- Copper(II)-Catalyzed Direct C-H (Hetero)arylation at the C3 Position of Indoles Assisted by a Removable N, N-Bidentate Auxiliary Moiety
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The regioselective arylation of inert C3-H bonds in indoles reacting with arylboronates via effective copper-mediated catalysis with the aid of a facile and removable 2-pyridinylisopropyl (PIP) group without ligand participation is reported. This newly established method features high compatibility with diverse functional groups between coupling partners, including both indole substrates and arylboron reagents, consequentially leading to operational simplicity and providing access to generate the desired arylated products in good to excellent yields of up to 97%. Synthetically, the PIP-derived amide moiety could subsequently be readily removed under mild reaction conditions to produce useful indole carboxylic acids for further transformation.
- Xu, Hai-Feng,Pan, You-Lu,Li, Gang-Jian,Hu, Xu-Yang,Chen, Jian-Zhong
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p. 1789 - 1801
(2021/02/03)
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- Extending the versatility of the Hemetsberger-Knittel indole synthesis through microwave and flow chemistry
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Microwave, flow and combination methodologies have been applied to the synthesis of a number of substituted indoles. Based on the Hemetsberger-Knittel (HK) process, modifications allow formation of products rapidly and in high yield. Adapting the methodology allows formation of 2-unsubstituted indoles and derivatives, and a route to analogs of the antitumor agent PLX-4032 is demonstrated. The utility of the HK substrates is further demonstrated through bioconjugation and subsequent ring closure and via Huisgen type [3+2] cycloaddition chemistry, allowing formation of peptide adducts which can be subsequently labeled with fluorine tags.
- Ranasinghe, Nadeesha,Jones, Graham B.
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p. 1740 - 1742
(2013/04/10)
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- Structural influence of indole C5-N-substitutents on the cytotoxicity of seco-duocarmycin analogs
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A series of racemic indole C5-substituted seco-cyclopropylindoline compounds (2,3 and 5-7) were prepared by coupling 1-(tert-butyloxycarbonyl)-3- (chlorocarbonyl)indoline (seg-A) with 5,6,7-trimethoxy-, 5,6-dimethoxy-, 5-amino-, 5-methylsulfonylamino- and 5-(N,N-dimethylaminosulfonylamino) indole-2-carboxylic acid as seg-B in the presence of 1-ethyl-3-(3- dimethylaminopropyl) carbodiimide. The synthetic compounds (2,3 and 5-7) were tested for cytotoxic activity against human cancer cell lines (COLO 205, SK-MEL-2, A549, and JEG-3) using the MTT assay.
- Choi, Taeyoung,Ma, Eunsook
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p. 357 - 367
(2012/05/04)
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- Cu(I)-catalyzed intramolecular cyclization of ene-carbamates: Synthesis of indoles and pyrrolo[2,3-c]pyridines
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Over the past few years, the use of palladium-catalyzed aromatic carbon-nitrogen bond forming reactions by the cross-coupling of aryl halides or triflates and amines has become a useful synthetic tool. Herein, we describe a copper(I) catalyst system that allows efficient synthesis of functionalized indoles and pyrrolo[2,3-c]pyridines. This method takes advantage of amino acid promoted copper coupling of amines with aryl halides, in particular, the use of the CuI/l-proline catalyst system.
- Barberis, Claude,Gordon, Thomas D.,Thomas, Christine,Zhang, Xiaolei,Cusack, Kevin P.
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p. 8877 - 8880
(2007/10/03)
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- Probing the subpockets of factor Xa reveals two binding modes for inhibitors based on a 2-carboxyindole scaffold: A study combining structure-activity relationship and X-ray crystallography
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Structure-activity relationships within a series of highly potent 2-carboxyindole-based factor Xa inhibitors incorporating a neutral P1 ligand are described with particular emphasis on the structural requirements for addressing subpockets of the factor Xa enzyme. Interactions with the subpockets were probed by systematic substitution of the 2-carboxyindole scaffold, in combination with privileged P1 and P4 substituents. Combining the most favorable substituents at the indole nucleus led to the discovery of a remarkably potent factor Xa inhibitor displaying a Ki value of 0.07 nM. X-ray crystallography of inhibitors bound to factor Xa revealed substituent-dependent switching of the inhibitor binding mode and provided a rationale for the SAR obtained. These results underscore the key role played by the P1 ligand not only in determining the binding affinity of the inhibitor by direct interaction but also in modifying the binding mode of the whole scaffold, resulting in a nonlinear SAR.
- Nazaré, Marc,Will, David W.,Matter, Hans,Schreuder, Herman,Ritter, Kurt,Urmann, Matthias,Essrich, Melanie,Bauer, Armin,Wagner, Michael,Czech, J?rg,Lorenz, Martin,Laux, Volker,Wehner, Volkmar
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p. 4511 - 4525
(2007/10/03)
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- Synthesis of methyl 5- and 6-nitroindole-2-carboxylates by nitration of indoline-2-carboxylic acid
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Indoline-2-carboxylic acid was transformed into 6-nitroindoline-2-carboxylic acid, the methyl ester of which was easily dehydrogenated by DDQ to methyl 6-nitroindole-2-carboxylate (total yield: 67%). Methyl 5-nitroindole-2-carboxylate was obtained by the nitration of methyl 1-acetylindoline-2-carboxylate acid followed by dehydrogenation with MnO2 in toluene in 40% total yield.
- Lavrenov, Sergei N.,Lakatosh, Sergei A.,Lysenkova, Ludmila N.,Korolev, Alexander M.,Preobrazhenskaya, Maria N.
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p. 320 - 322
(2007/10/03)
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