- An iron(iii)-catalyzed dehydrogenative cross-coupling reaction of indoles with benzylamines to prepare 3-aminoindole derivatives
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We report a green cascade approach to prepare a variety of 3-aminoindole derivatives in good to excellent yields through an iron(iii)-catalyzed dehydrogenative cross-coupling reaction of 2-arylindoles and primary benzylamines under mild reaction conditions. Mechanistic studies show that a cascade reaction involves a tert-butyl nitrite (TBN)-mediated nitrosation of 2-substituted indoles and a 1,5-hydrogen shift to afford indolenine oximes, sequential iron(iii)-catalyzed condensation and a 1,5-hydrogen shift over four steps in a one-pot reaction. The reaction shows a broad substrate scope of indoles and benzylamines and tolerates a wide range of functional groups. Moreover, the reaction is easily performed at the gram scale without producing waste after the reaction is completed. The 3-aminoindole product is purified by simple extraction, washing, and recrystallization without flash column chromatography. A double imine ligand containing the 3-aminoindole unit is facile to obtain in a 52% yield in one step. The present method highlights readily available starting materials, a simple purification procedure, and the usage of cheap, nontoxic, and environmentally benign iron(iii) catalysts. This journal is
- Chen, Wei-Li,Li, Kun,Liang, Cui,Liang, Wang-Fu,Liao, Wei-Cong,Mo, Dong-Liang,Qiu, Pei-Wen,Su, Gui-Fa
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p. 9610 - 9616
(2021/12/09)
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- Copper-Catalyzed Enantioselective C-H Arylation between 2-Arylindoles and Hypervalent Iodine Reagents
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The copper-catalyzed enantioselective C-H arylation between 2-arylindoles and hypervalent iodine reagents has been successfully developed, which provides a convenient and economical route to the highly atroposelective synthesis of axially chiral indole de
- Liang, Hao,Zhu, Guoxun,Pu, Xiaoyun,Qiu, Liqin
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supporting information
p. 9246 - 9250
(2021/12/06)
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- α-Imino Iridium Carbenes from Imidoyl Sulfoxonium Ylides: Application in the One-Step Synthesis of Indoles
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Imidoyl sulfoxonium ylides are presented for the first time as potential precursors to generate α-imino metal-carbene intermediates and applied in direct C-H functionalization reactions catalyzed by [Ir(cod)Cl]2 (4 mol %) to provide 2-substituted indoles (up to 70% yield) in just one step. This class of sulfur ylide is successfully obtained from imidoyl chloride and dimethylsulfoxonium methylide (23 new examples in 45-85% yield) or by imino group formation from the corresponding β-keto sulfoxonium ylides and anilines in the presence of TiCl4 as a Lewis acid (9 examples in 33-94% yield).
- Burtoloso, Antonio C. B.,Caiuby, Clarice A. D.,De Jesus, Matheus P.
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p. 7433 - 7445
(2020/06/27)
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- New Indole Tubulin Assembly Inhibitors Cause Stable Arrest of Mitotic Progression, Enhanced Stimulation of Natural Killer Cell Cytotoxic Activity, and Repression of Hedgehog-Dependent Cancer
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We designed 39 new 2-phenylindole derivatives as potential anticancer agents bearing the 3,4,5-trimethoxyphenyl moiety with a sulfur, ketone, or methylene bridging group at position 3 of the indole and with halogen or methoxy substituent(s) at positions 4-7. Compounds 33 and 44 strongly inhibited the growth of the P-glycoprotein-overexpressing multi-drug-resistant cell lines NCI/ADR-RES and Messa/Dx5. At 10 nM, 33 and 44 stimulated the cytotoxic activity of NK cells. At 20-50 nM, 33 and 44 arrested >80% of HeLa cells in the G2/M phase of the cell cycle, with stable arrest of mitotic progression. Cell cycle arrest was followed by cell death. Indoles 33, 44, and 81 showed strong inhibition of the SAG-induced Hedgehog signaling activation in NIH3T3 Shh-Light II cells with IC50 values of 19, 72, and 38 nM, respectively. Compounds of this class potently inhibited tubulin polymerization and cancer cell growth, including stimulation of natural killer cell cytotoxic activity and repression of Hedgehog-dependent cancer.
- La Regina, Giuseppe,Bai, Ruoli,Coluccia, Antonio,Famiglini, Valeria,Pelliccia, Sveva,Passacantilli, Sara,Mazzoccoli, Carmela,Ruggieri, Vitalba,Verrico, Annalisa,Miele, Andrea,Monti, Ludovica,Nalli, Marianna,Alfonsi, Romina,Di Marcotullio, Lucia,Gulino, Alberto,Ricci, Biancamaria,Soriani, Alessandra,Santoni, Angela,Caraglia, Michele,Porto, Stefania,Da Pozzo, Eleonora,Martini, Claudia,Brancale, Andrea,Marinelli, Luciana,Novellino, Ettore,Vultaggio, Stefania,Varasi, Mario,Mercurio, Ciro,Bigogno, Chiara,Dondio, Giulio,Hamel, Ernest,Lavia, Patrizia,Silvestri, Romano
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p. 5789 - 5807
(2015/08/24)
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- Synthesis of 6-bromo-2-arylindoles using 2-iodobenzoic acid as precursor
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The synthesis of 6-bromo-2-arylindoles starting from readily available 2-iodobenzoic acid is presented. Regioselective bromination of the latter was followed by Curtius rearrangement and trapping of the isocyanate with benzyl alcohol led to the benzyl carbamate of 2-iodo-5-bromoaniline. Chemoselective Sonogashira coupling of this compound with arylacetylenes followed by TBAF induced 5-endo-dig cyclization gave the desired bromo indoles. The method allows selective introduction of a bromine atom at the indole C-6 position.
- Valois-Escamilla, Ismael,Alvarez-Hernandez, Alejandro,Rangel-Ramos, Luis Felipe,Suárez-Castillo, Oscar Rodolfo,Ayala-Mata, Francisco,Zepeda-Vallejo, Gerardo
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supporting information; experimental part
p. 3726 - 3728
(2011/08/06)
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- Palladium-free zinc-mediated hydroamination of alkynes: efficient synthesis of indoles from 2-akynylaniline derivatives
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Reaction of 2-phenylethynyl N-tosylanilide prepared by Pd-free procedure with ZnBr2 (3 equiv) in refluxing toluene gave N-tosyl-2-phenylindole in 93% yield. Treatment of 2-phenylethynylaniline with ZnBr2 (1 equiv) in refluxing toluene resulted in the formation of 2-phenylindole in 91% yield. Catalytic ZnBr2 (0.05 equiv) effectively reacted with 2-alkynylanilines to afford 2-substituted indoles in high yields. Thus, complete Pd-free zinc catalyzed hydroamination of 2-alkynylanilines was achieved.
- Okuma, Kentaro,Seto, Jun-ichi,Sakaguchi, Ken-ichi,Ozaki, Saori,Nagahora, Noriyoshi,Shioji, Kosei
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supporting information; experimental part
p. 2943 - 2945
(2009/07/26)
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