- Luminescent Platinum(II) Complexes with Bidentate Diacetylide Ligands: Structures, Photophysical Properties and Application Studies
-
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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- Diaryliodonium Salt-Based Synthesis of N-Alkoxyindolines and Further Insights into the Ishikawa Indole Synthesis
-
A diaryliodonium salt-based strategy enabled the first systematic synthesis of rarely accessible N-alkoxyindolines. Mechanistic analyses suggested that the reaction likely involves reductive elimination of iodobenzene from iodaoxazepine via a four-membered transition state, followed by Meisenheimer rearrangement. Substrates with N-carbamate protection afforded indole in a manner similar to that of the Ishikawa indole synthesis. Preinstallation of a stannyl group as an iodonium salt precursor greatly expanded the substrate scope, and further mechanistic insights are discussed.
- Ogura, Akihiro,Shibata, Kouhei,Takao, Ken-Ichi
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p. 10067 - 10087
(2021/07/26)
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- Method for catalytically synthesizing indole derivative by using ferrous complex
-
The invention relates to a method for catalytically synthesizing an indole derivative by using a ferrous complex, which comprises the following step: by taking arylamine and acetaldehyde as raw materials and a ferrous complex containing a meta-carboboryl methylpyridine structure as a catalyst, conducting reacting at room temperature to prepare the indole derivative. Compared with the prior art, the method utilizes the ferrous complex to efficiently catalyze the reaction of arylamine and acetaldehyde at room temperature to prepare the indole derivative, the reaction condition is mild, the substrate range is wide, and the method has high catalytic activity and yield.
- -
-
Paragraph 0057-0060
(2021/07/31)
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- Monoamine Oxidase (MAO-N) Biocatalyzed Synthesis of Indoles from Indolines Prepared via Photocatalytic Cyclization/Arylative Dearomatization
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The biocatalytic aromatization of indolines into indole derivatives exploiting monoamine oxidase (MAO-N) enzymes is presented. Indoline substrates were prepared via photocatalytic cyclization of arylaniline precursors or via arylative dearomatization of unsubstituted indoles and in turn chemoselectively aromatized by the MAO-N D11 whole cell biocatalyst. Computational docking studies of the indoline substrates in the MAO-N D11 catalytic site allowed for the rationalization of the biocatalytic mechanism and experimental results of the biotransformation. This methodology represents an efficient example of biocatalytic synthesis of indole derivatives and offers a facile approach to access these aromatic heterocycles under mild reaction conditions.
- Black, Gary W.,Brancale, Andrea,Castagnolo, Daniele,Colonna, Serena,Ferla, Salvatore,Masci, Domiziana,Turner, Nicholas J.,Varricchio, Carmine,Zhao, Fei
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p. 6414 - 6421
(2020/07/09)
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- Decarboxylation of indole-3-carboxylic acids under metal-free conditions
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Two reaction systems have been developed for the decarboxylation of indole-3-carboxylic acids. The decarboxylation can be achieved smoothly under K2CO3-catalyzed or acetonitrile-promoted basic conditions. It provided an efficient and simple method for the transformation of indole-3-carboxylic acids and the corresponding indoles were isolated with good to excellent yields. From the experimental facts, we put forward the possible reaction mechanism.
- Chen, Xia,Zhou, Xiao-Yu
-
supporting information
p. 805 - 812
(2020/02/20)
-
- Electron Transfer Photoredox Catalysis: Development of a Photoactivated Reductive Desulfonylation of an Aza-Heteroaromatic Ring
-
Herein, we report a protocol for desulfonylation of aza-heteroaromatic rings via photoinduced electron transfer and hydrogen atom transfer. This general protocol has a wide substrate range and moderate to good yields. The utility of the method was demonstrated by the chemoselective desulfonylation of a molecule containing both an aliphatic and an aromatic sulfonamide. (Figure presented.).
- Qiang-Liu,Liu, Yu-Xiu,Song, Hong-Jian,Wang, Qing-Min
-
supporting information
p. 3110 - 3115
(2020/07/04)
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- Homoleptic Bis(trimethylsilyl)amides of Yttrium Complexes Catalyzed Hydroboration Reduction of Amides to Amines
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Homoleptic lanthanide complex Y[N(TMS)2]3 is an efficient homogeneous catalyst for the hydroboration reduction of secondary amides and tertiary amides to corresponding amines. A series of amides containing different functional groups such as cyano, nitro, and vinyl groups were found to be well-tolerated. This transformation has also been nicely applied to the synthesis of indoles and piribedil. Detailed isotopic labeling experiments, control experiments, and kinetic studies provided cumulative evidence to elucidate the reaction mechanism.
- Ye, Pengqing,Shao, Yinlin,Ye, Xuanzeng,Zhang, Fangjun,Li, Renhao,Sun, Jiani,Xu, Beihang,Chen, Jiuxi
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supporting information
p. 1306 - 1310
(2020/02/22)
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- Applications of rare earth silicon amination material as catalyst in preparation of indole or indole derivative
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The invention belongs to the technical field of chemical engineering, and specially provides applications of a rare earth silicon amination material as a catalyst in preparation of indole or an indolederivative, wherein the reaction raw materials comprise a compound I, the general formula of the compound I is shown in the specification, R is hydrogen, methyl, chlorine, fluorine, bromine or methoxyl, the rare earth silicon amination material M[N(SiMe3)2]3 is a catalyst, and M is a rare earth element. According to the invention, the indole or the indole derivative is prepared by taking the rareearth silicon amination material as the catalyst and taking the compound I and pinacol boron as the raw materials; the method is simple and convenient to operate and high in reaction selectivity; andthe synthesized indole derivative is good in product quality and high in yield.
- -
-
Paragraph 0048-0052
(2020/03/03)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Electrochemical Acceptorless Dehydrogenation of N-Heterocycles Utilizing TEMPO as Organo-Electrocatalyst
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Catalytic acceptorless dehydrogenation (CAD) has been a basically important organic transformation to ubiquitous unsaturated compounds without the usage of a sacrificial hydrogen acceptor. In this work, we successfully developed the first electrochemical acceptorless dehydrogenation (ECAD) of N-heterocycles using TEMPO as the organo-electrocatalyst. We have achieved the catalytic dehydrogenation of N-heterocycles in an anode and the release of H2 in a cathode using an undivided-cell system. A variety of six-membered and five-membered nitrogen-heteroarenes can be synthesized in good yields in this system. In addition, this protocol can also be used in the application of important molecular synthesis. Our electrochemical strategy provides a mild and metal-free route for (hetero)aromatic compounds synthesis via the CAD strategy.
- Wu, Yong,Yi, Hong,Lei, Aiwen
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p. 1192 - 1196
(2018/02/14)
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- Acceptorless Dehydrogenation of N-Heterocycles and Secondary Alcohols by Ru(II)-NNC Complexes Bearing a Pyrazoyl-indolyl-pyridine Ligand
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Ruthenium(II) hydride complexes bearing a pyrazolyl-(2-indol-1-yl)-pyridine ligand were synthesized and structurally characterized by NMR analysis and X-ray single crystal crystallographic determinations. These complexes efficiently catalyzed acceptorless dehydrogenation of N-heterocycles and secondary alcohols, respectively, exhibiting highly catalytic activity with a broad substrate scope. The present work has established a strategy to construct highly active transition metal complex catalysts and provides an atom-economical and environmentally benign protocol for the synthesis of aromatic N-heterocyclic compounds and ketones.
- Wang, Qingfu,Chai, Huining,Yu, Zhengkun
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p. 584 - 591
(2018/03/08)
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- A indole compound and its preparation method and application (by machine translation)
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The invention discloses a indole compound and its preparation method and application. The indole compounds of the structural formula such as formula (I) is shown. The indoles, rice galenical demonstrate the excellent inhibitory activity, the effect of most of the compound is obviously better than the positive control drug validamycin; especially compound I - 43, I - 44, I - 54, I - 73, II - 7 and II - 17, its galenical very good living body protection and treating effect, effect is better than the positive control; more specifically, compound I - 43 of the rice sheath blight bacteriostatic activity than validamycin activity is improved by nearly 300 times. The indole compounds in the prevention and/or treatment of rice sheath blight has great application prospects. In addition the compound of the invention is simple in construction, the preparation method is simple, and is suitable for large-scale industrial production. (I). (by machine translation)
- -
-
Paragraph 0131; 0158; 0159
(2018/10/02)
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- Pd-tBuONO Cocatalyzed Aerobic Indole Synthesis
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A Pd-tBuONO co-catalyzed scalable and practical synthesis of indoles with molecular oxygen as terminal oxidant is developed. Either terminal or internal 2-vinylanilines could be smoothly converted to desired indoles under one general condition. This method has been evaluated in the large scale synthesis of indomethacin and a potential anti-breast cancer drug candidate 1. (Figure presented.).
- Ning, Xiao-Shan,Liang, Xin,Hu, Kang-Fei,Yao, Chuan-Zhi,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 1590 - 1594
(2018/04/30)
-
- 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
-
supporting information
p. 2358 - 2363
(2017/07/22)
-
- Half-sandwich structured ruthenium complex and preparation method thereof, and method for reducing o-nitrobenzene ethanol compound into indole compound
-
The invention discloses a half-sandwich structured ruthenium complex and a preparation method thereof, and a method for reducing an o-nitrobenzene ethanol compound into an indole compound. The structure of the ruthenium complex is as shown in formula (A), wherein in the formula (A), X is halogen, R is H, -oxyl, halogen or nitro, and n is a positive integer ranging from 1 to 4. By the adoption of the preparation method, the ruthenium complex with excellent chemical stability can be obtained; meanwhile, the preparation method has the advantages of simple operation, low equipment requirement and batch production; furthermore, the ruthenium complex can be used as a catalyst for catalytically reducing the o-nitrobenzene ethanol compound (Refer to Specification).
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-
Paragraph 0080; 0082
(2017/07/22)
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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.
- -
-
Paragraph 0024; 0025; 0026; 0027; 0028; 0029; 0030; 0031
(2016/10/10)
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- Active and Recyclable Catalytic Synthesis of Indoles by Reductive Cyclization of 2-(2-Nitroaryl)acetonitriles in the Presence of Co-Rh Heterobimetallic Nanoparticles with Atmospheric Hydrogen under Mild Conditions
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A cobalt-rhodium heterobimetallic nanoparticle-catalyzed reductive cyclization of 2-(2-nitroaryl)acetonitriles to indoles has been achieved. The tandem reaction proceeds without any additives under the mild conditions (1 atm H2 and 25 °C). This procedure could be scaled up to the gram scale. The catalytic system is significantly stable under these reaction conditions and could be reused more than ten times without loss of catalytic activity.
- Choi, Isaac,Chung, Hyunho,Park, Jang Won,Chung, Young Keun
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p. 5508 - 5511
(2016/11/17)
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- Development of indole sulfonamides as cannabinoid receptor negative allosteric modulators
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Existing CB1 negative allosteric modulators (NAMs) fall into a limited range of structural classes. In spite of the theoretical potential of CB1 NAMs, published in vivo studies have generally not been able to demonstrate the expected therapeutically-relevant CB1-mediated effects. Thus, a greater range of molecular tools are required to allow definitive elucidation of the effects of CB1 allosteric modulation. In this study, we show a novel series of indole sulfonamides. Compounds 5e and 6c (ABD1075) had potencies of 4 and 3?nM respectively, and showed good oral exposure and CNS penetration, making them highly versatile tools for investigating the therapeutic potential of allosteric modulation of the cannabinoid system.
- Greig, Iain R.,Baillie, Gemma L.,Abdelrahman, Mostafa,Trembleau, Laurent,Ross, Ruth A.
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p. 4403 - 4407
(2016/08/25)
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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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- Synthesis of indoles from o,β-dinitrostyrenes via indium/acetic acid-mediated Reductive heterocyclizations
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Reductive heterocyclization reactions of various 1-nitro-2-(2-nitroaryl) ethenes to indoles were investigated. In the presence of indium/AcOH in toluene or benzene, 1-nitro-2-(2-nitroaryl)ethenes were cyclized to give corresponding indoles in good yields.
- Lee, Geunsoo,Choi, Jaehwan,Lee, Byung Min,Kim, Byeong Hyo
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p. 155 - 162
(2013/03/13)
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- Dehydrogenative N-heterocyclization of 2-(2-aminoaryl)ethyl alcohols to indole derivatives catalyzed by (μ-oxo)tetraruthenium cluster/1,2- bis(diphenylphosphino)benzene
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A novel catalyst system of (μ-oxo)tetraruthenium cluster (2) combined with 1,2-bis(diphenylphosphino)benzene (dppbz) realized a simple, selective, and practical synthesis of indole and its derivatives from 2-(2-aminoaryl)ethyl alcohols via dehydrogenative N-heterocyclization reaction. Spontaneous formation of a stoichiometric amount of hydrogen (H2) was observed, and the present reaction proceeded smoothly under an argon atmosphere without oxidants and/or hydrogen acceptors.
- Kondo, Teruyuki,Kanda, Takashi,Takagi, Daisuke,Wada, Kenji,Kimura,Toshimitsu, Akio
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p. 1015 - 1022
(2013/08/15)
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- Convenient modification of the Leimgruber-Batcho indole synthesis: Reduction of 2-nitro-p-pyrrolidinostyrenes by the FeCl3-activated carbon-N2H4H2O system
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A new catalytic system containing ferric chloride, activated carbon, and hydrazine has been proposed for the reductive cyclization of β-dialkylamino-2-nitrostyrenes to give the corresponding indoles (Leimgruber-Batcho synthesis). Various substituted indoles may be obtained in high yield under these conditions.
- Taydakov,Dutova,Sidorenko,Krasnoselsky
-
experimental part
p. 425 - 434
(2012/01/13)
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- Enantioselective N-H functionalization of indoles with α,β- unsaturated γ-lactams catalyzed by chiral Bronsted acids
-
Nitrogen revives: Cyclic N-acyliminium ions were generated from α,β-unsaturated γ-lactams (1) and underwent intermolecular addition by indole nucleophiles (2) under the catalysis of a chiral Bronsted acid (3). A variety of N-functionalized indole derivatives containing a pyrrolidinone moiety (4) were assembled with high enantioselectivity. Bn=benzyl. Copyright
- Xie, Yinjun,Zhao, Yingwei,Qian, Bo,Yang, Lei,Xia, Chungu,Huang, Hanmin
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supporting information; experimental part
p. 5682 - 5686
(2011/08/03)
-
- Oxidative cyclization of amino alcohols catalyzed by a Cp*lr complex. Synthesis of indoles, 1,2,3,4-tetrahydroquinolines, and 2,3,4,5-tetrahydro-1-benzazepine
-
A new iridium-catalyzed oxidative cyclization of amino alcohols has been revealed. Indole derivatives are synthesized in good to excellent yields from 2-aminophenethyl alcohols by means of a [Cp*IrCl2]2/K2CO3 catalytic system. The present catalytic system is also effective for syntheses of 1,2,3,4-tetrahydroquinolines from 3-(2-aminophenyl)propanols and 2,3,4,5-tetrahydro-1-benzazepine from 4-(2-aminophenyl)butanol.
- Fujita, Ken-Ichi,Yamamoto, Kazunari,Yamaguchi, Ryohei
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p. 2691 - 2694
(2007/10/03)
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- Selective cleavage of Cbz-protected amines
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(MatrixPresented) Under conditions of catalytic Ni(0) and in most cases just over 1 equiv of Me2NH·Br3/K2CO3 or Cs2CO3, a Cbz-protected nitrogen, which is part of a heteroaromatic ring, can
- Lipshutz, Bruce H.,Pfeiffer, Steven S.,Reed, Anthony B.
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p. 4145 - 4148
(2007/10/03)
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- Tricyclic compounds having fungicidal activity, their preparation and their use
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Compounds of formula (I): STR1 ?wherein: R1 represents halogen, alkyl, haloalkyl, alkoxy, haloalkoxy, cycloalkyl, or cycloalkyloxy; R2 represents hydrogen or halogen; R3 represents hydrogen, alkyl, or cycloalkyl; and the dotted line represents a single or double carbon--carbon bond!; and salts thereof have valuable fungicidal activities which make them of considerable value in agriculture and horticulture.
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- Indoles as insecticides and acaricides
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There are provided methods for the control of insects and the protection of crops from the damage caused thereby which comprise the use of compositions comprising an indole compound of formula I STR1
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-
- Palladium-Catalyzed Synthesis of Indoles from 2-Nitrostyrenes
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In the presence of palladium salts, oxidation of 2-nitrostyrenes 1 with nitrous acid alkyl esters 2 resulted in the formation of 2-nitrophenylacetaldehyde dialkyl acetals 3.Reductive cyclization of the acetals 3 with iron powder in acetic acid afforded indoles 5 in good yield.
- Izumi, Taeko,Soutome, Michihiko,Miura, Takashi
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p. 1625 - 1629
(2007/10/02)
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- Ruthenium-Catalyzed Dehydrogenative N-Heterocyclization: Indoles from 2-Aminophenethyl Alcohols and 2-Nitrophenethyl Alcohols
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Indole derivatives 3 were readily obtained from 2-aminophenethyl alcohols 1 in the presence of 2 mol percent (based on 1) of RuCl2(PPh3)3 under reflux in toluene.Indole (3a) was afforded from 2-aminophenethyl alcohol (1a) quantitatively.Other indoles (3) were also obtained in 73-99percent isolated yields from the corresponding 1, which were easily prepared by condensation between the corresponding 2-nitrotoluenes and aldehydes followed by reduction.During the reaction, a stoichiometric amount of hydrogen was spontaneously evolved into the gas phase.With a heterogeneous and homogeneous binary catalyst system, indoles were afforded in one pot from 2-nitrophenethyl alcohols 2 under a hydrogen atmosphere.
- Tsuji, Yasushi,Kotachi, Shinji,Huh, Keun-Tae,Watanabe, Yoshihisa
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p. 580 - 584
(2007/10/02)
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- Silica Gel Assisted Reductive Cyclization of 2-Nitro-β-piperidinostyrenes, Derived from 2-Nitrotoluenes, to Indoles
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An efficient modification of the Leimgruber-Batcho method of indole synthesis has been devised that facilitates the synthesis of a variety of 2,3-unsubstituted indoles containing halogen, methoxy and benzyloxy groups, from 2-nitrotoluenes, in high yields.The modified method involves the condensation of 2-nitrotoluenes with tripiperidinomethane followed by the reductive cyclization of the intermediate 2-nitro-β-piperidinostyrenes with iron and acetic acid in refluxing toluene in the presence of silica gel (column chromatography grade, 60-200 mesh).
- Kawase, Masami,Sinhababu, Achintya K.,Borchardt, Ronald T.
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p. 1499 - 1501
(2007/10/02)
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- Cyclization of 2-acetaldehyde Diethyl Acetals to Indoles. Evidence for Stereoelectronic Effects in Intramolecular Electrophilic Aromatic Substitution
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Methanesulfonamides of N-(2,2-diethoxyethyl)anilines can be cyclized to indoles in aromatic solvents by reaction with titanium tetrachloride.The temperature of the cyclization is substituent dependent, occurring at 0 deg C for the m-methoxy derivative but requiring 130 deg C for the p-bromo compound.Yields are good for various alkoxy-, alkyl-, and haloindoles, ranging from 60percent to 90percent.Meta-substituted reactants give rise to mixtures of 4- and 6-substituted indoles in which the 6-substituted product dominates by 2-4:1.The cyclization fails for ortho-substituted reactants.The major reaction process is N-dealkylation in the case of ortho-substituted compounds.An analogous cyclization occurs with the methanesulfonamides of N-(3,3-diethoxypropyl)anilines to give 1-(methylsulfonyl)-4-chloro-1,2,3,4-tetrahydroquinolines.This cyclization is much more rapid than for the five-membered ring closure leading to indoles and indicates a substantial rate retardation due to stereoelectronic effects in the indole cyclization.Ortho substitution also prevents cyclization in the six-membered-ring case.
- Sundberg, Richard J.,Laurino, Joseph P.
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p. 249 - 254
(2007/10/02)
-
- Synthesis of Substituted Indoles via Meerwein Arylation
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A new method for the synthesis of substituted indoles is detailed.Meerwein arylation of 4- and 6-substituted 2-nitrobenzenediazonium chlorides with vinyl acetate or vinyl bromide and subsequent reductive cyclization of the resulting adducts affords the corresponding 6- and 4-substituted (CH3, OCH3, Cl, Br, CF3) indoles.The diazonium bisulfates of weakly basic 2-nitroanilines (4-Cl, 6-Br, 4-CF3) gave higher yields of Meerwein arylation adducts than the corresponding diazonium chlorides.Coupling of 2-nitrobenzenediazonium chloride with 2-acetoxy-1-alkenes followed byreductive cyclization affords 2-alkylindoles.
- Raucher, Stanley,Koolpe, Gary A.
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p. 2066 - 2069
(2007/10/02)
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- The Decomposition of β-Phenethylsulfonyl Azides. Solution Chemistry and Flash Vacuum Pyrolysis
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The intramolecular cyclization of the parent title compound and a number of para-substituted derivatives (1) in solution was found to take place in low yield and to be accompanied by products of intermolecular reactions, namely, C-H insertion (4) and hydrogen abstraction (3).The use of an excess of a relatively inert solvent Freon 113 led to a better yield of the desired 3,4-dihydro-2,1-benzothiazine 2,2-dioxides (2).Flash vacuum pyrolysis (FVP) of 1 at 250-300 deg C also gave some 2, but the use of higher temperatures led to the formation of styrenes (8), indolines (9), indoles (10), sulfur dioxide, and the remarkable transformation products, the 4-substituted 6,7-dihydro-5H-1-pyrindines (7), in good yield.The styrenes result from the elimination of HN3 and SO2 from the azides, and indolines are formed in good yield by FVP of 2 at 650 deg C.The dihydropyrindines are not obtained from 2, and β-phenethynitrene is not a source of any of the above observed products.A mechanism is proposed for the formation of 7 from β-arylethylsulfonylnitrenes.Consistent with the mechanism is the observation that both 1- and 2-phenylpropanesulfonyl azide give a mixture of 6- and 7-methyl-6,7-dihydro-5H-1-pyrindines in the same ratio on FVP at 650 deg C.Thermolysis of 1a in benzene at 100 deg C gives an N-sulfonylazepine derivative.The FVP of 1 and 2 at 650 deg C are preparative routes to 7 and 9, respectively.
- Abramovitch, Rudolph A.,Holcomb, William D.,Wake, Shigeo
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p. 1525 - 1533
(2007/10/02)
-
- Intermediates for indoles
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Ortho-nitrotoluenes are condensed with formamide acetals to yield the corresponding otho-nitro-β-aminestyrenes which undergo cyclization upon reduction to yield indoles.
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