- Enantioselective formal [4+2] cycloadditions to 3-nitroindoles by trienamine catalysis: Synthesis of chiral dihydrocarbazoles
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The first enantioselective formal [4+2] cycloadditions of 3-nitroindoles are presented. By using 3-nitroindoles in combination with an organocatalyst, chiral dihydrocarbazole scaffolds are formed in moderate to good yields (up to 87 %) and enantioselectivities (up to 97 % ee). The reaction was extended to include enantioselective [4+2] cycloadditions of 3-nitrobenzothiophene. The reaction proceeds through a [4+2] cycloaddition/elimination cascade under mild reaction conditions. Furthermore, a diastereoselective reduction of an enantioenriched cycloadduct is presented. The mechanism of the reaction is discussed based on experimental and computational studies. A formal event: Enantioselective formal [4+2] cycloadditions of 3-nitroindoles in the presence of an organocatalyst are presented. Chiral dihydrocarbazole scaffolds are formed in moderate to good yields. The reaction also proceeds with 3-nitrobenzothiophene. The mechanism of the reaction is discussed based on experimental and computational studies.
- Li, Yang,Tur, Fernando,Nielsen, Rune Pagh,Jiang, Hao,Jensen, Frank,J?rgensen, Karl Anker
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- Dearomatization of 3-Nitroindoles with Highly γ-Functionalized Allenoates in Formal (3+2) Cycloadditions
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3-Nitroindoles are easily reacted with highly substituted γ-allenoates in the presence of a commercially available phosphine catalyst. For instance, allenoates derived from biomolecules such as amino and deoxycholic acids are combined for the first time w
- Birbaum, Léo,Gillard, Laurent,Gérard, Hélène,Oulyadi, Hassan,Vincent, Guillaume,Moreau, Xavier,De Paolis, Michael,Chataigner, Isabelle
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- Phosphine-catalyzed dearomative [3+2] annulation of 3-nitroindoles and allenoates
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The efficient phosphine-catalyzed dearomative [3+2] annulation of 3-nitroindoles with allenoates has been successfully developed, providing a facile access to cyclopenta[b]indolines with good to excellent yields and high diastereoselectivities. This strategy features mild reaction conditions, high functional group tolerance, and scalability. Additionally, the 2-nitrobenzofuran and 2-nitrobenzothiophene were good dearomative [3+2] annulation partners.
- Liu, Kui,Wang, Gang,Cheng, Shao-Jie,Jiang, Wen-Feng,He, Cheng,Ye, Zhi-Shi
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supporting information
p. 1885 - 1890
(2019/06/21)
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- Stereodivergent Synthesis of Tetrahydrofuroindoles through Pd-Catalyzed Asymmetric Dearomative Formal [3+2] Cycloaddition
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A stereodivergent synthesis of tetrahydrofuroindoles through palladium-catalyzed asymmetric dearomative formal [3+2] cycloaddition of nitroindoles with epoxybutenes was developed. The polarity of the solvent was found to play a key role in the diastereoselectivity. In toluene, good to excellent yields (70–99 %), diastereoselectivity (87/13->95/5 d.r.), and enantioselectivity (85/15–94/6 e.r.) were obtained, regardless of the properties of the substituents on nitroindoles. In acetonitrile, tetrahydrofuroindoles of a different diastereoisomer were produced with good to excellent yields (75–98 %) and stereoselectivity (78/22–93/7 d.r., 93/7–99/1 e.r.). Mechanistic studies were conducted to illustrate the origin of the diastereodivergency. The kinetic experiments indicate that the rate-determining step of this reaction is different in different solvents. ESI-MS experiments also support the existence of key palladium complex intermediates and the catalytic cycle of the reaction.
- Cheng, Qiang,Zhang, Fang,Cai, Yue,Guo, Yin-Long,You, Shu-Li
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supporting information
p. 2134 - 2138
(2018/02/06)
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- Palladium(0)-Catalyzed Dearomative [3 + 2] Cycloaddition of 3-Nitroindoles with Vinylcyclopropanes: An Entry to Stereodefined 2,3-Fused Cyclopentannulated Indoline Derivatives
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The palladium(0)-catalyzed diastereoselective dearomative cyclopentannulation of 3-nitroindoles with vinylcyclopropanes is described. This straightforward and highly atom-economical method leads to a wide range of functionalized indolines in good yields a
- Laugeois, Maxime,Ling, Johanne,Férard, Charlène,Michelet, Véronique,Ratovelomanana-Vidal, Virginie,Vitale, Maxime R.
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supporting information
p. 2266 - 2269
(2017/05/12)
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- Catalytic C-2 Allylation of Indoles by Electronic Modulation of the Indole Ring and its Application to the Synthesis of Functionalized Carbazoles
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We report a palladium-catalyzed C-2 allylation of indoles and subsequent cyclization of the allylated indoles. The electronic effects of chloro and ester groups that can be readily installed at the C-3 position of indoles facilitated a highly efficient C–H allylation at the C-2 position. The resulting 2-allyl-3-chloroindoles were found to be suitable substrates for benzannulation reactions with alkynes and norbornadiene as an acetylene synthon. This approach, utilizing readily available indoles, allyl acetates, and norbornadiene, allows a rapid access to complex carbazoles. (Figure presented.).
- Lee, Ju Young,Ha, Hyeri,Bae, Seri,Han, Inhyuk,Joo, Jung Min
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p. 3458 - 3470
(2016/11/13)
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- Diels-Alder reactions of N-tosyl-3-nitroindole and dienamides: Synthesis of intermediates of Aspidospermine alkaloids
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N-tosyl-3-nitroindole undergoes high yielding Diels-Alder reactions with 1-(N-acyl-N-alkylamino)-1,3-butadienes in a regioselective manner, to afford advanced intermediates for the synthesis of Aspidospermine alkaloids.
- Biolatto, Betina,Kneeteman, Maria,Mancini, Pedro
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p. 3343 - 3346
(2007/10/03)
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