- 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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- Nitroaromatics as n-type organic semiconductors for field effect transistors
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The nitro group (NO2) is one of the most common electron-withdrawing groups but it has rarely been used in the design of organic semiconductors (OSCs). Herein, we report the n-type semiconducting behavior of simple fluorenone derivatives functionalized with NO2and CN groups. While the electron mobilities measured in the thin film field-effect transistors are modest (10?6-10?4cm2V?1s?1), the nitrofluorenone OSCs offer excellent air-stability and remarkable tunability of energy levelsviafacile modification of the substitution pattern. We study the effect of substituents on the electrochemical properties, molecular and crystal structure, and the charge transport properties of nitrofluorenones to revitalize the underestimated potential of NO2functionalization in organic electronics.
- Ghamari, Pegah,Hamzehpoor, Ehsan,Niazi, Muhammad Rizwan,Perepichka, Dmitrii F.,Perepichka, Igor F.
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supporting information
p. 6432 - 6435
(2020/06/21)
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- 2-Methyl-1,3-disulfoimidazolium polyoxometalate hybrid catalytic systems as equivalent safer alternatives to concentrated sulfuric acid in nitration of aromatic compounds
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Ionic liquid-derived polyoxometalate salts [mdsim]3[PM12O40] (where M?=?W and Mo) of two heteropolyacids H3PW12O40.nH2O and H3PMo12O40.nH2O were synthesized using 2-methyl-1,3-disulfoimidazolium chloride ([mdsim][Cl]) ionic liquid and the corresponding heteropolyacids. Three equivalents of [mdsim][Cl] were treated with the respective Keggin-structured heteropolyacids (one equivalent) in aqueous medium at room temperature to afford the water-stable ionic polyoxometalates as acidic solids. They were completely characterized using spectroscopic and other analytical techniques including thermal analysis and Hammett acidity studies. The inherent Br?nsted acidic properties of ─SO3H group of these polyoxometalate salts were studied for the nitration of aromatic compounds with 69% HNO3 at normal temperature and 80°C without use of any external concentrated sulfuric acid. These strongly acidic polyoxometalates display good recyclability and efficient reusability.
- Saikia, Susmita,Borah, Ruli
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- Silver(I)-Promoted ipso-Nitration of Carboxylic Acids by Nitronium Tetrafluoroborate
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A novel and efficient method for the regioselective nitration of a series of aliphatic and aromatic carboxylic acids to their corresponding nitro compounds using nitronium tetrafluoroborate and silver carbonate in dimethylacetamide has been described. This transformation is believed to proceed via the alkyl-silver or aryl-silver intermediate, which subsequently reacts with the nitronium ion to form nitro substances. Mild reaction conditions, tolerant of a broad range of functional groups, and formation of only the ipso-nitrated products are the key features of this methodology when compared to known methods for syntheses of nitroalkyls and nitroarenes.
- Natarajan, Palani,Chaudhary, Renu,Venugopalan, Paloth
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p. 10498 - 10504
(2015/11/18)
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- A supramolecular sorting hat: Stereocontrol in metal-ligand self-assembly by complementary hydrogen bonding
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A combination of self-complementary hydrogen bonding and metal-ligand interactions allows stereocontrol in the self-assembly of prochiral ligand scaffolds. A unique, non-tetrahedral M4L6 structure is observed upon multicomponent self-assembly of 2,7-diaminofluorenol with 2-formylpyridine and Fe(ClO4)2. The stereochemical outcome of the assembly is controlled by self-complementary hydrogen bonding between both individual ligands and a suitably sized counterion as template. This hydrogen-bonding-mediated stereoselective metal-ligand assembly allows the controlled formation of nonsymmetric discrete cage structures from previously unexploited ligand scaffolds. Abracadabra: The stereoselective self-assembly of an unsymmetrical metal-ligand cage can be controlled by self-complementary hydrogen bonding between alcohol-containing ligands as well as between ligands and suitable anion guests.
- Young, Michael C.,Holloway, Lauren R.,Johnson, Amber M.,Hooley, Richard J.
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supporting information
p. 9832 - 9836,5
(2015/02/02)
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- Highly efficient synthesis of 9-fluorenones from 9H-fluorenes by air oxidation
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9-Fluorenones substituted with nitro, halogen, or alkyl groups can be easily obtained in high yield and purity by aerobic oxidation of 9H-fluorenes under ambient conditions in the presence of KOH in THF.
- Zhang, Xin,Ji, Xuan,Jiang, Shanshan,Liu, Lili,Weeks, Brandon L.,Zhang, Zhao
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experimental part
p. 1891 - 1896
(2011/09/14)
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- Improved, highly efficient, and green synthesis of bromofluorenones and nitrofluorenones in water
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A series of bromo-, nitro-, and bromonitrofluorenones were synthesized chemo-and regioselectively in 90-98% yield via electrophilic aromatic bromination and nitration under mild conditions using water as the sole solvent. These synthetic methods involve simple workup procedures and use only minimal amounts of organic solvents during the purification of products. The newly developed methods have the advantages of being cost-effective and environmentally friendly and could potentially be used for the large-scale synthesis of fluorenone derivatives. Copyright Taylor & Francis Group, LLC.
- Zhang, Xin,Han, Jun-Bin,Li, Peng-Fei,Ji, Xuan,Zhang, Zhao
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experimental part
p. 3804 - 3815
(2009/12/06)
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- Electrophotographic member
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Disclosed is an electrophotographic member containing as a charge transport material a fluorine-containing N,N,N',N'-tetraarylbenzidine derivative which is remarkably excellent in solubility in an organic solvent and/or a binder such as polycarbonate resin, etc., can show very excellent electrophotographic properties such as high sensitivity, low residual potential and high durability. Further, a fluorine-containing N,N,N',N'-tetraarylbenzidine derivative usable as a charge transport material, and a process for producing the same are disclosed. Furthermore, a fluorine-containing diarylamine usable for producing the fluorine-containing N,N,N',N'-tetraarylbenzidine derivative, and a process for producing the same are disclosed.
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- Reaction of Cerium(IV) Ammonium Nitrate with Aralkyl and Aromatic Ketones
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Fluoren-9-one on treatment with cerium(IV) ammonium nitrate (CAN) yields five compounds which have been identified as 3-nitro-; 2-nitro; 1,8-dinitro; 2,7-dinitro; and 2,7-dinitrofluoren-9-ones.Acetophenone on treatment with CAN, yields only benzoic acid while 2,4-dihydroxyacetophenone on similar treatment yields three compounds which have been identified as 2,4-dihydroxy-5-nitro; 2,4-dihydroxy-3-nitro; and 2,4-dihydroxy-3,5-dinitro-acetophenones.
- Chawla, H. Mohindra,Mittal, Ram S.,Johny, C. J.
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p. 992 - 993
(2007/10/02)
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