- Two-Step Synthesis of Polysubstituted 6-Nitroindoles under Flow Chemical and Microwave Conditions
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A new simple and efficient synthesis of 6-nitroindoles, starting from N-carboxylalkylpyrrole-2-carboxaldehydes and protected β-nitro ketones, has been developed. The method involves two distinct domino processes, respectively performed under flow chemical conditions and microwave irradiation. 6-Nitroindoles were produced in good to excellent overall yields. (Figure presented.).
- Sampaolesi, Susanna,Gabrielli, Serena,Ballini, Roberto,Palmieri, Alessandro
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- DEHYDROGENATION OF CERTAIN INDOLINE DERIVATIVES INTO INDOLES
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The dehydrogenation was studied of certain acceptor indoline derivatives in nitrobenzene, in the presence of cadmium, sodium, and potassium carbonates.A method has been proposed for a mild dehydrogenation of certain acceptor groups containing indoline derivatives in nitrobenzene, in the presence of potassium carbonate.
- Vorob'eva, S. L.,Buyanov, V. N.,Suvorov, N. N.
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- Monomeric vanadium oxide: A very efficient species for promoting aerobic oxidative dehydrogenation of N-heterocycles
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Monomeric active species are very interesting in heterogeneous catalysis. In this work, we proposed a method to prepare VOx-NbOy@C catalysts, which involve the one-pot hydrothermal synthesis of inorganic/organic hybrid materials containing V/Nb followed by thermal treatment under a reducing atmosphere. The prepared catalysts were characterized using different techniques, such as high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy. It was shown that monomeric VOx species were dispersed homogeneously in the catalysts. The VOx-NbOy@C catalysts displayed high performance in the aerobic oxidative dehydrogenation of N-heterocycles to aromatic heterocycles. It was demonstrated that the selectivity of reaction over the catalyst with a very small amount of V (0.07 wt%) was much higher than that over the NbOy@C, and the catalyst also exhibited excellent stability in the reaction. The detailed study indicated that monomeric VO2 species were the most effective for promoting the reaction. This journal is
- Xie, Zhenbing,Chen, Bingfeng,Zheng, Lirong,Peng, Fangfang,Liu, Huizhen,Han, Buxing
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p. 431 - 437
(2021/01/11)
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- Zwitterion-induced organic-metal hybrid catalysis in aerobic oxidation
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In many metal catalyses, the traditional strategy of removing chloride ions is to add silver salts via anion exchange to obtain highly active catalysts. Herein, we reported an alternative strategy of removing chloride anions from ruthenium trichloride using an organic [P+-N-] zwitterionic compound via multiple hydrogen bond interactions. The resultant organic-metal hybrid catalytic system has successfully been applied to the aerobic oxidation of alcohols, tetrahydroquinolines, and indolines under mild conditions. The performance of zwitterion is far superior to that of many other common Lewis bases or Br?nsted bases. Mechanistic studies revealed that the zwitterion triggers the dissociation of chloride from ruthenium trichloride via nonclassical hydrogen bond interaction. Preliminary studies show that the zwitterion is applicable to catalytic transfer semi-hydrogenation.
- Hu, Rong-Bin,Lam, Ying-Pong,Ng, Wing-Hin,Wong, Chun-Yuen,Yeung, Ying-Yeung
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p. 3498 - 3506
(2021/04/07)
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- Luminescent Platinum(II) Complexes with Bidentate Diacetylide Ligands: Structures, Photophysical Properties and Application Studies
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A series of platinum(II) complexes supported by terphenyl diacetylide as well as diimine or bis-N-heterocyclic carbene (NHC) ligands have been prepared. The diacetylide ligands adopt a cis coordination mode featuring non-planar terphenyl moieties as revealed by X-ray crystallographic analyses. The electrochemical, photophysical and photochemical properties of these platinum(II) complexes have been investigated. These platinum(II) diimine complexes show broad emission with peak maxima from 566 nm to 706 nm, with two of them having emission quantum yields >60% and lifetimes 2 μs in solutions at room temperature, whereas the platinum(II) diacetylide complexes having bis-N-heterocyclic carbene instead of diimine ligand display photoluminescence with quantum yields of up to 28% in solutions and excited state lifetimes of up to 62 μs at room temperature. Application studies revealed that one of the complexes can catalyze photoinduced aerobic dehydrogenation of alcohols and alkenes, and a relatively non-toxic water-soluble Pt(II) complex displays anti-angiogenic activity.
- Luo, Zaoli,Liu, Yungen,Tong, Ka-Chung,Chang, Xiao-Yong,To, Wai-Pong,Che, Chi-Ming
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p. 2978 - 2992
(2021/08/30)
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- The Relation Between Position and Chemical Composition of Bis-Indole Substituents Determines Their Interactions with G-Quadruplex DNA
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G-quadruplex (G4) DNA structures are linked to fundamental biological processes and human diseases, which has triggered the development of compounds that affect these DNA structures. However, more knowledge is needed about how small molecules interact with G4 DNA structures. This study describes the development of a new class of bis-indoles (3,3-diindolyl-methyl derivatives) and detailed studies of how they interact with G4 DNA using orthogonal assays, biophysical techniques, and computational studies. This revealed compounds that strongly bind and stabilize G4 DNA structures, and detailed binding interactions which for example, show that charge variance can play a key role in G4 DNA binding. Furthermore, the structure–activity relationships generated opened the possibilities to replace or introduce new substituents on the core structure, which is of key importance to optimize compound properties or introduce probes to further expand the possibilities of these compounds as tailored research tools to study G4 biology.
- Prasad, Bagineni,Das, Rabindra Nath,Jamroskovic, Jan,Kumar, Rajendra,Hedenstr?m, Mattias,Sabouri, Nasim,Chorell, Erik
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p. 9561 - 9572
(2020/07/09)
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- Ir-Catalyzed Reversible Acceptorless Dehydrogenation/Hydrogenation of N-Substituted and Unsubstituted Heterocycles Enabled by a Polymer-Cross-Linking Bisphosphine
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The polystyrene-cross-linking bisphosphine ligand PS-DPPBz was effective for the Ir-catalyzed reversible acceptorless dehydrogenation/hydrogenation of N-heterocycles. Notably, this protocol is applicable to the dehydrogenation of N-substituted indoline derivatives with various N-substituents with different electronic and steric natures. A reaction pathway involving oxidative addition of an N-adjacent C(sp3)-H bond to a bisphosphine-coordinated Ir(I) center is proposed for the dehydrogenation of N-substituted substrates.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 5240 - 5245
(2020/07/03)
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- DMSO/t-BuONa/O2-Mediated Aerobic Dehydrogenation of Saturated N-Heterocycles
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Aromatic N-heterocycles such as quinolines, isoquinolines, and indolines are synthesized via sodium tert-butoxide-promoted oxidative dehydrogenation of the saturated heterocycles in DMSO solution. This reaction proceeds under mild reaction conditions and has a good functional group tolerance. Mechanistic studies suggest a radical pathway involving hydrogen abstraction of dimsyl radicals from the N-H bond or α-C-H of the substrates and subsequent oxidation of the nitrogen or α-aminoalkyl radicals.
- Cai, Hu,Tan, Wei,Xie, Yongfa,Yang, Ruchun,Yue, Shusheng
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p. 7501 - 7509
(2020/07/07)
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- Heterogeneously palladium-catalyzed acceptorless dehydrogenative aromatization of cyclic amines
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In this manuscript, we report an efficient heterogeneously catalyzed acceptorless dehydrogenative aromatization of cyclic amines under relatively mild conditions. In the presence of a supported catalyst Pd/LDH (LDH = layered double hydroxide), various kinds of structurally diverse cyclic amines including piperidines, tetrahydro(iso)quinolines, and indolines could be converted into the corresponding heteroarenes. Pd/LDH could be reused several times though its catalytic activity gradually declined due to the increase in the palladium particle size.
- Oyama, Takashi,Yatabe, Takafumi,Jin, Xiongjie,Mizuno, Noritaka,Yamaguchi, Kazuya
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supporting information
p. 517 - 520
(2019/06/11)
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- Flexible Versus Rigid G-Quadruplex DNA Ligands: Synthesis of Two Series of Bis-indole Derivatives and Comparison of Their Interactions with G-Quadruplex DNA
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Small molecules that target G-quadruplex (G4) DNA structures are not only valuable to study G4 biology but also for their potential as therapeutics. This work centers around how different design features of small molecules can affect the interactions with G4 DNA structures, exemplified by the development of synthetic methods to bis-indole scaffolds. Our synthesized series of bis-indole scaffolds are structurally very similar but differ greatly in the flexibility of their core structures. The flexibility of the molecules proved to be an advantage compared to locking the compounds in the presumed bioactive G4 conformation. The flexible derivatives demonstrated similar or even improved G4 binding and stabilization in several orthogonal assays even though their entropic penalty of binding is higher. In addition, molecular dynamics simulations with the c-MYC G4 structure showed that the flexible compounds adapt better to the surrounding. This was reflected by an increased number of both stacking and polar interactions with both the residues in the G4 DNA structure and the DNA residues just upstream of the G4 structure.
- Prasad, Bagineni,Jamroskovic, Jan,Bhowmik, Sudipta,Kumar, Rajendra,Romell, Tajanena,Sabouri, Nasim,Chorell, Erik
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p. 7926 - 7938
(2018/06/15)
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- Ordered Porous Nitrogen-Doped Carbon Matrix with Atomically Dispersed Cobalt Sites as an Efficient Catalyst for Dehydrogenation and Transfer Hydrogenation of N-Heterocycles
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Single-atom catalysts (SACs) have been explored widely as potential substitutes for homogeneous catalysts. Isolated cobalt single-atom sites were stabilized on an ordered porous nitrogen-doped carbon matrix (ISAS-Co/OPNC). ISAS-Co/OPNC is a highly efficient catalyst for acceptorless dehydrogenation of N-heterocycles to release H2. ISAS-Co/OPNC also exhibits excellent catalytic activity for the reverse transfer hydrogenation (or hydrogenation) of N-heterocycles to store H2, using formic acid or external hydrogen as a hydrogen source. The catalytic performance of ISAS-Co/OPNC in both reactions surpasses previously reported homogeneous and heterogeneous precious-metal catalysts. The reaction mechanisms are systematically investigated using first-principles calculations and it is suggested that the Eley–Rideal mechanism is dominant.
- Han, Yunhu,Wang, Ziyun,Xu, Ruirui,Zhang, Wei,Chen, Wenxing,Zheng, Lirong,Zhang, Jian,Luo, Jun,Wu, Konglin,Zhu, Youqi,Chen, Chen,Peng, Qing,Liu, Qiang,Hu,Wang, Dingsheng,Li, Yadong
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supporting information
p. 11262 - 11266
(2018/08/28)
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- Gold(0) catalyzed dehydrogenation of N-heterocycles
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Gold nanoclusters are good catalyst precursors for the catalytic dehydrogenation of indolines, tetrahydroquinazolines, and related N-heterocycles. The catalytically active species is presumably Au(0) nanoparticles.
- Kumaran, Elumalai,Leong, Weng Kee
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supporting information
p. 3958 - 3960
(2018/10/02)
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- Dehydrogenation of Nitrogen Heterocycles Using Graphene Oxide as a Versatile Metal-Free Catalyst under Air
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Graphene oxide (GO) has been developed as an inexpensive, environmental friendly, metal-free carbocatalyst for the dehydrogenation of nitrogen heterocycles. Valuable compounds, such as quinoline, 3,4-dihydroisoquinoline, quinazoline, and indole derivatives, have been successfully used as substrates. The investigation of various oxygen-containing molecules with different conjugated systems indicated that both the oxygen-containing groups and large π-conjugated system in GO sheets are essential for this reaction. (Figure presented.).
- Zhang, Jingyu,Chen, Shiya,Chen, Fangfang,Xu, Wensheng,Deng, Guo-Jun,Gong, Hang
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supporting information
p. 2358 - 2363
(2017/07/22)
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- One-pot tandem synthesis of 2,3-unsubstituted indoles, an improved Leimgruber-Batchoindole synthesis
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A concise, fast and efficient one-pot methodology has been developed for preparing 2,3-unsubstituted indoles from 2-nitrotoluenes and dimethylformamide dimethyl acetal. Compared with the classical Leimgruber-Batcho reaction, such a one-pot process simplified the operation procedures, generated less by-products and chemical residues, and resulted in higher overall yields in a shorter reaction time.
- Chen, Jinchun,Zhang, Zhikai,Liu, Sujing,Yang, Cuiyun,Xia, Chuanhai
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p. 4672 - 4675
(2014/01/17)
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- Single bifunctional ruthenium catalyst for one-pot cyclization and hydration giving functionalized indoles and benzofurans
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Chemical equation Presented Bifunctional is more than twice as fun! At low loading, catalyst 1 (see scheme) can form two important heterocycle classes, apparently by attack of XH on a vinylidene intermediate. Aza- and nitroindoles can be formed, and all N-protecting groups tested (alkyl, allyl, sulfonyl) were tolerated. The newly formed ring can be deuterated in one step, and for substrates with two terminal alkynes, cyclization can be followed by hydration, making this catalyst uniquely versatile.
- Nair, Reji N.,Lee, Paul J.,Rheingold, Arnold L.,Grotjahn, Douglas B.
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experimental part
p. 7992 - 7995
(2010/09/18)
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- Palladium-catalyzed annulation of haloanilines and halobenzamides using norbornadiene as an acetylene synthon: A route to functionalized indolines, isoquinolinones, and indoles
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A general procedure for the palladium-catalyzed annulation of substituted haloanilines with norbornadiene gives functionalized indolines in 51-98% yield. These indolines can be rapidly converted to benzenoid- substituted indoles and tricyclic indolines. Extension to the use of substituted halobenzamides gives functionalized isoquinolinones in up to 86% yield.
- Thansandote, Praew,Hulcoop, David G.,Langer, Michael,Lautens, Mark
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supporting information; experimental part
p. 1673 - 1678
(2009/07/17)
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- Efficient synthesis of substituted indoles and benzazoles by oxidative aromatization using activated carbon-Molecular oxygen system
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Efficient synthesis of substituted indoles was achieved by oxidative aromatization of indolines using activated carbon-molecular oxygen (O2) system. Benzazoles (benzimidazole and benzothiazoles) were also prepared by the reaction of 1,2-phenylenediamine and 2-aminobenzenethiol with formaldehyde in the presence of activated carbon under oxygen atmosphere.
- Nomura, Yukiko,Kawashita, Yuka,Hayashi, Masahiko
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p. 629 - 635
(2008/09/18)
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- Dehydrogenation of indoline by cytochrome P450 enzymes: A novel "aromatase" process
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Indoline derivatives possess therapeutic potential within a variety of drug candidates. In this study, we found that indoline is aromatized by cytochrome P450 (P450) enzymes to produce indole through a novel dehydrogenation pathway. The indole products can potentially be bioactivated to toxic intermediates through an additional dehydrogenation step. For example, 3-substituted indoles like 3-methylindole and zafirlukast [4-(5-cyclopentyloxy-carbonylamino-1-methyl- indol-3-ylmethyl)-3-methoxy-N-o-tolylsulfonylbenzamide] are dehydrogenated to form 3-methyleneindolenine electrophiles, which react with protein and/or DNA nucleophilic residues to cause toxicities. Another potentially significant therapeutic consequence of indoline aromatization is that the product indoles might have dramatically different therapeutic potency than the parent indolines. In this study, indoline was indeed efficiently aromatized by human liver microsomes and by several P450s, but not by flavin-containing monooxygenase (FMO) 3. CYP3A4 had the highest aromatase activity. Four additional indoline metabolites [2,3,4,7-tetrahydro-4,5-epoxy-1H-indole (M1); N-hydroxyindole (M2), N-hydroxyindoline (M3), and M4 ([1,4,2,5]dioxadiazino[2,3-a:5,6-a′] diindole)] were characterized; none was a metabolite of indole. M1 was an arene oxide from P450 oxidation, and M2, M3, and M4 were produced by FMO3. Our data indicated that indoline was oxidized to M3 and then to an intermediate indoline nitrone, which tautomerized to form M2, and subsequently dimerized to a di-indoline. This dimer was immediately oxidized by FMO3 or atmospheric oxygen to the final product, M4. No evidence was found for the P450-mediated production of an aliphatic alcohol from indoline that might dehydrate to produce indole. Therefore, P450 enzymes catalyze the novel "aromatase" metabolism of indoline to produce indole. The aromatase mechanism does not seem to occur through N-oxidation or dehydration of an alcohol but rather through a formal dehydrogenation pathway. Copyright
- Sun, Hao,Ehlhardt, William J.,Kulanthaivel, Palaniappan,Lanza, Diane L.,Reilly, Christopher A.,Yost, Garold S.
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p. 843 - 851
(2008/02/12)
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- Nucleophilic substitution reaction of 1-methoxy-6-nitro-indole
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Nucleophilic substitution reaction of 1-methoxy-6-nitroindole (1) was examined. In the reaction with sodium methoxide or sodium cyanide as a nucleophile, 2- and 3-methoxy-6-nitroindoles, and 7-cyano-6-nitroindole were obtained, respectively. A novel methylene homologation at the 3-position was found in the reaction of 1 with sodium methyl sulfide or potassium salt of diethyl malonate to give 3-methylthiomethytyl-6-nitroindole and its 2-methylthio derivative, and diethyl 2-(6-nitroindol-3-yl)methylmalonate, respectively. Possible reaction mechanism is discussed.
- Yamada, Koji,Kawasaki, Toshiya,Fujita, Tomomi,Somei, Masanori
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p. 1151 - 1159
(2007/10/03)
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- A mild and efficient dehydrogenation of indolines
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A new mild and efficient dehydrogenation of indolines to indoles has been developed. For the dehydrogenation trichloroisocyanuric acid is used in combination with DBU. After work-up with sodium hydrogen sulfite it was possible to obtain indole in an almost quantitative yield. The new method is also suitable for indolines bearing electron withdrawing or electron donating groups. Under the reaction conditions no ring chlorination was observed.
- Tilstam, Ulf,Harre, Michael,Heckrodt, Thilo,Weinmann, Hilmar
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p. 5385 - 5387
(2007/10/03)
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- Synthesis of benzosultams via intramolecular vicarious nucleophilic substitution of hydrogen
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Intramolecular Vicarious Nucleophilic Substitution of Hydrogen (VNS) in N-(3-nitrophenyl)- and N-(3-nitrobenzyl)chloromethylsulfonamides leads to five-, six- and seven-membered benzosultam derivatives.
- Wojciechowski,Makosza
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p. 571 - 576
(2007/10/02)
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- Dehydrogenation of Indolines to Indoles via Azasulphonium Salts or N-Chloramines
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The dehydrogenation of indolines to indoles without using mineral oxidising reagents is described.The conversion was achieved via either azasulphonium salts or N-chloramines, the former route involving milder conditions but a more complex procedure.
- Kawase, Masami,Miyake, Yuko,Kikugawa, Yasuo
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p. 1401 - 1404
(2007/10/02)
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- HETEROGENEOUS-CATALYTIC E. FISCHER REACTION XIV. EFFECT OF ELECTRONIC FACTORS IN THE HETEROGENEOUS-CATALYTIC E. FISCHER REACTION
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The effect of electronic factors on the heterogeneous-catalytic E.Fischer reaction was studied for the case of methoxy- and nitro-substituted arylhydrazones.It was shown that the presence of the methoxy groups in all probability increases the basicity of the respective hydrazone and facilitates adsorption of the active centers of the catalyst.In this case indoles are obtained with high yields.The presence of nitro groups hinder the adsorption of the hydrazone on the catalyst and as a result leads to a decrease in the yield of indole.
- Suvorov, N. N.,Shkil'kova, V. N.,Podkhalyuzina, N. Ya.
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p. 2117 - 2120
(2007/10/02)
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- AN EFFECTIVE DEHYDROGENATIONS OF INDOLINES TO INDOLES WITH COBALT(II) SCHIFF'S BASE COMPLEXES
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Facile dehydrogenations of indolines to indoles were performed with the catalytic amount of bis(salicylidene)ethylenediaminatocobalt(II) and bis(3-methoxysalicylidene)ethylenediaminatocobalt(II) under mild conditions in 55-92percent yields.
- Inada, Akira,Nakamura, Yushin,Morita, Yutaka
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p. 1287 - 1290
(2007/10/02)
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