- α-Substituted β-mercapto ketone based synthesis of 3-alkyl-3-[(alkylsulfanyl)methyl]-2-methyl-3H-indoles
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[Figure not available: see fulltext.] A novel approach to the synthesis of 3-(alkylsulfanylmethyl)-substituted 1H-indoles was developed based on the Fischer indole synthesis involving accessible β-mercapto ketones. Heterocyclization of 3-[(alkylsulfanyl)methyl]alkan-2-ones and phenylhydrazine by the action of ZnCl2 in MeOH or EtOH gave previously unknown 3-alkyl-3-[(alkylsulfanyl)methyl]-2-methyl-3H-indoles.
- Baeva, Larisa А.,Fatykhov, Akhnef А.,Gataullin, Rail R.,Nugumanov, Radik M.
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Read Online
- Study of catalytic hydrogenation and dehydrogenation of 2,3-dimethylindole for hydrogen storage application
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2,3-Dimethylindole (2,3-DMID), a candidate with a hydrogen storage capacity of 5.23 wt%, was studied as a new liquid organic hydrogen carrier (LOHC) in detail in this report. Hydrogenation of 2,3-DMID was conducted over 5 wt% Ru/Al2O3 by investigating the influences of temperature and hydrogen pressure. 100% of fully hydrogenated product, 8H-2,3-DMID can be achieved at 190 °C and 7 MPa in 4 h. Dehydrogenation of 8H-2,3-DMID was performed over 5 wt% Pd/Al2O3 at 180-210 °C and 101 kPa. It is found that dehydrogenation of 8H-2,3-DMID followed first order kinetics with an apparent activation energy of 39.6 kJ mol-1. The structures of intermediates produced in the 8H-2,3-DMID dehydrogenation process were analyzed by DFT calculations.
- Dong, Yuan,Zhao, Haoming,Zhao, Yinheng,Yang, Ming,Zhang, Heshun,Cheng, Hansong
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Read Online
- Chiral-Phosphoric-Acid-Catalyzed C6-Selective Pictet-Spengler Reactions for Construction of Polycyclic Indoles Containing Spiro Quaternary Stereocenters
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Compared with the well-established asymmetric Pictet-Spengler reactions on the pyrrole ring of indoles, the catalytic asymmetric Pictet-Spengler reaction on the benzene ring of indoles has been rarely studied. Herein the C6-selective Pictet-Spengler react
- Huang, Wen-Jun,Wang, Han,Wang, Xin-Wei,Wu, Bo,Zhou, Yong-Gui
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supporting information
p. 1727 - 1731
(2022/03/14)
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- Direct Synthesis of Indoles from Azoarenes and Ketones with Bis(neopentylglycolato)diboron Using 4,4′-Bipyridyl as an Organocatalyst
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Multifunctionalized indole derivatives were prepared by reducing azoarenes in the presence of ketones and bis(neopentylglycolato)diboron (B2nep2) with a catalytic amount of 4,4′-bipyridyl under neutral reaction conditions, where 4,4′-bipyridyl acted as an organocatalyst to activate the B-B bond of B2nep2 and form N,N′-diboryl-1,2-diarylhydrazines as key intermediates. Further reaction of N,N′-diboryl-1,2-diarylhydrazines with ketones afforded N-vinyl-1,2-diarylhydrazines, which rearranged to the corresponding indoles via the Fischer indole mechanism. This organocatalytic system was applied to diverse alkyl cyclic ketones, dialkyl, and alkyl/aryl ketones, including heteroatoms. Methyl alkyl ketones gave the corresponding 2-methyl-3-substituted indoles in a regioselective manner. This protocol allowed us to expand the preparation of indoles having high compatibility with not only electron-donating and electron-withdrawing groups but also N- and O-protecting functional groups.
- Misal Castro, Luis C.,Sultan, Ibrahim,Nishi, Kohei,Tsurugi, Hayato,Mashima, Kazushi
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p. 3287 - 3299
(2021/03/01)
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- Synthesis of indoles through acceptorless dehydrogenative coupling catalyzed by nickel on silica-alumina
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The high atom-economical formation of indoles from anilines and diols was described with affordable and easy to handle Ni/SiO2-Al2O3. After optimization, 2,3-dimethylindole was isolated with an excellent 98% yield in neat conditions. The scope of the reaction was studied and 13 indoles were isolated in 16–80% yields.
- Charvieux, Aubin,Hammoud, Abdul Aziz,Duclos, Marie-Christine,Duguet, Nicolas,Métay, Estelle
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- Acceptorless dehydrogenative condensation: synthesis of indoles and quinolines from diols and anilines
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The use of diols and anilines as reagents for the preparation of indoles represents a challenge in organic synthesis. By means of acceptorless dehydrogenative condensation, heterocycles, such as indoles, can be obtained. Herein we present an experimental and theoretical study for this purpose employing heterogeneous catalysts Pt/Al2O3and ZnO in combination with an acid catalyst (p-TSA) and NMP as solvent. Under our optimized conditions, the diol excess has been reduced down to 2 equivalents. This represents a major advance, and allows the use of other diols. 2,3-Butanediol or 1,2-cyclohexanediol has been employed affording 2,3-dimethyl indoles and tetrahydrocarbazoles. In addition, 1,3-propanediol has been employed to prepare quinolines or natural and synthetic julolidines.
- Bellezza, Delia,Zaragozá, Ramón J.,José Aurell,Ballesteros, Rafael,Ballesteros-Garrido, Rafael
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supporting information
p. 677 - 683
(2021/02/06)
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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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supporting information
p. 627 - 634
(2021/02/06)
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- Palladium-catalyzed dearomative allylation of indoles with cyclopropyl acetylenes: access to indolenine derivatives
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A palladium-catalyzed redox-neutral allylic alkylation of indoles with cyclopropyl acetylenes has been disclosed. Various 1,3-diene indolenine framework bearing a quaternary stereocenter at the C3 position were synthesized straightforwardly in good to excellent yields with high regio- and stereoselectivities. The reaction could be further expanded to the dearomatization of naphthols to synthesize functionalized cyclohexadienones with 1,3-diene motifs. The reaction exhibited high atom economy and good functional group tolerance.
- Lu, Chuan-Jun,Chen, Yu-Ting,Wang, Hong,Li, Yu-Jin
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p. 635 - 644
(2021/02/06)
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- A Highly Dispersed Copper Nanoparticles Catalyst with a Large Number of Weak Acid Centers for Efficiently Synthesizing the High Value-Added 3-Methylindole by Aniline and Biomass-Derived Glycerin
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Abstract: An excellent catalyst with a large number of weak acid centers and highly dispersed copper nanoparticles embedded in mesoporous SBA-15 carrier was successfully constructed for the purpose of efficient conversion of aniline with biomass-derived glycerin to the high value-added 3-methylindole, in which the catalyst of Cu/SBA-15 was modified with Al2O3, La2O3 and CoO in sequence. The modified carrier and the copper-based catalysts were studied by scanning electron microscopy and energy-dispersive X-ray (SEM–EDX) spectroscopy, nitrogen physical adsorption, ammonia temperature programmed desorption (NH3-TPD), hydrogen temperature programmed reduction (H2-TPR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric and differential thermal analysis (TG–DTA) and inductively coupled plasma (ICP) emission spectroscopy. The research found that the Cu/CoO/La2O3/Al2O3/SBA-15 catalyst exhibited a very good catalytic performance with 3-methylindole yield up to 73.3% and selectivity reaching 86.4%. Besides, only a 3.9% yield decreased after the catalyst was circulated seven times. The characterizations revealed that Al2O3 could enhance the polarity of the carrier, thereby the interaction between the active component and the composite carrier was strengthened and the dispersion of copper was increased significantly. Adding La2O3 to Cu/SBA-15-Al2O3 could weaken the acidity and inhibit the formation of carbon deposits. CoO promoter could increase the number of weak acid centers, which was conducive to a good dispersion of active component and the high selectivity of 3-methylindole. Furthermore, the reaction pathway of gas-phase synthesis of 3-methylindole from glycerin and aniline on Cu/CoO/La2O3/Al2O3/SBA-15 was explored. Graphic Abstract: [Figure not available: see fulltext.]
- Sun, Pinghui,Lin, Shuyi,Guo, Huimei,Su, Jianhui,Shi, Lei
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p. 463 - 477
(2020/07/16)
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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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- Soluble asphaltene oxide: A homogeneous carbocatalyst that promotes synthetic transformations
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Carbocatalysts, materials which are predominantly composed of carbon and catalyze the synthesis of organic or inorganic compounds, are promising alternatives to metal-based analogues. Even though current carbocatalysts have been successfully employed in a broad range of synthetic transformations, they suffer from a number of drawbacks in part due to their heterogeneous nature. For example, the insolubility of prototypical carbocatalysts, such as graphene oxide (GO), may restrict access to catalytically-active sites in a manner that limits performance and/or challenges optimization. Herein we describe the preparation and utilization of soluble asphaltene oxide (sAO), which is a novel material that is composed of oxidized polycyclic aromatic hydrocarbons and is soluble in a wide range of organic solvents as well as in aqueous media. sAO promotes an array of synthetically useful transformations, including esterifications, cyclizations, multicomponent reactions, and cationic polymerizations. In many cases, sAO was found to exhibit higher catalytic activities than its heterogeneous analogues and was repeatedly and conveniently recycled, features that were attributed to its ability to form homogeneous phases.
- Bielawski, Christopher W.,Jung, Hyosic
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p. 15598 - 15603
(2020/05/05)
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- Palladium-Catalyzed Amination/Dearomatization Reaction of Indoles and Benzofurans
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This report describes a palladium-catalyzed dearomatization and amination tandem reaction of 2,3-disubstituted indoles and benzofurans via the Catellani strategy. This reaction provides a new method for the construction of amino-substituted indoline-fused cyclic and benzofuran spiro compounds in good yields. The reaction has broad functional group compatibility and substrate scope.
- Zhang, Zhe,Zhang, Bo-Sheng,Li, Kai-Li,An, Yang,Liu, Ce,Gou, Xue-Ya,Liang, Yong-Min
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p. 7817 - 7839
(2020/07/16)
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- Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes
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An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.
- Kawauchi, Daichi,Noda, Kenta,Komatsu, Yoshiyuki,Yoshida, Kei,Ueda, Hirofumi,Tokuyama, Hidetoshi
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supporting information
p. 15793 - 15798
(2020/10/12)
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- Transition-Metal-Free Coupling of 1,3-Dipoles and Boronic Acids as a Sustainable Approach to C?C Bond Formation
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The need for alternative, complementary approaches to enable C?C bond formation within organic chemistry is an on-going challenge in the area. Of particular relevance are transformations that proceed in the absence of transition-metal reagents. In the current study, we report a comprehensive investigation of the coupling of nitrile imines and aryl boronic acids as an approach towards sustainable C?C bond formation. In situ generation of the highly reactive 1,3-dipole facilitates a Petasis–Mannich-type coupling via a nucleophilic boronate complex. The introduction of hydrazonyl chlorides as a complementary nitrile imine source to the 2,5-tetrazoles previously reported by our laboratory further broadens the scope of the approach. Additionally, we exemplify for the first time the extension of this protocol into another 1,3-dipole, through the synthesis of aryl ketone oximes from aryl boronic acids and nitrile N-oxides.
- Livingstone, Keith,Bertrand, Sophie,Kennedy, Alan R.,Jamieson, Craig
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supporting information
p. 10591 - 10597
(2020/07/25)
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- Fe-Catalyzed Sequential C(sp3)-H/N-H Annulation of 2-Methylindoles with Ethyl Trifluoropyruvate at Room Temperature: Construction of Pyrrolo[1,2-α]indoles
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An efficient and benign iron-catalyzed room-temperature method was developed for direct sequential C(sp3)-H/N-H annulation to construct pyrroloindole scaffolds. This strategy features cheap and readily available raw materials and mild room-temperature reaction conditions and provides a green and practical method for the one-pot rapid synthesis of a wide range of diversely functionalized pyrrolo[1,2-α]indoles.
- Wang, Le,Wang, Le,Zhou, Jia,Chen, Han-Qia,Li, Dong-Li,Lin, Jun-Bing,Lin, Jun-Bing,Li, Ke,Ding, Tong-Mei,Zhang, Shu-Yu,Zhang, Shu-Yu
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supporting information
p. 4716 - 4720
(2020/06/29)
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- B(C6F5)3-Catalyzed Direct C3 Alkylation of Indoles and Oxindoles
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The direct C3 alkylation of indoles and oxindoles is a challenging transformation, and only a few direct methods exist. Utilizing the underexplored ability of triaryl boranes to mediate the heterolytic cleavage of α-nitrogen C-H bonds in amines, we have developed a catalytic approach for the direct C3 alkylation of a wide range of indoles and oxindoles using amine-based alkylating agents. We also employed this borane-catalyzed strategy in an alkylation-ring opening cascade.
- Basak, Shyam,Alvarez-Montoya, Ana,Winfrey, Laura,Melen, Rebecca L.,Morrill, Louis C.,Pulis, Alexander P.
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p. 4835 - 4840
(2020/04/22)
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- Ruthenium Pincer Complex Catalyzed Selective Synthesis of C-3 Alkylated Indoles and Bisindolylmethanes Directly from Indoles and Alcohols
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Herein, we presented Ru-SNS complex that serves as a useful catalyst for C-3 alkylation of 1H-indoles with various aliphatic primary and secondary alcohols including cyclic alcohols as well as benzylic alcohols. The selective synthesis of bisindolylmethane derivatives is also achieved from the same set of indole and alcohol just by altering the reaction parameters. Furthermore, the sustainable synthesis of C-3 alkylated indoles directly from 2-(2-nitrophenyl)ethan-1-ol and alcohols catalysed by a Ru-complex via “borrowing hydrogen” strategy is reported. This protocol provides an atom-economical sustainable route to access structurally important compounds like arundine, vibrindole A and tryptamine based derivatives. (Figure presented.).
- Biswas, Nandita,Sharma, Rahul,Srimani, Dipankar
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supporting information
p. 2902 - 2910
(2020/06/03)
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- Cu-Catalyzed Arylation/Acyl Migration Cascade Reaction of Enaminones: Access to N-Fused Polycyclic and 2,3-Disubstituted Indoles
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An efficient synthesis of N-fused polycyclic and 2,3-disubstituted indoles by copper-catalyzed direct annulation/acyl migration reaction of enaminones is reported. This strategy features cheap and low loading of the catalyst/ligand, readily available starting materials, and good functional group compatibilities. Notably, allyl-containing substrates are also tolerated, which allows the downstream derivatization toward indole alkaloids.
- Li, Weishuang,Dong, Zhan,Zhang, Yan,Zeng, Zhen,Usman, Muhammad,Liu, Wen-Bo
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p. 7995 - 8005
(2019/06/24)
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- Organic electroluminescent compound as well as preparation method and organic electroluminescent device thereof
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The invention relates to an organic electroluminescent compound as well as a preparation method and an organic electroluminescent device thereof. The organic electroluminescent compound has a structural formula shown by a chemical formula 1 as shown in the specification. The invention proposes a solution for introducing a novel pyrroloindole derivative. A high-quality organic electroluminescent material with excellent hole transporting capacity, high efficiency and long service life is obtained by introducing arylamine and the novel pyrroloindole derivative. The organic electroluminescent device prepared by using the organic electroluminescent compound provided by the invention as a hole transporting layer has a lower starting voltage by compared with that of the organic electroluminescentdevice prepared by using NPB as the hole transporting layer, the luminous efficiency is improved and the service life is significantly prolonged. The preparation method of the organic electroluminescent compound provided by the invention is simple and feasible, high in yield, and suitable for large-scale production.
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Paragraph 0070-0072; 0140-0142
(2019/09/17)
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- Supported dual-acidic 1,3-disulfoimidazolium chlorozincate@HZSM-5 as a promising heterogeneous catalyst for synthesis of indole derivatives
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HZSM-5-supported Br?nsted and Lewis acidic ionic solid 1,3-disulfoimidazolium chlorozincate materials ([dsim]2[ZnCl4]@HZSM-5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt-loaded HZSM-5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X-ray diffraction and inductively coupled plasma optical emission spectrometric techniques.
- Saikia, Susmita,Puri, Krishna,Borah, Ruli
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- Synthesis and evaluation of indole derivatives as photosynthesis and plant growth inhibitors
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Indole derivatives were synthetized based on the Fischer indole methodology using different phenyl hydrazine hydrochlorides and either cyclohexanone or 2-butanone. The pre- and post-emergent herbicidal activities were evaluated against Ipomoea grandifolia. A carbazole, 6-chloro-2,3,4,9-tetrahydro-1H-carbazole (3b), decreased the PIabs parameter by 32% and increased the cross-section related parameters, indicating the inactivation of the reaction center on photosystem II. Compound 3b acts as a post-emergent herbicide prototype since dry biomass was reduced by 50%, corroborating the fluorescence results. Comparing instead with a germination experiment, 2,3,4,9-tetrahydro-1H-carbazole (3a) was found to be the most effective agent, inhibiting seed germination by 22% and decreasing root length by 50%. The tetrahydrocarbazoles showed better results than indole derivatives potentially due to the presence of methylene groups at structures, which increase the compounds' lipophilicity and may facilitate their access to the plant. In addition, electron withdrawing groups on the aromatic ring were found to correlate with increased herbicide activity. Further optimization of this series towards the development of herbicides is ongoing.
- Mendes, Mylla Cristie Da Silva,Fazolo, Bruno Rodrigues,De Souza, Jéssica Maria,De Vasconcelos, Leonardo Gomes,De Sousa Junior, Paulo Teixeira,Dall'Oglio, Evandro Luiz,Soares, Marcos Ant?nio,Sampaio, Olívia Moreira,Vieira, Lucas Campos Curcino
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p. 1350 - 1358
(2019/06/19)
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- Visible-light-promoted sulfonylmethylation of imidazopyridines
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The visible light promoted C–H sulfonylmethylation of imidazopyridines with easily accessible bromomethyl sulfones under mild reaction conditions was described. This protocol provides an effective and practical access to sulfonylmethylated imidazopyridines with good functional group tolerance. The desired products were provided in moderate to excellent yields for 50 examples at room temperature. The method could also be an attractive strategy to install a methyl group on imidazopyridines.
- Mi, Xia,Kong, Yuanfang,Zhang, Jingyu,Pi, Chao,Cui, Xiuling
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supporting information
p. 2295 - 2298
(2019/10/28)
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- Br?nsted-Acid-Promoted Rh-Catalyzed Asymmetric Hydrogenation of N-Unprotected Indoles: A Cocatalysis of Transition Metal and Anion Binding
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The incorporation of Br?nsted acid, thiourea anion binding, and transition metal catalysis enables an efficient method to synthesize chiral indolines via hydrogenation of indoles. Catalyzed by a rhodium/ZhaoPhos complex, asymmetric hydrogenation of unprotected indoles is performed smoothly with excellent enantioselectivities (up to 99% ee, up to 400 TON). Br?nsted acid HCl activates indoles to form iminium ion intermediates. Mechanistic studies support the assumption that anion binding plays a crucial role as a secondary interaction. DFT calculations reveal an outer-sphere mechanism in this chemical transformation.
- Wen, Jialin,Fan, Xiangru,Tan, Renchang,Chien, Hui-Chun,Zhou, Qinghai,Chung, Lung Wa,Zhang, Xumu
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supporting information
p. 2143 - 2147
(2018/04/30)
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- Single-Pot Synthesis of Alkyl-Substituted Quinolines and Indoles via Photoinduced Oxidation of Primary Alcohols
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Single-pot synthesis of alkyl-substituted quinolines and indoles has been performed via photoinduced oxidation of primary aliphatic alcohols (C2–C5) and condensation of the aldehydes (products of the alcohols oxidation) with aniline under the action of iron-containing catalysts and inorganic oxidants. The synthesis was the most efficient in the presence of FeCl3·6H2O as catalyst and 10% aqueous solution of NaOCl as oxidant with irradiation by Hg lamp. The synthesis mechanism through photoinduced oxidation of primary aliphatic alcohol has been suggested.
- Makhmutov
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p. 892 - 897
(2018/07/06)
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- Arylamine-based compound and organic light emitting diode comprising the same
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An arylamine-based compound is represented by Formula 1 below. The arylamine-based compound is included in an organic light emitting diode.
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Page/Page column 98
(2018/05/16)
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- Mechanistic Studies on Tryptophan Lyase (NosL): Identification of Cyanide as a Reaction Product
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Tryptophan lyase (NosL) catalyzes the formation of 3-methylindole-2-carboxylic acid and 3-methylindole from l-tryptophan. In this paper, we provide evidence supporting a formate radical intermediate and demonstrate that cyanide is a byproduct of the NosL-catalyzed reaction with l-tryptophan. These experiments require a major revision of the NosL mechanism and uncover an unanticipated connection between NosL and HydG, the radical SAM enzyme that forms cyanide and carbon monoxide from tyrosine during the biosynthesis of the metallo-cluster of the [Fe-Fe] hydrogenase.
- Bhandari, Dhananjay M.,Fedoseyenko, Dmytro,Begley, Tadhg P.
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supporting information
p. 542 - 545
(2018/01/26)
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- C -Methylation of Alcohols, Ketones, and Indoles with Methanol Using Heterogeneous Platinum Catalysts
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A versatile, selective, and recyclable heterogeneous catalytic method for the methylation of C-H bonds in alcohols, ketones, and indoles with methanol under oxidant-free conditions using a Pt-loaded carbon (Pt/C) catalyst in the presence of NaOH is reported. This catalytic system is effective for various methylation reactions: (1) the β-methylation of primary alcohols, including aryl, aliphatic, and heterocyclic alcohols, (2) the α-methylation of ketones, and (3) the selective C3-methylation of indoles. The reactions are driven by a borrowing-hydrogen mechanism. The reaction begins with the dehydrogenation of the alcohol(s) to afford aldehydes, which subsequently undergo a condensation reaction with the nucleophile (aldehyde, ketone, or indole), followed by hydrogenation of the condensation product by Pt-H species to yield the desired product. In all of the methylation reactions explored in this study, the Pt/C catalyst exhibits a significantly higher turnover number than other previously reported homogeneous catalytic systems. Moreover, it is demonstrated that the high catalytic activity of Pt can be rationalized in terms of the adsorption energy of hydrogen on the metal surface, as revealed by density functional theory calculations on different metal surfaces.
- Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Jamil, Md. A. R.,Toyao, Takashi,Shimizu, Ken-Ichi
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p. 3091 - 3103
(2018/04/14)
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- Bifunctional Iron Complexes Catalyzed Alkylation of Indoles
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Cyclopentadienone iron carbonyl complexes have been applied in alkylation of indoles with various benzylic alcohols, aliphatic alcohols (butanol, ethanol, methanol and 2-methylpentanol) via the hydrogen autotransfer strategy in mild reaction conditions. Experimental works highlight the role of the bifunctional iron complexes and the base. These iron complexes demonstrated a broad applicability in mild conditions and extended the scope of substrates in iron catalyzed C?C bond formation. (Figure presented.).
- Seck, Charlotte,Mbaye, Mbaye Diagne,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
p. 4640 - 4645
(2018/10/31)
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- Iron-Catalyzed Methylation Using the Borrowing Hydrogen Approach
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A general iron-catalyzed methylation has been developed using methanol as a C1 building block. This borrowing hydrogen approach employs a Kn?lker-type (cyclopentadienone)iron carbonyl complex as catalyst (2 mol %) and exhibits a broad reaction scope. A variety of ketones, indoles, oxindoles, amines, and sulfonamides undergo mono- or dimethylation in excellent isolated yields (>60 examples, 79% average yield).
- Polidano, Kurt,Allen, Benjamin D. W.,Williams, Jonathan M. J.,Morrill, Louis C.
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p. 6440 - 6445
(2018/07/25)
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- Electron-Transfer and Hydride-Transfer Pathways in the Stoltz–Grubbs Reducing System (KOtBu/Et3SiH)
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Recent studies by Stoltz, Grubbs et al. have shown that triethylsilane and potassium tert-butoxide react to form a highly attractive and versatile system that shows (reversible) silylation of arenes and heteroarenes as well as reductive cleavage of C?O bonds in aryl ethers and C?S bonds in aryl thioethers. Their extensive mechanistic studies indicate a complex network of reactions with a number of possible intermediates and mechanisms, but their reactions likely feature silyl radicals undergoing addition reactions and SH2 reactions. This paper focuses on the same system, but through computational and experimental studies, reports complementary facets of its chemistry based on a) single-electron transfer (SET), and b) hydride delivery reactions to arenes.
- Smith, Andrew J.,Young, Allan,Rohrbach, Simon,O'Connor, Erin F.,Allison, Mark,Wang, Hong-Shuang,Poole, Darren L.,Tuttle, Tell,Murphy, John A.
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supporting information
p. 13747 - 13751
(2017/10/12)
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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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- Dearomatization of Indoles via Palladium-Catalyzed Allylic C-H Activation
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The first Pd-catalyzed allylic dearomatization of substituted indoles triggered by C-H bond activation is reported. The presence of a catalytic amount of 2,5-DMBQ is proven to be a key factor for the high yield. This one-pot tandem allylic C-H activation/dearomatization sequence provides a straightforward access to 3,3-disubstituted indolines.
- Zhang, Heng,Hu, Rong-Bin,Liu, Na,Li, Shi-Xia,Yang, Shang-Dong
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supporting information
p. 28 - 31
(2016/01/15)
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- Catalytic Synthesis of Substituted Indoles and Quinolines from the Dehydrative C-H Coupling of Arylamines with 1,2- and 1,3-Diols
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The cationic ruthenium-hydride complex catalyzes the dehydrative C-H coupling reaction of arylamines with 1,2-diols to form the indole products. The analogous coupling of arylamines with 1,3-diols afforded the substituted quinolines. The catalytic method directly forms these coupling products in a highly regioselective manner without generating any toxic byproducts.
- Lee, Hanbin,Yi, Chae S.
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supporting information
p. 1973 - 1977
(2016/07/06)
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- Novel and Efficient Heterogeneous 4-Methylbenzenesulfonic Acid-Based Ionic Liquid Supported on Silica Gel for Greener Fischer Indole Synthesis
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In this work, a functionalizing active species 4-methylbenzenesulfonic acid-based IL on silica gel (IL-SO3H-SiO2) has been prepared, and characterized by FT-IR, XRD, TGA, SEM and EDX spectra. Then, IL-SO3H-SiO2 was utilized as an efficient and heterogeneous catalyst for the synthesis of indoles via the one-pot Fischer reaction of phenyl hydrazines with ketones or aldehydes at room temperature. The heterogeneous catalyst could be recovered easily by filtration and reused many times without significant loss of its catalytic activity.
- Hu, Yu-Lin,Fang, Dong,Li, Dong-Sheng
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p. 968 - 976
(2016/04/20)
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- Method for preparing indole compounds through catalysis of ionic liquid
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The invention relates to a green synthesis method of one type of indole derivatives. The method is characterized by taking sulfonic acid ionic liquid as a catalyst, taking aliphatic ketone, aromatic ketone and aromatic hydrazine hydrochloride as raw materials, reacting in water, filtering and drying a reaction mixture to obtain indole compounds. The method is simple to operate; the raw materials are low intoxicity and low in costs; the reaction condition is mild; the product is easy to separate; the synthesis process is environmentally-friendly; the indole compounds are high in purity; the catalyst can be directly reused without treatment; the method is green and environmentally-friendly, and is suitable for industrial production.
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Paragraph 0031-0033
(2018/02/04)
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- Palladium-Catalyzed Dearomative Allylic Alkylation of Indoles with Alkynes to Synthesize Indolenines with C3-Quarternary Centers
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A palladium-catalyzed dearomative allylic alkylation of indoles with alkynes to construct indolenines with C3-quarternary centers was reported. The in situ formed arylallene intermediate omitted the need to install leaving groups on the allylic compounds and employ extra oxidants to oxidize the allylic C-H bonds. The reaction exhibited good functional group tolerance and high atom economy. Moreover, the reaction was further expanded to synthesize pyrroloindolines and furanoindolines.
- Gao, Shang,Wu, Zijun,Fang, Xinxin,Lin, Aijun,Yao, Hequan
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supporting information
p. 3906 - 3909
(2016/08/16)
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- A Convenient Modification of the Fischer Indole Synthesis with a Solid Acid
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(Chemical Equation Presented). A new one-pot version of the titled reaction involves heating a mixture of a carbonyl compound, a phenylhydrazine, and the cation exchange resin Amberlite IR 120 in refluxing ethanol. A variety of enolizable aldehydes, and ketones and several substituted phenylhydrazines could thus be converted to the corresponding indoles in excellent yields (70-88%). Reaction times were typically 6-10 h, with the resin being then filtered off and the product isolated after minimal workup.
- Chandrasekhar, Sosale,Mukherjee, Somnath
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supporting information
p. 1018 - 1022
(2015/03/30)
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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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- Copper nanoparticles from copper aluminum hydrotalcite: An efficient catalyst for acceptor- and oxidant-free dehydrogenation of amines and alcohols
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An efficient and simple process for the preparation of stable nanocopper(0) on alumina [Cu(0)/Al2O3] from the inorganic composite precursor copper aluminum hydrotalcite (Cu-AlHT) by a chemical reduction method is described. Cu(0)/ Al2O3 was employed as an efficient catalyst in the acceptor- and oxidant-free dehydrogenation of various amines and alcohols to their corresponding dehydrogenated products in good to excellent yields. The stability of Cu(0)/Al2O3 was assessed by studying its recoverability and reusability in the dehydrogenation of amines and alcohols for up to five cycles.
- Damodara, Dandu,Arundhathi, Racha,Likhar, Pravin R.
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supporting information
p. 189 - 198
(2014/03/21)
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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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supporting information
p. 312 - 317
(2014/01/06)
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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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p. 10476 - 10480
(2016/02/18)
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- Acceptorless dehydrogenation of nitrogen heterocycles with a versatile iridium catalyst
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Gas up: A cyclometalated iridium complex is found to catalyze the dehydrogenation of various benzofused N-heterocycles, thus releasing H 2. Driven by as low as 0.1 mol % catalyst, the reaction affords quinolines, indoles, quinoxalines, isoquinolines, and β-carbolines in high yields. Copyright
- Wu, Jianjun,Talwar, Dinesh,Johnston, Steven,Yan, Ming,Xiao, Jianliang
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supporting information
p. 6983 - 6987
(2013/07/26)
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- Improved indole syntheses from anilines and vicinal diols by cooperative catalysis of ruthenium complex and acid
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By developing a new and efficient dinuclear catalyst [Ru(CO) 2(Xantphos)]2 [Xantphos = 4,5-bis(diphenylphosphino)-9,9- dimethyl-9H-xanthene], an improved synthesis of indole from vicinal diols and anilines by cooperative catalysis of ruthenium complex and p-TSA (para-toluenesufonic acid) has been demonstrated. The presented synthetic protocol allows assembling a wide range of products in an efficient manner. Comparing to the existed protocols, our indole syntheses can be achieved at lower reaction temperature, in shorter reaction time, and with improved substrate tolerance.
- Zhang, Min,Xie, Feng,Wang, Xiaoting,Yan, Fengxia,Wang, Ting,Chen, Mengmeng,Ding, Yuqiang
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p. 6022 - 6029
(2013/05/09)
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- Oxidative palladium(II)-catalyzed dehydrogenative C-H/C-H cross-coupling of 2,3-substituted indolines with arenes at the C7 position
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Directed directing group: The C7 position of the indoline nucleus is difficult to address in C-H activation. An oxidative palladium(II) catalysis that allows for cross-dehydrogenative coupling in that position with activation of the C-H bond of the arene component is disclosed here. This C-H/C-H cross-coupling is applicable to various indolines acetylated at the nitrogen atom. Substitution at C2 is crucial for the C-H activation to occur at C7 (see scheme).
- Jiao, Lin-Yu,Oestreich, Martin
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supporting information
p. 10845 - 10848
(2013/09/02)
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- Vapor-phase synthesis of 3-methylindole from glycerol and aniline over zeolites-supported Cu-based catalysts
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Zeolites-supported Cu-based catalysts for the vapor-phase synthesis of 3-methylindole from glycerol and aniline were investigated. The catalysts were characterized by N2 adsorption, XRD, NH3-TPD and TG-DTA techniques. The results indicated that Cu/NaY catalyst exhibited higher activity and selectivity than Cu/5A, Cu/HZSM-5 or Cu/MCM-41 due to better dispersion of copper particles and larger amount of weak acid sites on the catalyst. The addition of Na2O to Cu/NaY not only improved the selectivity of the catalyst efficiently, but also inhibited the deactivation of the catalyst. Over Cu/NaY-Na2O, the selectivity of 3-methylindole reached 72.3% and the yield of the aim product was up to 50.4%. The characterizations revealed that Na2O promoter could decrease the amount of middle-strong acid sites of the catalyst remarkably as well as prevent from the formation of the coke. Furthermore, a probable catalytic mechanism for the synthesis of 3-methylindole from glycerol and aniline was proposed.
- Cui, Yanxi,Zhou, Xiaoshuang,Sun, Qi,Shi, Lei
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p. 238 - 245
(2013/08/23)
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- Coupling and cyclization of O-iodoanilines and propargylic bromides via allenes: An efficient entry to indomethacin
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A sequential allene synthesis and cyclization has been realized in a one-pot manner. A Pd(0)-catalyzed one-pot reaction of N-Ts or -Ms 2-iodoanilines and propargylic bromides afforded indoles with pharmaceutical importance highly efficiently with diversity via sequential carbon-carbon bond coupling forming allenes and azapalladation. With this newly established methodology, an efficient approach to indomethacin, an anti-inflammatory drug (NSAID), has been accomplished.
- Zhu, Can,Ma, Shengming
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p. 2782 - 2785
(2013/07/19)
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- Facile synthesis of 2-methylquinolines from anilines on mesoporous N-doped TiO2 under UV and visible light
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Nitrogen-doped TiO2 was synthesized by a simple wet method using a nitrogen precursor hydrazine hydrate and nano TiO2. This photocatalyst was characterized by X-ray diffraction, highresolution transmission electron microscopy, diffused reflectance spectra, photoluminescence, and X-ray photoelectron spectroscopy. XPS analysis indicates the incorporation of anionic nitrogen in TiO2 lattice as O-Ti-N linkage. N2 adsorption-desorpion isotherm indicates the mesoporous nature of N-TiO2 with the surface area 130.0 m2/g. Sizes of N-TiO2 particles are found to be in the range of 5-30 nm by HRTEM images. DRS spectra reveal the extended absorption to the visible range. N-TiO2 is found to be more efficient than Ag-TiO2, Au-TiO2, and Pt-TiO2 in quinaldine synthesis under visible light. Copyright Taylor & Francis Group, LLC.
- Selvam,Swaminathan
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p. 500 - 508
(2013/05/21)
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- Highly enantioselective Friedel-Crafts alkylation/N-hemiacetalization cascade reaction with indoles
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A new ring for your indole: An unprecedented copper-catalyzed enantioselective Friedel-Crafts alkylation/N-hemiacetalization cascade reaction with indoles and β,γ-unsaturated α-ketoesters is reported. This mild strategy provides new access to various synthetically and biologically important 2,3-dihydro-1H-pyrrolo[1,2-a]indoles in a highly enantioselective manner.
- Cheng, Hong-Gang,Lu, Liang-Qiu,Wang, Tao,Yang, Qing-Qing,Liu, Xiao-Peng,Li, Yang,Deng, Qiao-Hui,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 3250 - 3254
(2013/04/10)
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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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supporting information
p. 620 - 623
(2013/03/13)
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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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