- An amine template strategy to construct successive C-C bonds: Synthesis of benzo[: H] quinolines by a deaminative ring contraction cascade
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We developed a convergent strategy to build, cyclize and excise nitrogen from tertiary amines for the synthesis of polyheterocyclic aromatics. Biaryl-linked azepine intermediates can undergo a deaminative ring contraction cascade reaction, excising nitrogen with the formation of an aromatic core. This strategy and deaminative ring contraction reaction are useful for the synthesis of benzo[h]quinolines. This journal is
- McFadden, Timothy Patrick,Nwachukwu, Chideraa Iheanyi,Roberts, Andrew George
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p. 1379 - 1385
(2022/03/01)
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- Homologation of the Fischer Indolization: A Quinoline Synthesis via Homo-Diaza-Cope Rearrangement
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We disclose a new Br?nsted acid promoted quinoline synthesis, proceeding via homo-diaza-Cope rearrangement of N-aryl-N′-cyclopropyl hydrazines. Our strategy can be considered a homologation of Fischer's classical indole synthesis and delivers 6-membered N-heterocycles, including previously inaccessible pyridine derivatives. This approach can also be used as a pyridannulation methodology toward constructing polycyclic polyheteroaromatics. A computational analysis has been employed to probe plausible activation modes and to interrogate the role of the catalyst.
- De, Chandra Kanta,Gerosa, Gabriela Guillermina,List, Benjamin,Maji, Rajat,Schwengers, Sebastian Armin
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supporting information
p. 20485 - 20488
(2020/09/09)
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- Merging C-H Vinylation with Switchable 6π-Electrocyclizations for Divergent Heterocycle Synthesis
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Pyridinium-containing polyheterocycles exhibit distinctive biological properties and interesting electrochemical and optical properties and thus are widely used as drugs, functional materials, and photocatalysts. Here, we describe a unified two-step strategy by merging Rh-catalyzed C-H vinylation with two switchable electrocyclizations, including aza-6π-electrocyclization and all-carbon-6π-electrocyclization, for rapid and divergent access to dihydropyridoisoquinoliniums and dihydrobenzoquinolines. Through computation, the high selectivity of aza-electrocyclization in the presence of an appropriate "HCl"source under either thermal conditions or photochemical conditions is shown to result from the favorable kinetics and symmetries of frontier orbitals. We further demonstrated the value of this protocol by the synthesis of several complex pyridinium-containing polyheterocycles, including the two alkaloids berberine and chelerythrine.
- Hu, Tianhui,Hua, Yuhui,Jiang, Xunjin,Qiu, Huijuan,Shen, Yang,Wu, Yifan,Xiong, Jing,Xu, Beibei,Zeng, Zhixiong,Zhang, Yandong
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supporting information
p. 15585 - 15594
(2020/10/20)
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- Superacid-promoted synthesis of quinoline derivatives
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A series of vinylogous imines have been prepared from anilines and cinnamaldehydes. These substrates react in superacidic media to provide quinolines and related compounds. A mechanism for the conversion is proposed which involves the cyclization of dicationic superelectrophilic intermediates. Aromatization of the quinoline ring is thought to occur by superacid-promoted elimination of benzene.
- Klumpp, Douglas A.,Stentzel, Michael R.,Vuong, Hein
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supporting information
(2020/01/24)
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- Iodine-catalyzed convergent aerobic dehydro-aromatization toward benzazoles and benzazines
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An iodine-catalyzed aerobic dehydro-aromatization has been developed, providing straightforward and efficient access to various benzoazoles and benzoazines. The present transition-metal-free protocol enables the dehydro-aromatization of tetrahydrobenzazoles and tetrahydroquinolines with molecular oxygen as the green oxidant, along with some other N-heterocycles. Hence, a broad range of heteroaromatic compounds are generated in moderate to good yields under facile reaction conditions.
- Chen, Shanping,Deng, Guo-Jun,Jiang, Pingyu,Ni, Penghui,Tuo, Xiaolong,Wang, Xiaodong
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p. 8348 - 8351
(2020/03/11)
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- Hydrogenation of N-Heteroarenes Using Rhodium Precatalysts: Reductive Elimination Leads to Formation of Multimetallic Clusters
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A rhodium-catalyzed method for the hydrogenation of N-heteroarenes is described. A diverse array of unsubstituted N-heteroarenes including pyridine, pyrrole, and pyrazine, traditionally challenging substrates for hydrogenation, were successfully hydrogenated using the organometallic precatalysts, [(η5-C5Me5)Rh(N-C)H] (N-C = 2-phenylpyridinyl (ppy) or benzo[h]quinolinyl (bq)). In addition, the hydrogenation of polyaromatic N-heteroarenes exhibited uncommon chemoselectivity. Studies into catalyst activation revealed that photochemical or thermal activation of [(η5-C5Me5)Rh(bq)H] induced C(sp2)-H reductive elimination and generated the bimetallic complex, [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H]. In the presence of H2, both of the [(η5-C5Me5)Rh(N-C)H] precursors and [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H] converted to a pentametallic rhodium hydride cluster, [(η5-C5Me5)4Rh5H7], the structure of which was established by NMR spectroscopy, X-ray diffraction, and neutron diffraction. Kinetic studies on pyridine hydrogenation were conducted with each of the isolated rhodium complexes to identify catalytically relevant species. The data are most consistent with hydrogenation catalysis prompted by an unobserved multimetallic cluster with formation of [(η5-C5Me5)4Rh5H7] serving as a deactivation pathway.
- Kim, Sangmin,Loose, Florian,Bezdek, Máté J.,Wang, Xiaoping,Chirik, Paul J.
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supporting information
p. 17900 - 17908
(2019/11/19)
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- Potassium tert-Butoxide-Promoted Acceptorless Dehydrogenation of N-Heterocycles
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Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of six- and five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas. (Figure presented.).
- Liu, Tingting,Wu, Kaikai,Wang, Liandi,Yu, Zhengkun
-
supporting information
p. 3958 - 3964
(2019/08/01)
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- A Reusable Cobalt Catalyst for Reversible Acceptorless Dehydrogenation and Hydrogenation of N-Heterocycles
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The development of robust catalytic systems based on base-metals for reversible acceptorless dehydrogenation (ADH) and hydrogenation of feedstock chemicals is very important in the context of ‘hydrogen storage’. Herein, we report a highly efficient reusable cobalt-based heterogeneous catalyst for reversible dehydrogenation and hydrogenation of N-heterocycles. Both the ADH and the hydrogenation processes operate under mild, benign conditions.
- Jaiswal, Garima,Subaramanian, Murugan,Sahoo, Manoj K.,Balaraman, Ekambaram
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p. 2449 - 2457
(2019/05/10)
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- Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic N-Oxides
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A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
- Kim, Kyu Dong,Lee, Jun Hee
-
supporting information
p. 7712 - 7716
(2019/01/03)
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- Synthesis of benzoquinoline derivatives from formyl naphthylamines via Friedl?nder annulation under metal-free conditions
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Abstract: The synthesis of benzoquinolines and benzoquinolinones via Friedl?nder-type condensation of aminonaphthalene carbaldehydes with (1) primary or secondary alcohols mediated by urea/KOH or with (2) diketones or β-ketoesters is described. The behavi
- Malinowski, Zbigniew,Fornal, Emilia,Warpas, Anna,Nowak, Monika
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p. 1999 - 2011
(2018/09/25)
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- Dehydrogenation of N-Heterocycles by Superoxide Ion Generated through Single-Electron Transfer
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Nitrogen-containing heteroarene motifs are found in numerous pharmaceuticals, natural products, and synthetic materials. Although several elegant methods for synthesis of these compounds through dehydrogenation of the corresponding saturated heterocycles have been reported, some of the methods are hampered by long reaction times, harsh conditions, and the need for catalysts that are not readily available. This work reports a novel method for dehydrogenation of N-heterocycles. Specifically, O2.? generated in situ acts as the oxidant for N-heterocycle substrates that are susceptible to oxidation through a hydrogen atom transfer mechanism. This method provides a general, green route to N-heteroarenes.
- Huang, Yuan-Qiong,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
-
supporting information
p. 2065 - 2069
(2018/01/27)
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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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- Cycloisomerization – a straightforward way to benzo[h]quinolines and benzo[c]acridines
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[Figure not available: see fulltext.] Cycloisomerization of 3-alkynyl-2-arylpyridines and quinolines offers a straightforward approach to benzo[h]quinolines and benzo[c]-acridines. Substituent at the triple bond governs a choice between transition metal or Br?nsted acid catalysis. A direct electrophilic activation by trifluoromethanesulfonic acid induces an almost quantitative cyclization of the o-aryl(phenylethynyl) fragment. PtCl2 efficiently catalyzes cyclization of 2-aryl-3-ethynylhetarenes.
- Shestakov, Aleksandr N.,Pankova, Alena S.,Kuznetsov, Mikhail A.
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p. 1103 - 1113
(2017/12/08)
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- From Anilines to Quinolines: Iodide- and Silver-Mediated Aerobic Double C?H Oxidative Annulation–Aromatization
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Quinoline synthesis from easily accessible raw materials such as anilines is a valuable and meaningful task. Herein, we communicate an iodide- and silver-mediated C?H/C?H oxidative annulation–aromatization between anilines and allyl alcohols. This protocol provides a direct route to the synthesis of quinoline derivatives from inexpensive commodities. Various kinds of anilines, even heterocyclic anilines, were shown to be workable substrates, generating the corresponding multi-substituted quinolines in good yields.
- Wu, Jiwei,Liao, Zhixiong,Liu, Dong,Chiang, Chien-Wei,Li, Zheng,Zhou, Zhonghao,Yi, Hong,Zhang, Xu,Deng, Zixin,Lei, Aiwen
-
supporting information
p. 15874 - 15878
(2017/10/23)
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- Method for preparing quinoline derivative by catalyzing oxidative dehydrogenation of nitrogen-containing heterocyclic ring through carbon nitride material
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The invention belongs to the field of chemical synthesis, and particularly relates to a method for preparing a quinoline derivative by catalyzing oxidative dehydrogenation of a nitrogen-containing heterocyclic ring through a carbon nitride material. The carbon nitride material is prepared by using a nitrogen-containing organic macrocyclic compound as a precursor and calcining in an inert atmosphere. During a reaction, oxygen or air is used as an oxidant, and in the presence or absence of a solvent, the reaction is performed at 50-120 DEG C and the carbon nitrogen material can convert the nitrogen-containing heterocyclic ring into the corresponding quinoline derivative. According to the invention, no metal is introduced into a reaction system, and the method is easy to amplify; after being recycled for at least 9 times, a catalyst still maintain good selectivity and activity; therefore, the method has a significant practical prospect during industrial production.
- -
-
Paragraph 0026; 0027
(2017/08/29)
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- Organo-Photoredox Catalyzed Oxidative Dehydrogenation of N-Heterocycles
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We report here for the first time the catalytic oxidative dehydrogenation of N-heterocycles by a visible-light organo-photoredox catalyst with low catalyst loading (0.1–1 mol %). The reaction proceeds efficiently under base- and additive-free conditions with ambient air at room temperature. The utility of this benign approach is demonstrated by the synthesis of various pharmaceutically relevant N-heteroarenes such as quinoline, quinoxaline, quinazoline, acridine, and indole.
- Sahoo, Manoj K.,Jaiswal, Garima,Rana, Jagannath,Balaraman, Ekambaram
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supporting information
p. 14167 - 14172
(2017/10/16)
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- Palladium Nanoparticles Stabilized by Metal–Carbon Covalent Bonds as an Expeditious Catalyst for the Oxidative Dehydrogenation of Nitrogen Heterocycles
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The first method for the dehydrogenation of nitrogen heterocycles catalyzed by a palladium nanocatalyst was developed. Carbon–metal covalent-bond-stabilized nanoparticles were found to be efficient for the dehydrogenation process in the presence of tert-butyl hydroperoxide. A variety of N-heterocycles were transformed into functionalized quinolines in medium to excellent yields in water as the solvent under mild conditions by a simple operation.
- Sun, Xiao-Tao,Zhu, Jie,Xia, Yun-Tao,Wu, Lei
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p. 2463 - 2466
(2017/07/12)
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- Assembly of Diversely Substituted Quinolines via Aerobic Oxidative Aromatization from Simple Alcohols and Anilines
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An aerobic oxidative aromatization of simple aliphatic alcohols and anilines under the Pd(OAc)2/2,4,6-Collidine/Br?nsted acid catalytic system has been established, providing a direct approach for the preparation of diverse substituted quinoline derivatives in high yields with wide functional group tolerance. Practically, the protocol can be easily scaled up to gram-scale and was utilized in the concise formal synthesis of a promising herbicide candidate.
- Li, Jixing,Zhang, Jinlong,Yang, Huameng,Jiang, Gaoxi
-
supporting information
p. 3284 - 3290
(2017/03/23)
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- MAGNETICALLY SEPARABLE IRON-BASED HETEROGENEOUS CATALYSTS FOR DEHYDROGENATION OF ALCOHOLS AND AMINES
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The present invention discloses an iron-based nitrogen doped graphene catalyst, process for preparation thereof and use of said catalyst in oxidant-free catalytic dehydrogenation of alcohols and amines to the corresponding carbonyl compounds, amines and N-heterocylic compounds with extraction of molecular hydrogen as the only by-product.
- -
-
Page/Page column 19; 20; 21; 23
(2016/12/22)
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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.
-
supporting information
p. 1973 - 1977
(2016/07/06)
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- Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles
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Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.
- Kojima, Masahiro,Kanai, Motomu
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supporting information
p. 12224 - 12227
(2016/10/13)
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- Synthesis and Characterization of Iron-Nitrogen-Doped Graphene/Core-Shell Catalysts: Efficient Oxidative Dehydrogenation of N-Heterocycles
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An important goal for nanocatalysis is the development of flexible and efficient methods for preparing active and stable core-shell catalysts. In this respect, we present the synthesis and characterization of iron oxides surrounded by nitrogen-doped-graphene shells immobilized on carbon support (labeled FeOx@NGr-C). Active catalytic materials are obtained in a simple, scalable and two-step method via pyrolysis of iron acetate and phenanthroline and subsequent selective leaching. The optimized FeOx@NGr-C catalyst showed high activity in oxidative dehydrogenations of several N-heterocycles. The utility of this benign methodology is demonstrated by the synthesis of pharmaceutically relevant quinolines. In addition, mechanistic studies prove that the reaction progresses via superoxide radical anions (·O2-).
- Cui, Xinjiang,Li, Yuehui,Bachmann, Stephan,Scalone, Michelangelo,Surkus, Annette-Enrica,Junge, Kathrin,Topf, Christoph,Beller, Matthias
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supporting information
p. 10652 - 10658
(2015/09/28)
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- Catalytic Aerobic Dehydrogenation of Nitrogen Heterocycles Using Heterogeneous Cobalt Oxide Supported on Nitrogen-Doped Carbon
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Dehydrogenation of (partially) saturated heterocycles provides an important route to heteroaromatic compounds. A heterogeneous cobalt oxide catalyst, previously employed for aerobic oxidation of alcohols and amines, is shown to be effective for aerobic dehydrogenation of various 1,2,3,4-tetrahydroquinolines to the corresponding quinolines. The reactions proceed in good yields under mild conditions. Other N-heterocycles are also successfully oxidized to their aromatic counterparts.
- Iosub, Andrei V.,Stahl, Shannon S.
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supporting information
p. 4404 - 4407
(2015/09/28)
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- RhIII-Catalyzed C-H Activation with Pyridotriazoles: Direct Access to Fluorophores for Metal-Ion Detection
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The first C-H bond activation with pyridotriazoles as coupling partners is presented using a RhIII catalyst. The pyridotriazoles can be used as new carbene precursors in C-H activation for direct access to novel fluorescent scaffolds. These tunable fluorophores can be applied for the detection of metal ions.
- Kim, Ju Hyun,Gensch, Tobias,Zhao, Dongbing,Stegemann, Linda,Strassert, Cristian A.,Glorius, Frank
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supporting information
p. 10975 - 10979
(2015/09/15)
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- NaBH4-TMEDA and a palladium catalyst as efficient regio- and chemoselective system for the hydrodehalogenation of halogenated heterocycles
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The pair NaBH4-TMEDA as hydride source and a palladium catalyst in THF prove to be an efficient system for the hydrodehalogenation of halogenated heterocycles with one or more heteroatoms. In general, Pd(OAc) 2-PPh3 rapidly hydrodehalogenates reactive halo-heterocycles such as bromo-pyridines, -quinolines, -thiophenes, -indoles, -imidazoles, etc., at room temperature in very good yields, whereas in most cases PdCl2(dppf) reduces less reactive halides such as chloro-pyridines, -quinolines, -pyrimidines and bromo-indoles, -benzofurans, etc. Moreover, PdCl2(tbpf) shows to be even more active removing the 2- and 5-chlorine from both thiophene and thiazole rings. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene and nitrile substituents. Moreover, with a proper selection of the catalyst it is also possible to obtain a good control in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Figus, Susanna
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p. 191 - 209
(2014/07/21)
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- Direct carbo-acylation reactions of 2-arylpyridines with α-diketones via Pd-catalyzed C-H activation and selective C(sp2)-C(sp2) cleavage
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An efficient carbo-acylation reaction of 2-arylpyridines with α-diketones via Pd-catalyzed C-H bond activation and C-C bond cleavage in the presence of TBHP was developed that generated aryl ketones in good yields. The highly selective formation of aryl ketones was observed when 2-arylpyridines reacted with aromatic/aliphatic α-diketones.
- Zhou, Wei,Li, Hongji,Wang, Lei
-
supporting information
p. 4594 - 4597
(2012/10/29)
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- Hydrodehalogenation of halogenated pyridines and quinolines by sodium borohydride/N,N,N′,N′-tetramethylethylenediamine under palladium catalysis
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A protocol for the hydrodehalogenation of halogenated pyridines and quinolines by the sodium borohydride/N,N,N′,N′-tetramethylethylenediamine (NaBH4-TMEDA) system under palladium catalysts is reported. Catalytic amounts of [1,1′-bis(diphenylphosphino)ferrocene] dichloropalladium(II) in combination with NaBH4-TMEDA rapidly hydrodehalogenate chloro(bromo)-pyridines and -quinolines at room temperature in quantitative yields. Chemoselective reduction of 4,7-dichloroquinoline affords 7-chloroquinoline as the sole product in almost quantitative yield. Moreover, palladium(II) acetate-triphenylphosphine and NaBH4-TMEDA are able to reduce efficiently reactive bromo-pyridines and -quinolines.
- Chelucci, Giorgio
-
scheme or table
p. 1562 - 1565
(2010/06/14)
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- N-Heterocyclization of naphthylamines with 1,2- And 1,3-Diols catalyzed by an iridium Chloride/BINAP system
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Benzoquinoline derivatives were successfully synthesized by iridium-catalyzed N-heterocyclization of naphthylamines with diols. For instance, the reaction of 1-naphthylamine with 1,3-propanediol catalyzed by IrCl3 combined with BINAP as a ligand produced 7,8-benzoquinoline in quantitative yield. The VV-heterocyclization reaction was found to be markedly influenced by the ligands employed. Benzoindoles were also synthesized by the same strategy from napthylamines with 1,2-diols. A reaction mechanism for the N-heterocyclization of naphthylamines with 1,3-diols by IrCl3 was proposed.
- Aramoto, Hiroomi,Obora, Yasushi,Ishii, Yasutaka
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scheme or table
p. 628 - 633
(2009/06/28)
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- Friedlaender reactions of triacetylmethane- unusual distribution of products-
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Friedlaender reactions of triacetylmethane with selected β-amino-α,β-unsaturated aldehydes afforded pyridoheterocycles and their 2-methyl derivatives instead of triheteroarylmethane.
- Rahman, A.F.M. Motiur,Kwon, Youngjoo,Jahng, Yurngdong
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p. 2777 - 2782
(2007/10/03)
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- Studies into the generation and Diels-Alder reactions of 7,8-quinolyne with furan dienes
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Reaction of an appropriate ortho-halo tosylate precursor with organolithium reagents provides the first conclusive route to the intermediate, 7,8-quinolyne. The transient existence of this hetaryne was confirmed by Diels-Alder reactions with furan derivatives that provide endoxide adducts. Chemical induced rearrangement of these adducts allows entry to key compounds of 10-hydroxy[h]benzoquinoline and its 7-substituted derivatives in modest yields.
- Collis, Gavin E.,Burrell, Anthony K.
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p. 3653 - 3656
(2007/10/03)
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- Model reactions for the synthesis of azacorannulenes and related heteroaromatic compounds
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4-(2-Ethynylphenyl)pyridine (10), 3-(2-ethynylphenyl)pyridine (11), 2-(2-trimethylsilylethynylphenyl)pyridine (26), and 3-ethynyl-2-phenylpyridine (13) were prepared from readily available pyridine precursors by standard coupling reactions. Pyrolysis of 10 at 810 °C/0.5 Torr provided benzo[f]isoquinoline (45) and the benzopentalene dimer 47. Pyrolysis of 11 (820 °C/0.5 Torr) afforded benzo[f]quinoline (50), benzo[h]i-soquinoline (52), and a mixture of isomers of 47. Pyrolysis of 13 (820 °C/0.3 Torr) provided benzo[h]quinoline (56) and the novel azulene derivative azuleno[1,2-b]pyridine (58). When 26 was desilylated by treatment with TBAF in THF/water, the unusual "dimerization" product 37 was produced; its structure was confirmed by X-ray structural analysis. The mechanisms of these transformations are discussed. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Dix, Ina,Doll, Christian,Hopf, Henning,Jones, Peter G.
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p. 2547 - 2556
(2007/10/03)
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- A novel PdCl2/ZrO2-SO42- catalyst for synthesis of carbamates by oxidative carbonylation of amines
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At 170°C and ca. 4.0 MPa, oxidative carbonylation of aromatic amines to synthesize corresponding carbamates over a novel PdCl2/ZrO2-SO42- catalyst could proceed with high conversion and selectivity.
- Shi, Feng,Deng, Youquan,SiMa, Tianlong,Yang, Hongzhou
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p. 525 - 528
(2007/10/03)
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- Kinetics of the reduction of dialkyl peroxides. New insights into the dynamics of dissociative electron transfer
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The concerted dissociative reduction of di-tert-butyl peroxide (DTBP), dicumyl peroxide (DCP), and di-n-butyl peroxide (DNBP) is evaluated by both heterogeneous and homogeneous electron transfer using electrochemical methods. Electrochemical and thermochemical determination of the O-O bond energies and the standard potentials of the alkoxyl radicals allow the standard potentials for dissociative reduction of the three peroxides in N,N-dimethylformamide and acetonitrile to be evaluated. These values allowed the kinetics of homogeneous ET reduction of DTBP and DCP by a variety of radical anion donors to be evaluated as a function of overall driving force. Comparison of the heterogeneous ET kinetics of DTBP and DNBP as a function of driving force for ET allowed the distance dependence on the reduction kinetics of the former to be estimated. Results indicate that the kinetics of ET to DTBP is some 0.8 order of magnitude slower in reactivity than DNBP because of a steric effect imposed by the bulky tert-butyl groups. Experimental activation parameters were measured for the homogeneous reduction of DTBP with five mediators, covering a range of 0.4 eV in driving force over the temperature range -30 to 50°C in DMF. The temperature dependence of the kinetics leads to unusually low preexponential factors for this series. The low preexponential factor is interpreted in terms of a nonadiabatic effect resulting from weak electronic coupling between the reactant and product surfaces. Finally, the data are discussed in the context of recent advances of dissociative electron transfer reported by Saveant and by German and Kuznestov. In total the results suggest that these peroxides undergo a nonadiabatic dissociative electron transfer and represent the first reported class of compounds where this effect is reported.
- Donkers, Robert L.,Maran, Flavio,Wayner, Danial D. M.,Workentin, Mark S.
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p. 7239 - 7248
(2007/10/03)
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- Homogeneous and Heterogeneous Electron Transfer to Benzyl Phenyl Sulfide
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The thermodynamic and kinetic parameters of the elctron transfer (ET) to benzyl phenyl sulfide in DMF have been determined by cyclic voltammetry.The heterogeneous ET has been studied at three different electrodes: Hg, Pt, and glassy carbon.The activation parameters, namely the standard rate constant and the transfer coefficient, corrected for the double-layer contribution, show no significant difference for the three materials.The rate constants for the homogeneous ET to benzyl phenyl sulfide from eight electrogenerated anion radicals have been determined and compared with the corresponding reaction free energies, according to the current theories of the ET process.The results indicate that the ET is an endergonic process driven by a fast bond breaking of the ET product.Both the homogeneous and the heterogeneous reactions are consistent with an outer-sphere adiabatic electron-exchange process, characterized by a relatively high activation free energy.To account for the latter, inner reorganization energies must be considered, together with solvent reorganization.This is an agreement with the easy breaking of the C-S bond in the primari ET product.
- Severin, Maria Gabriella,Arevalo, Maria Carmen,Farnia, Giuseppe,Vianello, Elio
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p. 466 - 472
(2007/10/02)
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- Ruthenium Complex Catalyzed N-Heterocyclization. Syntheses of Quinolines and Indole Derivatives from Aminoarenes and 1,3-Propanediol of Glycols
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Aniline reacts with 1,3-propanediol under reflux in diglyme with spontaneous hydrogen evolution in the presence of a catalytic amount of ruth enium trichloride hydrate ( RuCl3*nH2O)-tributylphosphine (PBu3) to give quinoline in good yield.The yield of quinoline was markedly affected by the molar ratios of aniline to 1,3-propanediol and PBu3 to RuCl3*nH2O.The best yield (76percent) was achieved at the molar ratios of 2.5 of aniline / 1,3-propanediol and 2.0 of PBu3 / RuCl3*nH2O.Also, N-substituted anilines react with ethylene glycol in the presence of a catalytic amount of dichlor otris(triphenylphosphine)ruthenium (RuCl2(PPh3)3) to give N-substituted indole derivatives.The reactions were carried out at 180 deg C in dioxane with spontaneus hydrogen evolution.Aminoarenes also react with 2,3-butanediol and 1,2-cyclohexanediol ( mixture of cis and trans ) in the presence of RuCl2(PPh3)3 to give the corresponding 2,3-dimethylindoles and 1,2,3,4-tetrahydrocarbazoles in good to excellent yields.As the key intermediates of the reactions, N,N'-diarylpropylenediamine (5a) and N,N'-diarylethylenediamine (5b) and their dehydrogenated imine derivatives are postulated.
- Tsuji, Yasushi,Huh, Keun-Tae,Watanabe, Yoshihisa
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p. 1673 - 1680
(2007/10/02)
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- DEOXYGENATION OF TERTIARY AMINE N-OXIDES AND ARENE OXIDES BY IRON (II) PORPHYRIN AS A MODEL OF CYTOCHROME P-450 DEPENDENT REDUCTION
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Tetraphenylporphiratoiron (II), a model complex of reduced cytochrome P-450, reduces several substrates such as tertiary amine N-oxides and arene oxides at room temperature in anaerobic conditions.A process for the direct oxene transfer from oxide to reduced iron porphyrin is suggested.KEYWORDS - cytochrome P-450; reduction; deoxygenation; tertiary amine N-oxide; tetraphenylporphinatoiron (II); oxene transfer; arene oxide; ferryl oxide
- Miyata, Naoki,Santa, Tomofumi,Hirobe, Masaaki
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p. 377 - 380
(2007/10/02)
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- Photochemistry of Some Azaphenanthrene N-Oxides
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1- and 4-Azaphenanthrene N-oxides undergo solvent-dependent photoisomerization, yielding naphtho-1,3-oxazepines in aprotic solvents and benzoquinolin-1(2H)-ones in water.No ring enlargement but only isomerization to the corresponding lactam is observed to take place in the case of 9-azaphenanthrene N-oxide.Measurements of the quantum yield of two photoprocesses (lactam formation and ring enlargement) confirm the difference between the photochemical behaviour of 9-azaphenanthrene N-oxide and that of the other two N-oxides examined
- Albini, Angelo,Bettinetti, Gian Franco,Minoli, Giovanna
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p. 1159 - 1161
(2007/10/02)
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- THE REACTION OF HETEROAROMATIC AMINE OXIDES WITH TiCl4/NaBH4
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Treatment of 2-, 3-, 4-picoline N-oxides and 2,6-dimethylpyridine N-oxide with TiCl4/NaBH4 in dimethoxyethane afforded the corresponding picolines and 2,6-dimethylpyridine in acceptable yields.The same reaction of quinaldine N-oxide and benzoquinoline N-oxide succesfully gave quinaldine and benzoquinoline, respectively.In the case of quinoline N-oxide, 1,2,3,4-tetrahydroquinoline and quinoline were obtained.On the other hand, lepidine N-oxide and isoquinoline N-oxide afforded the corresponding 1,2-dihydro derivatives.Similarly, papaverine N-oxide gave 1,2-dihydropapaverine as major product accompanying with papaverine.
- Kano, Shinzo,Tanaka, Yasuyuki,Hibino, Satoshi
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