- Palladium-catalyzed direct C2-arylation of free (N–H) indoles via norbornene-mediated regioselective C–H activation
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A palladium-catalyzed direct C2-arylation reaction of free (N–H) indoles has been developed. This reaction relies on a norbornene-mediated C–H activation process on the indole ring, which features high regioselectivity and excellent functional group tolerance.
- Gao, Yadong,Zhu, Wangying,Yin, Long,Dong, Bo,Fu, Jingjing,Ye, Zhiwen,Xue, Fengtian,Jiang, Chao
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- Fischer indole synthesis in low melting mixtures
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Functionalized indoles are synthezised under mild conditions in a tartaric acid-dimethylurea melt. The melt serves as the solvent and as the catalyst. Under these reaction conditions, sensitive functional groups such as N-Boc, N-Cbz, or azides are stable, and indolenines are obtained regioselectively in excellent yields. The practical use of the method is demonstrated in the synthesis of the hormone melatonin.
- Gore, Sangram,Baskaran, Sundarababu,K?nig, Burkhard
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- Titanium-induced syntheses of furans and indoles
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Aromatic acyloxycarbonyl- and acylamidocarbonyl compounds on treatment with titanium on graphite (4 equivalents) readily afford (benzo)furans and indoles respectively, by an unprecedented McMurry-type reaction.
- Furstner,Jumbam,Weidmann
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- Facile construction of pyrrolophenanthridone skeleton via a one-pot intramolecular Heck reaction and oxidation
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Construction of pyrrolophenanthridone skeleton via a one-pot Pd-catalyzed intramolecular Heck reaction followed by oxidation has been achieved in moderate to good yields. The reaction mechanism has been proposed.
- Cong, Wei,Zhao, Lei,Wu, Xiaoming,Xu, Jinyi,Yao, Hequan
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- A practical one-pot synthesis of 2,3-disubstituted indoles from unactivated anilines
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2-Substituted-3-methyl indoles are synthesized with good regioselectivity from readily available substrates and catalysts, i.e. the reaction of anilines with propargyl alcohols in the presence of 0.36-1 mol% Ru3(CO)12.
- Tokunaga, Makoto,Ota, Mitsuru,Haga, Masa-aki,Wakatsuki, Yasuo
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- The regioselective Larock indole synthesis catalyzed by NHC-palladium complexes
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The first practical and regioselective process for the synthesis of 2,3-disubstituted indoles from the reaction of o-iodoanilines or o-bromoanilines and their derivatives with symmetrical and unsymmetrical internal alkynes catalyzed by a ferrocene-functionalized N-heterocyclic carbene (NHC)-palladium complex has been developed, and the indoles were isolated in good yields with high regioselectivity.
- He, Pan,Du, Yufeng,Liu, Gang,Cao, Changsheng,Shi, Yanhui,Zhang, Juan,Pang, Guangsheng
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- 3-Methyl-2-phenyl-1-substituted-indole derivatives as indomethacin analogs: Design, synthesis and biological evaluation as potential anti-inflammatory and analgesic agents
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In a new group of 3-methyl-2-phenyl-1-substituted-indole derivatives (10a-f), the indomethacin analogs were prepared via the Fisher indole synthesis reaction of propiophenone with appropriately substituted phenylhydrazine hydrochloride. This is followed by the insertion of the appropriate benzyl or benzoyl fragment. All the synthesized compounds were evaluated for their anti-inflammatory (in vitro and in vivo) and analgesic activities. The methanesulphonyl derivatives 10d, e and f showed the highest anti-inflammatory (in vitro and in vivo) and analgesic activities. In addition, molecular docking studies were performed on compounds 10a-f and the results were in agreement with that obtained from the in vitro COX inhibition assays. The significant anti-inflammatory and analgesic activities exhibited by 10d and 10e warrant continued preclinical development as potential anti-inflammatory and analgesic agents.
- Abdellatif, Khaled R. A.,Lamie, Phoebe F.,Omar, Hany A.
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- Phosphine-free palladium-catalyzed C-H bond arylation of free (N-H)-indoles and pyrroles
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(Chemical Equation Presented) This paper describes a phosphine-free palladium-catalyzed method for direct C-arylation of free (N-H)-indoles and pyrroles with iodo- and bromoarene donors. Employing commercially available materials, this new and operationally simple procedure provides a rapid entry to a wide range of C-arylated (N-H)-indoles including derivatives of tryptamine. In the course of this study, a profound halide effect was uncovered, affecting both the efficiency and regioselectivity of indole arylation.
- Wang, Xiang,Gribkov, Denis V.,Sames, Dalibor
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- Palladium/Copper Cocatalyzed Coupling Reaction of Aroyl Hydrazides with Indoles
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An unprecedented palladium/copper cocatalyzed coupling reaction of indoles with simple aroyl hydrazides has been developed under aerobic conditions. A range of aroyl hydrazides underwent palladium/copper cocatalyzed oxidative arylation with indoles open to air in a 1:1 mixture of dimethyl sulfoxide and nitromethane to give structurally diverse 2-arylindoles or 3-arylindoles in moderate to good yields. The reaction well tolerates a wide variety of functional groups such as alkoxy, halo, ester.
- Liu, Congrong,Yang, Fulai
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- One-pot, three-component Fischer indolisation-N-alkylation for rapid synthesis of 1,2,3-trisubstituted indoles
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A one-pot, three-component protocol for the synthesis of 1,2,3-trisubstituted indoles has been developed, based upon a Fischer indolisation-indoleN-alkylation sequence. This procedure is very rapid (total reaction time under 30 minutes), operationally straightforward, generally high yielding and draws upon readily available building blocks (aryl hydrazines, ketones, alkyl halides) to generate densely substituted indole products. We have demonstrated the utility of this process in the synthesis of 23 indoles, benzoindoles and tetrahydrocarbazoles bearing varied and useful functionality.
- Hughes-Whiffing, Christopher A.,Perry, Alexis
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- Synthesis of 2,3-Disubstituted Indoles Under Mild Conditions
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The reaction, at room temperature, between ketone phenylhydrazones and phosphorus trichloride gives the corresponding 2,3-disubstituted indoles in high yields (70 - 90 percent).
- Baccolini, Graziano,Todesco, Paolo E.
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- Gas-phase thermolysis of benzotriazole derivatives: Part 1 - Synthesis of α-N(1)- and N(2)-benzotriazolyl ketones and kinetics and mechanism of their gas-phase pyrolysis
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1-(Benzotriazol-1-yl)propan-2-one (1) and 3-(benzotriazol-1-yl)butan-2-one (2), and their respective phenyl analogues 2-(benzotriazol-1-yl)-1- phenylethanone (3) and 2-(benzotriazol-1-yl)-1-phenylpropan-1-one (4), together with 1-cyanobenzotriazole (5) and 1-(benzotriazol-2-yl)propan-2-one (6), were synthesized and then subjected to gas-phase thermolysis. The products of complete pyrolysis of 1-4 were found to be aniline in addition to either 2-substituted indoles or 2,3-disubstituted indoles. The kinetics of the gas-phase thermal elimination reactions of the present compounds were also studied, the first such investigation on benzotriazoles. The Arrhenius preexponential factor (A/s-1) and activation energy (Ea/kJ mol-1) are, respectively: 10.03 and 156.7 for (1), 9.93 and 158.0 for (2), 12.68 and 169.9 for (3), 9.45 and 144.4 for (4) and 15.40 and 163.6 for (5). Compound 6 appeared to have isomerized by a thermally allowed 1,5-group migration into 1 prior to thermolysis. The results of the kinetic and product analysis are rationalized with reference to a mechanism involving extrusion of a stable (N2) molecule and formation of a reactive 1,3-biradical intermediate, which in turn rearranges into the final products of reaction. 2004 John Wiley & Sons, Ltd.
- Dib, Hicham H.,Al-Awadi, Nouria A.,Ibrahim, Yehia A.,El-Dusouqui, Osman M.E.
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- Asymmetric N-Hydroxyalkylation of Indoles with Ethyl Glyoxalates Catalyzed by a Chiral Phosphoric Acid: Highly Enantioselective Synthesis of Chiral N,O-Aminal Indole Derivatives
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A method of SPINOL-derived chiral phosphoric acid catalyzed asymmetric intermolecular N-hydroxyalkylation of multisubstituted indoles with ethyl glyoxalates is described in this report. This protocol provides an alternative, convenient, and direct strategy for efficient access to structurally unique α-chiral indole N,O-acyclic aminals with a broad substrate scope and good to excellent enantioselectivities. The synthetic utility of this methodology is illustrated by a gram-scale experiment and the subsequent efficient synthesis of more complex chiral N,O-aminal indole derivatives.
- Wang, Le,Zhou, Jia,Ding, Tong-Mei,Yan, Zhi-Qiang,Hou, Si-Hua,Zhu, Guo-Dong,Zhang, Shu-Yu
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- Iridium- and ruthenium-catalysed synthesis of 2,3-disubstituted indoles from anilines and vicinal diols
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A straightforward and atom-economical method is described for the synthesis of 2,3-disubstituted indoles. Anilines and 1,2-diols are condensed under neat conditions with catalytic amounts of either [Cp*IrCl2] 2/MsOH or RuCl3·xH2O/phosphine (phosphine = PPh3 or xantphos). The reaction does not require any stoichiometric additives and only produces water and dihydrogen as byproducts. Anilines containing methyl, methoxy, chloro and fluoro substituents can participate in the cyclocondensation. Meta-substituted anilines give good regioselectivity for 6-substituted indoles, while unsymmetrical diols afford excellent regioselectivity for the indole isomer with an aryl or large alkyl group in the 2-position. The mechanism for the cyclocondensation presumably involves initial formation of the α-hydroxyketone from the diol. The ketone subsequently reacts with aniline to generate the α-hydroxyimine which rearranges to the corresponding α-aminoketone. Acid- or metal-catalysed electrophilic ring-closure with the release of water then furnishes the indole product.
- Tursky, Matyas,Lorentz-Petersen, Linda L. R.,Olsen, Lasse B.,Madsen, Robert
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- A microwave-assisted, propylphosphonic anhydride (T3P) mediated one-pot Fischer indole synthesis
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A rapid, mild, and high yielding protocol for the Fischer indolization of arylhydrazines with T3P under microwave irradiation is described. Significant features of this method include short reaction times and preparative ease.
- Desroses, Matthieu,Wieckowski, Krzysztof,Stevens, Marc,Odell, Luke R.
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- Catalytic Asymmetric N-Alkylation of Indoles and Carbazoles through 1,6-Conjugate Addition of Aza-para-quinone Methides
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Catalytic asymmetric N-alkylation of indoles and carbazoles represents a family of important but underdeveloped reactions. Herein, we describe a new organocatalytic strategy in which in situ generated aza-para-quinone methides are employed as the alkylating reagent. With the proper choice of a chiral phosphoric acid and an N-protective group, the intermolecular C?N bond formation with various indole and carbazole nucleophiles proceeded efficiently under mild conditions with excellent enantioselectivity and functional-group compatibility. Control experiments and kinetic studies provided important insight into the reaction mechanism.
- Chen, Min,Sun, Jianwei
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- A rapid and reliable assay for regioselectivity using fluorescence spectroscopy
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The first report of a fluorescence-based assay for the direct measurement of the regioselectivity of a reaction is described herein, developed from the desire to construct a quicker analytical method for the determination of the ratio of regioisomers obtained in the tandem hydroformylation/Fischer indole synthesis. The method allows for extremely rapid acquisition times, as the use of crude reaction mixtures is allowed. The assay is also shown to be overall very reliable, tolerating the presence of various functional groups and proceeding on average with a standard error of measurement comparable to that of NMR. As fluorescence is the only requirement for the employment of this analytical method, countless numbers of target-specific assays can undoubtedly be developed based upon this initial finding.
- Angelovski, Goran,Keraenen, Mark D.,Linnepe, Petra,Grudzielanek, Stefan,Eilbracht, Peter
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- 1,2-Disubstituted 1,2-Dihydro-1,2,4,5-tetrazine-3,6-dione as a Dynamic Covalent Bonding Unit at Room Temperature
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Dynamic covalent bonds are useful tools in a wide range of applications. Although various reversible chemical reactions have been studied for this purpose, the requirement for harsh conditions, such as high temperature and low or high pH, to activate generally stable covalent bonds limits their potential applications involving biomolecules or household utilization. Here, we report the design, synthesis, characterization, and dynamic covalent bonding properties of 1,2-disubstituted 1,2-dihydro-1,2,4,5-tetrazine-3,6-dione (TETRAD). Hetero-Diels–Alder reactions of TETRAD with furan derivatives and their retro-reactions proceeded rapidly at room temperature under neutral conditions, enabling a chemically induced sol–gel transition system.
- Ikeda, Kazuki,Kabasawa, Akira,Kakugo, Akira,Kawai, Kentaro,Kojima, Masahiro,Kokado, Kenta,Matsunaga, Shigeki,Sada, Kazuki,Sato, Akane,Yoshino, Tatsuhiko
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supporting information
p. 1370 - 1379
(2022/02/01)
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- Tris-NHC-propagated self-supported polymer-based Pd catalysts for heterogeneous C-H functionalization
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Three-dimensionally propagated imidazolium-containing mesoporous coordination polymer and organic polymer-based platforms were successfully exploited to develop single-site heterogenized Pd-NHC catalysts for oxidative arene/heteroarene C-H functionalization reactions. The catalysts were efficient in directed arene halogenation, and nondirected arene and heteroarene arylation reactions. High catalytic activity, excellent heterogeneity and recyclability were offered by these systems making them promising candidates in the area of heterogeneous C-H functionalization, where efficient catalysts are still scarce.
- Choudhury, Joyanta,Dutta, Tapas Kumar,Mandal, Tanmoy,Mohanty, Sunit
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supporting information
p. 10182 - 10185
(2021/10/12)
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- Modular counter-Fischer?indole synthesis through radical-enolate coupling
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A single-electron transfer mediated modular indole formation reaction from a 2-iodoaniline derivative and a ketone has been developed. This transition-metal-free reaction shows a broad substrate scope and unconventional regioselectivity trends. Moreover, important functional groups for further transformation are tolerated under the reaction conditions. Density functional theory studies reveal that the reaction proceeds by metal coordination, which converts a disfavored 5-endo-trig cyclization to an accessible 7-endo-trig process.
- Chung, Hyunho,Kim, Jeongyun,Gonzalez-Montiel, Gisela A.,Cheong, Paul Ha-Yeon,Lee, Hong Geun
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supporting information
p. 1096 - 1102
(2021/01/26)
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- Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
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A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
- Shee, Sujan,Kundu, Sabuj
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p. 6943 - 6951
(2021/05/29)
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- Et3SiH + KO: T Bu provide multiple reactive intermediates that compete in the reactions and rearrangements of benzylnitriles and indolenines
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The combination of potassium tert-butoxide and triethylsilane is unusual because it generates multiple different types of reactive intermediates simultaneously that provide access to (i) silyl radical reactions, (ii) hydrogen atom transfer reactions to cl
- Arokianathar, Jude N.,Clark, Kenneth F.,Dimitrova, Daniela,Leach, Stuart G.,Murphy, John A.,Poole, Darren L.,Smith, Andrew J.
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p. 12364 - 12370
(2020/12/08)
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- C2–H Arylation of Indoles Catalyzed by Palladium-Containing Metal-Organic-Framework in γ-Valerolactone
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An efficient and selective procedure was developed for the direct C2–H arylation of indoles using a Pd-loaded metal–organic framework (MOF) as a heterogeneous catalyst and the nontoxic biomass-derived solvent γ-valerolactone (GVL) as a reaction medium. The developed method allows for excellent yields and C-2 selectivity to be achieved and tolerates various substituents on the indole scaffold. The established conditions ensure the stability of the catalyst as well as recoverability, reusability, and low metal leaching into the solution.
- Anastasiou, Ioannis,Van Velthoven, Niels,Tomarelli, Elena,Lombi, Aurora,Lanari, Daniela,Liu, Pei,Bals, Sara,De Vos, Dirk E.,Vaccaro, Luigi
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p. 2786 - 2791
(2020/03/24)
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- Manganese(iii)-promoted tandem phosphinoylation/cyclization of 2-arylindoles/2-arylbenzimidazoles with disubstituted phosphine oxides
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A simple and practical method for the synthesis of phosphoryl-substituted indolo[2,1-a]isoquinolin-6(5H)-ones and benzimidazo[2,1-a]isoquinolin-6(5H)-ones through manganese(iii)-promoted tandem phosphinoylation/cyclization of 2-arylindoles or 2-arylbenzimidazoles with disubstituted phosphine oxides was developed. In this transformation, new C-P bond and C-C bond were constructed simultaneously under silver-free conditions, exhibiting a broad substrate scope. It was noted that not only diarylphosphine oxides but also dialkyl and arylalkyl-phosphine oxides were compatible with the conditions. This journal is
- Jiang, Shuai-Shuai,Li, Jin-Heng,Luo, Shu-Zheng,Song, Ren-Jie,Wu, Yan-Chen,Xiao, Yu-Ting
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supporting information
p. 4843 - 4847
(2020/07/13)
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- Iron-catalyzed reductive coupling of nitroarenes with olefins: Intermediate of iron-nitroso complex
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Using a single half-sandwich iron(II) compound, CpFe(1,2-Ph2PC6H4S)(NCMe) (Cp- = C5Me5-, 1) as a catalyst, reductive coupling of nitroarenes with olefins has been achieved by a well-defined iron(II)/(EtO)3SiH system. Through either inter- or intramolecular reductive coupling, various branched amines and indole derivatives have been directly synthesized in one-pot. Mechanistic studies showed that the catalysis is initiated by activation of nitroarenes by the iron(II) catalyst with silane, generating iron-nitrosoarene intermediate for the C-N bond coupling.
- Song, Heng,Yang, Zhuoyi,Tung, Chen-Ho,Wang, Wenguang
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p. 276 - 281
(2019/12/24)
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- Synthesis of indolo[2,1-: A] isoquinoline derivatives via visible-light-induced radical cascade cyclization reactions
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We describe a photocatalyzed transformation for the synthesis of the indolo[2,1-a]isoquinoline core structure. This redox neutral reaction features mild reaction conditions and exceptional functional group tolerance. A series of valuable indolo[2,1-a]isoquinoline derivatives bearing various functional groups were synthesized using this method in good to excellent yields.
- Wei, Yun-Long,Chen, Jian-Qiang,Sun, Bo,Xu, Peng-Fei
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supporting information
p. 5922 - 5925
(2019/05/27)
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- Metal-Free Visible-Light Promoted Radical Cyclization to Access Perfluoroalkyl-Substituted Benzimidazo[2,1-a]isoquinolin-6(5H)-ones and Indolo[2,1-a]isoquinolin-6(5H)-ones
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A metal-free visible-light-induced cyclization procedure was developed for the rapid synthesis of perfluoroalkyl-substituted benzimidazo[2,1-a]isoquinolin-6(5H)-ones and perfluoroalkyl-substituted indolo[2,1-a]isoquinolin-6(5H)-ones under mild reaction conditions. In this procedure, the formation of electron-donor-acceptor (EDA) complex is critical for the visible-light promoted process to avoid the utilization of external photocatalysts. (Figure presented.).
- Zeng, Fan-Lin,Sun, Kai,Chen, Xiao-Lan,Yuan, Xiao-Ya,He, Shuai-Qi,Liu, Yan,Peng, Yu-Yu,Qu, Ling-Bo,Lv, Qi-Yan,Yu, Bing
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supporting information
p. 5176 - 5181
(2019/11/11)
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- Rhodium(iii)-catalyzed regioselective oxidative annulation of anilines and allylbenzenes: Via C(sp3)-H/C(sp2)-H bond cleavage
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Described herein is the merging of allylic C(sp3)-H activation and directed C(sp2)-H activation into a single approach for discovering unprecedented chemical transformations. As a proof-of-concept, we disclose for the first time the
- Liu, Yunqi,Yang, Yudong,Wang, Chunxia,Wang, Zhishuo,You, Jingsong
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supporting information
p. 1068 - 1071
(2019/01/28)
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- Weakly Coordinating, Ketone-Directed (η5-Pentamethylcyclopentadienyl)cobalt(III)- and (η5-Pentamethylcyclopentadienyl)rhodium(III)-Catalyzed C?H Amidation of Arenes: A Route to Acridone Alkaloids
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The weakly coordinating, ketone-directed, regioselective monoamidation of aromatic ketones, chalcone, carbazole, and benzophenones was achieved by employing high-valent cobalt and rhodium catalysis to access numerous biologically important molecular building blocks. This amidation proceeded smoothly with a variety of ketones and several amidating partners. The application of the products in the synthesis of various heterocycles, including acridones, indoles, quinoline, quinolones, quinolinones, and quinazolines, was also explored. The total synthesis of acridone-based alkaloids, namely, toddaliopsin A, toddaliopsin D, and arborinine, and the formal synthesis of acronycine and noracronycin were also accomplished by applying this method. A mechanistic study revealed this amidation reaction follows a base-assisted intermolecular electrophilic substitution pathway.
- Bera, Sourav Sekhar,Sk, Md Raja,Maji, Modhu Sudan
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supporting information
p. 1806 - 1811
(2019/01/14)
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- Fluorine as a Traceless Directing Group for the Regiodivergent Synthesis of Indoles and Tryptophans
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Despite ample evidence for the unique reactivity offered by hypervalent F-iodanes, mechanistic investigations fall far behind. In order to shed light on the unusual behavior of such F-reagents, we conducted computational and experimental studies on the chemodivergent transformation of styrenes. We identified the spirocyclic F-cyclopropane as the common intermediate for both the C,H-fluorination and C,H-amination pathways. The fate of this key compound is determined by the extent of cationic charge delocalization controlled by the N-substituents. Exploiting this phenomenon, a multitude of different transformations have become available, leading, i.e., to the regiodivergent synthesis of indoles and tryptophans.
- Andries-Ulmer, Anna,Brunner, Christoph,Rehbein, Julia,Gulder, Tanja
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supporting information
p. 13034 - 13041
(2018/09/27)
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- Rh(III)-Catalyzed C-H Cyclization of Arylnitrones with Diazo Compounds: Access to 3-Carboxylate Substituted N-Hydroxyindoles
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Recently, N-hydroxyindole derivatives have received much interest because of their unique structural motif and various biological activities. In this study, we report the first example of a Rh(III)-catalyzed reaction of arylnitrones with α-diazoketoesters or α-diazodiketones to produce N-hydroxyindole derivatives. Intriguingly, we could build the N-hydroxyindole scaffold by blocking the cleavage of the N-O bond selectively, while eliminating the acyl group of α-diazoketoesters or α-diazodiketones preferentially.
- Li, Yazhou,Li, Jian,Wu, Xiaowei,Zhou, Yu,Liu, Hong
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p. 8984 - 8994
(2017/09/11)
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- Methylation of C(sp3)-H/C(sp2)-H bonds with methanol catalyzed by cobalt system
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A highly efficient Co-based catalytic system, composed of a commercially available Co salt, a tetradentate phosphine ligand P-(CH2CH2PPh2)3(PP3), and a base (denoted as [Co]/PP3/base), is developed for the methylation of C(sp3)-H and C(sp2)-H bonds using methanol as a methylating reagent. The Co(BF4)2.6H2O/PP3/K2CO3 catalytic system showed high catalytic activity for the methylation of C-H bonds in aryl alkyl ketones, aryl acetonitriles, and indoles, with wide substrate scope and good functional group tolerance, and methylsubstituted products were obtained in good to excellent yields at 100 °C. This cheap, readily available, and highly efficient Co-based catalytic system may have promising applications in methylation reaction using methanol.
- Liu, Zhenghui,Yang, Zhenzhen,Yu, Xiaoxiao,Zhang, Hongye,Yu, Bo,Zhao, Yanfei,Liu, Zhimin
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supporting information
p. 5228 - 5231
(2017/11/06)
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- Direct C-H Arylation of Heteroarenes with Copper Impregnated on Magnetite as a Reusable Catalyst: Evidence for CuO Nanoparticle Catalysis in Solution
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A reusable copper-based catalyst system was employed for the direct arylation of electron-rich heteroarenes. Under mild and operationally simple reaction conditions good yields and selectivities were obtained using diaryliodonium salts as coupling partners. A combination of experimental methods including kinetic studies, filtration tests, and a series of analytical tools (TXRF, ICP-MS, SEM, XPS, TEM, EFTEM) provide evidence for catalytically active soluble nanoparticles formed from an amorphous heterogeneous precursor. Mechanistic studies hint at a redox-neutral process which promotes counterion dissociation from the diaryliodonium salt by a copper(II) oxide species.
- Vásquez-Céspedes, Suhelen,Chepiga, Kathryn M.,M?ller, Nadja,Sch?fer, Andreas H.,Glorius, Frank
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p. 5954 - 5961
(2016/09/09)
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- Ruthenium-catalyzed decarboxylative and dehydrogenative formation of highly substituted pyridines from alkene-tethered isoxazol-5(4H)-ones
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A ruthenium-catalyzed reaction of alkene-tethered isoxazol-5(4H)-ones affording pyridines has been developed. Di-, tri-, and tetrasubstituted pyridines were obtained from various isoxazolones in good yields.
- Okamoto, Kazuhiro,Sasakura, Kohei,Shimbayashi, Takuya,Ohe, Kouichi
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supporting information
p. 988 - 990
(2016/08/13)
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- Base-promoted domino reaction for the synthesis of 2,3-disubstituted indoles from 2-aminobenzaldehyde/2-amino aryl ketones, tosylhydrazine, and aromatic aldehydes
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A base-promoted domino reaction to synthesize the 2,3-disubstituted indoles from 2-aminobenzaldehyde/2-amino aryl ketones, tosylhydrazine, and aromatic aldehydes has been developed. This strategy provides a simple and beneficial way for the construction of 2,3-disubstituted indole compounds from readily available starting materials under mild conditions.
- Wu, Yan-Dong,Ma, Jun-Rui,Shu, Wen-Ming,Zheng, Kai-Lu,Wu, An-Xin
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p. 4821 - 4826
(2016/07/18)
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- Cobalt(III)-Catalyzed Redox-Neutral Synthesis of Unprotected Indoles Featuring an N-N Bond Cleavage
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A redox-neutral cobalt(III)-catalyzed synthetic approach for the direct synthesis of unprotected indoles showcasing an N-N bond cleavage is reported. The herein newly introduced Boc-protected hydrazines establish a beneficial addition to the limited portfolio of oxidizing directing groups for cobalt(III) catalysis. Moreover, the developed catalytic methodology tolerates a good variety of functional groups.
- Lerchen, Andreas,Vásquez-Céspedes, Suhelen,Glorius, Frank
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supporting information
p. 3208 - 3211
(2016/03/12)
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- Catalytic α-Arylation of Imines Leading to N-Unprotected Indoles and Azaindoles
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A palladium N-heterocyclic carbene catalyzed methodology for the synthesis of substituted, N-unprotected indoles and azaindoles is reported. The protocol permits access to various, highly substituted members of these classes of compounds. Although two possible reaction pathways (deprotonative and Heck-like) can be proposed, control experiments, supported by computational studies, point toward a deprotonative mechanism being operative.
- Marelli, Enrico,Corpet, Martin,Minenkov, Yury,Neyyappadath, Rifahath M.,Bismuto, Alessandro,Buccolini, Giulia,Curcio, Massimiliano,Cavallo, Luigi,Nolan, Steven P.
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p. 2930 - 2938
(2016/07/06)
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- A kind of high-efficient synthetic indole and isoquinoline derivatives (by machine translation)
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The invention discloses a substituted indole and isoquinoline preparation method, which belongs to the technical field of organic chemical synthesis. This method adopts the oxygen as the oxidizing agent, various substituents substituted alkyne starting material of the aromatic amine or [...] , by transition metal-catalyzed, get containing indole or isoquinoline compound of the structure. The reaction raw material, oxidizing agent and cheap and easily obtained catalyst, synthesis technique is simple, which greatly reduces the cost of synthesizing; mild reaction conditions, high yield, easy industrialization; reaction raw materials and catalyst cleaning non-toxic, small pollution to the environment. Such compounds and their derivatives as an important fine chemicals, in the medical, agricultural chemicals, perfume and widely used photoelectric and other industries. (by machine translation)
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Paragraph 0058; 0059
(2016/10/07)
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- Catalytic synthesis method of indole compounds
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The invention discloses a catalytic synthesis method of indole compounds.The method includes the following steps of firstly, conducting stirring reaction on ortho-nitrostyrolene or derivatives of ortho-nitrostyrolene, bis(pinacolato)diboron, alkali and low-grade saturated monohydric alcohol under the atmosphere of nitrogen; secondly, cooling the reaction product in the first step to the room temperature, adding ethyl acetate to be sufficiently mixed, and washing with ethyl acetate after filtering; thirdly, spin-drying low-grade saturated monohydric alcohol in an organic phase of the material obtained in the second step, passing through a silica gel column, and drip washing the silica gel column with eluent composed of petroleum ether and ethyl acetate to obtain pure products, namely, the indole compounds.By means of the method, under the neutral conditions, bis(pinacolato)diboron low in price serves as the raw material, friendly low-grade saturated monohydric alcohol serves as the solvent, the indole compounds are obtained through simple operation, the raw materials are low in price and easy to obtain, efficiency and safety are high, and wide expandability and good industrial application prospects are achieved.
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Paragraph 0032; 0033; 0034; 0035
(2016/10/10)
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- Palladium-catalyzed direct arylation of indoles with arylsulfonyl hydrazides
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A novel method to synthesise 2-arylindoles is demonstrated via direct arylation of indoles with arylsulfonyl hydrazides. Under the optimized reaction conditions, the reaction well tolerates a wide variety of functional groups to afford structurally diverse 2-arylindoles in good to excellent yields at 70 °C.
- Liu, Congrong,Ding, Lianghui,Guo, Guang,Liu, Weiwei,Yang, Fu-Lai
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p. 2824 - 2827
(2016/03/12)
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- URAZOLE COMPOUNDS
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The present invention relates to a compound of formula (I) or a stereoisomer, enantiomer, racemic, or tautomer thereof, (I) wherein R1, R2, R3, R4, R5, R6, R7, L1 and Q1 have the meaning defined in the claims and the description. The present invention also relates to a process for the preparation of the compound of formula (I). The present invention also relates to the use of a compound of formula (I) as an in situ precursor of a triazolinedione reagent for the functionalization of enes, dienes, aryl and heteroaryl systems via the ene reactions, Diels-Alder reactions, and electrophilic aromatic substitution reactions of said reagent. The present invention also relates to the use of a compound of formula (I) in polymers, membranes, adhesives, foams, sealants, molded articles, films, extruded articles, fibers, elastomers, polymer based additives, pharmaceutical and biomedical products, varnishes, paints, coatings, inks, composite material, organic LEDs, organic semiconductors, conducting organic polymers, or 3D printed articles. The present invention also relates to article comprising said compound of formula (I) and to a process for reshaping and/or repairing said article.
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Page/Page column 175-176
(2015/02/25)
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- Iridium-catalyzed methylation of indoles and pyrroles using methanol as feedstock
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Iridium-catalyzed methylation of indoles and pyrroles using methanol as the methylating agent was achieved. This transformation takes place via a borrowing hydrogen methodology under an air atmosphere, which constitutes a direct route to 3-methyl-indoles and methyl-pyrroles.
- Chen, Shu-Jie,Lu, Guo-Ping,Cai, Chun
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p. 70329 - 70332
(2015/09/07)
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- Rhodium(III)-Catalyzed Redox-Neutral C-H Annulation of Arylnitrones and Alkynes for the Synthesis of Indole Derivatives
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By using a nitrone as the oxidizing directing group, a mild, practical and efficient rhodium(III)-catalyzed C-H functionalization for the synthesis of indole derivatives has been developed. This reaction obviates the need for an external oxidant and shows good functional group tolerance. The employment of a sterically hindered Mes group on the carbon center of the nitrone is crucial to produce indoles in high yield.
- Zhou, Zhi,Liu, Guixia,Chen, Yan,Lu, Xiyan
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supporting information
p. 2944 - 2950
(2015/09/28)
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- Ruthenium-catalyzed synthesis of indoles from anilines and epoxides
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A general synthetic route to indoles from readily available anilines and epoxides by using ruthenium catalysis is described. This straightforward transformation allows a variety of indoles to be obtained in good yields by using [Ru3(CO)12]/1,1-bis(diphenylphosphino)ferrocene as the catalytic system. Water and hydrogen are formed as the only stoichiometric by-products, making this process highly atom efficient.
- Pena-Lopez, Miguel,Neumann, Helfried,Beller, Matthias
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supporting information
p. 1818 - 1824
(2014/03/21)
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- Thiourea-catalyzed enantioselective addition of indoles to pyrones: Alkaloid cores with quaternary carbons
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We report the development of a catalytic method for the enantioselective addition of indoles to pyrone-derived electrophiles. Arylpyrrolidino-derived thioureas catalyze the addition with high stereoselectivity in the presence of catalytic quantities of an achiral Bronsted acid. The indole-pyrone adducts feature a quaternary stereocenter and represent an unusual class of indolines bearing structural resemblance to the hybrid natural product pleiocarpamine.
- Yeung, Charles S.,Ziegler, Robert E.,Porco, John A.,Jacobsen, Eric N.
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supporting information
p. 13614 - 13617
(2015/02/05)
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- Mild Rh(III)-catalyzed direct C-H bond arylation of (hetero)arenes with arylsilanes in aqueous media
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An efficient rhodium(III)-catalyzed C-H bond activation and further direct arylation of (hetero)arenes with organosilanes in aqueous media was developed. This reaction shows good substrate scope and excellent functional group compatibility and gives the products in good yields with excellent regioselectivity.
- Lu, Ming-Zhu,Lu, Ping,Xu, Yun-He,Loh, Teck-Peng
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p. 2614 - 2617
(2014/06/09)
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- Regioselective synthesis of indoles via rhodium-catalyzed C-H activation directed by an in-situ generated redox-neutral group
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A regioselective synthesis of indoles from arylhydrazine hydrochlorides with alkynes and diethyl ketone catalyzed by a rhodium complex is described. A possible mechanism involving an in-situ generated oxidizing directing group -N-Ni'CR1R2 assisted ortho-C-H activation and reductive elimination are proposed. The catalytic reaction is highly compatible with a wide range of functional arylhydrazines and alkynes. The reaction proceeds under mild reaction conditions and is atom-step economical.
- Muralirajan, Krishnamoorthy,Cheng, Chien-Hong
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supporting information
p. 1571 - 1576
(2014/06/09)
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- Rh-Catalyzed oxidative C-H activation/annulation: Converting anilines to indoles using molecular oxygen as the sole oxidant
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A practical and efficient Rh(iii)-catalyzed aerobic C-H activation has been developed for the facile synthesis of a broad range of indoles from simple anilines and alkynes. The protocol could be conducted under mild conditions and used environmentally friendly oxygen as the sole clear oxidant.
- Zhang, Guoying,Yu, Hui,Qin, Guiping,Huang, Hanmin
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supporting information
p. 4331 - 4334
(2014/04/17)
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- Catalytic methylation of C-H bonds using CO2 and H2
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Formation of C-C bonds from CO2 is a much sought after reaction in organic synthesis. To date, other than C-H carboxylations using stoichiometric amounts of metals, base, or organometallic reagents, little is known about C-C bond formation. In fact, to the best of our knowledge no catalytic methylation of C-H bonds using CO2 and H2 has been reported. Described herein is the combination of CO2 and H2 for efficient methylation of carbon nucleophiles such as indoles, pyrroles, and electron-rich arenes. Comparison experiments which employ paraformaldehyde show similar reactivity for the CO2/H2 system. Capturing: Carbon dioxide in the presence of H2 is shown to be an efficient methylating reagent for carbon nucleophiles such as 2-substituted indoles, pyrroles, and electron-rich arenes. Experimental data support the formal capture of formaldehyde. acac=acetylacetonate, triphos=1,1,1-tris(diphenylphosphinomethyl)ethane.
- Li, Yuehui,Yan, Tao,Junge, Kathrin,Beller, Matthias
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supporting information
p. 10476 - 10480
(2016/02/18)
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- Palladium-catalyzed annulation of internal alkynes in aqueous medium
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To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for carbo- and heteroannulation of internal alkynes with functionalized aryl halides in aqueous medium. A uniform reaction condition for these annulation reactions was also developed.
- Ang, Wei Jie,Tai, Chih-Hsuan,Lo, Lee-Chiang,Lam, Yulin
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p. 4921 - 4929
(2014/01/23)
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- Indole synthesis by rhodium(III)-catalyzed hydrazine-directed C-H activation: Redox-neutral and traceless by N-N bond cleavage
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Fishing for complements! There is an alternative to the useful Fischer indole synthesis. The new method utilizes the same retrosynthetic disconnection but is based on a RhIII-catalyzed directed C-H activation step and a successive coupling with alkynes. Copyright
- Zhao, Dongbing,Shi, Zhuangzhi,Glorius, Frank
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supporting information
p. 12426 - 12429
(2013/12/04)
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- Iron(II) bromide-catalyzed intramolecular c-h bond amination [1,2]-shift tandem reactions of aryl azides
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Iron(II) bromide catalyzes the transformation of ortho-substituted aryl azides into 2,3-disubstituted indoles through a tandem ethereal C-H bond amination [1,2]-shift reaction. The preference for the 1,2-shift component of the tandem reaction was established to be Me 1 2 Ph.
- Nguyen, Quyen,Nguyen, Tuyen,Driver, Tom G.
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p. 620 - 623
(2013/03/13)
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- Reactivity of tetrahydrochromeno[2,3-b]indoles: Chromic indicators of cyanide
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The synthesis and reactivity of a tetrahydrochromeno[2,3-b]indoles are reported. Evidence for reversible ring-opening is based on H/D exchange and trapping experiments. These compounds readily undergo reaction with tetra-n-butylammonium cyanide. The cyanide reaction is 10-100× faster when the solution is irradiated with 350 nm light. Reaction with trimethylsilyl cyanide occurs only with UV irradiation demonstrating photoreactivity. The rate of tetrahydrochromeno[2,3-b]indole ring-opening is greater for (i) Me substitution at the hemiaminal carbon (compared to Ph), and (ii) substitution of fluorine at the 9-position of the indole. Under acidic conditions, the ring-opened indolium ion is observed. Copyright
- Douglas, Nicholas,Neef, Charles J.,Rogers, Robert A.,Stanley, Jake A.,Armitage, Jacob,Martin, Ben,Hudnall, Todd W.,Brittain, William J.
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p. 688 - 695
(2013/08/23)
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- Novel SO3H-functionalized ionic liquids catalyzed a simple, green and efficient procedure for Fischer indole synthesis in water under microwave irradiation
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Novel SO3H-functionalized ionic liquids were successfully applied as catalysts for one-pot Fischer indole synthesis under microwave irradiation and in a water medium. Various types of indoles were prepared using single-carbonyl ketones/aldehydes or cyclohexandiones with aryhydrazine hydrochlorides in 86-96% yields in water under microwave irradiation. The indole products could be conveniently separated from the reaction mixture through filtration, and the catalytic system of [(HSO3-p)2im] [CF3SO3]/H2O could be reused directly without any treatment. The entire process is simple, time saving, and environmentally friendly.
- Li, Bai Lin,Zhong, Ai Guo,Xu, Dan-Qian
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p. 45 - 50,6
(2020/10/15)
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- Stereoselective synthesis of 2,3-disubstituted indoline diastereoisomers by chemoenzymatic processes
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Racemic indolines including a variety of structural motifs such as C-2 and C-3 substitutions (alkyl or aryl), cis/trans relative stereochemistry and functionalization of the aromatic ring (fluoro, methyl or methoxy groups) have been efficiently prepared through Fischer indolization and subsequent diastereoselective reduction of the unprotected indoles. Combination of Candida antarctica lipase type A and allyl 3-methoxyphenyl carbonate has been identified as the best tandem for their kinetic resolutions, observing excellent stereodiscriminations for most of the tested indolines.
- Lopez-Iglesias, Maria,Busto, Eduardo,Gotor, Vicente,Gotor-Fernandez, Vicente
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p. 8049 - 8055,7
(2020/10/15)
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- Efficient construction of fused indolines with a 2-quaternary center via an intramolecular heck reaction with a low catalyst loading
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An efficient construction of fused indolines with a 2-quaternary center through a palladium-catalyzed intramolecular Heck reaction of N-(2(2-halobenzoxyl)-2,3-disubstituted indoles is disclosed. This protocol provided a straightforward access to diverse fused indolines with good functional group tolerance.
- Zhao, Lei,Li, Ziyuan,Chang, Lin,Xu, Jinyi,Yao, Hequan,Wu, Xiaoming
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supporting information; scheme or table
p. 2066 - 2069
(2012/06/18)
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- Ruthenium-catalyzed direct C-H bond arylations of heteroarenes
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Ruthenium-catalyzed C-H bond arylations of indoles, thiophenes, and pyrroles were accomplished in a highly chemo- and site-selective manner through the use of removable directing groups.
- Ackermann, Lutz,Lygin, Alexander V.
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supporting information; experimental part
p. 3332 - 3335
(2011/09/12)
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- One-pot-one-step, microwave-assisted Fischer indole synthesis
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The Fischer indole synthesis was carried out using microwaves instead of conventional heating procedures. When the mixture of phenylhydrazine, cyclohexanone and zinc chloride was irradiated at 600 W for 3 min, 76% of 1,2,3,4-tetrahydrocarbazole was obtained. However, when zinc chloride was replaced with p-toluenesulfonic acid (p-TSA), the reaction yielded 91% of 1,2,3,4-tetrahydrocarbazole. Thus, a series of indoles were prepared using microwaves in the presence of p-TSA catalyst.
- Creencia, Evelyn Cuevas,Tsukamoto, Masayuki,Horaguchi, Takaaki
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experimental part
p. 1095 - 1102
(2011/11/04)
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