- Rhodium-catalyzed cyclization of diynes with nitrones: A formal [2+2+5] approach to bridged eight-membered heterocycles
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N-aryl-substituted nitrones were employed as fiveatom coupling partners in the rhodium-catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C-H activation of the N-aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight-membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles,.
- Wang, Chunxiang,Wang, Dongping,Yan, Hao,Wang, Haolong,Pan, Bin,Xin, Xiaoyi,Li, Xincheng,Wu, Fan,Wan, Boshun
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- Regio-and stereoselectivity of [3+2] cycloaddition reaction of methacrolein with diarylnitrones catalyzed by chiral rhodium complex
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Stereoselective 1,3-dipolar cycloadditions asymmetric reaction between C,N-diarylnitrones and methacrolein catalyzed by the aqueous complex [(C5Me5)Rh(DPPP*).(H2O)] (SbF6)2, (DPPP = bis 1,2- diphenylphosphinopropane) at -20 °C are described. We have succeeded in synthesizing nitrones described in the literature with good yields, and those, N-phenyl-Cphenylnitrones which are not described in the literature, with appreciable yields. The isoxazolidines formed from the condensation of these nitrones with methacrolein have been found to be new compounds. The resulting endoisoxazolidines are obtained in modest to high regioselectivity and with ee up to 91%.
- DJAHIECHE, Madiha,BOUFENAYA, Hamza,BOUKHARI, Abbes
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p. 973 - 980
(2021/02/05)
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- Tandem Chiral Cu(II) Phosphate-Catalyzed Deoxygenation of Nitrones/Enantioselective Povarov Reaction with Enecarbamates
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A new catalytic enantioselective tandem deoxygenation/aza-Diels-Alder reaction of nitrones with enecarbamates was serendipitously discovered in the presence of chiral copper(II) diphosphate complexes. This process affords a wide range of 4-aminotetrahydroquinolines in respectable yields under mild conditions with good to excellent ee values.
- Gelis, Coralie,Levitre, Guillaume,Guérineau, Vincent,Touboul, David,Neuville, Luc,Masson, Géraldine
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p. 5151 - 5155
(2019/06/27)
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- Regio-and stereoselectivity of [3+2] cycloaddition reaction of methacrolein with diarylnitrones catalyzed by chiral rhodium complex
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Stereoselective 1,3-dipolar cycloadditions asymmetric reaction between C,N-diarylnitrones and methacrolein catalyzed by the aqueous complex [(C5Me5)Rh(DPPP*).(H2O)] (SbF6)2, (DPPP = bis 1,2-diphenylphosphinopropane) at -20 oC are described. We have succeeded in synthesizing nitrones described in the literature with good yields, and those, N-phenyl-Cphenylnitrones which are not described in the literature, with appreciable yields. The isoxazolidines formed from the condensation of these nitrones with methacrolein have been found to be new compounds. The resulting endoisoxazolidines are obtained in modest to high regioselectivity and with ee up to 91%.
- Djahieche, Madiha,Boufenaya, Hamza,Boukhari, Abbes
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p. 973 - 980
(2020/06/27)
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- Preparation method of 2-amino-5-halogen phenol compounds
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The invention relates to a preparation method of 2-amino-5-halogen phenol compounds. The compounds are very important intermediates in fine chemistry. Due to the ortho-position special relation of a hydroxyl group in an amino group, the compounds are important raw materials for preparing heterocyclic compounds such as the benzoxazolone compound and the benzothiazolone compound which are intermediates with the important value in medical drugs. The 2-amino-5-halogen phenol compounds can serve as anti-cancer drugs such as hydroxamic acid anti-cancer drugs and intermediates of dye and have wide application in chemical engineering, soft matter, materials and the like. According to the method, nitrone is taken as a raw material and easily prepared from a halogen nitrobenzene compound; raw materials of the halogen nitrobenzene compound are low in cost and wide in source.
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Paragraph 0019; 0020; 0021
(2017/08/28)
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- Visible-light-mediated anti-regioselective nitrone 1, 3-dipolar cycloaddition reaction and synthesis of bisindolylmethanes
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The development of photoredox reactions of 1, 3- dipolar cycloaddition of nitrones with alkenes is reported. It offers an efficient synthetic method to obtain isoxazolidine derivatives under mild conditions in synthetically useful yields. The nitrones are cyclized with oxidizable styrenes and aliphatic alkenes via a polar radical crossover cycloaddition reaction through photocatalytic reaction without additives. In addition, bis(indole)methanes can also be prepared through this method.
- Zheng, Lewei,Gao, Fei,Yang, Chao,Gao, Guo-Lin,Zhao, Yating,Gao, Yuan,Xia, Wujiong
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supporting information
p. 5086 - 5089
(2017/11/07)
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- Synthesis of 2,3-Disubstituted NH Indoles via Rhodium(III)-Catalyzed C-H Activation of Arylnitrones and Coupling with Diazo Compounds
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A rhodium-catalyzed intermolecular coupling between arylnitrones and diazo compounds by C-H activation/[4 + 1] annulation with a C(N2)-C(acyl) bond cleavage is reported, and 2,3-disubstituted NH indoles are directly synthesized in up to a 94% yield. A variety of functional groups are applicable to this reaction to give the corresponding products with high selectivity. Compared to other previously reported Rh(III)-catalyzed synthesis of homologous series, this method is simpler, more general, and more efficient.
- Guo, Xin,Han, Jianwei,Liu, Yafeng,Qin, Mingda,Zhang, Xueguo,Chen, Baohua
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p. 11505 - 11511
(2017/11/10)
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- Synthesis of Benzimidazolones via One-Pot Reaction of Hydroxylamines, Aldehydes, and Trimethylsilyl Cyanide Promoted by Diacetoxyiodobenzene
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A novel and efficient PhI(OAc)2-promoted one-pot reaction of aromatic hydroxylamines, aldehydes, and TMSCN in the presence of BF3·Et2O is described. A wide variety of N-substituted benzimidazolones are obtained with satisfactory yields under mild reaction conditions. The method was proven to be efficient for the synthesis of benzimidazolone derivatives from readily available starting materials.
- Zhang, Huaiyuan,Huang, Danfeng,Wang, Ke-Hu,Li, Jun,Su, Yingpeng,Hu, Yulai
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p. 1600 - 1609
(2017/02/10)
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- Iron-Catalyzed Cyclization of Nitrones with Geminal-Substituted Vinyl Acetates: A Direct [4 + 2] Assembly Strategy Leading to 2,4-Disubstituted Quinolines
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An iron-catalyzed intermolecular [4 + 2] cyclization of arylnitrones with geminal-substituted vinyl acetates was developed for the synthesis of 2,4-disubstituted quinolines in moderate to good yields with good functional group compatibilities. Preliminary mechanistic studies suggest a plausible iron-catalyzed C-H activation process under external-oxidant-free conditions.
- Zhong, Mingbing,Sun, Song,Cheng, Jiang,Shao, Ying
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p. 10825 - 10831
(2016/11/29)
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- Gold-catalyzed cyclization-cycloaddition cascade reactions of allenyl acetals with nitrones
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Gold and silver: When allenyl acetals and nitrones are treated with a catalytic amount of a gold complex and a silver salt they react through a cyclization-cycloaddition cascade reaction to give a mixture of diastereomeric tricyclic products. The mixture converges to a single product upon acid hydrolysis (see scheme). The key intermediate is postulated to be a 1-methoxyfulvene species. Copyright
- Vasu, Dhananjayan,Liu, Rai-Shung
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supporting information
p. 13638 - 13641
(2013/01/15)
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- Cu(I)/Bis(azaferrocene)-catalyzed enantioselective synthesis of β-lactams via couplings of alkynes with nitrones
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As a consequence of the wide-ranging significance of β-lactams (e.g., use as drugs and as chiral building blocks), a great deal of effort has been dedicated to the development of methods for their stereoselective synthesis. Although considerable progress has been achieved, nearly all of the approaches that have been described are based on the use of chiral precursors; direct catalytic enantioselective routes to β-lactams are rare as well as limited in scope. In this communication, we establish that, using a new C2-symmetric planar-chiral bis(azaferrocene) ligand, we can generate β-lactams with very good enantiomeric excess and cis diastereoselection via catalytic enantioselective Kinugasa reactions (couplings of alkynes with nitrones). Appealing attributes of this process include the ready availability of the starting materials, the functional-group tolerance of the reaction, and the convergency of the approach. Copyright
- Lo, Michael M.-C.,Fu, Gregory C.
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p. 4572 - 4573
(2007/10/03)
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- 13C and 1H NMR of Arylnitrones. Substituent Effects of α-Phenyl-N-(p-substituted phenyl)nitrones
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Substituent effects on the chemical shifts of the conjugation sites in α-phenyl-N-arylnitrones (2) have been investigated.Resonance effects predominate at these positions.The electronic effects of the substituents should be treated separately between electron-donating groups and electron-donating groups and electron-withdrawing ones.A plausible mechanism for the transmission of substituent effects in 2 has been proposed.
- Suda, Kohji,Tsujimoto, Toshio,Yamauchi, Masashige
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p. 3607 - 3612
(2007/10/02)
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