- Br?nsted Base-Catalyzed Umpolung Intramolecular Cyclization of Alkynyl Imines
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A novel “umpolung” intramolecular cyclization of alkynyl imines, in which the electrophilic imine sp2-carbon formally serves as a nucleophilic site, was developed under Br?nsted base catalysis. The reaction involves the unprecedented catalytic generation of α-aminoester enolates from α-iminoesters via the 1,2-addition of the anion of a secondary phosphite to an imine moiety followed by the [1,2]-rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen, which is a formal umpolung process, and the intramolecular addition to an alkyne. This is a rare example of a [1,2]-rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen to generate an α-amino carbanion and the first catalytic carbon–carbon bond forming reaction utilizing the resulting carbanion as a nucleophile.
- Kondoh, Azusa,Terada, Masahiro
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- Synthesis of 3-((trifluoromethyl)thio)indoles via trifluoromethylthiolation of 2-alkynyl azidoarenes with AgSCF3
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Direct and effective trifluoromethylthiolation of 2-alkynyl azidoarenes with silver(I) trifluoromethanethiolate (AgSCF3) has been developed for the construction of 3-((trifluoromethyl)thio)indoles. The trifluoromethylthiolation protocol is compatible with a broad substrate scope, providing a variety of 3-((trifluoromethyl)thio)indoles in moderate to good yields within one step, open-air, and short reaction time.
- Betterley, Nolan M.,Kuhakarn, Chutima,Leowanawat, Pawaret,Phetcharawetch, Jongkonporn,Reutrakul, Vichai,Soorukram, Darunee
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supporting information
(2021/09/10)
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- Cyclization of Alkyne-Azide with Isonitrile/CO via Self-Relay Rhodium Catalysis
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A self-relay rhodium(I)-catalyzed cyclization of alkyne-azides with two σ-donor/π-acceptor ligands (isonitriles and CO) to form sequentially multiple-fused heterocycle systems via tandem nitrene transformation and aza-Pauson-Khand cyclization has been dev
- Zhang, Zhen,Xiao, Fan,Huang, Baoliang,Hu, Jincheng,Fu, Bin,Zhang, Zhenhua
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supporting information
p. 908 - 911
(2016/03/15)
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- Tandem synthesis of benzo[b]carbazoles and their photoluminescent properties
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5 H-Benzo[b]carbazoles were prepared through a tandem reaction between 2-ethynyl-N-triphenylphosphoranylidene anilines and α-diazoketones through ketenimine intermediates in moderate-to-good yields. By using this approach, benzo[b]benzo[5,6]indolo[3,2-h]carbazoles, fluoreno[9,1-ab]carbazoles, and fluoreno[9,1-ab]fluoreno[1′,9′:5,6,7]indolo[3,2-h]carbazoles were constructed in one pot. Moreover, the resulting products emitted light within the range 410-521a nm, with quantum yields of up to 62 %. Lord of the rings: A series of benzo[b]carbazoles was synthesized through a tandem Wolff-rearrangement/aza-Wittig-reaction/biradical-ketenimine-cyclization/1, 5-H-shift process. The products emitted intense light with high emission quantum yields (see scheme). Copyright
- Xing, Yanpeng,Hu, Binbin,Yao, Qijun,Lu, Ping,Wang, Yanguang
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supporting information
p. 12788 - 12793
(2013/10/01)
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- Umpolung reactivity of indole through gold catalysis
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Electrophilic indole? Indoles, which are typically nucleophilic, can be made electrophilic through gold catalysis. By using an ortho-azido group to deliver a nitrene intramolecularly, an arylalkyne is converted into a gold carbene intermediate containing an indole skeleton that is highly electrophilic at the 3-position. A range of functionalized indoles is readily accessed by utilizing this strategy.
- Lu, Biao,Luo, Yingdong,Liu, Lianzhu,Ye, Longwu,Wang, Yanzhao,Zhang, Liming
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supporting information; experimental part
p. 8358 - 8362
(2011/10/31)
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- A novel heterocumulenic Pauson-Khand reaction of alkynylcarbodiimides: A facile and efficient synthesis of heterocyclic ring-fused pyrrolinones
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The first examples of the heterocumulenic Pauson-Khand reaction are described. Alkynylcarbodiimides undergo an intramolecular Pauson-Khand cycloaddition upon heating in the presence of Mo(CO)6 and DMSO to afford 4,5-dihydro-1H-pyrrolo[2,3-b]pyrrolin-2-ones and 1H-pyrrolo[2,3-b]indol-2-ones.
- Saito, Takao,Shiotani, Masahiro,Otani, Takashi,Hasaba, Satoshi
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p. 1045 - 1048
(2007/10/03)
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- A study of vinyl radical cyclization onto the azido group by addition of sulfanyl, stannyl, and silyl radicals to alkynyl azides
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Thermal radical reactions of azidoalkynes 2, 8, 14, and 21a-c with thiols 1a-c afford 2-sulfanylvinyl radicals by selective addition of sulfanyl radicals to the triple bond. 1-Phenylvinyl radicals 23 and 30a, as well as vinyl radical 30b, undergo fast 5-cyclization onto the aromatic azide function to give cyclized indoles. In contrast, both 1-phenyl (15, 17) and 1-alkyl (3a,b, 9) vinyl radicals fail to add to their aliphatic azido substituents and exclusively undergo cyclization onto the aromatic sulfanyl ring and H transfer from the thiol precursor. Azidoalkynes 14 and 21a react with Bu3SnH and TMSS under radical conditions to give instead the corresponding amines as a result of preferential attack of Bu3Sn · and (TMS)3Si · radicals on the azido group rather than on the triple bond. Evidence is provided that alkyl radical cyclizations onto azides are not feasible in the presence of thiol, in contrast with the reported utility of these cyclization reactions in the presence of Bu3SnH and TMSS.
- Montevecchi, Pier Carlo,Navacchia, Maria Luisa,Spagnolo, Piero
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p. 1219 - 1226
(2007/10/03)
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