- Intramolecular Reductive Cyclization of o-Nitroarenes via Biradical Recombination
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A visible-light-induced/thiourea-mediated intramolecular cyclization of o-nitroarenes under mild conditions is realized for the first time, which provides an efficient and environmentally friendly way to access pharmaceutical relevant quinazolinone derivatives. The reaction can be easily extended to gram level by using a continuous-flow setup with high efficiency. Mechanistic investigation including control experiments, transient fluorescence, UV-vis spectra, and DFT calculations suggests that the formation of active biradical intermediates via intramolecular single electron transfer (SET) is key stage in the catalytic cycle.
- Lu, Cong,Su, Zhishan,Jing, Dong,Jin, Songyang,Xie, Lijuan,Li, Liangrui,Zheng, Ke
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p. 1438 - 1443
(2019/03/07)
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- Metal-Free Synthesis of Polycyclic Quinazolinones Enabled by a (NH4)2S2O8-Promoted Intramolecular Oxidative Cyclization
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An efficient metal-free, (NH4)2S2O8 mediated intramolecular oxidative cyclization for the construction of polycyclic heterocycles was disclosed. A series of polycyclic quinazolinone derivatives with good functional group tolerance were obtained in high yields. The natural products tryptanthrin and rutaecarpine, as well as their derivatives, were easily synthesized by this strategy. A preliminary mechanism study suggested the carbon-centered radical was involved in the catalytic cycle.
- Xie, Lijuan,Lu, Cong,Jing, Dong,Ou, Xinrui,Zheng, Ke
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p. 3649 - 3653
(2019/06/04)
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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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p. 12072 - 12075
(2019/10/14)
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- Light-Driven Intramolecular C?N Cross-Coupling via a Long-Lived Photoactive Photoisomer Complex
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Reported herein is a visible-light-driven intramolecular C?N cross-coupling reaction under mild reaction conditions (metal- and photocatalyst-free, at room temperature) via a long-lived photoactive photoisomer complex. This strategy was used to rapidly prepare the N-substituted polycyclic quinazolinone derivatives with a broad substrate scope (>50 examples) and further exploited to synthesize the natural products tryptanthrin, rutaecarpine, and their analogues. The success of gram-scale synthesis and solar-driven transformation, as well as promising tumor-suppressing biological activity, proves the potential of this strategy for practical applications. Mechanistic investigations, including control experiments, DFT calculations, UV-vis spectroscopy, EPR, and X-ray single-crystal structure of the key intermediate, provides insight into the mechanism.
- Jing, Dong,Lu, Cong,Chen, Zhuo,Jin, Songyang,Xie, Lijuan,Meng, Ziyi,Su, Zhishan,Zheng, Ke
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p. 14666 - 14672
(2019/09/06)
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- NOVEL TETRAHYDROISOQUINOLINES AND TERAHYDRONAPHTHYRIDINES FOR THE TREATMENT AND PROPHYLAXIS OF HEPATITIS B VIRUS INFECTION
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The present invention provides novel compounds having the general formula (I): wherein R1, R 2, R 3, U, V, W, X and Y are as described herein, compositions including the compounds and methods of using the compounds.
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- Activation of electrophilicity of stable Y-delocalized carbamate cations in intramolecular aromatic substitution reaction: Evidence for formation of diprotonated carbamates leading to generation of isocyanates
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Although cations with three heteroatoms, such as monoprotonated guanidine and urea, are stabilized by Y-shaped conjugation and such Y-conjugated cations are sufficiently basic to be further protonated (or protosolvated) to dications in strongly acid media, only O-monoprotonated species have been detected in the case of carbamates even in magic acid. We found that the trifluoromethanesulfonic acid-catalyzed cyclization of arylethylcarbamates proceeds to afford dihydroisoquinolones in high yield. In strong acids, methyl carbamates are fully O-monoprotonated, and these monocations do not undergo cyclization even under heating. But, as the acidity of the reaction medium is further increased, the cyclization reaction of methyl phenethylcarbamates starts to proceed as a first-order reaction, with a linear relationship between rate and acidity. The sign and magnitude of the entropy of activation ΔS ? were found to be similar to those of other AAc1 reactions. These results strongly support the idea that further protonation of the O-protonated carbamates is involved in the cyclization, but the concentration of the dications is very low and suggests that the rate-determining step is dissociation of methanol from the diprotonated carbamate to generate protonated isocyanate, which reacts with the aromatic ring. Therefore, O-protonated carbamates are weak bases in sharp contrast to other Y-shaped monocations.
- Kurouchi, Hiroaki,Kawamoto, Kyoko,Sugimoto, Hiromichi,Nakamura, Satoshi,Otani, Yuko,Ohwada, Tomohiko
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p. 9313 - 9328,16
(2012/12/11)
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- Tetrahydrobenzindole derivatives
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Compounds containing tetrahydrobenzindole which bind to serotonin receptor and are useful in treatment or prevention of disease induced by abnormality of central peripheral serotonin controlling functions.
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