- Synthesis and reactions of 2-bis(methylthio)methylene-1-methyl-3- oxoindole: A facile access to benzo- and heterocyclo- fused carbazoles and indoles
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The synthesis and reactions of 2-bis(methylthio)methylene-1-methyl-3- oxoindole 5 as a novel 3-carbon 1,3-bielectrophilic component are described. Thus cycloaromatization of 5 with allyl, methallyl and crotyl Grignard reagents affords substituted carbazoles 12a-c in good yields. Cycloaromatization of 5 with various anions derived from aryl/heteroaryl acetonitriles and antipyrine gives novel benzo[c]- (16), naphtho[1,2-c]- (19), indolo[3,2-a]- (21), thieno[2,3-c]- (23), pyrrolo[2,3c]- (25) and pyrazolo[4,3-b]- (29) carbazole ring systems in good yields. Similarly heterocyclo[b]fused indoles like pyrido[3,4-b]- (36), pyrido[3,2-b]- (39) indoles and indolo[3,2-b]quinolizinium salt 42 were synthesized by cyclization of 5 with lithioacetonitrile, lithioaminocrotonitrile, and 2- picolyl lithium respectively via our heteroaromatic annelation protocol.
- Basaveswara Rao,Syam Kumar,Ila,Junjappa
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- Synthesis and biological evaluation of novel carbazolyl glyoxamides as anticancer and antibacterial agents
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A new library of 24 carbazolyl glyoxamides 14a-x were designed and synthesized from glyoxalic acids and arylamines in the presence of HATU as a coupling reagent under MW irradiation. The synthesized carbazolyl glyoxamides were evaluated for their in vitro anticancer and antibacterial activities. Of the synthesized carbazolyl glyoxamides, compounds 14l and 14q exhibited the most potent cytotoxicity towards a breast cancer cell line with IC50 values of 9.3 and 9.8 μM, respectively. Further, caspase-3 assay for carbazolyl glyoxamides indicated that these compounds induced apoptotic cell death in Jurkat cells. Furthermore, some of the synthesized carbazolyl glyoxamides 14g, 14k, 14l and 14n exhibited comparable or even better antibacterial activity (MIC = 8-16 μg mL-1) than chloramphenicol against the selected bacterial strains.
- Venkataramana Reddy,Tantak, Mukund P.,Valdez, Reyna,Singh, Rajnish Prakash,Singh, Okram Mukherjee,Sadana, Rachna,Kumar, Dalip
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- Synthesis of polyconjugated carbazolyl-oxazolones by a tandem hydrozirconation-Erlenmeyer reaction. Study of their hyperpolarizability values
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New push-pull systems with carbazole as donor moiety and oxazolone as electron withdrawing group have been synthesized by an AgClO4-catalyzed hydrozirconation and ulterior Erlenmeyer reaction. Studies carried out with the semiempirical quantum method PM3 (MOPAC93) pointed a low dependence of the hyperpolarizability value on the number of double bonds at the conjugated bridge by β(0)∝n0.8. Introduction of rigidity in the polyene chain or additional donor groups in the carbazole moiety pointed to exertion of a large effect on hyperpolarizability values that could avoid unnecessary efforts in costly path elongation synthesis.
- Díaz, José Luis,Villacampa, Belén,López-Calahorra, Francisco,Velasco, Dolores
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- Enhanced photochemical [6π] electrocyclization within the lipophilic protein binding site
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Photocyclization of N-methyldiphenylamine to N-methylcarbazole is achieved within the microenvironment provided by site I of serum albumins. Quantum yield determinations, combined with transient absorption spectroscopic detection of the dihydrocarbazole intermediate, demonstrate that protein encapsulation provides a subtle control of the kinetic parameters, leading to optimized efficiencies.
- Marin, Mireia,Lhiaubet-Vallet, Virginie,Miranda, Miguel A.
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- Design, synthesis, and evaluations of the antiproliferative activity and aqueous solubility of novel carbazole sulfonamide derivatives as antitumor agents
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Optimization of IG-105 (1) on the carbazole ring provided five series of new carbazole sulfonamides derivatives, 7a–e, 8a–g, 9a–g, 10a–e, and 11a–g. All of the compounds were evaluated against HepG2, MCF-7, MIA PaCa-2, and Bel-7402 cells for antiproliferative activity. Each series of compounds was 2–5 times more active against HepG2 cells (IC50: 1.00–10.0 μM) than the other three tumor cell lines. Several representative compounds, selected from each series, showed aqueous solubility (13.4–176.5 μg/mL at pH 7.4 and 2.0) better than 1, with the aqueous solubility of corresponding salts > 30 mg/mL. From the results of evaluating the effects of the compounds 7b, 8c, 9c, 10c and 11c on tubulin in vitro, we speculated that their targets were different from those of 1 and CA-4P. We tested the antitumor activity of the representative compound 7b·HCl (10 mg/kg) in an in vivo study and found that its tumor growth inhibition rate was 41.1%. The tumor growth inhibition rate of 7b·HCl (20 mg/kg) was 54.6%, whereas the tumor growth inhibition rate of CA-4P (50 mg/kg) was 48.3%. And in another batch of in vivo antitumor activity testing, 9c·HCl and 11c·HCl at doses of 10 mg/kg resulted in 61.1% and 50.0% inhibition, respectively. These promising results warrant further development of the derivatives, which may use a novel mechanism and show potential potency as antitumor drug candidates.
- Sun, Lianqi,Wang, Chenxi,Hu, Xinyue,Wu, Yanbin,Jiang, Zhi,Li, Zhuorong,Chen, Xiaofang,Hu, Laixing
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- 9,10-Bis(N-methylcarbazol-3-yl-vinyl-2)anthracene: High contrast piezofluoro-chromism and remarkably doping-improved electroluminescence performance
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This paper reported the synthesis, optical and electroluminescent properties of 9,10-bis(N-methylcarbazol-3-yl-vinyl-2)anthracene (MCA). MCA could be facilely prepared by the Wittig-Horner reaction of N-methyl-3-formylcarbazole and 9,10-bis(diethoxyphosphorylmethyl)anthracene and exhibited strong aggregation-induced and crystallization-enhanced emission (AIE/CEE) effect. Simple mechanical force could change MCA solid from initial green to final red emission, affording high contrast piezofluorochromism with large spectral shift of up to 90 nm. When MCA was used as the emissive material in light-emitting diodes, the doped devices showed remarkably improved electroluminescence (EL) performance whose EL efficiency was 8 times higher than that of the non-doped device. Moreover, the dopant concentrations did not affect significantly the fluorescence properties of doped films and EL performances of doped devices, demonstrating the potential advantage of AIE/CEE luminogens applicable for EL dopants.
- Liu, Wei,Ying, Shian,Sun, Qikun,Qiu, Xu,Zhang, Haichang,Xue, Shanfeng,Yang, Wenjun
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- Synthesis of Novel 3-N-substituted Carbazole Derivatives and Evaluation of their Abilities to Inhibit Platelet Aggregation
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The carbazole moiety exhibits various biological activities, including anticancer, antiviral, anti-inflammatory, and antimicrobial activities; some compounds containing the moiety also inhibit platelet aggregation. In the present study, we synthesized a series of 3-N-substituted carbazole derivatives and evaluated their abilities to inhibit in vitro platelet aggregation induced by collagen (5 μg/mL). Of the synthesized compounds, compound 5q (JSCa15), with a urea linkage within the carbazole framework, exhibited the strongest inhibitory activity (98.25% at 30 μM). Interestingly, reduction of the nitro group of compound 5q to an amine exhibited significantly decreased activity (compound 5r, 5.18% at 30 μM). Also, substitution of the urea moiety of compound 5q with a carbamate moiety resulted in a considerable loss of activity (compound 8a, 5.91% at 30 μM). These results suggest that the urea moieties and nitro groups of 3-N-substituted carbazole derivatives may play key roles in inhibiting in vitro platelet aggregation induced by collagen.
- Kim, Jiseon,Jung, Sang-Hyuk,Yun, Eunju,Cho, Soo-Hyun,Yuseok,Kim, Ji-Eun,Kim, Young-Ho,Myung, Chang-Seon,Song, Gyu-Yong
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- Novel 3-substituted N-methylcarbazole–imidazolium salt derivatives: Synthesis and cytotoxic activity
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A series of novel 3-substituted N-methylcarbazole–imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of tumor cell lines (Hep G-2, Hela and PC12). The results suggest that the presence of substituted 2-methyl-imidazole or imidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 4-bromophenacyl group were important for improving cytotoxic activity. Compounds 17, 18, 27, and 28 with 4-bromophenacyl and naphthylacyl groups displayed good activities with IC50 values of 0.09–7.20?μm against three tumor cell lines investigated and more active than DDP. Compound 35 exhibited cytotoxic activity selectively against Hela cell.
- Li, Yan-Hua,Zhou, Bei,Shi, Yi-Min,Xun, Yu-Peng,Yang, Yun-Han,Yang, Li-Juan
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- Versatile synthesis of polyfunctionalized carbazoles from (3-iodoindol-2-yl)butynols via a gold-catalyzed intramolecular iodine-transfer reaction
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The controlled gold-catalyzed preparation of 3-iodo 2,4,6-trisubstituted 9H-carbazoles has been developed by starting from (3-iodoindol-2-yl)butynols. These results could be explained through an initial 6-endo-dig alkyne carbocyclization by chemo- and regiospecific attack of the C3-indole position at the external alkyne carbon followed by a stepwise 1,3-iodine transfer and dehydration. This reaction outcome for the gold-catalyzed transformation of (3-iodoindol-2-yl)alkynols sharply contrasts with that observed for conventional metal-catalyzed processes of iodoarenes, because iodine transfer is feasible. This selective reaction has been studied experimentally; additionally, its mechanism has been investigated by means of density functional theory calculations.
- Alcaide, Benito,Almendros, Pedro,Alonso, José M.,Busto, Eduardo,Fernández, Israel,Ruiz, M. Pilar,Xiaokaiti, Gulinigaer
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- PHOTOCHEMICAL REACTION OF CARBAZOLE AND SOME DERIVATIVES IN DICHLOROMETHANE
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By irradiation of carbazole and some derivatives in CH2Cl2 soln two different reaction pathways were observed depending on the substitution of the heterocyclic compound.
- Balsells, R. Erra,Frasca, A. R.
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- Aromatic and heteroaromatic annelation studies on 3-[bis(methylthio)methylene]-1-methyloxindole: Synthesis of carbazoles and an efficient route to pyrido[2,3-b]indoles
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The 3-[bis(methylthio)methylene]-1-methyloxindole (2) is shown to undergo cycloaromatization with allyl and methallyl magnesium chlorides to afford substituted carbazoles. A novel route to 2-substituted-3-cyano-4-methylthio/aminopyrido[2,3-b]indoles has been developed via heteroaromatic annelation of 2 with in situ generated 2-lithioamino-2-substituted acrylonitriles.
- Suresh,Syam Kumar,Ila,Junjappa
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- 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) and microwave-accelerated green chemistry in methylation of phenols, indoles, and benzimidazoles with dimethyl carbonate
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(Equation Presented) 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is a novel and active catalyst in promoting the methylation reaction of phenols, indoles and benzimidazoles with dimethyl carbonate under mild condition. Additional rate enhancement is accomplished by applying microwave irradiation. By incorporating tetrabutylammonium iodide, the same microwave reactions can be further accelerated. By combining these acceleration strategies, very low chemical transformations that take up to several days can be performed efficiently in high yield within minutes.
- Shieh, Wen-Chung,Dell, Steven,Repic, Oljan
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- Synthesis, evaluation and molecular modelling studies of 2-(carbazol-3-yl)-2-oxoacetamide analogues as a new class of potential pancreatic lipase inhibitors
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A series of twenty four 2-(carbazol-3-yl)-2-oxoacetamide analogues were synthesized, characterized and evaluated for their pancreatic lipase (PL) inhibitory activity. Porcine PL was used against 4-nitrophenyl butyrate (method A) and tributyrin (methods B and C) as substrates during the PL inhibition assay. Compounds 7e, 7f and 7p exhibited potential PL inhibitory activity (IC50values of 6.31, 8.72 and 9.58 μM, respectively in method A; and Xi50of 21.85, 21.94 and 26.2, respectively in method B). Further, inhibition kinetics of 7e, 7f and 7p against PL, using method A, revealed their competitive nature of inhibition. A comparison of the inhibition profiles of the top three compounds in methods B and C, provided a preliminary idea of covalent bonding of the compounds with Ser 152 of PL. Molecular docking studies of the compounds 7a–x into the active site of human PL (PDB ID: 1LPB) was in agreement with the in vitro results, and highlighted probable covalent bond formation with Ser 152 apart from hydrophobic interactions with the lid domain. Molecular dynamics simulation of 7e complexed with PL, further confirmed the role of aromatic groups in stabilising the ligand (RMSD ? 4 ?). The present study led to the identification of 2-(carbazol-3-yl)-2-oxoacetamide analogues 7a–x as a new class of potential PL inhibitors.
- Sridhar,Ginson, George,Venkataramana Reddy,Tantak, Mukund P.,Kumar, Dalip,Paul, Atish T.
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- REGIOSPECIFIC C-9 SUBSTITUTION OF ELLIPTICINE DERIVATIVES
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6-Methylellipticine (6) undergoes acylation at the C(9)-position, under Friedel Crafts reaction conditions.The C(9)-formyl compound (8) rearranges to the corresponding hydroxy derivative (9) upon treatment with hydrogen peroxide, in methanol, in the presence of sulphuric acid.The two steps provide a convenient procedure for the specific C(9)-hydroxylation of the ellipticine template.
- Langendoen, Albert,Plug, Johannes P. M.,Koomen, Gerrit-Jan,Pandit, Upendra K.
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- Interaction of bisbenzimidazole-substituted carbazole derivatives with G-quadruplexes and living cells
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G-quadruplex (G4) ligands have potential as chemotherapeutic agents because of the important roles of G4s in regulation of genomic function. Previously, we have developed a fluorescent probe (termed as BPBC) with excellent selectivity to parallel G4s, which possesses a V-shaped bisbenzimidazole-substituted carbazole planar core and two methylpiperazine side arms. Here, we further investigated the interactions of BPBC derivatives with different DNA and living cells. The spectral analysis showed that non-substituted bisbenzimidazole-substituted carbazole (7c) and bisdimethylamino-substituted 7c (7b) exhibited good selectivity to parallel G4s. The binding affinities of BPBC derivatives to parallel G4s were BPBC > 7b 7c. BPBC and 7b entered living cells and mainly located in the cytoplasma and nucleoli; 7c mainly located in the lysosome. BPBC exhibited the highest cytotoxicity with IC50 around 1 μM. Our results suggest that the bisbenzimidazole-substituted carbazole core is the key factor for selectively binding BPBC derivatives to parallel G4s; the side arms can change their affinity to specific G4s, as well as their interaction with cells. Further optimization of the side arms will provide the opportunity to obtain chemotherapeutic agents targeting specific G4s in cells.
- Wei, Yongbiao,Zhang, Xin,Wang, Linlin,Liu, Ying,Bing, Tao,Liu, Xiangjun,Shangguan, Dihua
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- Dual-site fluorescent probe for highly selective and sensitive detection of sulfite and biothiols
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A dual-site fluorescent probe with double bond and aldehyde as reactive sites, was designed for the selective detection of sulfite and biothiols. Sulfite reacts with conjugate bond selectively, while Cys responses with aldehyde and GSH occurs substitution reaction. Different interactions cause different absorption and fluorescence responses. Moreover, it could be further applied in imaging in living cells.
- Li, Mengyang,Cui, Pengcheng,Li, Kun,Feng, Jiahui,Zou, Mingming,Yu, Xiaoqi
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- N-lodosuccinimide - An effective reagent for regioselective heterocyclization of o-cyclohex-2′-enylanilines for the synthesis of hexahydrocarbazoles
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A number of carbazoles are synthesized in good yields by the N-iodosuccinimide mediated heterocyclization of o-cyclohex-2′-enylanilines in acetonitrile at -10 °C for 45 min followed by heating with palladium-charcoal (10%) in benzene (80 °C) for 18-20 h.
- Majumdar,Kundu,Das,Jana,Roy
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- A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
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A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
- Tang, Yu,Yu, Biao
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- Selective C(sp3)?N Bond Cleavage of N,N-Dialkyl Tertiary Amines with the Loss of a Large Alkyl Group via an SN1 Pathway
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Polar disconnection of the C(sp3)?N bond of N,N-dialkyl-substituted tertiary amines via ammonium species conventionally favored the loss of the smaller alkyl group by an SN2 displacement, while selective C(sp3)?N bond cleavage by cutting off the larger alkyl group is still underdeveloped. Herein, we present a novel Pd0-catalyzed [2+2+1] annulation, proceeding through an alkyne-directed palladacycle formation and consecutive diamination with a tertiary hydroxylamine by cleaving its N?O bond and one C(sp3)?N bond, for the rapid assembly of tricyclic indoles in a single-step transformation. Noteworthy, experimental results indicated that large tert-butyl and benzyl groups were selectively cleaved via an SN1 pathway, in the presence of a smaller alkyl group (Me, Et, iPr). Under the guidance of this new finding, tricyclic indoles bearing a removable alkyl group could be exclusively obtained by using a (α-methyl)benzyl/benzyl or tert-butyl/2-(methoxycarbonyl)ethyl mixed amino source.
- Bai, Lu,Li, Linqiang,Liu, Mengtian,Luan, Xinjun,Wu, Jiaoyu
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supporting information
(2021/12/01)
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- Novel yellow- to red-emitting fluorophores: Facile synthesis, aggregation-induced emission, two-photon absorption properties, and application in living cell imaging
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Four novel yellow-to red-emitting fluorophores with a 1-(2-hydroxyethyl) pyridinium core and different electron-donating terminal moieties (N-methylcarbazole, N,N-dibutylbenzenamine, N-methylpyrrole, and 2-methylfuran) were designed and facilely synthesized via the one-step Knoevenagel condensation. All these compounds (HPs) were characterized by 1H NMR, 13C NMR, and HRMS. Their photophysical properties including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated in various solvents. And the density functional theory calculations were conducted to analyze the electronic structures of HPs. The two-photon absorption cross-sections (δ) values of HPs measured by the Z-scan technique were determined to be as large as 1354 (1HP-CZ), 4462 (2HP-BA), 836 (3HP-PR), and 2944 GM (4HP-FU) in DMSO. The two-photon action cross-sections (Φ × δ) values of 1HP-CZ and 2HP-BA in H2O measured by the two-photon induced fluorescence method were about 50 GM. 1HP-CZ, 3HP-PR, and 4HP-FU also exhibited good water solubility. Meanwhile, it was found that 2HP-BA exhibited notable aggregation-induced emission characteristic in DMSO/H2O mixture. The aggregate particle size distribution of 2HP-BA was measured by the dynamic light scattering method, and the aggregation characteristic of 2HP-BA was observed by the transmission electron microscopy. Besides, 2HP-BA also exhibited red emission. Then, HPs with relatively low cytotoxicity were used for one- and two-photon excited fluorescence imaging in living HepG2 cells. The results indicate that HPs are potential candidates in the bioimaging field due to their photophysical properties and biocompatibility.
- Dong, Qi-Ji,Cai, Zhi-Bin,Ding, Ling,Luo, Pei-Hua,He, Qiao-Jun,Li, Sheng-Li,Chen, Li-Jun,Ye, Qing,Tian, Yu-Peng
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- Design, synthesis and evaluation of carbazole derivatives as potential antimicrobial agents
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Five series of novel carbazole derivatives containing an aminoguanidine, dihydrotriazine, thiosemicarbazide, semicarbazide or isonicotinic moiety were designed, synthesised and evaluated for their antimicrobial activities. Most of the compounds exhibited potent inhibitory activities towards different bacterial strains (including one multidrug-resistant clinical isolate) and one fungal strain with minimum inhibitory concentrations (MICs) between 0.5 and 16 μg/ml. Compounds 8f and 9d showed the most potent inhibitory activities (MICs of 0.5–2 μg/ml). Furthermore, compounds 8b, 8d, 8f, 8k, 9b and 9e with antimicrobial activities were not cytotoxic to human gastric cancer cell lines (SGC-7901 and AGS) or a normal human liver cell line (L-02). Structure–activity relationship analyses and docking studies implicated the dihydrotriazine group in increasing the antimicrobial potency and reducing the toxicity of the carbazole compounds. In vitro enzyme activity assays suggested that compound 8f binding to dihydrofolate reductase might account for the antimicrobial effect.
- Xue, Yi-Jie,Li, Ming-Yue,Jin, Xue-Jun,Zheng, Chang-Ji,Piao, Hu-Ri
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p. 295 - 306
(2021/01/13)
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- Dearomatization-Rearomatization Strategy for Synthesizing Carbazoles with 2,2′-Biphenols and Ammonia by Dual C(Ar)-OH Bond Cleavages
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Carbazole is an essential building block in various pharmaceuticals, agrochemicals, natural products, and materials. For future sustainability, it is highly desirable to synthesize carbazole derivatives directly from renewable resources or cheap raw materials. Phenolic compounds are a class of degradation products of lignin. On the other hand, ammonia is a very cheap industrial inorganic chemical. Herein, an efficient dearomatization-rearomatization strategy has been developed to directly cross-couple 2,2′-biphenols with ammonia by dual C(Ar)-OH bond cleavages. This strategy provides a greener pathway to synthesize valuable carbazole derivatives from phenols.
- Cao, Dawei,Yu, Jing,Zeng, Huiying,Li, Chao-Jun
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p. 13200 - 13205
(2020/12/18)
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- Design and synthesis of aryl-functionalized carbazole-based porous coordination cages
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A subset of coordination cages have garnered considerable recent attention for their potential permanent porosity in the solid state. Herein, we report a series of functionalized carbazole-based cages of the structure type M12(R-cdc)12 (M = Cr, Cu, Mo) where the functional groups include a range of aromatic substituents. Single-crystal X-ray structure determinations reveal a variety of intercage interactions in these materials, largely governed by pi-pi stacking. Density functional theory for a subset of these cages was used to confirm that the nature of the increased stability of aryl-functionalized cages is a result of inter-cage ligand interactions. This journal is
- Rowland, Casey A.,Lorzing, Gregory R.,Bhattacharjee, Rameswar,Caratzoulas, Stavros,Yap, Glenn P. A.,Bloch, Eric D.
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supporting information
p. 9352 - 9355
(2020/10/02)
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- Divergent Syntheses of Indoles and Quinolines Involving N1-C2-C3 Bond Formation through Two Distinct Pd Catalyses
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Pd-catalyzed annulative couplings of 2-alkenylanilines with aldehydes using alcohols as both the solvent and hydrogen source have been developed. These domino processes allow divergent syntheses of two significant N-heterocycles, indoles and quinolines, from the same substrate by tuning reaction parameters, which seems to invoke two distinct mechanisms. The nature of the ligand and alcoholic solvent had a profound influence on the selectivity and efficiency of these protocols. Particularly noteworthy is that indole formation was achieved by overcoming two significant challenges, regioselective hydropalladation of alkenes and subsequent reactions between the resulting Csp3-Pd species and less reactive imines.
- San Jang, Su,Kim, Young Ho,Youn, So Won
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supporting information
p. 9151 - 9157
(2020/11/03)
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- Structure-reactivity relationship of probes based on the H2S-mediated reductive cleavage of the CC bond
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Recently, we discovered the H2S-mediated reductive cleavage of the CC bond, and applied this reaction to design probes for the detection of H2S. To extensively elucidate the structure-reactivity relationship, our current work further investigated the effect of substitutes that connected to the CC bond on the H2S-mediated reductive cleavage, wherein different kinds of electron-withdrawing groups (such as pyridine, bipyridine, terpyridine) and electron donating groups (such as carbazole, N,N-dimethylaniline and phenothiazine) were conjugated to the CC bond of interest. Experimental results and DFT calculations showed that the strength of the electron-donating and withdrawing substitutes could significantly affect the reductive cleavage of the CC bond. Unexpectedly, the reductive cleavage was not influenced by the change of the C(2) and C(3) positions in phenothiazine. On this basis, two probes (NPTZ-P1 and NPTZ-P2) with a C(3)-substituted phenothiazine were thus developed and successfully applied for sensing exogenous H2S in living HeLa cells, which implied their potential in bioimaging. This study provides further understanding on the structure-reactivity relationship of the H2S-mediated reductive cleavage of the CC bond, and is also valuable for exploring new reactions of the CC bond in organic synthesis. This journal is
- Tan, Jingyun,Wang, Chunfei,Zhang, Xuanjun
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p. 11667 - 11677
(2020/07/28)
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- Synthesis and Biological Evaluation of Novel Carbazole Hybrids as Promising Antimicrobial Agents
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Two series of carbazole analogs of 8-methoxy-N-substituted-9H-carbazole-3-carboxamides (series 1) and carbazolyl substituted rhodanines (series 2) were synthesized through facile synthetic routes. All the final compounds from these two series were evaluated for their preliminary in vitro antifungal and antibacterial activity against four fungal (Candida albicans, Cryptococcus neoformans, Cryptococcus tropicalis and Aspergillus niger) and four bacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) strains, respectively. Among the tested compounds, three compounds of series 1 displayed promising antifungal and antibacterial activity, especially against C. neoformans and S. aureus. In addition, one compound of series 1 displayed notable antimicrobial activity (MIC: 6.25 μg/mL) against clinical isolates of C. albicans and C. neoformans (MIC: 12.5 μg/mL). From the second series, four compounds exhibited significant antifungal and antibacterial activity, especially against C. neoformans and S. aureus. The most active compound of series 2 displayed a prominent antimicrobial activity against C. neoformans (MIC: 3.125 μg/mL) and S. aureus (MIC: 1.56 μg/mL), respectively.
- Shaikh, Mahamadhanif S.,Chandrasekaran, Balakumar,Palkar, Mahesh B.,Kanhed, Ashish M.,Kajee, Afsana,Mlisana, Koleka P.,Singh, Parvesh,Ghai, Meenu,Cleopus Mahlalela, Mavela,Karpoormath, Rajshekhar
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- Redox-neutral decarboxylative photocyclization of anthranilic acids
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A mild metal-, catalyst-, and oxidant-free photoredox neutral system has been found to efficiently enable intramolecular decarboxylative cyclization of anthranilic acids. This facile protocol provides an alternative method for the synthesis of carbazoles. Mechanistic studies reveal a key photoinduced 6π-electrocyclization process and formic acid was released as the sole byproduct.
- Huang, Huawen,Deng, Kun,Deng, Guo-Jun
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p. 8243 - 8247
(2020/12/29)
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- Aryl radical-induced desulfonylative: Ipso -substitution of diaryliodonium salts: An efficient route to sterically hindered biarylamines
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By using vicinal aryl sulfonamide substituted diaryliodonium salts, a cascade of desulfonylation/aryl migration was promoted by triethylamine in the synthesis of sterically hindered biarylamines, which operated via a radical-induced reaction pathway. The products were readily converted into a variety of important synthons. Furthermore, coupling reactions of N-methyl biarylamine and 1,6-dibromopyrene provided a potentially attractive molecule in OLEDs.
- Chen, Huangguan,Han, Jianwei,Wang, Limin
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p. 5697 - 5700
(2020/06/09)
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- 1,2-Difunctionalization of Aryl Triflates: A Direct and Modular Access to Diversely Functionalized Anilines
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ortho-Amino difunctionalization of aryl triflates has been achieved via a three-component reaction. The cascade reaction proceeds through a zincate base-mediated deprotonative formation of a reactive aryne intermediate, in situ nucleophilic addition, and coupling with electrophilic partners. This strategy leverages the advantageous reactivity of organozincate intermediates, enabling the installation of various functionalities such as amine, azide, oxygen, sulfur, halide, alkynyl, aryl, vinyl, and alkyl groups in a modular manner for the synthesis of diverse aniline skeletons.
- Cho, Seoyoung,Wang, Qiu
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supporting information
(2020/02/28)
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- NaH-mediated direct C-H arylation in the presence of 1,10-phenanthroline
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Transition-metal-free coupling of haloarenes with unactivated arenes has been developed in the presence of NaH and 1,10-phenanthroline. Various haloarenes bearing methyl, methoxy, halogen (fluoride, chloride, and bromide), cyano, trifluoromethyl, ester, and amide groups can be cross-coupled with unactivated arenes, or heteroarenes in this reaction.
- Nozawa-Kumada, Kanako,Iwakawa, Yuki,Onuma, So,Shigeno, Masanori,Kondo, Yoshinori
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supporting information
p. 7773 - 7776
(2020/07/27)
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- Discovery of novel N-methyl carbazole tethered rhodanine derivatives as direct inhibitors of Mycobacterium tuberculosis InhA
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InhA (Enoyl-ACP reductase) plays a crucial role in the biosynthetic pathway of cell wall synthesis in Mycobacterium tuberculosis (Mtb). Isoniazid (INH) is an important first-line drug, which inhibits InhA. The rapid increase in resistance to INH and currently marketed drugs as well as emergence of MDR-TB and XDR-TB has complicated the diagnosis and treatment of Mtb with ever increasing threat to human kind. Herein, we report novel N-methyl carbazole derivatives as potential anti-TB compounds acting directly via InhA inhibition. All the synthesized final compounds were screened against Mtb virulent cell line H37Rv and investigated the InhA enzyme inhibition. Interestingly, compound 9e displayed promising inhibition (91%) at 50 μM concentration and IC50 of 2.82 μM against InhA. To understand the ligand receptor interaction between compound 9e and InhA, molecular docking and molecular dynamics experiments were performed. The computational results were in agreement with the observed experimental data. Further, the cytotoxicity studies on mammalian cells revealed that all the compounds were safe.
- Shaikh, Mahamadhanif S.,Kanhed, Ashish M.,Chandrasekaran, Balakumar,Palkar, Mahesh B.,Agrawal, Nikhil,Lherbet, Christian,Hampannavar, Girish A.,Karpoormath, Rajshekhar
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supporting information
p. 2338 - 2344
(2019/06/20)
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- Copper(II)-Catalyzed Iodinations of Carbazoles: Access to Functionalized Carbazoles
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A copper-catalyzed iodination of carbazoles has been developed. Barluenga's reagent IPy2BF4 is used to generate a soft electrophilic halonium species for the iodination of the carbazoles. This report represents the first concept of copper-catalyst-promoted electrophilic halogenation of carbazoles. We demonstrated numerous applications of this methodology synthesizing diverse carbazole derivatives, i.e., both electron-rich and electron-deficient systems.
- Przypis, Lukasz,Walczak, Krzysztof Zdzislaw
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- Endergonic addition of N -methylamines to aromatic ketones driven by photochemical offset of the entropic cost
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Intermolecular addition reactions are generally accompanied by an entropic penalty due to the decrease of molecular numbers during the reaction, which sometimes makes the reaction endergonic. Here we demonstrate that such an endergonic reaction can be promoted with light-energy as a driving force; N-methylamines were added to aromatic ketones to produce aminoalcohols under UV-light irradiation. The reaction represents an obvious example showing that the photochemical approach is effective to offset such an entropic cost, and thereby to drive thermodynamically uphill addition reactions. Moreover the present reactions are highly expedient from the synthetic view point, being transition-metal-catalyst-free, scalable, highly atom economical, and regioselective. The product amines can be converted in one step to functional multi-arylated enamines, which are potentially valuable compounds in electronic materials.
- Iwamoto, Takahiro,Hosokawa, Atsushi,Nakamura, Masaharu
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supporting information
p. 11683 - 11686
(2019/10/02)
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- Pd-Catalyzed Intramolecular Chemoselective C(sp2)-H and C(sp3)-H Activation of N-Alkyl- N-arylanthranilic Acids
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A controllable palladium-catalyzed intramolecular C-H activation of N-alkyl-N-arylanthranilic acids has been developed. The methodology allows selective synthesis of 1,2-dihydro-(4H)-3,1-benzoxazin-4-ones and carbazoles from the same starting materials and palladium catalyst. The selectivity is controlled by the oxidant. Silver oxide promotes C(sp3)-H activation/C-O cyclization to provide 1,2-dihydro-(4H)-3,1-benzoxazin-4-ones, while copper acetate contributes to C(sp2)-H activation/decarboxylative arylation to afford carbazoles. This protocol is demonstrated by its wide substrate scope and good functional group tolerance.
- Hu, Zhe-Yao,Zhang, Yan,Li, Xin-Chang,Zi, Jing,Guo, Xun-Xiang
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p. 989 - 992
(2019/05/16)
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- Method for preparing carbazole compound
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The invention discloses a method for synthesizing a carbazole compound by utilizing N,N-di-substituted o-aminobenzoate compound. The synthesis method comprises the following steps of adopting a palladium salt as a catalyst, mixing the palladium salt, the N,N-di-substituted o-aminobenzoate compound, an oxidant and an organic solvent, and carrying out heating reaction to obtain the carbazole compound. The method disclosed by the invention has the advantages that the preparation route is short, the universality of a substrate is good, the synthesis yield is high, the used catalyst is simple and easy to obtain and the like.
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Paragraph 0029-0037
(2019/04/13)
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- Method for methylation reaction
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The invention relates to a method for a methylation reaction. The method is characterized in that a reaction substrate is reacted in an organic solvent in the presence of an alkali with methyl trifluoroacetate as a methylation reagent to obtain a corresponding methylated product. The method is a new methylation method, and has the advantages of cheapness, easiness in operation, mild reaction conditions, wide application range of the substrate, avoiding of dimethyl sulfate, iodomethane and other highly toxic methylation reagents, and obtaining of the methylated product with a high yield.
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Paragraph 0013
(2019/01/21)
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- Fluorinated tetraketone derivatives of N-substituted carbazoles and their Eu(III) complexes for fluorescence immunoassay
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[Figure not available: see fulltext.] New fluorinated tetraketone derivatives of N-substituted carbazoles were synthesized and tested as ligands for fluorescence immunoassay. The spectral properties of the obtained heterocyclic tetraketones and their Eu(III) complexes were studied. The complexes showed longwave absorption at 360–380 nm, high extinction coefficient values, long lifetime of excited states, and intense luminescence, allowing to consider the use of such lanthanide complexes in immunofluorescence analysis.
- Pugachov, Dmitriy E.,Kostryukova, Tatiana S.,Zatonsky, Georgy V.,Vatsadze, Sergey Z.,Vasil’ev, Nikolai V.
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p. 528 - 534
(2018/07/05)
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- Quinoline carbazole fluorescence dye and preparation method and application thereof
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The invention relates to a quinoline carbazole fluorescence dye and a preparation method and an application thereof. The fluorescence dye has a structural general formula I, wherein Y is selected from halogen negative ions, which are I, Cl and Br, and preferably selects I. The quinoline carbazole fluorescence dye is a two-photon fluorescence dye, has high efficiency and specific identification capability on a PBS buffer solution and mtDNA in living cells, and has high light stability and low biotoxicity. In addition, the compound preparation route is simple, and the industry application is easy.
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Paragraph 0053-0056
(2018/07/30)
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- Nickel-Catalyzed Reductive Cleavage of Carbon-Oxygen Bonds in Anisole Derivatives Using Diisopropylaminoborane
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The catalytic removal of a methoxy group on an aromatic ring allows this group to be used as a traceless activating and directing group for aromatic functionalization reactions. Although several catalytic methods for the reductive cleavage of anisole derivatives have been reported, all are applicable only to π-extended aryl ethers, such as naphthyl and biphenyl ethers, while monocyclic aryl ethers cannot be reduced. Herein, we report a nickel-catalyzed reductive cleavage reaction of C-O bonds in aryl ethers using diisopropylaminoborane as the reducing agent. Unlike previously reported methods, this reducing reagent allows effective C-O bond reduction in a much wider range of aryl ether substrates, including monocyclic and heterocyclic ethers bearing various functional groups.
- Igarashi, Takuya,Haito, Akira,Chatani, Naoto,Tobisu, Mamoru
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p. 7475 - 7483
(2018/07/21)
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- Divergent and Orthogonal Approach to Carbazoles and Pyridoindoles from Oxindoles via Indole Intermediates
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The previously unexplored Grignard addition to oxindoles provides a regiospecific approach to 2- and 2,3-disubstituted indole derivatives in high yields via a one-pot aromatization driven dehydration pathway. This method allows a convenient preparation of diallyl indoles that are used as ring-closing metathesis (RCM) precursors for the orthogonal synthesis of pyrido[1,2-a]indoles and carbazoles. The synthetic utility of this method is illustrated by the synthesis of a microtubulin inhibitor and naturally occurring carbazole alkaloids.
- Mandal, Tirtha,Chakraborti, Gargi,Karmakar, Shilpi,Dash, Jyotirmayee
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p. 4759 - 4763
(2018/08/24)
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- Photoinduced Cross-Coupling of Amines with 1,2-Diiodobenzene and Its Application in the Synthesis of Carbazoles
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A facile and efficient process for the preparation of various tertiary aminobenzenes and carbazole derivatives via photoinduced cross-coupling of amines with 1,2-diiodobenzene is reported. Mechanistic investigations indicate that the transformation proceeds via nucleo-philic addition of an amine to the benzyne intermediate accompanied with a proton transfer process, followed by an oxidative cyclization of the generated diphenylamine to furnish the corresponding carbazole products.
- Zhao, Xinxin,Chen, Ming,Huang, Binbin,Yang, Chao,Gao, Yuan,Xia, Wujiong
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p. 2981 - 2989
(2018/05/15)
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- 1-CYANO-PYRROLIDINE DERIVATIVES AS INHIBITORS OF USP30.
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The present invention relates to novel compounds and methods for the manufacture of inhibitors of deubiquitylatingenzymes (DUBs). In particular, the invention relates to the inhibition of ubiquitin C- terminal hydrolase 30 or Ubiquitin Specific Peptidase 30 (USP30). The invention further relates to the use of DUB inhibitors in the treatment of conditions involving mitochondrial dysfunction and cancer. Compounds of the invention include compounds having the formula (I) (I) or a pharmaceutically acceptable salt thereof, wherein R1, R 2, R 3, m, L and X are as defined herein.
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Page/Page column 63
(2018/02/03)
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- Novel carbazole sulfonamide derivatives of antitumor agent: Synthesis, antiproliferative activity and aqueous solubility
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The current optimization of IG-105 (3) on the carbazole-ring provided a series of new carbazole sulfonamides derivatives 13a–13m. All of the compounds have been evaluated against HepG2 cells (hepatoma cancer) for antiproliferative activity. Compounds that showed activity better or comparable to that of 3 versus HepG2 were evaluated against MCF-7 (breast cancer), MIA PaCa-2 (pancreatic cancer), and Bel-7402 (hepatoma/liver cancer) for antiproliferative activity. Of the seven compounds selected for further study five (13b, 13g, 13j, 13k and 13l) were found to give IC50values against the four cell lines comparable to those for 3. Two compounds (13f and 13i) were more active than 3 and their activity against HepG2 and MCF-7 (IC50:0.01–0.07?μM) approached that of the positive controls podophyllotoxin (podo) and CA-4. Most of compounds showed aqueous solubility (0.11–19.60?μg/mL at pH 7.4 and 2.0) better than 3. These promising results warrant further development of new compounds 13f and 13i as potential potent antitumor drug candidates.
- Sun, Lianqi,Wu, Yanbin,Liu, Yonghua,Chen, Xiaofang,Hu, Laixing
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p. 261 - 265
(2016/12/27)
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- Novel carbazole skeleton-based photoinitiators for led polymerization and LED projector 3D printing
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Radical chemistry is a very convenient way to produce polymer materials. Here an application of a particular photoinduced radical chemistry is illustrated. Seven new carbazole derivatives Cd1–Cd7 are incorporated and proposed as high performance near-UV photoinitiators for both the free radical polymerization (FRP) of (meth)acrylates and the cationic polymerization (CP) of epoxides utilizing Light Emitting Diodes LEDs @405 nm. Excellent polymerization-initiating abilities are found and high final reactive function conversions are obtained. Interestingly, these new derivatives display much better near-UV polymerization-initiating abilities compared to a reference UV absorbing carbazole (CARET 9H-carbazole-9-ethanol) demonstrating that the new substituents have good ability to red shift the absorption of the proposed photoinitiators. All the more strikingly, in combination with iodonium salt, Cd1–Cd7 are likewise preferred as cationic photoinitiators over the notable photoinitiator bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (BAPO) for mild irradiation conditions featuring their remarkable reactivity. In particular their utilization in the preparation of new cationic resins for LED projector 3D printing is envisioned. A full picture of the included photochemical mechanisms is given.
- Mousawi, Assi Al,Garra, Patxi,Dumur, Frédéric,Bui, Thanh-Tuan,Goubard, Fabrice,Toufaily, Joumana,Hamieh, Tayssir,Graff, Bernadette,Gigmes, Didier,Fouassier, Jean Pierre,Lalevée, Jacques
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supporting information
(2018/01/12)
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- Isocyanide-Induced Activation of Copper Sulfate: Direct Access to Functionalized Heteroarene Sulfonic Esters
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A novel and direct approach to alkyl/aryl heteroarene sulfonic esters using copper sulfate as the environmentally benign inorganic sulfonation reagent was first realized with the aid of isocyanide. A variety of heterocycles reacted to afford the corresponding sulfonic esters through C?H functionalization. In this transformation, the otherwise inert copper sulfate was unusually activated by an isocyanide and employed as the source of the sulfonic substituents in an unprecedented fashion. The findings suggest that an appropriate activator may liberate the chemical activities of some relatively inert inorganic salts for organic synthesis.
- Hong, Xiaohu,Tan, Qitao,Liu, Bingxin,Xu, Bin
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supporting information
p. 3961 - 3965
(2017/03/27)
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- p-TsOH-mediated, Versatile, and Efficient Approach for the Synthesis of Triazolyl-Carbazoles from Nitrovinylcarbazoles and Azide via 1, 3-Dipolar Cycloaddition
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An efficient method for the synthesis of N-alkylated 3-(1-benzyl-1H-1,2,3-triazole-4-yl)-9H-carbazoles (5, 6, 7, 8, 9, 10) and 9-ethyl-3,6-di(1H-1,2,3-triazole-4-yl)-9H-carbazole (13) has been developed from nitroolefines. The effects of catalyst and solvent on these reactions have been investigated. p-TsOH-THF was found to be the best system for this reaction. Various triazolyl-carbazoles were prepared in good to excellent yields.
- Avula, Vijay Kumar Reddy,Vallela, Swetha,Anireddy, Jaya Shree,Chamarthi, Naga Raju
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p. 1361 - 1368
(2017/03/27)
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- A Green Synthesis of 2-Amino-4-(9H-carbazole-3-yl)thiophene-3-carbonitriles by a Step-wise and One-pot Three-component Gewald Reaction
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An eco-friendly method has been developed for the synthesis of 2-amino-4-(9H-carbazole-3-yl)thiophene-3-carbonitriles from preliminary carbazole (1) through an intermediate of 2-(1-(9H-carbazole-3-yl)ethylidene)malononitriles using the Knoevenagel condensation followed by the Gewald reaction. On the other hand, the target compounds could also be prepared in a one-pot three-component manner by treating equimolar quantities of 1-(9H-carbazole-3-yl)ethanone (3), malononitrile, and elemental sulfur. The merits of this preparation are mild reaction conditions. The Gewald reaction is executed with inorganic base NaHCO3 (H2O) in tetrahydrofuran, easy work-up procedure with good yields.
- Avula, Vijay Kumar Reddy,Vallela, Swetha,Anireddy, Jaya Shree,Chamarthi, Naga Raju
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p. 2471 - 2482
(2017/07/25)
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- An Expedient Synthesis of Carbazoles through Potassium tert-Butoxide-Promoted Intramolecular Direct C–H Bond Arylation
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Transition-metal-free access to carbazoles was achieved through base-mediated intramolecular C–C bond formation. Reactions of N-substituted o-halodiarylamines with potassium tert-butoxide in the presence of ethylene glycol or 1,10-phenanthroline provided carbazoles in moderate to excellent yields. This transformation may proceed through a radical pathway according to a control experiment with a radical scavenger.
- Lin, Songbo,He, Xingrui,Meng, Jinpeng,Gu, Haining,Zhang, Peizhi,Wu, Jun
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supporting information
p. 443 - 447
(2017/02/05)
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- A Novel and Chemoselective Process of N -Alkylation of Aromatic Nitrogen Compounds Using Quaternary Ammonium Salts as Starting Material
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The process of N-alkylation of several pyrroles, indoles, and derivative heterocycles is herein described, using quaternary ammonium salts as the source of an alkylating agent. These reactions were carried out on several heterocyclic rings with triethylbenzylammonium chloride or tetradecyltrimethylammonium bromide and an NaOH solution at 50%, leading to a chemoselective N-alkylated product and an average yield of 73%. This is an alternative process to the traditional benzylation and methylation of N-heterocycles with direct handling of alkyl halides.
- González-González, Carlos A.,Vega, Juan Javier Mejía,Monroy, Ricardo García,González-Calderón, Davir,Corona-Becerril, David,Fuentes-Benítes, Aydeé,Mascarúa, Joaquín Tamariz,González-Romero, Carlos
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- Silyloxyarenes as Versatile Coupling Substrates Enabled by Nickel-Catalyzed C-O Bond Cleavage
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Silyloxyarenes are demonstrated to be a versatile substrate class in a variety of nickel-catalyzed coupling processes. The C(sp2)-O bond of aryl silyl ethers is directly transformed into C-H or C-Si bonds using Ti(O-i-Pr)4 or trialkylsilanes as reagents using nickel catalysts with N-heterocyclic carbene (NHC) ligands. Paired with the useful characteristics of silyl protecting groups, these methods enable protected hydroxyls to directly participate in high-value bond-forming steps rather than requiring deprotection-activation strategies that conventional approaches require. These processes of silyloxyarenes provide reactivity complementary to widely used phenol derivatives such as aryl pivalates, carbamates, and methyl ethers, thus enabling a powerful strategy for sequential chemoselective derivatization of complex substrates without protecting group and activating group manipulations.
- Wiensch, Eric M.,Todd, David P.,Montgomery, John
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p. 5568 - 5571
(2017/09/15)
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- Reductive C(sp2)-N elimination from isolated Pd(IV) amido aryl complexes prepared using H2O2 as oxidant
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Di-2-pyridyl ketone (dpk)-supported amidoarylpallada(Il)cycles derived from various 2-(N-R-amino)biphenyls (R = H, Me, CF3CO, MeSOj, CF3SO2) react with hydrogen peroxide in MeOH, THF, MeCN or AcOH to form the corresponding C-N coupled products, N-R-substituted carbazoles, in 82-98% yield. For R = MeS02 and CF3SO2, the corresponding reaction intermediates, amidoaryl Pd(IV) complexes were isolated and characterized by single crystal X-ray diffraction and/or NMR spectroscopy. For the first time, the C(sp2)-N reductive elimination from isolated amidoaryl Pd(lV) complexes has been studied in detail.
- Abada, Elikplim,Zavalij, Peter Y.,Vedernikov, Andrei N.
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supporting information
p. 643 - 646
(2017/05/16)
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- A general synthesis of arylindoles and (1-arylvinyl)carbazoles: Via a one-pot reaction from N -tosylhydrazones and 2-nitro-haloarenes and their potential application to colon cancer
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A convergent and effective synthesis of 3-aryl-indoles, 2,3-diaryl indoles, and (1-arylvinyl)carbazoles from a one-pot sequence involving the coupling of N-tosylhydrazones with ortho-nitro-haloarenes followed by a cyclization has been developed. Compound 5i exhibits excellent antiproliferative activity in the low nM range against colon cancer cell lines.
- Bzeih, Tourin,Naret, Timothée,Hachem, Ali,Jaber, Nada,Khalaf, Ali,Bignon, Jerome,Brion, Jean-Daniel,Alami, Mouad,Hamze, Abdallah
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supporting information
p. 13027 - 13030
(2016/11/09)
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- Imaging Beta-Amyloid Peptides Aggregation
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The present invention is in the field of pharmaceuticals and chemical industries. In particular, one aspect of the present invention relates to methods for labeling, imaging and detecting the beta-amyloid (Aβ) peptides, oligomers, and fibrils in vitro and in vivo via magnetic resonance and florescence imaging by using modified carbazole-based fluorophores. A further aspect of the present invention relates to a method of reducing and preventing aggregation of beta-amyloid peptides for Alzheimer's disease (AD) as well as of treating and/or preventing Alzheimer's disease by using the modified carbazole-based fluorophore. The modified carbazole-based fluorophore according to an embodiment of the present invention is prepared by conjugating a carbazole-based fluorophore with magnetic nanoparticles to form a conjugate which is permeable to blood brain barrier of a subject being introduced therewith.
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Paragraph 0099
(2016/09/26)
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- Nickel-catalyzed reductive cleavage of aryl alkyl ethers to arenes in absence of external reductant
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The reductive cleavage of the C-O bonds of aryl ethers has great potential in organic synthesis. Although several catalysts that can promote the reductive cleavage of aryl ethers have been reported, all such systems require the use of an external reductant, e.g., hydrosilane or hydrogen. Here, we report the development of a new nickel-based catalytic system that can cleave the C-O bonds of ethers in the absence of an external reductant. The hydrogen atom required in this new reductive cleavage reaction is provided by the alkoxy group of the substrate, which serves as an internal reductant. The absence of an external reductant enables the unique chemoselectivity, i.e., the selective reduction of an alkoxy group over alkenes and ketones. This journal is
- Tobisu, Mamoru,Morioka, Toshifumi,Ohtsuki, Akimichi,Chatani, Naoto
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p. 3410 - 3414
(2015/05/27)
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- N-methylation of aromatic amines and N-heterocycles under acidic conditions with the TTT (1,3,5-trioxane-triethylsilane-trifluoroacetic acid) system
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A novel reductive N-methylation protocol under acidic conditions with the TTT (1,3,5-trioxane-triethylsilane-trifluoroacetic acid) system is disclosed. This method is highly specific for aromatic amines and several N-heterocycles (indoles and annulated analogues, phenoxazine, phenothiazine), insensitive to steric hindrance, and compatible with a wide range of functional groups. Further the N-methylation step can be combined with an in situ N-Boc deprotection. Compounds in which the nucleophilicity of the NH group is eliminated by protonation under the reaction conditions (aliphatic amines, azaarenes of noteworthy basicity) are inert. In several examples, it was demonstrated that the TTT system is complementary to other N-methylation protocols.
- Popp, Tobias A.,Bracher, Franz
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p. 3333 - 3338
(2016/11/29)
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- Synthesis of Carbazole Alkaloids by Ring-Closing Metathesis and Ring Rearrangement-Aromatization
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Aprocess for the assembly of carbazole alkaloids has been developed on the basis of ring-closing metathesis (RCM) and ringrearrangement-aromatization (RRA) as the key steps. This method is based on allyl Grignard addition to isatin derivatives to provide smooth access to 2,2-diallyl 3-oxindole derivatives through a 1,2-allyl shift. The diallyl derivatives were used as RCM precursors to afford a novel class of spirocyclopentene-3-oxindole derivatives, which underwent a novel RRA reaction to afford carbazole derivatives. The synthetic sequence to carbazoles was shortened by combining the RCM and RRA steps in an orthogonal tandem catalytic process. The utility of this methodology was further demonstrated by the straightforward synthesis of carbazole alkaloids, including amukonal derivative, girinimbilol, heptaphylline, and bis(2-hydroxy-3-methylcarbazole). Just a hop, skip, and a jump away: The addition of allyl Grignard/indium reagents to isatins, ring-closing metathesis (RCM), and ring rearrangement-aromatization (RRA) provided carbazole derivatives in high overall yield (see scheme). The RCM step afforded spirocyclic 3-oxindoles, which underwent acid-catalyzed RRA to give carbazoles. A step-economical tandem RCM/RRA process was also developed and applied to the synthesis of carbazole alkaloids.
- Dhara, Kalyan,Mandal, Tirtha,Das, Joydeb,Dash, Jyotirmayee
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p. 15831 - 15835
(2016/01/29)
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- Palladium-catalyzed α-arylation of enones in the synthesis of 2-alkenylindoles and carbazoles
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A new unified strategy has been developed for the synthesis of substituted 2-alkenylindoles and carbazoles. The strategy uses palladium-catalyzed α-arylation of TES-enol ethers of enones as the key step. The method is highly regioselective, provides good yields, and is expected to have wide application.
- Kale, Ajit Prabhakar,Kumar, Gangam Srikanth,Mangadan, Arun Raj Kizhakkayil,Kapur, Manmohan
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supporting information
p. 1324 - 1327
(2015/03/14)
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- A tuned bicyclic proazaphosphatrane for catalytically enhanced n-arylation reactions with aryl chlorides
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The N-arylation of various amines with aryl chlorides proceeded in good-to-excellent yields in the presence of P[N{(p-NMe2)C6H4CH2}CH2CH2]3N (1e, a new electron-rich proazaphosphatrane ligand) and small amounts of Pd2(dba)3 (dba = dibenzylideneacetone). This catalytic system was also very effective for the synthesis of carbazoles. An efficient palladium-catalyzed N-arylation reaction of amines under mild conditions with a tuned bicyclic proazaphosphatrane has been developed.
- Kim, So Han,Kim, Min,Verkade, John G.,Kim, Youngjo
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p. 1954 - 1960
(2015/03/18)
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