- A nanophase segregated mesophase morphology in self-organized novel disc-rod oligomesogens
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A nanophase segregated layered phase (SmA) with alternating calamitic and discotic layers was observed for the first time in novel linked disc-rod oligomesogens, containing six cyanobiphenyl moieties radially-attached to a central tricycloquinazoline discotic heteroaromatic core via flexible alkyl spacers. The Royal Society of Chemistry 2009.
- Bisoyi, Hari Krishna,Raghunathan,Kumar, Sandeep
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- Hexaalkoxytricycloquinazolines: New Discotic Liquid Crystals
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Tricycloquinazoline (TCQ), a molecule of both biological and physical interest, has been found to function as the core fragment for a new family of discotic mesogens, which have C3 symmetry and six aliphatic side chains.Six representative homologous 2,3,7,8,12,13-hexaalkoxy-TCQ derivatives 5 were synthesized, with alkyl side chain lengths varying from 3 to 16 carbon atoms.These highly fluorescent, heteroaromatic compounds are conveniently obtained by alkylation of hexahydroxy-TCQ, 10.The latter is prepared by trimerization of 5,6-dimethoxyanthranil, 8, followed by demethylation of the resultant hexamethoxy-TCQ, 9.All compounds, 5, are mesogenic within a very broad temperature range.The nature of these new mesophases was studied by DSC and by optical microscopy with polarized light and X-ray diffraction.DSC measurements show highly reversible behavior at both melting and clearing points, indicating high chemical stability.Photomicroscopic pictures show mosaic textures, characteristic of an ordered hexagonal, columnar phase (Dho), that are very similar to those we reported earlier for hexakis(thioalkoxy)-TCQ derivatives 4.The diffraction spacings of two representative compounds (having 5 and 11 carbon atoms in the side chain) in the mesophase are consistent with a two-dimensional hexagonal lattice having unit cell sides of a = 21.2 and 28.7 Angstroem, respectively, and containing one molecule per unit cell.
- Kumar, Sandeep,Wachtel, Ellen J.,Keinan, Ehud
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- Rh(iii)-Catalyzed tandem indole C4-arylamination/annulation with anthranils: Access to indoloquinolines and their application in photophysical studies
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An efficient Rh(iii)-catalyzed straightforward strategy was developed for the tandem C4 arylamination/annulation of indole derivatives with anthranil to provide indoloquinoline moieties. This method is simple and regioselective with a wide scope and functional group tolerance. Mechanistic studies revealed the important role of the newly installed azacycle in the conversion of O-protected aldoximes to their cyano derivatives. Studies were carried out to explore the promising photophysical properties of the obtained indoloquinoline derivatives.
- Biswas, Aniruddha,Bera, Satabdi,Poddar, Puja,Dhara, Dibakar,Samanta, Rajarshi
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p. 1440 - 1443
(2020/02/11)
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- Ambient reductive synthesis of N-heterocyclic compounds over cellulose-derived carbon supported Pt nanocatalyst under H2atmosphere
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N-heterocyclic compounds are important chemicals, and their reductive synthesis using H2 under mild conditions is attractive but challenging. Herein, we report chemoselective hydrogenation of 2-nitroacylbenzenes to 2,1-benzisoxazoles under ambient conditions for the first time, wihch is achieved over cellulose-derived carbon (c-C) supported Pt nanocatalyst (Pt/c-C), and a series of 2,1-benzisoxazoles can be obtained in excellent yields. Pt/c-C also shows high performance for ambient reductive amination of levulinic acid with H2, accessing various pyrrolidones in excellent yields. The systematic studies indicated that the c-C support played multiple roles in catalysis with enhancing electron density of the Pt nanoparticles and activating reactant molecules. Especially, the O-containing groups on the c-C surface provided the c-C support with both acid and base features, thus endowing Pt/c-C with high performances. This work provides an accessible and highly efficient catalyst for reductive synthesis of N-heterocycles using H2 under ambient conditions, which may have promising applications.
- Wu, Yunyan,Wu, Yunyan,Zhao, Yanfei,Zhao, Yanfei,Wang, Huan,Wang, Huan,Zhang, Fengtao,Zhang, Fengtao,Li, Ruipeng,Li, Ruipeng,Xiang, Junfeng,Wang, Zhenpeng,Han, Buxing,Liu, Zhimin
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p. 3820 - 3826
(2020/07/06)
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- Simple and scalable electrochemical synthesis of 2,1-benzisoxazoles and quinoline: N -oxides
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Cathodic reduction of the nitro moiety and subsequent intramolecular cyclization affords different substituted 2,1-benzisoxazoles and quinoline N-oxides. This methodology allows the synthesis of two different types of heterocycles from common simple starting materials, using electrons as a sole reagent for this transformation. The electrolysis can be conducted in a very simple undivided electrolysis cell under constant current conditions. This permits working on a larger scale compared to other electrochemical methodologies and represents a significant advantage.
- Rodrigo, Eduardo,Baunis, Haralds,Suna, Edgars,Waldvogel, Siegfried R.
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p. 12255 - 12258
(2019/10/22)
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- RhIII-Catalyzed Straightforward Synthesis of Benzophenanthroline and Benzophenanthrolinone Derivatives using Anthranils
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An efficient pot-economic and step-economic RhIII-catalyzed site-selective direct amination/annulation strategy was developed for the synthesis of benzophenanthroline derivatives using quinoline N-oxides and anthranils. The method was further extended to the synthesis of nitrogen-containing extended π-conjugated benzophenanthrolinone derivatives. Late-stage functionalizations of cinchonidine and cinchophen derivatives and synthesis of a bioactive quinolino-indole were achieved.
- Biswas, Aniruddha,Sarkar, Souradip,Samanta, Rajarshi
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p. 3000 - 3004
(2019/02/13)
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- Gold-Catalyzed Annulations of N-Propargyl Ynamides with Anthranils with Two Distinct Chemoselectivities
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Gold-catalyzed annulation of N-propargyl ynamides with anthranils can proceed by two distinct mechanisms. In the case of a terminal N-propargyl ynamide, its resulting α-imino gold carbene reacts with a tethered alkyne to generate a vinyl cation to enable hydrolysis, which ultimately yields a pyrrolo[2,3-b]quinoline derivative after treatment with p-toluenesulfonic acid. For an internal alkyne, its α-imino gold carbene reacts with a tethered alkyne via either a vinyl cation or an alkenylgold carbene; both paths ultimately lead to a 4-ketone-2-aminopyrrole derivative. Our mechanistic analysis indicates that water is a better nucleophile than anthranil for terminal ynamides, whereas water and anthranils are equally reactive for internal ynamides.
- Hsu, Yu-Chen,Hsieh, Shu-An,Liu, Rai-Shung
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p. 5288 - 5297
(2019/03/26)
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- Catalyst-free cyclization of anthranils and cyclic amines: One-step synthesis of rutaecarpine
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An efficient synthesis of a variety of quinazolinone derivatives via a direct cyclization reaction between commercially available anthranils and cyclic amines is described. The developed transformation proceeds with the merits of high step- and atom-efficiency, a broad substrate scope, and good to excellent yields, without additional catalysts, and offers a practical way for the preparation of rutaecarpine and its derivatives with structural diversity.
- Li, Jian,Wang, Zheng-Bing,Xu, Yue,Lu, Xue-Chen,Zhu, Shang-Rong,Liu, Li
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supporting information
p. 12072 - 12075
(2019/10/14)
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