- Gold-Catalyzed Synthesis of Dibenzo[1,5]diazocines from β-(2-Aminophenyl)-α,β-ynones
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β-(2-Aminophenyl)-α,β-ynones afforded exclusively challenging dibenzo[1,5]diazocines by means of (JonPhosAuNCMe)SbF6 catalysis. In contrast with the known gold-catalyzed reaction path of 2-alkynylanilines that leads to indoles, ynones underwent an auto intermolecular hydroamination. This process resulted finally in the formation of an eight-membered ring, likely through a selective 8-exo-dig intramolecular hydroamination that prevailed over the possible cyclocondensation reaction (that would result in the formation of 4-aminoquinoline derivatives). The easy availability of β-(2-aminophenyl)-α,β-ynones and the simple cyclization procedure make this approach suitable for the preparation of a wide range of useful dibenzodiazocines. The methodology can be extended to the use of β-(2-aminophenyl)-α,β-ynoates as substrates. (Figure presented.).
- Rode, Navnath D.,Arcadi, Antonio,Chiarini, Marco,Marinelli, Fabio,Portalone, Gustavo
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- Evaluation of antioxidant activity and cytotoxicity of polyfluorinated diarylacetylenes and indoles toward human cancer cells
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A large series of polyfluorinated diarylacetylenes and indoles was evaluated for antitumor activity in MCF-7, RPMI 8226, T98 G, HCT 116 human cancer cells and for cytotoxicity effect on HEK-293, WI-38, LMTK, AG 17 normal mammalian cell lines. It was found that with the increased number of fluorine atoms on the benzene ring of the compounds, their cytotoxicity increases, reaching a maximum in case of the perfluorinated structures. Polyfluorinated diarylacetylenes containing three fluorine atoms and trifluoromethyl and amino groups in one aryl ring, inhibit the proliferation of human myeloma RPMI 8226 and human breast cancer MCF-7 cells. Indoles showed more pronounced cytotoxicity as compared with their arylacetylene precursors. Compounds I9, I11, and I13 were found to have a high growth-inhibitory activity toward the human cancer cell lines tested, with half-inhibitory concentrations (IC50) of 1–10 μM. The structures of these compounds are characterized by complete fluorination of the benzene part of the indole core and the presence of an aromatic moiety at the 2nd position of the five-membered ring. Further, DNA fragmentation and Annexin V-FITC/PI staining assays confirm that I9 – I11 induce apoptosis. Mutagenic and antioxidant properties of the polyfluorinated indoles and of selected diarylacetylenes were also studied. On a Salmonella tester strain, it was demonstrated that the compounds are good antioxidants.
- Zakharova, Olga,Nevinsky, Georgy,Politanskaya, Larisa,Baev, Dmitry,Ovchinnikova, Ludmila,Tretyakov, Evgeny
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- A Cascade Synthesis of Hetero-arylated Triarylmethanes Through a Double 5-endo-dig Cyclization Sequence
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A sequential two-step method for the synthesis of hetero-arylated triarylmethanes through a Ag-catalyzed sequential double cyclization–nucleophilic addition cascade is described. This methodology basically involves an initial 5-endo-dig cyclization of o-alkynyl anilines to provide 2-substituted indole derivatives, which then react with 2-(2-enynyl)-pyridines to afford indolizine-containing unsymmetrical triarylmethanes through another 5-endo-dig cyclization.
- Paluru, Dilip K.,Mahesh, Sriram,Ahmad, Feroz,Vijaya Anand, Ramasamy
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- Synthesis of C2-Phosphorylated Indoles via Metal-Free 1,2-Phosphorylation of 3-Indolylmethanols with P(O)-H Species
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An efficient and practical method for synthesis of C2-phosphorylated indoles has been disclosed via a metal-free 1,2-phosphorylation of 3-indolylmethanols with H-phosphine oxides or H-phosphonates. This alternative protocol features a broad substrate scope with respect to both 3-indolylmethanols derived from isatins, acyclic α-keto amide, α-keto ester, 1,2-diketone and simple ketones and H-phosphine oxides or H-phosphonates, moderate to high yields and mild reaction conditions. Mechanistic studies indicate that this reaction proceeds via an unusual direct 1,2-addition pathway, in which the existence of an electron-withdrawing group adjacent to the hydroxyl group of 3-indolylmethanols plays a decisive role. (Figure presented.).
- Zou, Yun-Xiang,Liu, Xiao-Yan,Zhang, Jing,Yang, Hong-Li,Yang, Xin-Yue,Liu, Xiao-Ling,Chu, Yi-Wen,Chen, Long
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- Ga(OTf)3-Catalyzed Temperature-Controlled Regioselective Friedel-Crafts Alkylation of Trifluoromethylated 3-Indolylmethanols with 2-Substituted Indoles: Divergent Synthesis of Trifluoromethylated Unsymmetrical 3,3′-and 3,6′-Bis(indolyl)methanes
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An unprecedented Ga(OTf)3-catalyzed, temperature-controlled regiodivergent alkylation of 2-substituted indoles with trifluoromethylated 3-indolylmethanols is described that provides structurally diverse unsymmetrical 3,3′- and 3,6′-bis(indolyl)methanes with a CF3-containing quaternary carbon center in good to excellent yields under mild conditions. In addition, this present protocol could be successfully extended to the synthesis of difluoromethylated 3,3′- and 3,6′-bis(indolyl)methanes with excellent efficiency.
- Ling, Yuan,An, Di,Zhou, Yuanyuan,Rao, Weidong
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- Enhancement of gold catalytic activity and stability by immobilization on the surface of graphene
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The catalytic performance of gold complexes is evaluated at the molecular level and when supported onto reduced graphene oxide (rGO). Gold complexes of general formula [(NHC)AuX] catalyse the synthesis of indoles via intramolecular hydroamination reaction of alkynes. The catalytic properties of the molecular gold complexes are highly improved when supported onto graphene. Faster reaction rates and higher catalyst stability are observed for the immobilized gold complexes. The use of graphene as support of molecular complexes has a positive benefit in the catalytic gold properties in terms of activity and stability.
- Ventura-Espinosa, David,Sabater, Sara,Mata, Jose A.
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- SYNTHESIS OF 2-SUBSTITUTED INDOLES
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2-Substituted indoles are obtained upon the cyclocondensation of (2-R-2-oxoethyl)trimethylammonium bromides.
- Zav'yalov, S. I.,Zavozin, A. G.,Dorofeeva, O. V.,Rumyantseva, E. E.
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- Evaluation of PVP/Au nanocomposite fibers as heterogeneous catalysts in indole synthesis
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Electrospun nanocomposite fibers consisting of crosslinked polyvinylpyrrolidone (PVP) chains and gold nanoparticles (Au NPs) were fabricated, starting from highly stable PVP/Au NP colloidal solutions with different NP loadings, followed by thermal treatment. Information on the morphological characteristics of the fibers and of the embedded Au NPs was obtained by electron microscopy. Cylindrical, bead-free fibers were visualized by Scanning Electron Microscopy (SEM) while Transmission Electron Microscopy (TEM) and Energy Diffraction X-ray (EDX) analysis supported the presence of Au NPs within the fibers and gave information on their morphologies and average diameters. These materials were briefly evaluated as heterogeneous catalytic supports for the gold-catalyzed intramolecular cyclisation of 2-(phenylethynyl)aniline to form 2-phenyl-1H-indole. The performance of the gold catalyst was strongly dependent on the Au NP size, with the system containing the smallest Au NPs being the more effective. Moreover, a slight drop of their catalytic efficiency was observed after three consecutive reaction runs, which was attributed to morphological changes as a consequence of fiber merging.
- Savva, Ioanna,Kalogirou, Andreas S.,Achilleos, Mariliz,Vasile, Eugenia,Koutentis, Panayiotis A.,Krasia-Christoforou, Theodora
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- Three-component Au—Chitosan—SiO2 systems as heterogeneous catalysts for intramolecular cyclization of 2-(2-phenylethynyl)aniline
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A series of three-component heterogeneous catalysts Au—Ch—SiO2 with Ch for chitosan was prepared. The size of gold nanoparticles immobilized on the chitosan matrix depends on the method of sample preparation. The particles with the size 2. The catalysts were tested in the intramolecular cyclization reaction of 2-(2-phenylethynyl)aniline to for 2-phenylindole. The maximum conversion of 2-(2-phenylethynyl)aniline (25% within 35 h) was obtained on the Au(0.4%)—Ch(2.9%)/SiO2 catalyst.
- Finashina,Tkachenko,Startseva, A. Yu.,Krasovsky,Kustov,Beletskaya
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- Stereoselective Construction of Methylenecyclobutane-Fused Indolines through Photosensitized [2+2] Cycloaddition of Allene-Tethered Indole Derivatives
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Irradiation of 1-(hexa-4,5-dienoyl)indole derivatives in the presence of an aromatic ketone by a high-pressure mercury lamp through Pyrex glass gave the corresponding cyclized products stereoselectively in high yields. The major part of the products was an all-cis-fused methylenecyclobutane-type compound produced through [2+2] cycloaddition, accompanied by small amounts of alkynes via 1,5-hydrogen transfer of a biradical intermediate. Among a range of aromatic ketones, 3′,4′-dimethoxyacetophenone was found to sensitize the substrate quite effectively.
- Arai, Noriyoshi,Ohkuma, Takeshi
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- Domino cyclization-alkylation protocol for the synthesis of 2,3-functionalized indoles from o-alkynylanilines and allylic alcohols
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A practical and efficient protocol for the one-pot synthesis of 2,3-substituted indoles was developed via a palladacycle catalyzed domino cyclization-alkylation reaction involving 2-alkynylanilines and allylic alcohols under mild conditions without any additives.
- Xu, Chang,Murugan, Vinod K.,Pullarkat, Sumod A.
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- Efficient Synthesis of Indole Derivatives Containing the Tetrazole Moeity Utilizing an Ugi-Azide Post-Transformation Strategy
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An efficient strategy has been developed for the synthesis of indole derivatives containing the tetrazole moiety using a AuCl 3 -catalyzed cyclization reaction. The precursors of the cycloadduct were easily prepared by an Ugi-azide 4-CR in methanol at room temperature. The merit of this protocol lies in its operational simplicity, readily available starting materials, high yields of product, and good functional group tolerance.
- Nikbakht, Ali,Balalaie, Saeed,Baghestani, Fatemeh,Rominger, Frank
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- Recent developments in hybrid iron oxide–noble metal nanocatalysts for organic reactions
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A review of recent developments in the synthesis of hybrid iron oxide–noble metal nanocomposites and their application to various organic reactions is presented herein. Focus is placed on various strategies for achieving (1) Au nanoparticles (NPs) on Fe3O4@polymer catalysts, (2) optimized dispersion and stability of Fe3O4/Pd catalysts, (3) Au NPs supported on Fe2O3–graphene oxide hybrid nanosheets and (4) rose-like Pd–Fe3O4 hybrid nanocomposite-supported Au nanocatalysts. Further application of such hybrid nanocomposites as catalysts for various organic reactions is discussed in brief.
- Woo, Hyunje,Park, Kang Hyun
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- Ortho -selective C-H arylation of phenols with N -carboxyindoles under Br?nsted acid- or Cu(i)-catalysis
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Control over chemo- and regioselectivity is a critical issue in the heterobiaryl synthesis via C-H oxidative coupling. To address this challenge, a strategy to invert the normal polarity of indoles in the heterobiaryl coupling was developed. With N-carboxyindoles as umpoled indoles, an exclusively ortho-selective coupling with phenols has been realized, employing a Br?nsted acid- or Cu(i)-catalyst (as low as 0.01 mol%). A range of phenols and N-carboxyindoles coupled with exceptional efficiency and selectivity at ambient temperature and the substrates bearing redox-active aryl halides (-Br and -I) smoothly coupled in an orthogonal manner. Notably, preliminary examples of atropselective heterobiaryl coupling have been demonstrated, based on a chiral disulfonimide or a Cu(i)/chiral bisphosphine catalytic system. The reaction was proposed to occur through SN2′ substitution or a Cu(i)-Cu(iii) cycle, with Br?nsted acid or Cu(i) catalysts, respectively.
- Nguyen, Nguyen H.,Oh, Soo Min,Park, Cheol-Min,Shin, Seunghoon
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p. 1169 - 1176
(2022/02/02)
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- Chiral-Phosphoric-Acid-Catalyzed C6-Selective Pictet-Spengler Reactions for Construction of Polycyclic Indoles Containing Spiro Quaternary Stereocenters
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Compared with the well-established asymmetric Pictet-Spengler reactions on the pyrrole ring of indoles, the catalytic asymmetric Pictet-Spengler reaction on the benzene ring of indoles has been rarely studied. Herein the C6-selective Pictet-Spengler react
- Huang, Wen-Jun,Wang, Han,Wang, Xin-Wei,Wu, Bo,Zhou, Yong-Gui
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supporting information
p. 1727 - 1731
(2022/03/14)
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- Straightforward Synthesis of α-Chloromethylketimines Catalyzed by Gold(I). A Clean Way to Building Blocks
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α-Chloromethylketimines have been obtained through a gold-catalyzed hydroamination of aromatic and aliphatic 1-chloroalkynes with aromatic amines by using equimolar amounts of both reagents. This procedure has allowed the preparation and spectroscopic characterization of α-chloromethylketimines for the first time with a high degree of purity, complete conversion, and atom economy. The synthetic usefulness of the methodology has been demonstrated with the preparation of β-chloroamines and indoles.
- Asensio, Gregorio,Cárcel, María,Olmos, Andrea,Ramírez De Arellano, Carmen,Sarmiento, Jeymy T.,Varea, Teresa
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supporting information
p. 3114 - 3122
(2022/03/14)
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- Synthesis of Indoles by Reductive Cyclization of Nitro Compounds Using Formate Esters as CO Surrogates
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Alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of 2-nitrostyrenes to give indoles. Whereas the use of alkyl formates requires the presence of a ruthenium catalyst such as Ru3(CO)12, the reaction with phenyl formate can be performed by using a Pd/phenanthroline complex alone. Phenyl formate was found to be the most effective CO source and the desired products were obtained in excellent yields, often higher than those previously reported using pressurized CO. The reaction tolerates many functional groups, including sensitive ones like a free aldehydic group or a pendant pyrrole. Detailed experiments and kinetic studies allow to conclude that the activation of phenyl formate is base-catalyzed and that the metal doesn't play a role in the decarbonylation step. The reactions can be performed in a single thick-walled glass tube with as little as 0.2 mol-% palladium catalyst and even on a 2 g scale. The same protocol can be extended to other nitro compounds, affording different heterocycles.
- Ahmed Fouad, Manar,Ferretti, Francesco,Formenti, Dario,Milani, Fabio,Ragaini, Fabio
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supporting information
p. 4876 - 4894
(2021/09/20)
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- Visible-light-driven Cadogan reaction
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Visible-light-driven photochemical Cadogan-type cyclization has been discovered. The organic D-A type photosensitizer 4CzIPN found to be an efficient mediator to transfer energy from photons to the transient intermediate that breaks the barriers of deoxygenation in Cadogan reaction and enables a mild metal-free access to carbazoles and related heterocycles. DFT calculation results indicate mildly endergonic formation of the intermediate complex of nitrobiarenes and PPh3, which corresponds with experimental findings regarding reaction temperature. The robust synthetic capacity of the photoredox Cadogan reaction systems has been demonstrated by the viable productivity of a broad range of carbazoles and related N-heterocycles with good tolerance of various functionalities.
- Qu, Zhonghua,Wang, Pu,Chen, Xing,Deng, Guo-Jun,Huang, Huawen
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supporting information
p. 2582 - 2586
(2021/03/09)
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- Iminyl-radicals by electrochemical decarboxylation of α-imino-oxy acids: construction of indole-fused polycyclics
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Iminyl radicals are reactive intermediates that can be used for the construction of various valuable heterocycles. Herein, the electrochemical decarboxylation of α-imino-oxy acids for the generation of iminyl radicals has been accomplished under exogenous-oxidant- and metal-free conditions through the use ofnBu4NBr as a mediator. The resulting iminyl radicals undergo intramolecular cyclization smoothly with the adjacent (hetero)arenes to afford a series of indole-fused polycyclic compounds.
- Wan, Jin-Lin,Cui, Jian-Feng,Zhong, Wei-Qiang,Huang, Jing-Mei
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supporting information
p. 10242 - 10245
(2021/10/12)
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- Regioselective Direct C2 Arylation of Indole, Benzothiophene and Benzofuran: Utilization of Reusable Pd NPs and NHC-Pd@MNPs Catalyst for C–H Activation Reaction
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Abstract: A regioselective C2 arylation of indoles, benzothiophene and benzofuran without directing group has been accomplished using economically cheap Pd NPs and NHC-Pd@MNPs catalyst. The reusable catalyst is efficiently employed to access C2 arylated heterocycles in good to excellent yield. The reusability of the catalyst is studied up to five cycles and a gram-scale synthesis has been achieved. The reaction mechanism is well supported by control experiments and literature precedents. Grapic Abstract: [Figure not available: see fulltext.]
- Hegde, Rajeev V.,Ong, Tiow-Gan,Ambre, Ram,Jadhav, Arvind H.,Patil, Siddappa A.,Dateer, Ramesh B.
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p. 1397 - 1405
(2020/10/02)
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- Biogenic synthesis of Pd-nanoparticles using Areca Nut Husk Extract: a greener approach to access α-keto imides and stilbenes
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An eco-friendly green method for a one-step synthesis of palladium nanoparticles and their synthetic utility are reported. Phytochemicals like amines, alcohols, and phenols present in the Areca Nut Husk extract facilitate the reduction of Pd(ii) to Pd(0). The phytochemicals serve as stabilising agents and ligands for palladium reduction and the need for an external ligand is avoided. The Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy of newly synthesized palladium nanoparticles revealed a spherical morphology. The catalytic activity of the nanoparticles was tested for 1,2-difunctionalization of ynamides, Heck coupling, denitrogenative coupling of phenylhydrazine and C-H arylation of indole. Moreover, catalyst recyclability, control experiments, mechanistic elucidation, and gram-scale synthesis are elaborated.
- Dateer, Ramesh B.,Ghosh, Arnab,Hegde, Rajeev V.,Jadhav, Arvind H.,Nizam, Aatika,Patil, Siddappa A.,Peter, Febina
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p. 16213 - 16222
(2021/09/22)
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- In Situ Preparation of Palladium Nanoparticles for C-2 Selective Arylation of Indoles in Agro-Waste Extract Based Mixed Solvents
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An efficient and practical method for the in situ generation of palladium nanoparticles was successfully established in a water extract of pomelo peel ash. The produced palladium nanoparticles were characterized by energy-dispersive X-ray spectroscopy elemental mapping, field emission scanning electron microscopy, high-resolution transmission electron microscope, X-ray powder diffraction, and showed high catalytic activity for selective C-2 arylation of indoles. A series of 2-arylindoles were smoothly installed in moderate to good yields through the direct palladium-catalyzed cross-coupling reactions of indoles and iodoarenes without external ligand, base, oxidant, and preinstallation directing group.
- Jin, Weiwei,Liu, Chenjiang,Liu, Tianxiang,Sun, Yajun,Wang, Bin,Wang, Rui,Xia, Yu,Zhang, Yonghong
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supporting information
p. 2470 - 2473
(2021/06/25)
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- Synthesis and Catalytic Use of Polar Phosphinoferrocene Amidosulfonates Bearing Bulky Substituents at the Ferrocene Backbone
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Anionic phosphinoferrocene amidosulfonates bearing sterically demanding tert-butyl substituents in positions 3 and 3′ of the ferrocene scaffold, viz. rac-(Et3NH)[Fe(η5-tBuC5H3PR2)(η5-tBuC5H3C(O)NHCH2SO3)] (R = phenyl, cyclohexyl), were synthesized by amidation of the corresponding phosphinocarboxylic acids, [Fe(η5-tBuC5H3PR2)(η5-tBuC5H3CO2H)]. These ditopic polar phosphinoferrocenes and their non-tert-butylated analogues have been used as ligands to prepare zwitterionic (η3-allyl)palladium(II) complexes [Pd(η3-C3H5){Fe(η5-R′C5H3PR2)(η5-R′C5H3C(O)NHCH2SO3)}] (R′ = H, tBu; R = Ph, Cy). Depending on the isolation procedure and crystallization conditions, some complexes were isolated in two isomeric forms which differed in the coordination of the amidosulfonate pendant group, where either amide or sulfonated oxygen ligated the Pd(II) center. The preference for coordination of the amide or sulfonate oxygen atoms has been explained by the interplay of electrostatic and solvation effects and further supported by DFT calculations. The (η3-allyl)PdII complexes have been applied as defined precatalysts for Pd-catalyzed C-H arylation of an unprotected indole with aryl iodides in polar solvents. Under the optimized reaction conditions at 100 °C in water, C2-arylation proceeded selectively with various aryl iodides to produce the respective 2-arylindoles in acceptable yields at a low catalyst loading (1 mol % Pd) and in the absence of any phase transfer agent. The catalyst possessing tert-butyl groups at the ferrocene core and an electron-rich dicyclohexylphosphino group exhibited the best catalytic performance.
- Vosáhlo, Petr,Radal, Leá,Labonde, Marine,Císa?ová, Ivana,Roger, Julien,Pirio, Nadine,Hierso, Jean-Cyrille,?těpni?ka, Petr
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p. 1934 - 1944
(2021/06/28)
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- Room Temperature C-H Arylation of Benzofurans by Aryl Iodides
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A robust method of room temperature direct arylation for benzofuran is reported. This discovery allows for mild arylation by commercially available aryl iodides with complete C-2 regioselectivity and tolerates a range of functional groups, including heat sensitive groups. Mechanistically, a Heck-type oxyarylation product from a direct arylation process is reported as a key piece of evidence for a carbopalladation intermediate.
- Mayhugh, Amy L.,Luscombe, Christine K.
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supporting information
p. 7079 - 7082
(2021/09/18)
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- Cobalt-Catalyzed Dearomatization of Indoles via Transfer Hydrogenation to Afford Polycyclic Indolines
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A cobalt-catalyzed dearomatization of indoles via transfer hydrogenation with HBpin and H2O has been developed. This reaction offered a straightforward platform to access hexahydropyrido[1,2-a]indoles in high regio- and chemoselectivity. A preliminary reaction mechanism was proposed on the basis of deuterium-labeling experiments, and a cobalt hydride species was involved in the reaction.
- Chen, Siwei,Cai, Min,Huang, Junru,Yao, Hequan,Lin, Aijun
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supporting information
p. 2212 - 2216
(2021/04/05)
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- Synthesis of Ester-Substituted Indolo[2,1-a]isoquinolines via Photocatalyzed Alkoxycarbonylation/Cyclization Reactions
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A direct alkoxycarbonylation/cyclization reaction is accomplished under visible light-induced photoredox catalysis. With this approach, a variety of ester-substituted indolo[2,1-a]isoquinolines are prepared in good to excellent yields. It is worth noting that this method not only can afford the synthesis of indolo[2,1-a]isoquinolines but also can provide an alternative route for generating complex target structures bearing carboxylic esters.
- Chen, Jian-Qiang,Huang, Shaoxin,Qin, Binyan,Tu, Xiaodong,Wu, Jie,Zhang, Jun
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supporting information
(2022/01/20)
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- Regioselective mercury(I)/palladium(II)-catalyzed single-step approach for the synthesis of imines and 2-substituted indoles
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An efficient synthesis of ketimines was achieved through a regioselective Hg(I)-catalyzed hydroamination of terminal acetylenes in the presence of anilines. The Pd(II)-catalyzed cycliza-tion of these imines into the 2-substituted indoles was satisfactorily carried out by a C-H acti-vation. In a single-step approach, a variety of 2-substituted indoles were also generated via a Hg(I)/Pd(II)-catalyzed, one-pot, two-step process, starting from anilines and terminal acetylenes. The arylacetylenes proved to be more effective than the alkyl derivatives.
- Delgado, Francisco,Gutiérrez, Rsuini U.,Hernández-Montes, Mayra,Mendieta-Moctezuma, Aarón,Tamariz, Joaquín
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- Synthesis of functionalised 2,3-dihydroquinolin-4(1: H)-ones vs. quinoline or N -alkenylindole derivatives through sequential reactions of 2-alkynylanilines with ketones
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This study describes diversity-oriented synthesis of 2,2,3-substituted-2,3-dihydroquinolin-4(1H)-ones vs. functionalised quinoline or N-alkenylindole derivatives through Br?nsted acid mediated or Lewis acid catalyzed sequential reactions of 2-alkynylanilines with ketones. In particular, a series of challenging quinolin-4-one derivatives are prepared with good functional group tolerance in an atom-economical fashion by using p-toluenesulfonic acid monohydrate as a promoter of the reaction of ketones with 2-alkynylanilines in EtOH at reflux, while the same starting materials give the corresponding 4-substituted quinolines in toluene at 110 °C both in the presence of p-toluenesulfonic acid monohydrate as the promoter and FeCl3 as the catalyst. The divergent formation of N-alkenylindole derivatives occurs by switching to the use of ZnBr2 as the catalyst under the same reaction conditions. Conversely, only 4-methylsubstituted quinoline derivatives were isolated by reacting 2-ethynylanilines and/or 2-trimethylsylilanilines with ketones in all examined cases. This journal is
- Marsicano, Vincenzo,Arcadi, Antonio,Chiarini, Marco,Fabrizi, Giancarlo,Goggiamani, Antonella,Iazzetti, Antonia
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p. 421 - 438
(2021/01/29)
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- Metal-Free and syn-Selective Hydrohalogenation of Alkynes through a Pseudo-Intramolecular Process
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A new metal-free hydrohalogenation method for alkynes has been developed, which proceeds through a pseudo-intramolecular process. In this reaction, ethynylaniline serves as a substrate to quantitatively form an anilinium salt upon treatment with hydrochloric acid. The spatial proximity facilitates the efficient electrophilic addition of HCl to the ethynyl group in syn-mode, affording the corresponding chloroalkene without overaddition. This protocol was applied to HBr and HI, and the corresponding bromo- and iodoalkenes were obtained, respectively. The obtained chloroalkene was converted to tri-substituted alkenes possessing different aryl/alkynyl groups through Pd-catalyzed cross-coupling reactions.
- Asahara, Haruyasu,Mukaijo, Yusuke,Muragishi, Kengo,Iwai, Kento,Ito, Akitaka,Nishiwaki, Nagatoshi
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p. 5747 - 5755
(2021/10/20)
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- Ligand effects in the stabilization of gold nanoparticles anchored on the surface of graphene: Implications in catalysis
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Gold nanoparticles (Au NPs) functionalized with N-heterocyclic carbene (NHC) ligands immobilized onto graphene are obtained via spontaneous decomposition of well-defined gold-NHC complexes by reduced graphene oxide (rGO) without reducing agents. NHC ligands are responsible for the formation of air-stable, crystalline and small (3.0–4-0 nm) Au NPs homogeneously distributed on the surface of graphene. The catalytic properties of three Au NPs functionalized with different ligands were tested in two benchmark reactions (hydration of alkynes and intramolecular hydroamination of alkynes). The results reveal a pronounced ligand effect on the stability of Au NPs on graphene, by acting as a bridge between them. The Au NPs functionalized with a NHC ligand lacking a polyaromatic group or having a naphthyl tag displayed limited stability and fast deactivation in the first run. On the contrary, the Au NPs functionalized with a NHC ligand containing a pyrenyl handle showed superior catalytic activity and can be recycled at least ten times. The particle size of the Au NPs is preserved after the recycling process indicating a high stability. These results illustrate the use of purposely designed ligands having affinity for both Au NPs and graphene to increase the stability of the hybrid catalyst.
- Ventura-Espinosa, David,Martín, Santiago,García, Hermenegildo,Mata, Jose A.
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p. 113 - 120
(2021/02/02)
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- Aniline-initiated and Br?nsted acid-catalyzed one-pot reaction toward 2-aryl-3-sulfenylindoles by using α-aminocarbonyl compounds and primary amines with RSSR
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A highly novel method of direct synthesis of 2-aryl-3-sulfenylindoles in moderate to good yields was developed via one-pot tandem reaction of readily available α-aminocarbonyl compounds and catalytic amount of benzenamines with RSSR.
- Chen, De,Cheng, Chaozhihui,Deng, Wei,Guan, Wenjian,Liu, Yuxuan,Luo, Yongyue,Xiang, Jiannan,Zhang, Jiajia
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- N-Hydroxyphthalimidyl diazoacetate (NHPI-DA): A modular methylene linchpin for the C-H alkylation of indoles
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Despite the extensive studies on the reactions between conventional diazocompounds and indoles, these are still limited by the independent synthesis of the carbene precursors, the specific catalysts, and the required multi-step manipulation of the products. In this work, we explore redox-Active carbenes in the expedited and divergent synthesis of functionalized indoles. NHPI-DA displays unusual efficiency and selectivity to yield insertion products that can be swiftly elaborated into boron and carbon substituents that are particularly problematic in carbene-mediated reactions.
- Chowdhury, Rajdip,Mendoza, Abraham
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supporting information
p. 4532 - 4535
(2021/05/17)
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- Investigation of indole functionalized pyrazoles and oxadiazoles as anti-inflammatory agents: Synthesis, in-vivo, in-vitro and in-silico analysis
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There are several potential side and adverse effects are found to be associated with the anti-inflammatory drugs in clinical practice. The long-term use of these clinical agents highly unsafe. It encouraged the development of novel heterocyclic compounds with potential anti-inflammatory activity and low to no toxicity. In present investigation, a total of 12 indole functionalized pyrazole and oxadiazole derivatives were designed, synthesized and evaluated for the in-vivo anti-inflammatory and analgesic potential. These compounds displayed comparable anti-inflammatory and analgesic potential to the reference drugs. Finally, molecular docking analysis was performed considering different anti-inflammatory targets to determine the mechanistic target of the designed molecules. Detailed analysis suggested that the molecules inhibit COX-2, preferably over other anti-inflammatory targets. The results suggested that two compounds (15c and 15f) were found promising candidates for the development of novel anti-inflammatory agents.
- Kalra, Sourav,Kumar, Bhupinder,Kumar, Devendra,Kumar, Ravi Ranjan,Pathania, Shelly,Singh, Pankaj Kumar
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- Discovery of New 4-Indolyl Quinazoline Derivatives as Highly Potent and Orally Bioavailable P-Glycoprotein Inhibitors
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The major drawbacks of P-glycoprotein (P-gp) inhibitors at the clinical stage make the development of new P-gp inhibitors challenging and desirable. In this study, we reported our structure-activity relationship studies of 4-indolyl quinazoline, which led to the discovery of a highly effective and orally active P-gp inhibitor, YS-370. YS-370 effectively reversed multidrug resistance (MDR) to paclitaxel and colchicine in SW620/AD300 and HEK293T-ABCB1 cells. YS-370 bound directly to P-gp, did not alter expression or subcellular localization of P-gp in SW620/AD300 cells, but increased the intracellular accumulation of paclitaxel. Furthermore, YS-370 stimulated the P-gp ATPase activity and had moderate inhibition against CYP3A4. Significantly, oral administration of YS-370 in combination with paclitaxel achieved much stronger antitumor activity in a xenograft model bearing SW620/Ad300 cells than either drug alone. Taken together, our data demonstrate that YS-370 is a promising P-gp inhibitor capable of overcoming MDR and represents a unique scaffold for the development of new P-gp inhibitors.
- Chen, Zhe-Sheng,Dai, Qing-Qing,Li, Guo-Bo,Liu, Hong-Min,Liu, Hui,Wang, Bo,Wang, Shaomeng,Yu, Bin,Yuan, Shuo,Zhang, Jing-Ya,Zhang, Xiao-Nan,Zuo, Jia-Hui
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p. 14895 - 14911
(2021/10/12)
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- An iron(iii)-catalyzed dehydrogenative cross-coupling reaction of indoles with benzylamines to prepare 3-aminoindole derivatives
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We report a green cascade approach to prepare a variety of 3-aminoindole derivatives in good to excellent yields through an iron(iii)-catalyzed dehydrogenative cross-coupling reaction of 2-arylindoles and primary benzylamines under mild reaction conditions. Mechanistic studies show that a cascade reaction involves a tert-butyl nitrite (TBN)-mediated nitrosation of 2-substituted indoles and a 1,5-hydrogen shift to afford indolenine oximes, sequential iron(iii)-catalyzed condensation and a 1,5-hydrogen shift over four steps in a one-pot reaction. The reaction shows a broad substrate scope of indoles and benzylamines and tolerates a wide range of functional groups. Moreover, the reaction is easily performed at the gram scale without producing waste after the reaction is completed. The 3-aminoindole product is purified by simple extraction, washing, and recrystallization without flash column chromatography. A double imine ligand containing the 3-aminoindole unit is facile to obtain in a 52% yield in one step. The present method highlights readily available starting materials, a simple purification procedure, and the usage of cheap, nontoxic, and environmentally benign iron(iii) catalysts. This journal is
- Chen, Wei-Li,Li, Kun,Liang, Cui,Liang, Wang-Fu,Liao, Wei-Cong,Mo, Dong-Liang,Qiu, Pei-Wen,Su, Gui-Fa
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supporting information
p. 9610 - 9616
(2021/12/09)
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- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
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Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
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supporting information
p. 7832 - 7837
(2021/09/28)
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- Copper(I)-Mediated Cascade Annulation via Dual C-H/C-H Activation: Access to Benzo[a]carbazolic AEEgens
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A Cu(I)-mediated cascade cyclization/annulation of unprotectedo-alkynylanilines with maleimides in one pot is developed. The protocol offers sequential formation of one C-N and two C-C bonds to deliver fused benzo[a]carbazoles having free NH skeletons. The annulated products display fluorescence emission in the range of 485-502 nm with a large Stokes shift and fluorescence lifetime of ~17 ns. The annulated3aadisplays AEE behavior in the ethanol/hexane system and possesses marigold-flower-like morphology at the aggregated state. Cell viability assays enumerate biocompatible AEEgens, while their high intracellular fluorescence depicts cell imaging applicability.
- Khandelia, Tamanna,Ghosh, Subhendu,Panigrahi, Pritishree,Shome, Rajib,Ghosh, Siddhartha Sankar,Patel, Bhisma K.
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p. 16948 - 16964
(2021/12/02)
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- Tris-NHC-propagated self-supported polymer-based Pd catalysts for heterogeneous C-H functionalization
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Three-dimensionally propagated imidazolium-containing mesoporous coordination polymer and organic polymer-based platforms were successfully exploited to develop single-site heterogenized Pd-NHC catalysts for oxidative arene/heteroarene C-H functionalization reactions. The catalysts were efficient in directed arene halogenation, and nondirected arene and heteroarene arylation reactions. High catalytic activity, excellent heterogeneity and recyclability were offered by these systems making them promising candidates in the area of heterogeneous C-H functionalization, where efficient catalysts are still scarce.
- Choudhury, Joyanta,Dutta, Tapas Kumar,Mandal, Tanmoy,Mohanty, Sunit
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supporting information
p. 10182 - 10185
(2021/10/12)
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- Pd/β-cyclodextrin-catalyzed C-H functionalization in water: A greener approach to regioselective arylation of (NH)-indoles with aryl bromides
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A greener and more practical strategy for the site-selective C-H arylation of (NH)-indoles via coupling of (hetero)aryl bromides was developed, in which β-cyclodextrin, acting as both a ligand for Na2PdCl4 and a host for indoles, enables the reactions to occur easily in water. The key advantage of this method is the ingenious merging of aqueous homogeneous catalysis and ligand mediation, leading to the highly regioselective formation of C3-arylindoles with a broad substrate scope and functional-group tolerance. Moreover, the regioselectivity can be switched from the C3 to the C2-position by varying the nature of the base without recourse to employing ArI as substrates.
- Duan, Xin Hong,Xu, Peng
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supporting information
p. 19425 - 19431
(2021/11/09)
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- Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
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Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.
- Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
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supporting information
p. 13725 - 13729
(2021/09/08)
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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
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N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.
- Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
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p. 3679 - 3686
(2021/06/18)
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- Modular counter-Fischer?indole synthesis through radical-enolate coupling
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A single-electron transfer mediated modular indole formation reaction from a 2-iodoaniline derivative and a ketone has been developed. This transition-metal-free reaction shows a broad substrate scope and unconventional regioselectivity trends. Moreover, important functional groups for further transformation are tolerated under the reaction conditions. Density functional theory studies reveal that the reaction proceeds by metal coordination, which converts a disfavored 5-endo-trig cyclization to an accessible 7-endo-trig process.
- Chung, Hyunho,Kim, Jeongyun,Gonzalez-Montiel, Gisela A.,Cheong, Paul Ha-Yeon,Lee, Hong Geun
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supporting information
p. 1096 - 1102
(2021/01/26)
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- Pd-Catalyzed Indole Synthesis via C-H Activation and Bisamination Sequence with Diaziridinone
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This work describes an efficient Pd-catalyzed indole synthesis. A wide variety of indoles can be obtained in good yields from readily available vinyl bromides. The reaction likely proceeds through a sequential aryl C-H activation and bisamination of a resulting pallada(II)cycle with diaziridinone.
- Wang, Jianjun,Sun, Xiaofeng,Hu, Daguo,Shi, Yian
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p. 7561 - 7565
(2021/10/02)
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- Facile C-S Bond Cleavage of Aryl Sulfoxides Promoted by Bronsted Acid
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A method for the Bronsted acid promoted desulfination of aryl sulfoxides is presented. In the presence of a thiol, electron-rich sulfoxides undergo C-S bond cleavage to give the corresponding protodesulfinated arenes and disulfides.
- Brutiu, Bogdan R.,Klose, Immo,Maulide, Nuno
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p. 488 - 490
(2021/03/09)
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- Exploiting Iminoquinones as Electrophilic at Nitrogen "n+" Synthons for C-N Bond Construction
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New methods for C-N bond construction exploiting the N-centered electrophilic character of iminoquinones are reported. Iminoquinones, generated in situ via the condensation of o-vinylanilines with benzoquinones, undergo acid-catalyzed cyclization to afford N-arylindoles in excellent yields. Under similar reaction conditions, homoallylic amines react analogously to afford N-arylpyrroles. Additionally, organometallic nucleophiles are shown to add to the nitrogen atom of N-alkyliminoquinones to provide amine products. Finally, iminoquinones are shown to be competent electrophiles for copper-catalyzed hydroamination.
- Mori-Quiroz, Luis M.,Comadoll, Chelsea G.,Super, Jonathan E.,Clift, Michael D.
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p. 7008 - 7013
(2021/09/18)
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- Synthesis of indoles through acceptorless dehydrogenative coupling catalyzed by nickel on silica-alumina
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The high atom-economical formation of indoles from anilines and diols was described with affordable and easy to handle Ni/SiO2-Al2O3. After optimization, 2,3-dimethylindole was isolated with an excellent 98% yield in neat conditions. The scope of the reaction was studied and 13 indoles were isolated in 16–80% yields.
- Charvieux, Aubin,Hammoud, Abdul Aziz,Duclos, Marie-Christine,Duguet, Nicolas,Métay, Estelle
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supporting information
(2021/07/25)
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- Method for synthesizing 2-substituted indole derivative under catalysis of copper
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The invention relates to a method for synthesizing a 2-substituted indole derivative under the catalysis of copper, which comprises the following step of: reacting by taking copper acetylacetonate (Cu (acac) 2) as a catalyst and taking indole and halogenated hydrocarbon as raw materials to obtain the 2-substituted indole derivative. Compared with the prior art, the method has the advantages that the copper acetylacetonate Cu (acac) 2 which is low in price, easy to obtain and stable in property is used as the catalyst, the method is green and economical, the catalyst is used for catalyzing the indole and halogenated hydrocarbon to react to synthesize the 2-substituted indole derivative, the reaction condition is mild, and the selectivity and yield of the product are high; and the synthesis method is simple and green, the 2-substituted indole derivative is directly constructed by using cheap and easily available raw materials indole and halogenated hydrocarbon, and the 2-substituted indole derivative has good substrate universality and has wide application value in the fields of pharmaceutical chemistry, fine chemical industry and the like.
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-
Paragraph 0039-0042
(2021/09/11)
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- Sequential Sonogashira/intramolecular aminopalladation/cross-coupling ofortho-ethynyl-anilines catalyzed by a single palladium source: rapid access to 2,3-diarylindoles
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We have developed a practical and efficient one-pot protocol for the synthesis of 2,3-diarylindolesviaPd-catalyzed bis-arylative cyclization of variouso-ethynylanilines with aryl iodides. Mechanism studies showed that a Pd-catalyzed Sonogashira reaction took place firstly, giving an internal alkyne intermediate, which subsequently underwent intramolecular aminopalladation/cross-coupling to give access to 2,3-diarylindoles. The present methodology exhibits a broad substrate scope, producing various 2,3-diaryl indoles bearing two different aryl groups.
- Wang, Jiwei,Wang, Gendi,Cheng, Xiang,Liu, Ye,Zhang, Jun
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p. 1329 - 1333
(2021/02/26)
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- Synthesis of Substituted Anilines from Cyclohexanones Using Pd/C-Ethylene System and Its Application to Indole Synthesis
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The synthesis of anilines and indoles from cyclohexanones using a Pd/C-ethylene system is reported. A simple combination of NH4OAc and K2CO3 under nonaerobic conditions was found to be the most suitable to perform this reaction. Hydrogen transfer between cyclohexanone and ethylene generates the desired products. The reaction tolerates a variety of substitutions on the starting cyclohexanones.
- Maeda, Katsumi,Matsubara, Ryosuke,Hayashi, Masahiko
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p. 1530 - 1534
(2021/03/08)
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- Iron-catalyzed reductive coupling of nitroarenes with olefins: Intermediate of iron-nitroso complex
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Using a single half-sandwich iron(II) compound, CpFe(1,2-Ph2PC6H4S)(NCMe) (Cp- = C5Me5-, 1) as a catalyst, reductive coupling of nitroarenes with olefins has been achieved by a well-defined iron(II)/(EtO)3SiH system. Through either inter- or intramolecular reductive coupling, various branched amines and indole derivatives have been directly synthesized in one-pot. Mechanistic studies showed that the catalysis is initiated by activation of nitroarenes by the iron(II) catalyst with silane, generating iron-nitrosoarene intermediate for the C-N bond coupling.
- Song, Heng,Yang, Zhuoyi,Tung, Chen-Ho,Wang, Wenguang
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p. 276 - 281
(2019/12/24)
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- Discovery of novel multi-substituted benzo-indole pyrazole schiff base derivatives with antibacterial activity targeting DNA gyrase
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The design and synthesis of novel multi-substituted benzo-indole pyrazole Schiff base derivatives of potent DNA gyrase inhibitory activity were the main aims of this study. All the novel synthesized compounds were examined for their antibacterial activities against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella. In addition, we selected 20 compounds for the in vitro antibacterial activities assay of 6 drug-resistant bacteria strains. The result revealed compound 8I-w exhibited excellent antibacterial activity against 4 drug-resistant E. coli bacteria strains with IC50 values of 7.0, 17.0, 13.5, and 1.0 μM, respectively. In vitro enzyme inhibitory assay showed that compound 8I-w displayed potent inhibition against DNA gyrase with IC50 values of 0.10 μM. The molecular docking model indicated that compounds 8I-w can bind well to the DNA gyrase by interacting with various amino acid residues. This study demonstrated that the compound 8I-w can act as the most potent DNA gyrase inhibitor in the reported series of compounds and provide valuable information for the commercial DNA gyrase inhibiting bactericides.
- Cao, Hai-Qun,Chu, Zhi-Wen,Liu, Hao,Lv, Xian-Hai,Xia, Dong-Guo
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- Merging Visible Light Photocatalysis and l-/d-Proline Catalysis: Direct Asymmetric Oxidative Dearomatization of 2-Arylindoles to Access C2-Quaternary Indolin-3-ones
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A mild and effective method for asymmetric synthesis of C2-quaternary indolin-3-ones directly from 2-arylindoles by combining visible light photocatalysis and organocatalysis is described. In this reaction, 2-substituted indoles undergo photocatalyzed oxidative dearomatization, followed by an organocatalyzed asymmetric Mannich reaction with ketones or aldehydes. Products with opposite configurations are easily obtained in satisfactory yields with excellent enantio- A nd diastereoselectivity by employing readily available l- A nd d-proline as chiral organocatalysts.
- Dong, Chun-Lin,Ding, Xuan,Huang, Lan-Qian,He, Yan-Hong,Guan, Zhi
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supporting information
p. 1076 - 1080
(2020/02/15)
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- Highly enantioselective electrosynthesis of C2-quaternary indolin-3-ones
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A highly enantioselective and direct synthesis of C2-quaternary indolin-3-ones from 2-arylindoles by combining electrochemistry and organocatalysis is described. Excellent enantioselectivities (up to 99% ee) and diastereoselectivities (>20 : 1) can be obtained through anodic oxidation in combination with asymmetric proline-catalyzed alkylation in an undivided cell under constant-current conditions.
- Chen, Yu-Jue,Chen, Yuan,Ding, Xuan,Guan, Zhi,He, Yan-Hong,Lu, Fo-Yun
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supporting information
p. 623 - 626
(2020/01/28)
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- Synthesis of 2,3-disubstituted indoles from alkynylanilines and 2-chlorophenols using palladium–dihydroxyterphenylphosphine catalyst
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2,3-Disubstituted indoles bearing 2-hydroxyphenyl moieties at their C3 positions were synthesized from readily available 2-chlorophenols and alkynylanilines via aminopalladation/reductive elimination using Pd–dihydroxyterphenylphosphine catalyst. The catalyst accelerates the introduction of the 2-hydroxyphenyl group at the C3 position of the indole.
- Yamaguchi, Miyuki,Ogihara, Kota,Konishi, Hideyuki,Manabe, Kei
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- Manganese(iii)-promoted tandem phosphinoylation/cyclization of 2-arylindoles/2-arylbenzimidazoles with disubstituted phosphine oxides
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A simple and practical method for the synthesis of phosphoryl-substituted indolo[2,1-a]isoquinolin-6(5H)-ones and benzimidazo[2,1-a]isoquinolin-6(5H)-ones through manganese(iii)-promoted tandem phosphinoylation/cyclization of 2-arylindoles or 2-arylbenzimidazoles with disubstituted phosphine oxides was developed. In this transformation, new C-P bond and C-C bond were constructed simultaneously under silver-free conditions, exhibiting a broad substrate scope. It was noted that not only diarylphosphine oxides but also dialkyl and arylalkyl-phosphine oxides were compatible with the conditions. This journal is
- Jiang, Shuai-Shuai,Li, Jin-Heng,Luo, Shu-Zheng,Song, Ren-Jie,Wu, Yan-Chen,Xiao, Yu-Ting
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supporting information
p. 4843 - 4847
(2020/07/13)
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- Selective synthesis of 2-indolyl-3-oxoindolines or 2-(2-aminophenyl)quinolines through Cu(II)- or Bi(III)-catalyzed tunable dimerizations of 2-alkynylanilines
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A novel and selective synthesis of 2-indolyl-3-oxoindolines or 2-(2-aminophenyl)quinolines through tunable dimerizations of 2-alkynylanilines is presented. Mechanistically, the formation of 2-indolyl-3-oxoindolines involves a Cu(OAc)2/O2-promoted intramolecular cyclization of 2-alkynylaniline to give the required indole and 3H-indol-3-one intermediates followed by the indolylation of 3H-indol-3-one. On the other hand, the formation of 2-(2-aminophenyl)quinolines is believed to go through a Bi(OTf)3/MesCO2H-catalyzed intermolecular N-nucleophilic addition between two 2-alkynylaniline molecules to give an enamine intermediate followed by its intramolecular C-nucleophilic addition/annulation. Notable features of these new methods include easily obtainable substrates, economical catalysts and oxidant, controllable selectivity, and high versatility toward diverse products.
- Jia, Ruixue,Li, Bin,Zhang, Xinying,Fan, Xuesen
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supporting information
p. 6810 - 6815
(2020/09/15)
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- Ferrocenyl induced one-pot synthesis of 3,3′-ferrocenylbiindoles
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When we used 2-ferrocenethynylaniline (1a) as reactant and NaAuCl4·2H2O (5%) as catalyst to prepare 2-ferrocenylindole (2a), we were surprised to find that 3,3′-ferrocenylbiindole (3a) was obtained simultaneously. 3a was characterized by elemental analysis, FT-IR, MS, NMR, and X-ray single crystal diffraction. The reactant substitution reaction, in-situ HNMR, XPS, EPR characterization, and calculations were carried out to interpret why 3a was obtained in one pot. The results showed that the hydroperoxyl radical played a key role in the reaction, which induced synthesis of 3a.
- Yan, Ligang,Han, Limin,Xie, Ruijun
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p. 1325 - 1338
(2020/07/03)
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- Palladium-Catalyzed Ligand-Free Double Cyclization Reactions for the Synthesis of 3-(1′-Indolyl)-phthalides
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Indole and phthalide are privileged heterocyclic scaffolds in numerous natural products and bioactive molecules. The synthesis and biological evaluation of the compounds combining these two scaffolds have rarely been reported. Herein, we repot the first palladium-catalyzed ligand-free double cyclization reactions that enable efficient synthesis of 3-(1′-indolyl)-phthalides (42 examples, up to 96% yield) under mild conditions. Notably, only 1.0 mol % of catalyst loading is used, suggesting high efficiency. Late-stage elaborations give highly functionalized analogues.
- Yuan, Shuo,Zhang, Dan-Qing,Zhang, Jing-Ya,Yu, Bin,Liu, Hong-Min
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p. 814 - 817
(2020/02/04)
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- Self-Assembled Multilayer Iron(0) Nanoparticle Catalyst for Ligand-Free Carbon-Carbon/Carbon-Nitrogen Bond-Forming Reactions
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Self-assembled multilayer iron(0) nanoparticles (NPs, 6-10 nm), namely, sulfur-modified Au-supported Fe(0) [SAFe(0)], were developed for ligand-free one-pot carbon-carbon/carbon-nitrogen bond-forming reactions. SAFe(0) was successfully prepared using a well-established metal-nanoparticle catalyst preparative protocol by simultaneous in situ metal NP and nanospace organization (PSSO) with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (Si-DHP) as a strong reducing agent. SAFe(0) was easy to handle in air and could be recycled with a low iron-leaching rate in reaction cycles.
- Akiyama, Toshiki,Arisawa, Mitsuhiro,Haneoka, Hitoshi,Harada, Kazuo,Hasegawa, Jun-Ya,Honma, Tetsuo,Mashima, Kazushi,Sato, Yoshihiro,Shimoda, Shuhei,Shio, Yasunori,Suzuki, Takeyuki,Tamenori, Yusuke,Tsurugi, Hayato,Tsuruta, Kazuki,Wada, Yuki,Yamada, Makito
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supporting information
p. 7244 - 7249
(2020/10/12)
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- Catalytic C(sp2)?H amination reactions using dinickel imides
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C?H amination reactions are valuable transformations for the construction of C?N bonds. Due to their relatively high bond dissociation energies, C(sp2)?H bonds are generally not susceptible toward direct nitrene insertion, necessitating alternative mechanisms for C?H activation. Here, we report that cationic dinuclear (NDI)Ni2 (NDI = naphthyridine?diimine) complexes catalyze intramolecular nitrene insertions into aryl and vinyl C(sp2)? H bonds. Mechanistic studies suggest that a bridging imido ligand supported at a Ni2 site induces C?H activation by a 1,2-addition pathway to generate an azametallacyclic intermediate. This organometallic mechanism contrasts with the electrocyclization/1,2-shift mechanism proposed for analogous transformations using Rh2 catalysts. The implications of these mechanistic differences for the stereoselectivity and chemoselectivity of C?H amination are described.
- Andjaba, John M.,Powers, Ian G.,Uyeda, Christopher,Zeller, Matthias
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supporting information
p. 3794 - 3801
(2020/11/23)
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- Pd-Catalyzed Reductive Cyclization of Nitroarenes with CO2 as the CO Source
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A reductive amination process that constructs indoles, carbazoles or benzimidazoles from nitroarenes – irrespective of their electronic or steric nature – was developed that uses CO2 as the source of CO. The process is robust, tolerating common gaseous components of flue gas (H2S, SO2, NO and H2O) without adversely affecting the reductive cyclization.
- Guan, Xinyu,Zhu, Haoran,Zhao, Yingwei,Driver, Tom G.
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supporting information
p. 57 - 60
(2019/12/11)
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- Characterization of heterogeneous aryl-Pd(ii)-oxo clusters as active species for C-H arylation
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C-H arylation with heterogeneous palladium was investigated. The surface oxidation of Pd nanoparticles with a hypervalent iodine reagent, [Ph2I]BF4, resulted in the generation of Pd(ii)-aryl-oxo clusters, which were characterized as the crucial intermediate.
- Shin, Taeil,Kim, Minjun,Jung, Younjae,Cho, Sung June,Kim, Hyunwoo,Song, Hyunjoon
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supporting information
p. 14404 - 14407
(2020/12/01)
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