt ferrite nanoparticles (CoFe2O4 NPs). The latter was prepared upon co-precipitation. Its purity, fine crystallinity, elemental distributions, morphology, magnetic features, and thermal stability were confirmed by Fourier transform infrared, X-ray diffraction, energy dispersive X-ray spectrometry, scanning electron microscopy, vibrating sample magnetometry, and thermal gravimetric analysis analyses. Thus, CoFe2O4 NPs acted as an excellent green heterogeneous nanocatalyst for synthesis of β-enaminones and gave good recyclability, while showing insignificant loss of their activity. Graphical Abstract: [Figure not available: see fulltext.].
- Eidi, Esmaiel,Kassaee, Mohamad Z.,Cummings, Peter T.
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p. 5787 - 5799
(2018/05/14)
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- Structural comparison of Mtb-DHFR and h-DHFR for design, synthesis and evaluation of selective non-pteridine analogues as antitubercular agents
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Tuberculosis is an infectious disease that affects millions of population every year. Mtb-DHFR is a validated target that is vital for nucleic acids biosynthesis and therefore DNA formation and cell replication. This paper report identification and synthesis of novel compounds for selective inhibition of Mtb-DHFR and unleash the selective structural features necessary to inhibit the same. Virtual screening of databases was carried out to identify novel compounds on the basis of difference between the binding pockets of the two proteins. Consensus docking was performed to improve upon the results and best ten hits were selected. Hit 1 was subjected to analogues design and the analogues were docked against Mtb-DHFR. From the docking results 11 compounds were selected for synthesis and biological assay against H37Rv. Most potent compound (IND-07) was tested for selectivity using enzymatic assay against Mtb-DHFR and h-DHFR. The compounds were found to have good inhibitory activity (25–200 μM) against H37Rv and in enzyme assay against Mtb-DHFR and h-DHFR the compound was found selective towards Mtb-DHFR with selectivity index of 6.53. This work helped to identify indole moiety as novel scaffold for development of novel selective Mtb-DHFR inhibitors as antimycobacterial agents.
- Sharma, Kalicharan,Tanwar, Omprakash,Sharma, Shweta,Ali, Shakir,Alam,Zaman,Akhter, Mymoona
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p. 319 - 333
(2018/07/25)
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- Effect of solvent ratio and counter ions on the morphology of copper nanoparticles and their catalytic application in β-enaminone synthesis
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This work reports the synthesis of shape selective copper nanoparticles (NPs) using a microwave irradiation method, using diverse ratios of an ethylene glycol (EG)/water system. The solvent ratio of EG/water plays a pivotal role in the selective formation of CuO NPs. The alteration of the counter ion of the copper precursor leading to the selective synthesis of copper (CuO, Cu2O, Cu(OH)2) NPs has been observed. The synthesized copper NPs are well characterized using FEG-SEM, TEM, XRD, XPS, NH3-TPD and BET surface area. The prepared CuO NPs show high activity towards the synthesis of β-enaminones and β-enamino esters from 1,3 diketones and amines.
- Gajengi, Aravind L.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
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p. 101800 - 101807
(2016/11/09)
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- Nano-SiO2 catalyzed synthesis of β-enaminones under solvent free conditions
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Nano-SiO2 efficiently catalyzed the synthesis of β-enaminones using direct condensation of various (cyclic and acyclic) β-diketones with aromatic and aliphatic amines under solvent-free conditions. This eco-friendly catalyst can be recovered and reused without significant loss of activity. This methodology provides a simple synthetic route to enaminones in excellent yields at room temperature. Graphical abstract: [Figure not available: see fulltext.]
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Sarkati, Malihe Norouzi,Zare, Mahboobe
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p. 1591 - 1596
(2016/08/16)
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- Bimetallic Ag-Cu alloy nanoparticles as a highly active catalyst for the enamination of 1,3-dicarbonyl compounds
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Bimetallic nanoparticles, particularly those based on copper, have recently attracted a great deal of attention for the development of low cost and highly active catalysts due to the synergistic interaction between individual metal components. In this work, bimetallic Ag-Cu alloy nanoparticles were explored as a highly active and reusable catalyst for the enamination of 1,3-dicarbonyls using diverse amines. The nanocatalysts were intensively characterized by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy-energy-dispersive spectroscopy (HRTEM-EDS) and valence band and core level X-ray photoelectron spectroscopy (XPS) to study the effect of the bimetallic structure and composition. In comparison to monometallic Ag and Cu nanoparticles, the alloyed Ag-Cu nanoparticles showed a high catalytic performance and the resultant catalytic activity was dependant on the Ag to Cu ratio. This enhanced catalytic activity should be related to the electronic interaction between Ag and Cu nanoparticles formed due to the intimate contact between them. Our study may serve as a foundation for designing efficient alloyed nanocatalysts for fine chemical synthesis via enamination reactions.
- Rout, Lipeeka,Kumar, Aniket,Dhaka, Rajendra S.,Dash, Priyabrat
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p. 49923 - 49940
(2016/06/15)
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- Continuous Flow Liquid-Liquid Separation Using a Computer-Vision Control System: The Bromination of Enaminones with N -Bromosuccinimide
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Incorporating open-source software components (Python, OpenCV), a computer-vision system was used to control the interface level in a gravity-based inline liquid-liquid separation device. This was used in the continuous flow bromination of a series of enaminone substrates. The main byproduct of the reaction, succinimide, was efficiently extracted into the aqueous stream, providing clean products without the need for further purification.
- O'Brien, Matthew,Cooper, Dennis
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supporting information
p. 164 - 168
(2015/12/26)
-
- Synthesis, characterization, and catalytic activity of sodium ketminiate complexes toward the ring-opening polymerization of l-lactide
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Studies of the ring-opening polymerization of l-lactide (LA) using Na complexes with Schiff base ligands as catalysts have revealed high catalytic activity but poor controllability of the polymer molecular weight. In this study, Na complexes bearing ketiminate ligands instead of Schiff base ligands were synthesized and their application in LA polymerization was tested. The polymerization results revealed that the catalytic activity of Na complexes bearing ketiminate ligands was higher than that of Na complexes bearing Schiff base ligands, but the poor controllability of polymer molecular weight was still a drawback. However, the poor controllability could be improved by means of using a high concentration of initiators in the polymerization system at 0 °C for 1 min. LPy-Na revealed the excellent controllability of polymer molecular weight depending on the ratio of [LA]/[initiator] (the molar averages of the number from 4500 to 35 000) with narrow polydispersity indexes, ranging from 1.29 to 1.35.
- Chuang, Wan-Jung,Huang, Yen-Tzu,Chen, Yu-Hsieh,Lin, Yu-Shan,Lu, Wei-Yi,Lai, Yi-Chun,Chiang, Michael Y.,Hsu, Sodio C. N.,Chen, Hsuan-Ying
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p. 33014 - 33021
(2016/05/09)
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- 5,7-Dihydropyrrolo[3,4-d][1,2]diazepin-1(2H)-ones. Synthesis and transformations
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A preparative procedure has been developed for the synthesis of substituted 5,7-dihydropyrrolo-[3,4-d][1,2]diazepines by recyclization of 6-phenylpyrano[3,4-c]pyrrol-4(2H)-one with hydrazine hydrate. The stability of the seven-membered ring in the products under acidic conditions, alkylation, and heteroring fusion to the diazepine ring have been studied.
- Kharaneko,Bogza
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p. 1043 - 1049
(2016/09/04)
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- Design of a graphene oxide-SnO2 nanocomposite with superior catalytic efficiency for the synthesis of β-enaminones and β-enaminoesters
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A graphene oxide (GO)-SnO2-based nanocomposite was synthesized by decorating the graphene oxide surface with SnO2 nanoparticles via a solvothermal process. The nanocomposite was characterized using Fourier transform infrared spectra (FTIR), FT-Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field-emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) and N2 adsorption/desorption study. The FE-SEM and TEM images demonstrate the uniform distribution of the SnO2 nanoparticles on the GO surface and high-resolution transmission electron microscopy (HRTEM) confirms an average particle size of 8-12 nm. The GO-SnO2 nanocomposite has been found to be an extremely efficient catalyst for the synthesis of β-enaminones and β-enaminoesters in methanol solvent and also, in solventless conditions. The GO-SnO2 nanocomposites exhibited synergistically more superior catalytic efficiency compared to pure graphene oxide and SnO2 nanoparticles. The reaction conditions were optimized by changing different parameters such as catalyst, solvent, catalyst loading, and temperature. It has been found that the catalyst gave higher activity under solventless conditions than methanol. The GO-SnO2 composite was recycled for up to four cycles with minimal loss in activity.
- Kumar, Aniket,Rout, Lipeeka,Dhaka, Rajendra S.,Samal, Saroj L.,Dash, Priyabrat
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p. 39193 - 39204
(2015/05/20)
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- Fabrication of Ag/γ-Fe2O3@TiO2 hollow magnetic core-shell nanospheres as highly efficient catalysts for the synthesis of β-enaminones
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Herein, we describe a method to prepare hollow magnetic mesoporous sphere catalysts (Ag/γ-Fe2O3@meso-TiO2). The core-shell strategy efficiently prevents the aggregation of Ag NPs in the high temperature calcination process and the leaching of Ag NPs for the catalytic reaction in the liquid phase. The catalyst is characterized by TEM, XRD and ICP-AES. Moreover, the catalyst exhibited improved activity for the synthesis of β-enaminones, and it could be easily recovered by an external magnet from the reaction mixture and recycled five times without any significant loss in activity.
- Huo, Hongfei,Li, Xinzhe,Zhou, Xingchun,Jiao, Lixin,Zhao, Shiling,Zhang, Le,Li, Wenzhu,Li, Shuwen,Li, Rong
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p. 73612 - 73618
(2015/09/15)
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- K-10 clay as a reusable catalyst for the solvent-free, MW-induced synthesis of enaminones
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A series of β-amino-a,β-unsaturated ketones and esters were synthesized in good to excellent yields from the reaction of different amines with 1,3-dicarbonyl compounds in solvent-free media using montmorillonite K-10 clay as.
- Marvi, Omid,Giahi, Masoud,Ayub, Pouran Pur,Nikpasand, Mohammad
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p. 921 - 926
(2014/11/07)
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- Ionic liquid promoted synthesis of β-Enamino ketones and esters under microwave irradiation
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A facile amination of 1,3-dicarbonyl compounds with amines or ammonium salts has been achieved under microwave irradiation in the presence of acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulphate. The method has the advantage of solvent free reactions, short reaction time and mild conditions.
- Singh, Ashima,Gupta, Neeru,Sharma,Singh, Jasvinder
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p. 900 - 906
(2014/08/05)
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- Well-controlled ring-opening polymerization of cyclic esters initiated by dialkylaluminum β-diketiminates
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A series of aluminum alkyl complexes nacnacRAlMe2 (2a-2h) bearing aliphatic N-substituted β-diketiminate ligands (nacnac RH = N,N′-dialkyl-2-amino-4-iminopent-2-enes), were prepared from the reaction of trialkyl aluminum and the corresponding β-diketimines. All these aluminum complexes were characterized by NMR, elemental analysis and HRMS spectroscopy. The molecular structures of complexes 2a, 2c and 2h were confirmed by single-crystal X-ray diffraction. These aluminum alkyl complexes show notable activity towards the ring-opening polymerization of ε-caprolactone in the absence and presence of alcohol, and the resulting polymers have narrow molecular weight distributions.
- Li, Di,Peng, Ying,Geng, Chao,Liu, Kaipeng,Kong, Dexu
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p. 11295 - 11303
(2013/08/23)
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- Cu(TFA)2-catalyzed oxidative tandem cyclization/1,2-alkyl migration of enamino amides for synthesis of pyrrolin-4-ones
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A novel Cu(TFA)2-catalyzed oxidative tandem cyclization/1,2- alkyl migration of readily available enamino amides for the synthesis of pyrrolin-4-ones has been developed. The reaction tolerates a wide range of functional groups and is a reliable method for the rapid synthesis of substituted pyrrolin-4-ones in high yields under mild conditions.
- Zhang, Zhi-Jing,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
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supporting information
p. 4822 - 4825
(2013/10/08)
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- A synthesis of functionalized dihydro-1H-pyrroles from Nef-isocyanide adducts and enamines
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α-Ketoimidoyl chlorides, obtained from α-addition of acyl chlorides onto alkyl isocyanides, are treated with enamines to afford 5-(alkylimino)-4-hydroxy-4,5-dihydro-1H-pyrrole-2,3,4-tricarboxylates and 2-(alkylimino)-3-hydroxy-2,3-dihydro-1H-pyrrole-3,4-dicarboxylates in good to excellent yields. Georg Thieme Verlag Stuttgart · New York.
- Yavari, Issa,Hosseinpour, Reza,Pashazadeh, Ramin
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experimental part
p. 1662 - 1666
(2012/08/13)
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- Facile synthesis of substituted pyrrole-fused isocoumarins from ninhydrin
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A simple and efficient procedure has been developed for the synthesis of substituted pyrrole-fused isocoumarins from easily available ninhydrin. The cyclic hemiaminal dihydroxy-indenopyrroles, the adducts of ninhydrin with enamines of acetylacetone, give pyrrole-fused isocoumarins upon heating in acidic medium. The process constitutes an interesting acid-catalyzed rearrangement to eight-membered lactams followed by intramolecular cyclization involving the amino and keto groups.
- Pathak, Sudipta,Kundu, Ashis,Pramanik, Animesh
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experimental part
p. 5180 - 5183
(2011/10/12)
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- Ni(OAc)2: A highly efficient catalyst for the synthesis of enaminone and enamino ester derivatives under solvent-free conditions
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Ni(OAc)2 was found to be an efficient catalyst for the synthesis of β-enamino ketones or esters from β-dicarbonyl compounds and amines under solvent-free conditions. The reusability of the catalyst was successfully examined without noticeable loss of its catalytic activity. Copyright
- Liu, Ju-Yan,Cao, Gai-E.,Xu, Wei,Cao, Jie,Wang, Wei-Lu
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experimental part
p. 685 - 691
(2010/11/20)
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- Solvent-free synthesis of β-enamino compounds promoted by Ferric(III) ammonium nitrate
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A variety of β-enamino esters and β-enaminones can be synthesized by the reaction of 1,3-dicarbonyl compounds and various primary amines in the presence of catalytic amount of ferric(III) ammonium nitrate at room temperature. This method is simple, requires short reaction times, high yield and the reaction proceeds under solvent-free conditions.
- Murthy,Venu,Govindh,Diwakar,Nagalakshmi,Singh
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experimental part
p. 3047 - 3053
(2010/11/04)
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- B2O3/Al2O3 as a new, highly efficient and reusable heterogeneous catalyst for the selective synthesis of β-enamino ketones and esters under solvent-free conditions
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Boron oxide adsorbed on alumina (B2O3/Al 2O3) has been found to be a new and highly efficient heterogeneous catalyst for the synthesis of β-enamino ketones and esters by the enamination of various primary and secondary amines with β-dicarbonyl compounds under solvent-free conditions. The important features of this methodology are broad substrate scope, high yield, no requirement of metal catalysts, high regio-and chemoselectivity and environmental friendliness. In addition, the catalyst could be recovered easily after the reactions and reused without evident loss of reactivity.
- Chen, Jiu-Xi,Zhang, Chang-Fu,Gao, Wen-Xia,Jin, Hui-Le,Ding, Jin-Chang,Wu, Hua-Yue
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experimental part
p. 1552 - 1556
(2010/11/16)
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- A green solventless protocol for the synthesis of β-Enaminones and β -Enamino esters using silica sulfuric acid as a highly efficient, heterogeneous and reusable catalyst
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Silica sulfuric acid is utilized as a green, highly efficient, heterogeneous and recyclable catalyst for the preparation of β-enaminones and β -enamino esters from amines and β -dicarbonyl compounds under solvent-free conditions at 80 °C. Using this method, the title compounds are produced in high to excellent yields and in short reaction times.
- Hasaninejad, Alireza,Zare, Abdolkarim,Mohammadizadeh, Mohammad Reza,Shekouhy, Mohsen,Moosavi-Zare, Ahmad Reza
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experimental part
p. 1546 - 1554
(2011/12/05)
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- Expedient, one-pot preparation of fused indoles via CAN-catalyzed three-component domino sequences and their transformation into polyheterocyclic compounds containing pyrrolo[1,2-a]azepine fragments
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The CAN-catalyzed three-component between reaction between primary amines, β-dicarbonyl compounds and naphthoquinones or 2-bromonaphthoquinones afforded, respectively, 5-hydroxybenzo[g]indoles and benzo[f]indole-4,9-diones, the former of which were transformed into tetracyclic azepino[1,2-a]benzo[g] indole systems through a γ-alkylation/ring-closing metathesis sequence. The Royal Society of Chemistry 2010.
- Suryavanshi, Padmakar A.,Sridharan, Vellaisamy,Menendez, J. Carlos
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experimental part
p. 3426 - 3436
(2010/08/21)
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- Silver nanoparticles as an efficient, heterogeneous and recyclable catalyst for synthesis of β-enaminones
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A simple and efficient protocol has been developed for synthesis of β-enaminones and β-enamino esters catalyzed by silver nanoparticles as a novel, heterogeneous, moisture stable and recyclable catalyst under mild reaction conditions. The reaction was optimized with respect to various parameters such as catalyst screening, catalyst loading, different solvents and temperature. The silver nanoparticle exhibited excellent activity and the methodology is applicable to diverse substrates providing good to excellent yields of desired products. The catalyst was recycled for three consecutive cycles without any significant loss in activity.
- Bhatte, Kushal D.,Tambade, Pawan J.,Dhake, Kishor P.,Bhanage, Bhalchandra M.
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experimental part
p. 1233 - 1237
(2011/01/03)
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- Construction of Hydroxylated Alkaloids (+/-)-Mannonolactam, (+/-)-Deoxymannojirimycin, and (+/-)-Prosopinine through Aza-Annulation
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The aza-annulation of β-enamino carbonyl substrates with acrylate derivatives provides an efficient and convenient route for the regioselective construction of δ-lactams.This two-step ring-forming sequence involved initial generation of the benzyl enamine through either a condensation or conjugate addition reaction with BnNH2, followed by aza-annulation with acryloyl chloride or acrylic anhydride.Controlled by the rigid framework of the intermediate lactam, introduction of ring substituents was accomplished with high relative stereoselectivity.The carbonyl functionality, which was necessary to direct the regioselectivity of the aza-annulation reaction, was then transformed into a protected hydroxyl substituent through Baeyer-Villiger oxidation.The resultant δ-lactam product was used as a valuable intermediate in the synthesis of three natural products.Subsequent modification of this δ-lactam gave the naturally occurring α-mannosidase inhibitors (+/-)-mannonolactam and (+/-)-deoxymannojirimycin, while synthesis of the alkaloid (+/-)-prosopinine was accomplished through homologation of the lactam carbonyl.
- Cook, Gregory R.,Beholz, Lars G.,Stille, John R.
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p. 3575 - 3584
(2007/10/02)
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- Pyrrole and Pyrazole Ring Closure in Heterogeneous Media
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Pyrroles and pyrazoles may be conveniently prepared by dispersing primary amines or hydrazines and 1,4- or 1,3-diketones, respectively, on alumina or clay (montmorillonite K 10) without solvent, keeping the mixture at 20 deg C or higher temperatures for 1-26 h, and then eluting the product with dichloromethane.
- Texier-Boullet, F.,Klein, B.,Hamelin, J.
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p. 409 - 411
(2007/10/02)
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- Reaction of Maleimides and Ethyl 3-Aminocrotonates. A Reinvestigation Leading to an Improved Synthesis of Pyrrolopyridines
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Conditions employed for the reaction between maleimides and ethyl aminocrotonates were shown to yield pyrrolopyridines rather than the previously reported pyrrolopyrroles.
- Shah, Kanhaiya R.,Blanton, C. DeWitt
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p. 502 - 508
(2007/10/02)
-