- Easy Access to 2,4-Disubstituted Cyclopentenones by a Gold(III)-Catalyzed A3-Coupling/Cyclization Cascade
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An efficient and convenient synthesis of 2,4-disubstituted cyclopentenones has been achieved through a Au(III)-catalyzed isomerization-A3-coupling/cyclization cascade. A possible mechanism involving an initial Au(III)-catalyzed isomerization, A3-type coupling, and cyclization via an enol intermediate is postulated.
- Hu, Xiwen,Li, Jian,Liu, Li,Xu, Yue,Zhu, Shangrong
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supporting information
p. 9478 - 9483
(2020/12/21)
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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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- 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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supporting information
p. 14666 - 14672
(2019/09/06)
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- Retro Aza Diels-Alder Reactions of 2-Azanorbornenes: Improved Methods for the Unmasking of Primary Amines
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The unmasking of primary amines via the heterocycloreversion of N-alkyl-2-azanorbornenes can be catalyzed by either copper(II) or a sulfonic acid based ion exchange resin which obviates the necessity of employing a reactive dienophile to trap the cyclopentadiene as it is produced.
- Grieco, Paul A.,Clark, Jerry D.
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p. 2271 - 2272
(2007/10/02)
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- Evidence for a Radical Chain Mechanism for the Knabe Reaction of 1,2-Dihydro-2-methylpapaverine
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A free radical chain mechanism is proposed for the Knabe reaction and the accompanying elimination reaction on account of their nonintegral reaction order and of successful inhibition experiments. 3,4-Dimethoxybenzyl radicals are the chain carrying species.Battersby's synthesis of N-methylpavine (19) from 1,2-dihydro-2-methylpapaverine (9) is dependent on the presence of formic acid as radical chain inhibitor.In the presence of inhibitors 1-benzyl-1,4-dihydro-2-methylisoquinolinium ions like 10 are persistent species whose chemistry can now be investigated.
- Langhals, Elke,Langhals, Heinz,Ruechardt, Christoph
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p. 1436 - 1454
(2007/10/02)
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- 1,2,4-Oxadiazine derivatives, process for their preparation and pharmaceutical compositions containing them
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The invention concerns new compounds of the general formula (I) STR1 wherein R1 is hydrogen or phenyl optionally substituted by one or more of the following substituents: alkyl having 1 to 4 carbon atoms, halogen, alkoxy having 1 to 4 carbon atoms or nitro; R2 is alkyl having 1 to 4 carbon atoms, cycloalkyl having 5 to 7 carbon atoms or phenyl, optionally substituted with one or more of the following groups: alkyl having 1 to 4 carbon atoms, halogen, alkoxy having 1 to 4 carbon atoms or nitro; or R2 is a naphthyl group; R3 is alkyl having 1 to 4 carbon atoms, acyl or hydrogen; R4 hydrogen or alkyl having 1 to 4 carbon atoms; R5 is cycloalkyl having 5 to 7 carbon atoms, alkyl having 1 to 6 carbon atoms, phenyl-(C1-4 -alkyl) in which the phenyl moiety may optionally be substituted with alkoxy having 1 to 4 carbon atoms, halogen or nitro; or R4 and R5 together represent a group of the general formula (V) STR2 wherein R6 is hydrogen or alkoxy having 1 to 4 carbon atoms, m and n stand for 0, 1 or 2 and acid addition and quaternary salts thereof. The compounds of the general formula (I) are potent peripheral vasodilators and hypotensive agents. They increase the coronary blood flow and in addition to their slight antiinflammatory and diuretic acidivity possess strong antiarrhythmic properties. A process for the preparation of these compounds and pharmaceutical compositions containing them are also within the scope of the invention.
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