- Vapor phase methylation of indole over nanocrystalline Cd1-xCrxFe2O4 (x = 0, 0.25, 0.5, 0.75 and 1.0) ferrospinels
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Vapor phase methylation of indole has been carried out over nanocrystalline Cd1-xCrxFe2O4 (x = 0, 0.25, 0.5, 0.75 and 1.0) ferrospinels in a fixed bed down-flow reactor. Catalyst characterization was performed by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy with EDX, BET surface area and temperature programmed ammonia-desorption method. Product selectivity is shown to be strongly influenced by acidic properties of the catalyst. A maximum yield of 64.29 % of 3-methyl indole with 91.46 % selectivity at 70.3 % indole conversion was obtained under optimized reaction conditions.
- Kadian,Siwach,Gupta,Duhan
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- CITORELLAMINE, A NEW BROMOINDOLE DERIVATIVE FROM POLYCITORELLA MARIAE
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The structure of citorellamine, isolated from the tunicate Polycitorella mariae, has been deduced from spectroscopic analyses and chemical transformations.
- Roll, Deborah M.,Ireland, Chris M.
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- A remarkable mechanistic dichotomy in the acid-catalysed decomposition of the N- And C-adducts of indolide anions with 1,3,5-trinitrobenzene
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Decomposition of the N- and C-adducts of indolide anions with 1,3,5-trinitrobenzene is subject to specific acid-catalysis in the former case and general-acid-catalysis in the latter through an SEAr process.
- Sepulcri, Patricia,Goumont, Regis,Terrier, Francois,Buncel, Erwin
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- Catalytic signal amplification using a heck reaction. An example in the fluorescence sensing of Cu(II)
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Catalytic signal enhancement using an organometallic reaction is demonstrated. The reactivity of a Heck cross-coupling reaction that creates a fluorophore is modulated by the addition of a polyazacyclam inhibitor. The inhibitor will complex with Cu(II), which restores the activity of the Pd(II). The addition of Cu(II) therefore leads to the generation of fluorescence, thereby creating a very sensitive assay for Cu(II). The rate of the Heck reaction is followed by monitoring emission as a function of time. The rate is proportional to the Cu(II) concentration and correlates to the affinity of the inhibitor to various metals. This strategy represents a general technique that can be exploited with other catalytic organometallic reactions. Copyright
- Wu, Qiaoyin,Anslyn, Eric V.
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- Synthesis of 3-methylindole from glycerol cyclization with aniline over CuCr/Al2O3 catalysts modified by alkali earth oxides
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In the present work, CuCr catalysts supported on γ-Al 2O3 are prepared and modified with alkali earth elements by impregnation, characterized by N2 adsorption-desorption, XRD, H2-TPR (temperature-programmed reduction by H2), CO 2-TPD and NH3-TPD (temperature-programmed desorption of NH3 or CO2), and applied in the synthesis of 3-methylindole (3-MI) with a N-heterocycle from glycerol and aniline in the fixed-bed reactor. The results show that the introduction of alkali earth elements into the CuCr/Al2O3 catalyst can improve the yield of target 3-MI in the order of Mg 2O3 gives rise to a high 3-MI yield of 39.09% and 65.17% in N2 as a carrier gas and 20%H2-N2 mixture gas, respectively. According to catalysts characterization and catalytic tests, the reaction pathway of glycerol cyclization with aniline is proposed, the formation of 3-MI and 3H-indol-3-yl methanol is hypothesized to be through the aniline cyclization with 2,3-hydroxypropanal from glycerol dehydrogenation over Cu0 centers and basic sites. The acidic sites mainly play a role on activating aniline, which interacts with glycerol to form 3-MI or quinoline through cyclization and dehydration.
- Chen, Yu,Xu, Chenghua,Liu, Chuanqi,Li, Xue,Liu, Jianying,Cao, Yang,Yang, Jie
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- Ring-methylation of pyrrole and indole using supercritical methanol
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The ring-methylation of pyrrole or indole using supercritical methanol proceeded at 623 K without the further addition of catalysts. Pyrrole produced a mixture of unreacted pyrrole and mono-, di-, tri-, and tetra-methylpyrroles at the reaction time of 8 h. On the other hand, indole was selectively methylated at the C3 position to afford 3-methylindole in 79% yield at the reaction time of 5 h. The ring-methylation of indole using supercritical methanol was claimed to proceed via (1H-indol-3-yl)methanol. The conversion of indole to (1H-indol-3-yl)methanol would be achieved by the electrophilic aromatic substitution between the indol-1-ide (indole anion) and H2C +-OH. The (1H-indol-3-yl)methanol must be reduced to 3-methylindole in the presence of supercritical methanol.
- Kishida, Nobuhiro,Kamitanaka, Takashi,Fusayasu, Masafumi,Sunamura, Takashi,Matsuda, Tomoko,Osawa, Tsutomu,Harada, Tadao
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- A new efficient approach to 3-methylindole: Vapor-phase synthesis from aniline and glycerol over Cu-based catalyst
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A novel efficient method for vapor-phase synthesis of 3-methylindole from aniline and glycerol has been developed over Cu-based catalysts. The catalysts were characterized by BET, XRD, H2-TPR and NH3-TPD techniques. The results indicated that Cu/SiO2-Al2O 3 catalyst exhibited high activity. The yield of 3-methylindole could be up to 40% when the Cu loading was 5.41 wt% and the reaction temperature was 240 °C. Moreover, the catalyst could be reused without obvious loss of the yield even after reaction time of 46 h. Copper-based catalyst with good dispersion and large amount of weak acid sites was favorable for producing 3-methylindole. A possible reaction pathway for the catalytic synthesis of 3-methylindole was proposed.
- Sun, Wei,Liu, Dong-Yan,Zhu, Hai-Yan,Shi, Lei,Sun, Qi
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- Efficient synthesis of 3-methylindole using biomass-derived glycerol and aniline over ZnO and CeO2 modified Ag/SBA-15 catalysts
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An efficient mesoporous catalyst of Ag/SBA-15 modified with ZnO and CeO2 was successfully constructed with the purpose of efficiently synthesizing 3-methylindole by biomass-derived glycerol and aniline, which up to 62% yield and 75% selectivity for 3-methylindole were achieved when Ag loading was 1.00 mmol/g?1, ZnO or CeO2 content was 1.00 or 0.05 mmol/g?1, respectively. And only 3% yield decreased when the catalyst was circulated five times. The characterizations researches on N2 physical adsorption, Fourier transform infrared (FT-IR), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX), temperature programmed reduction of hydrogen (H2-TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed desorption (TPD) of NH3 and CO2, thermogravimetric and differential thermal analysis (TG-DTA) indicated that adding the promoter of ZnO to Ag/SBA-15 increased the dispersion of the silver particles significantly and controlled the aggregation of Ag nanoparticles during the reaction remarkably because doping ZnO greatly increased the polarity of the composite carrier SBA–15–ZnO and brought about the interaction between Ag and carrier enhanced. CeO2 could promote the reduction of Ag2O and suppress the formation of carbon deposition effectively. In addition, doping ZnO and CeO2 increased the number of the weak-acid centers of the SBA-15 supported Ag-based catalyst observably, thereby the catalyst of Ag/SBA-15-ZnO-–ZnO–CeO2 acquired a good selectivity. Moreover, the reaction pathway for 3-methylindole synthesis by biomass-derived glycerol and aniline was probed in depth and a reasonable route was proposed.
- Gao, Yining,Lin, Shuyi,Qu, Yi,Shi, Lei
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- Highly selective synthesis of 3-methylindole from glycerol and aniline over Cu/NaY modified by K2O
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The vapor-phase synthesis of 3-methylindole from glycerol and aniline over Cu/NaY modified by K2O was investigated. The catalysts were characterized by X-ray diffraction (XRD) and the temperature-programmed desorption of ammonia (NH3-TPD). The effect of the reaction temperature on the activity and selectivity of Cu/NaY-K2O catalyst was also investigated. The results indicated that the addition of K2O to Cu/NaY increased the selectivity of the catalyst remarkably because the amount of middle-strong acid sites decreased clearly. The decrease of the reaction temperature was beneficial for the increase of 3-methylindole selectivity. Over Cu/NaY-K2O, the selectivity of 3-methylindole reached 75% and the yield of the target product was up to 47% at 220 C. A probable catalytic mechanism for the synthesis of 3-methylindole from glycerol and aniline was proposed.
- Cui, Yan-Xi,Sun, Li-Dong,Sun, Qi,Shi, Lei
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- Biotransformation of Indole to 3-Methylindole by Lysinibacillus xylanilyticus Strain MA
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An indole-biotransforming strain MA was identified as Lysinibacillus xylanilyticus on the basis of the 16S rRNA gene sequencing. It transforms indole completely from the broth culture in the presence of an additional carbon source (i.e., sodium succinate). Gas-chromatography-mass spectrometry identified indole-3-acetamide, indole-3-acetic acid, and 3-methylindole as transformation products. Tryptophan-2-monooxygenase activity was detected in the crude extracts of indole-induced cells of strain MA, which confirms the formation of indole-3-acetamide from tryptophan in the degradation pathway of indole. On the basis of identified metabolites and enzyme assay, we have proposed a new transformation pathway for indole degradation. Indole was first transformed to indole-3-acetamide via tryptophan. Indole-3-acetamide was then transformed to indole-3-acetic acid that was decarboxylated to 3-methylindole. This is the first report of a 3-methylindole synthesis via the degradation pathway of indole.
- Arora, Pankaj Kumar,Dhar, Kartik,Veloz García, Rafael Alejandro,Sharma, Ashutosh
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- Interrupted Intramolecular Hydroaminomethylation of N-Protected-2-vinyl Anilines: Novel Access to 3-Substitued Indoles or Indoline-2-ols
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A new synthetic alternative to the synthesis of 3-methyl indoles and 3-methyl indoline-2-ols with an excellent atomic economy is presented in this study. It is demonstrated that the intramolecular interrupted hydroaminomethylation (HAM) reaction is a powerful tool for the formation of these compounds, which exhibit wide-ranging biological activity. Several N-Protected-2-vinyl anilines were synthesized and involved in the reaction producing the corresponding 3-methylindole or 3-methyl indoline-2-ol depending on the nature of the N-protecting groups.
- Daran, Jean-Claude,García-Ríos, Perla H.,Gouygou, Maryse,Hochberger-Roa, Frank,López-Cortés, José G.,Ortega-Alfaro, M. Carmen,Urrutigo?ty, Martine
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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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- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
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Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
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supporting information
p. 9029 - 9039
(2021/06/28)
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- Cu-Catalyzed Dimerization of Indole Derived Oxime Acetate for Synthesis of Biimidazo[1,2- a]indoles
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A copper-mediated cyclization and dimerization of indole derived oxime acetate was developed to generate a series of biimidazo[1,2-a]indole scaffolds with two contiguous stereogenic quaternary carbons in one step.
- Xie, Tao,Sui, Qi-Bang,Qin, Lu-Zhe,Wen, Xiaoan,Sun, Hongbin,Xu, Qing-Long,Zhen, Le
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supporting information
p. 5518 - 5529
(2021/05/04)
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- Ir(iii)-Catalysed electrooxidative intramolecular dehydrogenative C-H/N-H coupling for the synthesis of N-H indoles
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Herein, an iridium(iii)-catalysed electrooxidative intramolecular dehydrogenative C-H/N-H coupling of unprotected 2-alkenyl anilines is described. The developed method allows the synthesis of a variety of 3-substituted N-H indole scaffolds under undivided electrolytic conditions. Mechanistic studies suggest that the reaction proceeds through the electro-oxidation induced reductive elimination pathway.
- Chang, Sukbok,Kim, Dongwook,Kim, Youyoung
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supporting information
p. 12309 - 12312
(2021/12/07)
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- Nickel-catalyzed C3-alkylation of indoles with alcohols: Via a borrowing hydrogen strategy
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An efficient method for the Ni-catalyzed C3-alkylation of indoles using readily available alcohols as the alkylating reagents has been developed. The alkylation was addressed with an air and moisture-stable binuclear nickel complex ligated by tetrahydroquinolin-8-one as the effective pre-catalyst. The newly developed transformation could accommodate a broad substrate scope including primary/secondary benzylic and aliphatic alcohols and substituted indoles. Mechanistic studies suggested that the reaction proceeds through a borrowing hydrogen pathway.
- Hu, Miao,Jiang, Yong,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan,Jin, Liqun
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p. 10057 - 10062
(2021/06/15)
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- Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
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A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
- Shee, Sujan,Kundu, Sabuj
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p. 6943 - 6951
(2021/05/29)
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- A Highly Dispersed Copper Nanoparticles Catalyst with a Large Number of Weak Acid Centers for Efficiently Synthesizing the High Value-Added 3-Methylindole by Aniline and Biomass-Derived Glycerin
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Abstract: An excellent catalyst with a large number of weak acid centers and highly dispersed copper nanoparticles embedded in mesoporous SBA-15 carrier was successfully constructed for the purpose of efficient conversion of aniline with biomass-derived glycerin to the high value-added 3-methylindole, in which the catalyst of Cu/SBA-15 was modified with Al2O3, La2O3 and CoO in sequence. The modified carrier and the copper-based catalysts were studied by scanning electron microscopy and energy-dispersive X-ray (SEM–EDX) spectroscopy, nitrogen physical adsorption, ammonia temperature programmed desorption (NH3-TPD), hydrogen temperature programmed reduction (H2-TPR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric and differential thermal analysis (TG–DTA) and inductively coupled plasma (ICP) emission spectroscopy. The research found that the Cu/CoO/La2O3/Al2O3/SBA-15 catalyst exhibited a very good catalytic performance with 3-methylindole yield up to 73.3% and selectivity reaching 86.4%. Besides, only a 3.9% yield decreased after the catalyst was circulated seven times. The characterizations revealed that Al2O3 could enhance the polarity of the carrier, thereby the interaction between the active component and the composite carrier was strengthened and the dispersion of copper was increased significantly. Adding La2O3 to Cu/SBA-15-Al2O3 could weaken the acidity and inhibit the formation of carbon deposits. CoO promoter could increase the number of weak acid centers, which was conducive to a good dispersion of active component and the high selectivity of 3-methylindole. Furthermore, the reaction pathway of gas-phase synthesis of 3-methylindole from glycerin and aniline on Cu/CoO/La2O3/Al2O3/SBA-15 was explored. Graphic Abstract: [Figure not available: see fulltext.]
- Sun, Pinghui,Lin, Shuyi,Guo, Huimei,Su, Jianhui,Shi, Lei
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p. 463 - 477
(2020/07/16)
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- Palladium-Catalyzed Sequential C-H Activation/Amination with Diaziridinone: An Approach to Indoles
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Indoles are an important class of molecules. This paper describes an efficient palladium-catalyzed synthesis of indoles from 2-iodostyrenes and di-t-butyldiaziridinone with a simultaneous installation of two C-N bonds. The reaction process likely proceeds through the oxidative insertion of Pd to aryl iodide and subsequent vinyl C-H activation to from a pallada(II)cycle intermediate, which is bisaminated by di-t-butyldiaziridinone to give the indole product.
- Li, Jing,Chen, Jinhua,Wang, Luying,Shi, Yian
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supporting information
p. 3646 - 3651
(2021/05/10)
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- Hydrogenation or Dehydrogenation of N-Containing Heterocycles Catalyzed by a Single Manganese Complex
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A highly chemoselective base-metal catalyzed hydrogenation and acceptorless dehydrogenation of N-heterocycles is presented. A well-defined Mn complex operates at low catalyst loading (as low as 2 mol %) and under mild reaction conditions. The described catalytic system tolerates various functional groups, and the corresponding reduced heterocycles can be obtained in high yields. Experimental studies indicate a metal-ligand cooperative catalysis mechanism.
- Borghs, Jannik C.,Rueping, Magnus,Zubar, Viktoriia
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supporting information
(2020/05/19)
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- Visible-Light-Promoted Efficient Aerobic Dehydrogenation of N-Heterocycles by a Tiny Organic Semiconductor Under Ambient Conditions
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An efficient reusable catalytic system has been developed based on perylene diimide (PDI) organic semiconductor for the aerobic dehydrogenation of N-heterocycles with visible light. This practical catalytic system without any additives proceeds under ambient conditions. The minute aggregates of PDI molecules on the surface of SiO2 nanospheres form tiny organic semiconductors, resulting in high-efficiency photo-oxidative activity. Notably, the robustness of this method is demonstrated by the synthesis of a wide range of N-heteroarenes, gram-scale experiments as well as reusability tests.
- Su, Chenliang,Yu, Kunyi,Zhang, Hanjie,Zhu, Yongfa
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supporting information
p. 1956 - 1960
(2020/04/10)
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- Monoamine Oxidase (MAO-N) Biocatalyzed Synthesis of Indoles from Indolines Prepared via Photocatalytic Cyclization/Arylative Dearomatization
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The biocatalytic aromatization of indolines into indole derivatives exploiting monoamine oxidase (MAO-N) enzymes is presented. Indoline substrates were prepared via photocatalytic cyclization of arylaniline precursors or via arylative dearomatization of unsubstituted indoles and in turn chemoselectively aromatized by the MAO-N D11 whole cell biocatalyst. Computational docking studies of the indoline substrates in the MAO-N D11 catalytic site allowed for the rationalization of the biocatalytic mechanism and experimental results of the biotransformation. This methodology represents an efficient example of biocatalytic synthesis of indole derivatives and offers a facile approach to access these aromatic heterocycles under mild reaction conditions.
- Black, Gary W.,Brancale, Andrea,Castagnolo, Daniele,Colonna, Serena,Ferla, Salvatore,Masci, Domiziana,Turner, Nicholas J.,Varricchio, Carmine,Zhao, Fei
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p. 6414 - 6421
(2020/07/09)
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- Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes
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An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.
- Kawauchi, Daichi,Noda, Kenta,Komatsu, Yoshiyuki,Yoshida, Kei,Ueda, Hirofumi,Tokuyama, Hidetoshi
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supporting information
p. 15793 - 15798
(2020/10/12)
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- Recyclable Pd/C catalyzed one-step reduction of carbonyls to hydrocarbons under simple conditions without extra base
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The reductions of carbonyls for the synthesis of hydrocarbons were developed with hydrazine hydrate, hydrogen gas and ammonium formate respectively. The simple, mild and efficient conditions were provided by employing recyclable Pd/C as catalyst in normal solvents at 100 °C and the reactions proceeded smoothly to produce the corresponding products with good to excellent yields. And gram-scale reactions and recycling of the catalyst were also demonstrated. Furtherly, the mechanism has been proposed.
- Zhou, Xiao-Yu,Chen, Xia
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supporting information
(2019/12/06)
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- Synthesis of Pyrido[2,3-b]indole Derivatives via Rhodium-Catalyzed Cyclization of Indoles and 1-Sulfonyl-1,2,3-triazoles
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Acyloxy-substituted α,β-unsaturated imines generated in situ from triazoles can act as aza-[4 C] synthons and be trapped by indoles in a stepwise [4 + 2] cycloaddition reaction, thus providing rapid access to valuable pyrido[2,3-b]indoles in high yields. Attractive features of this reaction system include operational simplicity, readily available substrates, construction of sterically demanding quaternary centers, and convenient derivatization using triflate. (Figure presented.).
- An, Yuehui,Chen, Yidian,Duan, Shengguo,Li, Chuan-Ying,Xu, Ze-Feng,Xue, Bing,Zhang, Wan
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supporting information
(2020/04/22)
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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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p. 3794 - 3801
(2020/11/23)
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- Ruthenium Pincer Complex Catalyzed Selective Synthesis of C-3 Alkylated Indoles and Bisindolylmethanes Directly from Indoles and Alcohols
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Herein, we presented Ru-SNS complex that serves as a useful catalyst for C-3 alkylation of 1H-indoles with various aliphatic primary and secondary alcohols including cyclic alcohols as well as benzylic alcohols. The selective synthesis of bisindolylmethane derivatives is also achieved from the same set of indole and alcohol just by altering the reaction parameters. Furthermore, the sustainable synthesis of C-3 alkylated indoles directly from 2-(2-nitrophenyl)ethan-1-ol and alcohols catalysed by a Ru-complex via “borrowing hydrogen” strategy is reported. This protocol provides an atom-economical sustainable route to access structurally important compounds like arundine, vibrindole A and tryptamine based derivatives. (Figure presented.).
- Biswas, Nandita,Sharma, Rahul,Srimani, Dipankar
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supporting information
p. 2902 - 2910
(2020/06/03)
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- Reductive aromatization of oxindoles to 3-substituted indoles
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A practical and scalable approach for the synthesis of 3-substituted indoles is delineated via hydride nucleophilic addition to 3-substituted-2-oxindoles. The reaction proceeds through reductive aromatization involving indolinium ion intermediate. A wide range of 3-functionalized indoles have been synthesized. The method is employed for the synthesis of 3,3?-bis-indoles and a dimeric 3-indole derivative. Moreover, this protocol is used to obtain naturally occuring amino acid tryptamine.
- Mandal, Tirtha,Chakraborti, Gargi,Dash, Jyotirmayee
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supporting information
(2020/06/21)
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- Preparation method of alkyl aromatic compound based on alkenyl ether Friedel-Crafts reaction
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The invention discloses a preparation method of an alkyl aromatic compound based on an alkenyl ether Friedel-Crafts reaction, and belongs to the technical field of pharmaceutical and chemical intermediates and related chemistry. According to the method, alkenyl ether and an aromatic compound are used as raw materials, and green and efficient synthesis of the alkyl-substituted aromatic compound isrealized under the catalytic action of Lewis acid or protonic acid. The method has the advantages of high selectivity, mild reaction conditions, good functional group compatibility, the wide substraterange, environmental friendliness and the like. The alkyl-substituted aromatic compound is an important organic synthesis intermediate and has very wide application in the fields of organic synthesisand pharmacy, so that the alkyl-substituted aromatic compound has relatively high application value and social and economic benefits.
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Paragraph 0055-0056; 0058
(2020/07/24)
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- Electron Transfer Photoredox Catalysis: Development of a Photoactivated Reductive Desulfonylation of an Aza-Heteroaromatic Ring
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Herein, we report a protocol for desulfonylation of aza-heteroaromatic rings via photoinduced electron transfer and hydrogen atom transfer. This general protocol has a wide substrate range and moderate to good yields. The utility of the method was demonstrated by the chemoselective desulfonylation of a molecule containing both an aliphatic and an aromatic sulfonamide. (Figure presented.).
- Qiang-Liu,Liu, Yu-Xiu,Song, Hong-Jian,Wang, Qing-Min
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supporting information
p. 3110 - 3115
(2020/07/04)
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- A NaH-promoted N-detosylation reaction of diverse p-toluenesulfonamides
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A NaH-mediated detosylation reaction of various Ts-protected indoles, azaheterocycles, anilines and dibenzylamine was reported. The method features cheap reagent, convenient operations, mild reaction conditions and broad substrate scope. Moreover, this study revealed that the loading of NaH in tosylation reactions of nitrogen-containing compounds with NaH as a base in DMA or DMF should be controlled due to the possibility of adverse detosylation.
- Sun, Wanwan,Chen, Xiaobei,Hu, Ying,Geng, Huihui,Jiang, Yuanrui,Zhou, Yuxin,Zhu, Wenjing,Hu, Min,Hu, Haohua,Wang, Xingyi,Wang, Xinli,Zhang, Shilei,Hu, Yanwei
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supporting information
(2020/10/05)
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- Decyanation method of nitrile organic compound
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The invention provides a decyanation method of a nitrile organic compound. The nitrile organic compound shown in a general formula (1), a sodium reagent, crown ether and a proton donor are subjected to decyanation reaction in an organic solvent I to generate an organic compound shown in a general formula (2). According to the method, a Na/15-crown-5/H2O system is adopted, so that nitrile organic matters can be converted into a decyanation product, and the generation of amine byproducts is inhibited. The new method does not need to use liquid ammonia as a solvent, and is safer and more convenient to operate. The required sodium dispersoid is low in price; and the 15-crown-5 can be recycled and repeatedly used. The method has the advantages of good chemical selectivity, wide substrate application range, good functional group compatibility and the like.
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Paragraph 0079-0082
(2020/02/10)
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- Preparation method of indole compound
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The invention discloses a preparation method of a novel efficient indole compound, which comprises the following steps: by using o-nitroalkylbenzene containing various substituents as a raw material,controlling the reaction temperature to be 70-160 DEG C in an organic solution under the protection of inert gas and the participation of inorganic base, thereby obtaining the indole compound; preparing the novel indole compound containing various substituent groups through a hydrocarbon activation reaction catalyzed by a metal rhodium catalyst. The synthetic method is not reported in literature,the raw materials are easy to synthesize, no reducing agent needs to be added additionally, the method is simple in step, the indole compound containing various substituent groups does not need to beconstructed in one step through a nitroso intermediate, and the yield is high; The method is simple in unit operation, low in equipment requirement and suitable for rapidly synthesizing the indole compounds containing various substituent groups.
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Paragraph 0074-0075
(2020/12/29)
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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
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supporting information
p. 3958 - 3964
(2019/08/01)
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- On/Off O2 Switchable Photocatalytic Oxidative and Protodecarboxylation of Carboxylic Acids
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Photoredox catalysis in recent years has manifested a powerful branch of science in organic synthesis. Although merging photoredox and metal catalysts has been a widely used method, switchable heterogeneous photoredox catalysis has rarely been considered. Herein, we open a new window to use a switchable heterogeneous photoredox catalyst which could be turned on/off by changing a simple stimulus (O2) for two opponent reactions, namely, oxidative and protodecarboxylation. Using this strategy, we demonstrate that Au@ZnO core-shell nanoparticles could be used as a switchable photocatalyst which has good catalytic activity to absorb visible light due to the localized surface plasmon resonance effect of gold, can decarboxylate a wide range of aromatic and aliphatic carboxylic acids, have multiple reusability, and are a reasonable candidate for synthesizing both aldehydes/ketones and alkane/arenes in a large-scale set up. Some biologically active molecules are also shown via examples of the direct oxidative and protodecarboxylation which widely provided pharmaceutical agents.
- Bazyar, Zahra,Hosseini-Sarvari, Mona
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p. 13503 - 13515
(2019/10/11)
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- Method for preparing 3-alkyl indole derivative
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The invention relates to a novel method for one-step reduction synthesis a 3-alkyl indole derivative using an indole-3-substituted aldehyde (or ketone) derivative as a raw material in a solvent underthe alkaline condition. The indole-3-substituted aldehyde (or ketone) derivative is used as the raw material, the solvent, alkali and hydrazine hydrate are added, reflux reaction is carried out underordinary pressure, water and by-products are removed by distillation, heat preservation reaction is carried out, and reduced pressure distillation is carried out to remove the solvent to obtain a product. The preparation method is easy to get, has high product yield and good quality, further has the characteristics of simple operation, safety and reliability, low cost, friendly environment and thelike, and has a great industrialization prospect.
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Paragraph 0024-0027
(2019/05/08)
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- N-Alkylation-Initiated Redox-Neutral [5 + 2] Annulation of 3-Alkylindoles with o-Aminobenzaldehydes: Access to Indole-1,2-Fused 1,4-Benzodiazepines
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Described herein is an unprecedented N-Alkylation-initiated redox-neutral [5 + 2] annulation of 3-Alkylindoles with o-Aminobenzaldehydes via a cascade N-Alkylation/dehydration/[1,5]-hydride transfer/Friedel-Crafts alkylation sequence. A series of indole-1,2-fused 1,4-benzodiazepines are facilely constructed in moderate to good yields in one step. This protocol features excellent regioselectivity, metal-free conditions, high step economy, and wide substrate scope.
- Wang, Shuai,Shen, Yao-Bin,Li, Long-Fei,Qiu, Bin,Yu, Liping,Liu, Qing,Xiao, Jian
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supporting information
p. 8904 - 8908
(2019/11/19)
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- Iron-Promoted Construction of Indoles via Intramolecular Oxidative C-N Coupling of 2-Alkenylanilines Using Persulfate
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Indole scaffold synthesis relies primarily on oxidative C-H amination of N-protected alkenylanilines for C-N intramolecular cyclization reactions. Herein, for the first time, without N-protection, various readily prepared 2-alkenylanilines were transformed into the desired indole products in good yields by using K 2 S 2 O 8 as oxidant in the presence of catalytic amounts of FeF 2. The K 2 S 2 O 8 /FeF 2 system offers a direct and benign synthetic route to 3-arylindoles and it is applicable to a wide range of substituted indoles including drug intermediates.
- Li, Yudong,Li, Yuehui,Luo, Shuping,Wang, Menglan,Wu, Qing-An
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p. 3085 - 3090
(2019/08/07)
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- Formal Deoxygenative Hydrogenation of Lactams Using PNHP-Pincer Ruthenium Complexes under Nonacidic Conditions
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A formal deoxygenative hydrogenation of amides to amines with RuCl2(NHC)(PNHP) (NHC = 1,3-dimethylimizadol-2-ylidene, PNHP = bis(2-diphenylphosphinoethyl)amine) is described. Various secondary amides, especially NH-lactams, are reduced with H2 (3.0-5.0 MPa) to amines at a temperature range of 120-150 °C with 1.0-2.0 mol % of PNHP-Ru catalysts in the presence of Cs2CO3. This process consists of (1) deaminative hydrogenation of secondary amides to generate primary amines and alcohols, (2) dehydrogenative coupling of the transient amines with alcohols to generate imines, and (3) hydrogenation of imines to give the formally deoxygenated secondary amine products.
- Ogata, Osamu,Nara, Hideki,Matsumura, Kazuhiko,Kayaki, Yoshihito
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supporting information
p. 9954 - 9959
(2019/12/24)
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- Decarboxylation method for heterocyclic carboxylic acid compounds
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The invention relates to a decarboxylation method for heterocyclic carboxylic acid compounds. The method comprises the following steps: dissolving the heterocyclic carboxylic acid compounds in an aprotic polar solvent N,N-dimethylformamide, and performing decarboxylation at 85-150 DEG C with an organic acid as a catalyst. The method in the invention allows the yield of decarboxylation products obtained after a reaction to be higher than the yield of the products obtained through decarboxylation methods in the prior art, and does not need an expensive metal catalyst; and the solvent (DMF) in the present invention is more stable than DMSO, is not prone to decompose at a high temperature, and it can be recycled, so the cost is reduced. The method has the advantages of simple operation process, zero pollution, greenness, environmental protection and excellent application prospect.
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Paragraph 0030; 0031; 0041-0049
(2019/05/11)
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- Reductive Cleavage of Unactivated Carbon-Cyano Bonds under Ammonia-Free Birch Conditions
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A general protocol for the reductive cleavage of unactivated carbon-cyano bonds in aliphatic nitriles has been achieved under single-electron-transfer conditions using Na/15-crown-5/H2O. Electron is supplied by the electride derived from bench-stable sodium dispersions and recoverable 15-crown-5. H2O provides the proton source and suppresses the reduction of aromatic moieties. Compared with the Na/NH3 electride system generated under traditional Birch conditions, this ammonia-free electride system is more practical and features better reactivity and chemoselectivity for the decyanations of a broad range of aliphatic nitriles.
- An, Jie,Ding, Yuxuan,Luo, Shihui,Ma, Lifu
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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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- 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
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supporting information
p. 2065 - 2069
(2018/01/27)
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- Electrochemical Acceptorless Dehydrogenation of N-Heterocycles Utilizing TEMPO as Organo-Electrocatalyst
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Catalytic acceptorless dehydrogenation (CAD) has been a basically important organic transformation to ubiquitous unsaturated compounds without the usage of a sacrificial hydrogen acceptor. In this work, we successfully developed the first electrochemical acceptorless dehydrogenation (ECAD) of N-heterocycles using TEMPO as the organo-electrocatalyst. We have achieved the catalytic dehydrogenation of N-heterocycles in an anode and the release of H2 in a cathode using an undivided-cell system. A variety of six-membered and five-membered nitrogen-heteroarenes can be synthesized in good yields in this system. In addition, this protocol can also be used in the application of important molecular synthesis. Our electrochemical strategy provides a mild and metal-free route for (hetero)aromatic compounds synthesis via the CAD strategy.
- Wu, Yong,Yi, Hong,Lei, Aiwen
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p. 1192 - 1196
(2018/02/14)
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- Fluorine as a Traceless Directing Group for the Regiodivergent Synthesis of Indoles and Tryptophans
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Despite ample evidence for the unique reactivity offered by hypervalent F-iodanes, mechanistic investigations fall far behind. In order to shed light on the unusual behavior of such F-reagents, we conducted computational and experimental studies on the chemodivergent transformation of styrenes. We identified the spirocyclic F-cyclopropane as the common intermediate for both the C,H-fluorination and C,H-amination pathways. The fate of this key compound is determined by the extent of cationic charge delocalization controlled by the N-substituents. Exploiting this phenomenon, a multitude of different transformations have become available, leading, i.e., to the regiodivergent synthesis of indoles and tryptophans.
- Andries-Ulmer, Anna,Brunner, Christoph,Rehbein, Julia,Gulder, Tanja
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supporting information
p. 13034 - 13041
(2018/09/27)
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- C -Methylation of Alcohols, Ketones, and Indoles with Methanol Using Heterogeneous Platinum Catalysts
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A versatile, selective, and recyclable heterogeneous catalytic method for the methylation of C-H bonds in alcohols, ketones, and indoles with methanol under oxidant-free conditions using a Pt-loaded carbon (Pt/C) catalyst in the presence of NaOH is reported. This catalytic system is effective for various methylation reactions: (1) the β-methylation of primary alcohols, including aryl, aliphatic, and heterocyclic alcohols, (2) the α-methylation of ketones, and (3) the selective C3-methylation of indoles. The reactions are driven by a borrowing-hydrogen mechanism. The reaction begins with the dehydrogenation of the alcohol(s) to afford aldehydes, which subsequently undergo a condensation reaction with the nucleophile (aldehyde, ketone, or indole), followed by hydrogenation of the condensation product by Pt-H species to yield the desired product. In all of the methylation reactions explored in this study, the Pt/C catalyst exhibits a significantly higher turnover number than other previously reported homogeneous catalytic systems. Moreover, it is demonstrated that the high catalytic activity of Pt can be rationalized in terms of the adsorption energy of hydrogen on the metal surface, as revealed by density functional theory calculations on different metal surfaces.
- Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Jamil, Md. A. R.,Toyao, Takashi,Shimizu, Ken-Ichi
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p. 3091 - 3103
(2018/04/14)
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- Iron-Catalyzed Methylation Using the Borrowing Hydrogen Approach
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A general iron-catalyzed methylation has been developed using methanol as a C1 building block. This borrowing hydrogen approach employs a Kn?lker-type (cyclopentadienone)iron carbonyl complex as catalyst (2 mol %) and exhibits a broad reaction scope. A variety of ketones, indoles, oxindoles, amines, and sulfonamides undergo mono- or dimethylation in excellent isolated yields (>60 examples, 79% average yield).
- Polidano, Kurt,Allen, Benjamin D. W.,Williams, Jonathan M. J.,Morrill, Louis C.
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p. 6440 - 6445
(2018/07/25)
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- Bifunctional Iron Complexes Catalyzed Alkylation of Indoles
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Cyclopentadienone iron carbonyl complexes have been applied in alkylation of indoles with various benzylic alcohols, aliphatic alcohols (butanol, ethanol, methanol and 2-methylpentanol) via the hydrogen autotransfer strategy in mild reaction conditions. Experimental works highlight the role of the bifunctional iron complexes and the base. These iron complexes demonstrated a broad applicability in mild conditions and extended the scope of substrates in iron catalyzed C?C bond formation. (Figure presented.).
- Seck, Charlotte,Mbaye, Mbaye Diagne,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
p. 4640 - 4645
(2018/10/31)
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- Biphilic Organophosphorus-Catalyzed Intramolecular Csp2-H Amination: Evidence for a Nitrenoid in Catalytic Cadogan Cyclizations
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A small-ring phosphacycloalkane (1,2,2,3,4,4-hexamethylphosphetane, 3) catalyzes intramolecular C-N bond forming heterocyclization of o-nitrobiaryl and -styrenyl derivatives in the presence of a hydrosilane terminal reductant. The method provides scalable access to diverse carbazole and indole compounds under operationally trivial homogeneous organocatalytic conditions, as demonstrated by 17 examples conducted on 1 g scale. In situ NMR reaction monitoring studies support a mechanism involving catalytic PIII/PV=O cycling, where tricoordinate phosphorus compound 3 represents the catalytic resting state. For the catalytic conversion of o-nitrobiphenyl to carbazole, the kinetic reaction order was determined for phosphetane catalyst 3 (first order), substrate (first order), and phenylsilane (zeroth order). For differentially 5-substituted 2-nitrobiphenyls, the transformation is accelerated by electron-withdrawing substituents (Hammett factor ? = +1.5), consistent with the accrual of negative charge on the nitro substrate in the rate-determining step. DFT modeling of the turnover-limiting deoxygenation event implicates a rate-determining (3 + 1) cheletropic addition between the phosphetane catalyst 3 and 2-nitrobiphenyl substrate to form an unobserved pentacoordinate spiro-bicyclic dioxazaphosphetane, which decomposes via (2 + 2) cycloreversion giving 1 equiv of phosphetane P-oxide 3·[O] and 2-nitrosobiphenyl. Experimental and computational investigations into the C-N bond forming event suggest the involvement of an oxazaphosphirane (2 + 1) adduct between 3 and 2-nitrosobiphenyl, which evolves through loss of phosphetane P-oxide 3·[O] to give the observed carbazole product via C-H insertion in a nitrene-like fashion.
- Nykaza, Trevor V.,Ramirez, Antonio,Harrison, Tyler S.,Luzung, Michael R.,Radosevich, Alexander T.
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supporting information
p. 3103 - 3113
(2018/03/08)
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- Method and device for preparing 3-methylindole from aniline with one-step method
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The invention relates to a process for catalytically synthesizing 3-methylindole from aniline and 1,2-propylene glycol as raw materials with a one-step method. According to the process, an Ag based heterogeneous catalyst is subjected to a flowing type gas-solid phase catalytic reaction in a fixed bed reactor; aniline and 1,2-propylene glycol are proportionally mixed and continuously fed to enter the fixed bed reactor, a mixture is subjected to a heterogeneous catalytic reaction on a solid catalyst bed layer under the atmosphere of water vapor and hydrogen, and 3-methylindole is synthesized with the one-step method. The catalyzing process has the advantages of higher activity, selectivity and stability and has the characteristics of adopting a simple technology, realizing continuous operation, being low in cost and environment-friendly and the like.
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Paragraph 0012; 0013; 0014; 0015; 0016; 0017; 0018-0030
(2017/04/29)
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- An Efficient and Selective Nickel-Catalyzed Direct N-Alkylation of Anilines with Alcohols
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Herein, we developed an efficient and selective nickel-catalyzed monoalkylation of various primary alcohols with aryl and heteroaryl amines together with diols and amino alcohol derivatives. Notably, the catalytic protocol consisting of an earth-abundant and non-precious NiBr2/L1 system enables the transformations in the presence of hydroxyl, alkene, nitrile, and nitro functionalities. As a highlight, we have demonstrated the alkylation of diamine, intramolecular cyclization to N-heterocycles, and functionalization of complex vitamin E, an (±)-α-tocopherol derivative. Preliminary mechanistic studies revealed the participation of a benzylic C-H bond in the rate-determining step.
- Vellakkaran, Mari,Singh, Khushboo,Banerjee, Debasis
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p. 8152 - 8158
(2017/12/08)
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- Acceptorless Dehydrogenation of N-Heterocycles by Merging Visible-Light Photoredox Catalysis and Cobalt Catalysis
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Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N-heterocycles, by merging visible-light photoredox catalysis and cobalt catalysis at ambient temperature, is described. The potential applications to organic transformations and hydrogen-storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.
- He, Ke-Han,Tan, Fang-Fang,Zhou, Chao-Zheng,Zhou, Gui-Jiang,Yang, Xiao-Long,Li, Yang
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supporting information
p. 3080 - 3084
(2017/03/14)
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- Electron-Transfer and Hydride-Transfer Pathways in the Stoltz–Grubbs Reducing System (KOtBu/Et3SiH)
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Recent studies by Stoltz, Grubbs et al. have shown that triethylsilane and potassium tert-butoxide react to form a highly attractive and versatile system that shows (reversible) silylation of arenes and heteroarenes as well as reductive cleavage of C?O bonds in aryl ethers and C?S bonds in aryl thioethers. Their extensive mechanistic studies indicate a complex network of reactions with a number of possible intermediates and mechanisms, but their reactions likely feature silyl radicals undergoing addition reactions and SH2 reactions. This paper focuses on the same system, but through computational and experimental studies, reports complementary facets of its chemistry based on a) single-electron transfer (SET), and b) hydride delivery reactions to arenes.
- Smith, Andrew J.,Young, Allan,Rohrbach, Simon,O'Connor, Erin F.,Allison, Mark,Wang, Hong-Shuang,Poole, Darren L.,Tuttle, Tell,Murphy, John A.
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supporting information
p. 13747 - 13751
(2017/10/12)
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- Heterogeneous catalytic synthesis of quinoline compounds from aniline and C1-C4 alcohols over zeolite-based catalysts
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The synthesis of quinolines from aniline and a C1-C4 alcohol was conducted under gas-phase reaction conditions over a series of zeolite-based catalysts. The texture and acid properties of catalysts were characterized by XRD, FT-IR, BET and NH3-TPD techniques. It was found that the total yield of quinolines was positively related to the relative content of Lewis acid sites of the catalyst. Among others, the ZnCl2/Ni-USY-acid catalyst possessed the best performance. Over this catalyst, the reactions of aniline and most of the alcohols provided a 42.3-79.7% total yield of quinolones under mild conditions, however, those of aniline and methanol, ethanol and iso-propanol predominantly led to N-alkylanilines. Furthermore, the reaction pathways for synthesizing quinolines via aniline reacting with polyhydric alcohols or monohydric alcohols was proposed in our work.
- Huang, Chen,Li, An,Chao, Zi-Sheng
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p. 48275 - 48285
(2017/10/31)
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- Indole synthesis by palladium-catalyzed tandem allylic isomerization-furan Diels-Alder reaction
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A Pd(0)-catalyzed elimination of an allylic acetate generates a π-allyl complex that is postulated to initiate a novel intramolecular Diels-Alder cycloaddition to a tethered furan (IMDAF). Under the reaction conditions, this convergent, microwave-accelerated cascade process provides substituted indoles in moderate to good yields after Pd-hydride elimination, aromatization by dehydration, and in situ N-Boc cleavage.
- Xu, Jie,Wipf, Peter
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supporting information
p. 7093 - 7096
(2017/09/07)
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- Iron-Catalyzed Intramolecular Aminations of C(sp3)?H Bonds in Alkylaryl Azides
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The nucleophilic iron complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the direct intramolecular amination of unactivated C(sp3)?H bonds in alkylaryl azides, which results in the formation of substituted indoline and tetrahydroquinoline derivatives.
- Alt, Isabel T.,Guttroff, Claudia,Plietker, Bernd
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supporting information
p. 10582 - 10586
(2017/08/22)
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- Continuous niobium phosphate catalysed Skraup reaction for quinoline synthesis from solketal
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Solketal is derived from the reaction of acetone with glycerol, a by-product of the biodiesel industry. We report here the continuous reaction of solketal with anilines over a solid acid niobium phosphate (NbP), for the continuous generation of quinolines in the well-established Skraup reaction. This study shows that NbP can catalyse all the stages of this multistep reaction at 250 °C and 10 MPa pressure, with a selectivity for quinoline of up to 60%. We found that the catalyst eventually deactivates, most probably via a combination of coking and reduction processes but nevertheless we show the promise of this approach. We demonstrate here the application of our approach to synthesize both mono- and bis-quinolines from the commodity chemical, 4,4′-methylenedianiline.
- Jin, Jing,Guidi, Sandro,Abada, Zahra,Amara, Zacharias,Selva, Maurizio,George, Michael W.,Poliakoff, Martyn
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supporting information
p. 2439 - 2447
(2017/07/17)
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- Copper-mediated intramolecular aza-Wacker-type cyclization of 2-alkenylanilines toward 3-aryl indoles
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A copper-mediated intramolecular aza-Wacker-type cyclization was developed for the direct and efficient synthesis of 3-aryl indoles using 2-alkenylanilines in moderate to good yields with good functional group compatibility. This strategy shows the high efficiency, operational simplicity as well as broad substrate scope.
- Yang, Rui,Yu, Jin-Tao,Sun, Song,Zheng, Qingheng,Cheng, Jiang
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p. 445 - 448
(2017/01/11)
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- Methylation of C(sp3)-H/C(sp2)-H bonds with methanol catalyzed by cobalt system
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A highly efficient Co-based catalytic system, composed of a commercially available Co salt, a tetradentate phosphine ligand P-(CH2CH2PPh2)3(PP3), and a base (denoted as [Co]/PP3/base), is developed for the methylation of C(sp3)-H and C(sp2)-H bonds using methanol as a methylating reagent. The Co(BF4)2.6H2O/PP3/K2CO3 catalytic system showed high catalytic activity for the methylation of C-H bonds in aryl alkyl ketones, aryl acetonitriles, and indoles, with wide substrate scope and good functional group tolerance, and methylsubstituted products were obtained in good to excellent yields at 100 °C. This cheap, readily available, and highly efficient Co-based catalytic system may have promising applications in methylation reaction using methanol.
- Liu, Zhenghui,Yang, Zhenzhen,Yu, Xiaoxiao,Zhang, Hongye,Yu, Bo,Zhao, Yanfei,Liu, Zhimin
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supporting information
p. 5228 - 5231
(2017/11/06)
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