- Zinc mediated straightforward access to diacylpyrroles
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In this article, we report the preparation of various 2,4- and 2,5-diacylpyrroles via two zinc-mediated acylation reactions of non-protected pyrroles.
- Faye, Djiby,Mbaye, Mbaye Diagne,Coufourier, Sébastien,Lator, Alexis,Dieng, Samba Yandé,Gaillard, Sylvain,Renaud, Jean-Luc
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p. 492 - 499
(2017/05/19)
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- Synthesis and properties of polyquinolines and polyanthrazolines containing pyrrole units in the main chain
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A series of eight new polyquinolines and polyanthrazolines with pyrrole isomeric units in main chain were synthesized and characterized. The new polymers showed high glass transition temperatures (Tg = 242-339°C) and excellent thermal stability (T5% = 398-536°C in air, TGA). Compared to the series of polyanthrazolines, the series of polyquinolines exhibited higher thermal stability, better solubility in common organic solvents, and lower maximum absorption wavelengths (λmaxa). Polyanthrazolines with 2,5-pyrrole linkage showed an unusually high λmaxa (565 nm) and small band gap (2.02 eV). All polymers in solution had low photoluminescence quantum yields between 10-2% and 10-5% and excited-state lifetimes of 0.28-1.29 ns. The effects of molecular structure, especially pyrrole linkage structures, on the electronic structure, thermodynamics, and some of the optical properties of the polymers were explored. A model of hydrogen bonds in the main chain of the polymers was suggested to explain the difference in the properties of the isomer polymers. In addition, a polyquinoline (PBM) was chosen to examine the proton conductivity; the result indicated that the PBM/H3PO4 complex exhibited a high conductivity of 1.5 × 10-3 S cm-1 at 157°C. The new polymers are expected to have improved proton-conducting properties for the application as the membranes in fuel cells.
- Hou, Shifa,Ding, Mengxian,Gao, Lianxun
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p. 3826 - 3832
(2007/10/03)
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- 2-SUBSTITUTED 1,3-BENZODITHIOLIUM TETRAFLUOROBORATES AS USEFUL ACYLATING AGENTS OF PYRROLE
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A comparative study on the acylation of pyrrole by utilizing 2-substituted 1,3-benzodithiolium tetrafluoroborates instead of 2-substituted 1,3-benzoxathiolium tetrafluoroborates has been accomplished.The use of 2-substituted 1,3-benzodithiolium tetrafluoroborates proved to be more convenient since it gives higher yields of 2-acylpyrroles (58-90percent) and appears of larger applicability for the preparation of symmetrical and unsymmetrical 2,5-diacylpyrroles which were obtained in most cases in quantitative yields.
- Barbero, Margherita,Cadamuro, Silvano,Degani, Iacopo,Dughera, Stefano,Fochi, Rita,et al.
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p. 619 - 627
(2007/10/02)
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- Acylation of Pyrrole and N-Methylpyrrole with 1,3-Benzoxathiolium Tetrafluroborates. A High-Yield Method for the Synthesis of Diacylpyrroles
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2-Substituted 1,3-benzoxathiolium tetrafluoroborates (I) were used as masked acylating agents for pyrrole and N-methylpyrrole.The reactions on pyrrole (II) were regiospecific, and according to the molar ratio of the reagents (I:II = 1:3 or 2.5-3:1), 2-acylpyrroles were obtained in moderate to good yields (38-82percent) and 2,5-diacylpyrroles were obtained in excellent yields (in most cases, quantitative).The reactions on N-methylpyrrole (III) were not regioselective, and both α- and β-positions were attacked.So, depending on the molar ratio of the reagents (I:III = 1:3 or 2,5-3:1), 2- and 3-acyl-N-methylpyrroles (9-51percent and 27-68percent yields, respectively) and 2,4- and 2,5-diacyl-N-methylpyrroles (60-93percent and 17-40percent, respectively) were obtained.A very interesting feature of the new method is the possibility of introducing two identical or different acyl groups in the pyrrole ring under mild conditions. 1H and 13C NMR spectra of all the new compounds and IR spectra, recorded in the gas phase, of 2- and 3-acylpyrroles and of 2,4- and 2,5-diacylpyrroles are reported.
- Barbero, Margherita,Cadamuro, Silvano,Degani, Iacopo,Fochi, Rita,Gatti, Antonella,Regondi, Valeria
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p. 2245 - 2250
(2007/10/02)
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