- Continuous Synthesis and Separation ofp-Bromobenzyl Bromide Using Atom-Efficient Bromination ofp-Bromotoluene without Any Organic Effluent: Potential for Green Industrial Practice
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This work focuses on the bromination ofp-bromotoluene (PBT) using different brominating agents such as liquid Br2, NaBr-NaBrO3, NaBr-NaBrO3-NaCl, NaBr-H2O2, and HBr-H2O2. NaBr-NaBrO3-NaCl is an eco-friendly brominating agent obtained from a bromine recovery plant. Both NaBr-NaBrO3and NaBr-NaBrO3-NaCl were found to be nonhazardous and efficient brominating agents. Pure NaBr-NaBrO3resulted in the best PBT conversion with 79.7% Br atom efficiency in water and 98.2% average Br atom efficiency using dichloroethane as a solvent. Dichloroethane is de facto no longer used in the US and Europe and is not eco-friendly; the process with water as a solvent is the best. The substrate to active bromine molar ratio of 3:1 was found to be sufficient to get the maximum selectivity ofp-bromobenzyl bromide (PBBB). The low-temperature crystallization method was used for separation cum purification of the product. Unreacted PBT was recycled along with the dibromo byproduct obtained. The dibromo product, which was built up gradually in the reaction mixture over 10 successive batches, was converted back into PBBB/PBT through NaBH4treatment of the mother liquor. This continuous process is highly sustainable and produces zero organic waste, making it potentially attractive toward green industrial implementation.
- Sancheti, Sonam V.,Yadav, Ganapati D.
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p. 2071 - 2080
(2021/09/13)
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- Synthesis, inhibition properties against xanthine oxidase and molecular docking studies of dimethyl N-benzyl-1H-1,2,3-triazole-4,5-dicarboxylate and (N-benzyl-1H-1,2,3-triazole-4,5-diyl)dimethanol derivatives
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This study focused on synthesis various dimethyl N-benzyl-1H-1,2,3-triazole-4,5-dicarboxylate and (N-benzyl-1H-1,2,3-triazole-4,5-diyl)dimethanol derivatives under the conditions of green chemistry without the use of solvent and catalysts. Their inhibition properties were also investigated on xanthine oxidase (XO) activity. All dimethanol and dicarboxylate derivatives exhibited significant inhibition activities with IC50 values ranging from 0.71 to 2.25 μM. Especially, (1-(3-bromobenzyl)-1H-1,2,3-triazole-4,5-diyl)dimethanol (5c) and dimethyl 1-(4-chlorobenzyl)-1H-1,2,3-triazole-4,5-dicarboxylate (6 g) compounds were found to be the most promising derivatives on the XO enzyme inhibition with IC50 values 0.71 and 0.73 μM, respectively. Moreover, the double docking procedure was to evaluate compound modes of inhibition and their interactions with the protein (XO) at atomic level. Surprisingly, the docking results showed a good correlation with IC50 [correlation coefficient (R2 = 0.7455)]. Also, the docking results exhibited that the 5c, 6f and 6 g have lowest docking scores ?4.790, ?4.755, and ?4.730, respectively. These data were in agreement with the IC50 values. These results give promising beginning stages to assist in the improvement of novel and powerful inhibitor against XO.
- Yagiz, Güler,Noma, Samir Abbas Ali,Altundas, Aliye,Al-khafaji, Khattab,Taskin-Tok, Tugba,Ates, Burhan
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- [1,3]-Claisen rearrangement via removable functional group mediated radical stabilization
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A thermal O-to-C [1,3]-rearrangement of α-hydroxy acid derived enol ethers was achieved under mild conditions. The 2-aminothiophenol protection of carboxylic acids facilitates formation of the [1,3] precursor and its thermal rearrangement via stabilization of a radical intermediate. Experimental and theoretical evidence for dissociative radical pair formation, its captodative stability via aminothiophenol, and a unique solvent effect are presented. The aminothiophenol was deprotected from rearrangement products as well as after derivatization to useful synthons.
- Alam, Md Nirshad,Dash, Soumya Ranjan,Mukherjee, Anirban,Pandole, Satish,Marelli, Udaya Kiran,Vanka, Kumar,Maity, Pradip
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supporting information
p. 890 - 895
(2021/02/01)
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- New 3-(1H-benzo[d]imidazol-2-yl)quinolin-2(1H)-one-based triazole derivatives: Design, synthesis, and biological evaluation as antiproliferative and apoptosis-inducing agents
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A series of 1,2,3-triazole derivatives based on the quinoline–benzimidazole hybrid scaffold was designed, synthesized, and screened against a panel of NCI-60 humanoid cancer cell lines for in vitro cytotoxicity evaluation, which revealed that compound Q6 was the most potent cytotoxic agent with excellent GI50, TGI, and LC50 values on multiple cancer cell lines. Q6 was tested further on the BT-474 breast cancer line to evaluate the mechanism of action. Preliminary screening studies based on the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay revealed that compound Q6 had an excellent antiproliferative effect against human breast cancer cells, BT-474, with IC50 values of 0.59 ± 0.01 μM. The detailed study based on the acridine orange/ethidium bromide staining (AO/EB) and the 4′,6-diamidino-2-phenylindole (DAPI) assay suggested that the antiproliferative activity shown was due to the induction of apoptosis on exposure to Q6. Further, DCFDA staining showed the generation of reactive oxygen species, altering the mitochondrial potential and leading to the initiation of apoptosis. This was further supported by JC-1 staining, indicating that this scaffold can contribute to the development of more potent derivatives.
- Gaikwad, Nikhil B.,Bansode, Sapana,Biradar, Shankar,Ban, Mayuri,Srinivas, Nanduri,Godugu, Chandraiah,Yaddanapudi, Venkata M.
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- Decarboxylative Bromination of Sterically Hindered Carboxylic Acids with Hypervalent Iodine(III) Reagents
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Sterically hindered three-dimensional (3D) alkyl halides are promising precursors for various reactions; however, they are difficult to synthesize via conventional reactions. We present an efficient and practical method for decarboxylative bromination of sterically hindered 3D aliphatic carboxylic acids using commercially available (diacetoxyiodo)benzene and potassium bromide, one of the most stable and cheapest bromine sources in nature. The present method features a metal-free/Br2-free system, mild reaction conditions, one-pot operation under air at room temperature, wide functional group compatibility, and gram-scale synthetic capability. This highly efficient reaction cleanly converts a broad range of carboxylic acids, the most inexpensive and readily available sources of highly strained/naturally occurring/drug-related scaffolds, into the corresponding alkyl bromides in good to high yields.
- Kanazawa, Junichiro,Koyamada, Kenta,Miyamoto, Kazunori,Uchiyama, Masanobu,Watanabe, Ayumi
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supporting information
p. 1328 - 1334
(2020/08/14)
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- NOVEL APOPTOSIS SIGNAL-REGULATING KINASE 1 INHIBITORS
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The present invention relates to inhibitors of apoptosis signal-regulating kinase 1 ("ASK1"), a process for synthesis of the compounds of the present invention, composition comprising the compounds and use of the compounds for inhibition of ASK1.
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- Thiourea-Catalyzed C?F Bond Activation: Amination of Benzylic Fluorides
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We describe the first thiourea-catalyzed C?F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.
- Houle, Camille,Savoie, Paul R.,Davies, Clotilde,Jardel, Damien,Champagne, Pier Alexandre,Bibal, Brigitte,Paquin, Jean-Fran?ois
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supporting information
p. 10620 - 10625
(2020/07/24)
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- Promotion of Appel-type reactions by N-heterocyclic carbenes
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N-Heterocyclic carbenes (NHCs) have been extensively used as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a fresh and interesting aspect and enriches the chemistry of NHCs in an underexplored area. The potential of performing this chemical transformation at the catalytic level using an NHC-oxide derivative is also investigated.
- Hussein, Mohanad A.,Nguyen, Thanh Vinh
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supporting information
p. 7962 - 7965
(2019/07/12)
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- THERAPEUTIC COMPOUNDS AND METHODS TO TREAT INFECTION
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Disclosed herein are compounds of formula I: or a salt thereof and compositions comprising a compound of formula I or a pharmaceutically acceptable salt thereof. Also disclosed herein are methods for treating or preventing a bacterial infection in an animal comprising administering to the animal a compound of formula I or a pharmaceutically acceptable salt thereof, alone or in combination with a bacterial efflux pump inhibitor.
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-
Paragraph 0418-0419
(2019/02/13)
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- Design, synthesis and biological evaluation of low molecular weight CXCR4 ligands
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The chemokine receptor CXCR4/stromal cell-derived factor-1 (SDF-1: CXCL12) signaling axis represents a crucial drug target due to its relevance to several diseases such as HIV-1 infection, cancer, leukemia, and rheumatoid arthritis. With the aim of enhancing the binding affinity and anti-HIV activity of a potent CXCR4 ligand as a lead, 23 low molecular weight compounds containing dipicolylamine (Dpa) and cyclam cationic moieties with varying spacers and spatial positioning were designed, synthesized and biologically evaluated. All of the synthesized compounds screened at 1.0 μM in the NanoBRET assay system exhibited >70% inhibition of the binding of a competitive probe TAMRA-Ac-TZ14011 (10 nM) to CXCR4 in the presence of zinc (II) ion. Furthermore, selected compounds 3, 8, 9, 19 and 21 with spatial distances between the next carbon to Dpa and the next carbon to cyclam within the range of 6.5–7.5 ? showed potent binding affinity selective for CXCR4 with IC50 values of 1.6, 7.9, 5.7, 3.5 and 4.5 nM, respectively, with corresponding high anti-HIV activity with EC50s of 28, 13, 21, 28 and 61 nM, respectively, in the presence of zinc (II) ion. Some compounds with remarkably more potent CXCR4-binding affinity than that of an initial lead were obtained. These compounds interact with different but overlapping amino acid residues of CXCR4. The present studies have developed new low molecular weight CXCR4 ligands with high CXCR4-binding and anti-HIV activities, which open avenue into the development of more potent CXCR4 ligands.
- Sakyiamah, Maxwell M.,Kobayakawa, Takuya,Fujino, Masayuki,Konno, Makoto,Narumi, Tetsuo,Tanaka, Tomohiro,Nomura, Wataru,Yamamoto, Naoki,Murakami, Tsutomu,Tamamura, Hirokazu
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supporting information
p. 1130 - 1138
(2019/02/16)
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- Photochemical benzylic bromination in continuous flow using BrCCl3 and its application to telescoped p-methoxybenzyl protection
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BrCCl3 represents a rarely used benzylic brominating reagent with complementary reactivity to other reagents. Its reactivity has been revisited in continuous flow, revealing compatibility with electron-rich aromatic substrates. This has brought about the development of a p-methoxybenzyl bromide generator for PMB protection, which was successfully demonstrated on a pharmaceutically relevant intermediate on 11 g scale, giving 91% yield and a PMB-Br space-time-yield of 1.27 kg L?1 h?1
- Otake, Yuma,Williams, Jason D.,Rincón, Juan A.,De Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
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supporting information
p. 1384 - 1388
(2019/02/14)
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- Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
- Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
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p. 4933 - 4939
(2018/12/14)
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- Halogenation through Deoxygenation of Alcohols and Aldehydes
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An efficient reagent system, Ph3P/XCH2CH2X (X = Cl, Br, or I), was very effective for the deoxygenative halogenation (including fluorination) of alcohols (including tertiary alcohols) and aldehydes. The easily available 1,2-dihaloethanes were used as key reagents and halogen sources. The use of (EtO)3P instead of Ph3P could also realize deoxy-halogenation, allowing for a convenient purification process, as the byproduct (EtO)3Pa?O could be removed by aqueous washing. The mild reaction conditions, wide substrate scope, and wide availability of 1,2-dihaloethanes make this protocol attractive for the synthesis of halogenated compounds.
- Chen, Jia,Lin, Jin-Hong,Xiao, Ji-Chang
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supporting information
p. 3061 - 3064
(2018/05/28)
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- Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
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The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
- Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
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supporting information
p. 4197 - 4204
(2018/09/25)
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- Selective C-H halogenation over hydroxylation by non-heme iron(iv)-oxo
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Non-heme iron based halogenase enzymes promote selective halogenation of the sp3-C-H bond through iron(iv)-oxo-halide active species. During halogenation, competitive hydroxylation can be prevented completely in enzymatic systems. However, synthetic iron(iv)-oxo-halide intermediates often result in a mixture of halogenation and hydroxylation products. In this report, we have developed a new synthetic strategy by employing non-heme iron based complexes for selective sp3-C-H halogenation by overriding hydroxylation. A room temperature stable, iron(iv)-oxo complex, [Fe(2PyN2Q)(O)]2+ was directed for hydrogen atom abstraction (HAA) from aliphatic substrates and the iron(ii)-halide [FeII(2PyN2Q)(X)]+ (X, halogen) was exploited in conjunction to deliver the halogen atom to the ensuing carbon centered radical. Despite iron(iv)-oxo being an effective promoter of hydroxylation of aliphatic substrates, the perfect interplay of HAA and halogen atom transfer in this work leads to the halogenation product selectively by diverting the hydroxylation pathway. Experimental studies outline the mechanistic details of the iron(iv)-oxo mediated halogenation reactions. A kinetic isotope study between PhCH3 and C6D5CD3 showed a value of 13.5 that supports the initial HAA step as the RDS during halogenation. Successful implementation of this new strategy led to the establishment of a functional mimic of non-heme halogenase enzymes with an excellent selectivity for halogenation over hydroxylation. Detailed theoretical studies based on density functional methods reveal how the small difference in the ligand design leads to a large difference in the electronic structure of the [Fe(2PyN2Q)(O)]2+ species. Both experimental and computational studies suggest that the halide rebound process of the cage escaped radical with iron(iii)-halide is energetically favorable compared to iron(iii)-hydroxide and it brings in selective formation of halogenation products over hydroxylation.
- Rana, Sujoy,Biswas, Jyoti Prasad,Sen, Asmita,Clémancey, Martin,Blondin, Geneviève,Latour, Jean-Marc,Rajaraman, Gopalan,Maiti, Debabrata
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p. 7843 - 7858
(2018/10/31)
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- Design, synthesis and neuroprotective activities of novel cinnamide derivatives containing benzylpiperazine moiety
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A new series of cinnamide derivatives 6a–l were synthesized by the reaction of acyl chlorides with various substituted benzylpiperazines. The structures were characterized by 1H NMR, 13C NMR, and HRMS. The potential neuroprotective activities of cinnamide analogs were evaluated in differentiated rat pheochromocytoma cells (PC12 cells) and in mice subjected to acute cerebral ischemia. Among the series, 6a, 6b, and 6c, featuring a 1,3-benzodioxole moiety, showed potent neuroprotection both in vivo and in vitro. The three compounds were selected and further studied to determine their mechanism of action. MTT assay, Hoechst 33342/PI double staining, and high content screening (HCS) revealed that pretreatment of the cells with 6a, 6b, and 6c has significantly decreased the extent of cell apoptosis in a dose-dependent manner. The results of western blot analysis demonstrated these compounds suppressed apoptosis of glutamate-induced PC12 cells via caspase-3 pathway. These compounds can be lead compounds for further discovery of neuroprotective agents for treating cerebral ischemic stroke.
- Zhong, Yan,Li, Xiaofeng,Zhang, Aixia,Xu, Yi,Li, Ping,Wu, Bin
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p. 1366 - 1373
(2018/02/28)
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- Synthesis of Novel Triazole-incorporated Isatin Derivatives as Antifungal, Antitubercular, and Antioxidant Agents and Molecular Docking Study
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A library of 1,2,3-triazoles efficiently prepared via click chemistry and evaluated for their antifungal, antitubercular, antioxidant, cytotoxicity, molecular docking and ADME prediction.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Khan, Firoz A. Kalam,Sangshetti, Jaiprakash N.,Nawale, Laxman,Arkile, Manisha,Sarkar, Dhiman,Shingate, Bapurao B.
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p. 413 - 421
(2017/02/03)
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- Method for preparing benzyl bromide
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The invention provides a method for preparing benzyl bromide. The method comprises the following steps: by taking bromine released from a redox reaction between bromates and negative bromide ions in the presence of an acid as a bromine source in an organic solvent, carrying out a benzyl radical substitution reaction with a methylbenzene compound shown as a formula I under initiation of an initiator, thereby obtaining a corresponding benzyl bromide compound shown a formula II, wherein in the formula II, m represents the number of Br and is equal to 1 or 2; when m is equal to 1, the formula II shows a benzyl monobromo compound; and when m is equal to 2, the formula II shows a benzyl dibromo compound. The reaction is carried out in an organic solvent, the initiator is combined and used, the radical substitution reaction is high in selectivity and wide in substrate application range, the substituent group replacing methylbenzene may be an electron-withdrawing group or an electron-donating group and can give extremely high yield on strong electron-donating groups (such as methoxy group). Moreover, the method disclosed by the invention is also applicable to preparation of benzyl dibromo compounds, and the product yield is high.
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-
Paragraph 0049-0051
(2017/10/05)
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- Design, synthesis and biological evaluation of dual acetylcholinesterase and phosphodiesterase 5A inhibitors in treatment for Alzheimer's disease
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With the recent research advances in molecular biology and technology, multiple credible hypotheses about the progress of Alzheimer's disease (AD) have been proposed; multi-target drugs have emerged as an innovative therapeutic approach for AD. Current clinical therapy for AD patients is mainly palliative treatment targeting acetylcholinesterase (AChE). Inhibition of phosphodiesterase 5A (PDE5A) has recently been validated as a potentially novel therapeutic approach for Alzheimer's disease (AD). In this work, series of new compounds were designed, synthesized and evaluated as dual cholinesterase and PDE5A inhibitor. Biological results revealed that some of these compounds display good biological activities against AChE with IC50 values about 44.67–169.80 nM (donepezil IC50 50.12 nM). Notably, compound 12 presented potent activities against PDE5A with IC50 values about 50 μM (sildenafil IC50 12.59 μM), and some of these compounds showed low cell toxicity to A549 cells in vitro.
- Zhou, Li-yun,Zhu, Yao,Jiang, Yu-ren,Zhao, Xiong-jie,Guo, Dong
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supporting information
p. 4180 - 4184
(2017/08/23)
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- 2-Indolone derivatives and open-ring derivatives, and synthetic methods and use thereof
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The invention discloses 2-indolone derivatives and open-ring derivatives thereof, and synthetic method and a use thereof, belongs to the technical field of medicines, and relates to 2-indolone derivatives with the structure represented by general formula (I), and open-ring derivatives (II) thereof. In the formula (I) and formula (II), X is CO(CH2)n-1 and n is 1 to 10, or X is CO(CH2)n-1NH2 and n is 1 to 10; Y is CO or CH2; and R1, R2, R3, R4, R5, R6, R7 and R8 are different substituent groups. The invention also discloses structures, the synthetic methods and an in-vitro acetylcholinesterase and phosphodiesterase 5 inhibition activity, and can be further developed into new medicines for treating the Alzheimer's disease.
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Paragraph 0044-0048
(2017/08/31)
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- Synthesis, biological evaluation and molecular docking of novel coumarin incorporated triazoles as antitubercular, antioxidant and antimicrobial agents
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A series of new coumarin-based 1,2,3-triazole derivatives were designed, synthesized and evaluated for their antitubercular activity in vitro against Mycobacterium tuberculosis H37Ra, antioxidant activity by DPPH radical scavenging assay, antimicrobial activity in vitro against three gram-positive bacteria (Staphylococcus aureus, Micrococcus luteus and Bacillus cereus) and three gram-negative bacteria (Escherichia coli, Pseudomonas fluorescens and Flavobacterium devorans as well as three fungi (Aspergillus niger, Penicillium chrysogenum and Curvularia lunata). The bioactive assay showed that some synthesized coumarin triazoles displayed comparable or even better antitubercular, antioxidant, antibacterial and antifungal efficacy in comparison with reference drugs. Furthermore, docking study has been performed against DprE1 enzyme of M. tuberculosis that showed good binding interactions. Moreover, the synthesized compounds were also analyzed for ADME properties and showed potential to build up as good oral drug candidates. Graphical Abstract: New coumarin-based 1,2,3-triazole derivatives were designed, synthesized and evaluated for their antitubercular, antioxidant, antibacterial and antifungal activity. Some of the coumarin-based triazole derivatives displayed comparable or even better efficacy in comparison with reference drugs. Molecular docking study has been performed against DprE1 enzyme of Mycobacterium tuberculosis showed good binding interactions.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Shingate, Bapurao B.,Kalam Khan, Firoz A.,Sangshetti, Jaiprakash N.,Khedkar, Vijay M.,Nawale, Laxman,Sarkar, Dhiman,Navale, Govinda R.,Shinde, Sandip S.
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p. 790 - 804
(2016/03/08)
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- 1,2,3-Triazole tethered acetophenones: Synthesis, bioevaluation and molecular docking study
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A small focused library of eighteen new 1,2,3-triazole tethered acetophenones has been efficiently prepared via click chemistry approach and evaluated for their antifungal and antioxidant activity. The antifungal activity was evaluated against five human pathogenic fungal strains: Candida albicans, Fusarium oxysporum, Aspergillus flavus, Aspergillus niger, and Cryptococcus neoformans. Among the synthesized compounds, 9c, 9i, and 9p found to be more potent antifungal agents that the reference standard. These 1,2,3-triazole based derivatives were also evaluated for antioxidant activity, and compound 9h was found to be the most potent antioxidant as compared to the standard drug. Furthermore, molecular docking study of the newly synthesized compounds was performed and results showed good binding mode in the active site of fungal C. albicans enzyme P450 cytochrome lanosterol 14α-demethylase. Moreover, the synthesized compounds were also analyzed for ADME properties and showed potential as good oral drug candidates.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Khedkar, Vijay M.,Jha, Prakash C.,Khan, Firoz A. Kalam,Sangshetti, Jaiprakash N.,Shingate, Bapurao B.
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p. 1058 - 1063
(2016/07/29)
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- 1,2,3-Triazole incorporated coumarin derivatives as potential antifungal and antioxidant agents
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A series of novel ethyl-7-((1-(benzyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-oxo-2H-chromene-3-carboxylates 8a-h as potential antifungal agents were synthesized via click chemistry. The antifungal activity was evaluated against five human pathogenic fungal strains, such as Candida albicans, Fusarium oxysporum, Aspergillus flavus, Aspergillus niger and Cryptococcus neoformans. Compound 8c, 8d, 8e and 8h were found to be equipotent against C. albicans when compared with miconazole and compound 8f was found to be two-fold more active compared with miconazole and equipotent to fluconazole against C. albicans. The coumarin-based triazole derivatives were also evaluated for antioxidant activity and compound 8a was found to be potent antioxidant when compared with standard drug. Furthermore, molecular docking study of the newly synthesized compounds was performed and results showed good binding mode in the active site of fungal C. albicans enzyme P450 cytochrome lanosterol 14α-demethylase. Moreover, the synthesized compounds were also analyzed for ADME properties and showed potential to build up as good oral drug candidates.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Khan, Firoz A. Kalam,Sangshetti, Jaiprakash N.,Shingate, Bapurao B.
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p. 295 - 301
(2018/03/22)
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- An efficient and selective method for the iodination and bromination of alcohols under mild conditions
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A straightforward and effective procedure for the conversion of a variety of alcohols into the corresponding alkyl iodides and bromides is described using KX/P2O5 (X = I, Br). The reactions were easily carried out in acetonitrile under mild conditions. Using this method, the selective conversion of benzylic alcohols in the presence of aliphatic alcohols was achieved.
- Khazdooz, Leila,Zarei, Amin,Aghaei, Hamidreza,Azizi, Ghobad,Gheisari, Mohammad Mehdi
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p. 168 - 171
(2015/12/30)
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- A mild and highly chemoselective iodination of alcohol using polymer supported DMAP
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The synthesis of organic compounds using polymer supported catalysts and reagents, where the required product is always in solution, has been of great interest in recent years, both in industries and academia especially in pharmaceutical research. Here, a simple and efficient method for conversion of alcohols into their iodides in high yield using polymer supported 4-(Dimethylamino)pyridine (DMAP) is described. Polymer supported DMAP is used in catalytic amount and is recovered and reused several times. Additionally, this method is highly chemoselective. [Figure not available: see fulltext.]
- Das, Diparjun,H Anal, Jasha Momo,Rokhum, Lalthazuala
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p. 1695 - 1701
(2017/03/08)
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- Synthesis and bioactivity of novel triazole incorporated benzothiazinone derivatives as antitubercular and antioxidant agent
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In search of new active molecules against Mycobacterium tuberculosis (MTB) H37Ra and M. bovis BCG, a small focused library of benzothiazinone based 1,2,3-triazoles has been efficiently prepared via click chemistry approach. Several derivatives were found to be promising inhibitors of MTB and M. bovis BCG characterized by lower MIC values (27.34-29.37 μg/mL). Among all the synthesized compounds, 6c and 6e is the most active compound against MTB and M. bovis BCG. The compounds were further tested for anti-proliferative activity against HeLa, A549 and A431 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antioxidant activity with IC50 range = 14.14-47.11 μg/mL. Furthermore, to rationalize the observed biological activity data, the molecular docking study also been carried out against a potential target MTB DprE1, which revealed a significant correlation between the binding score and biological activity for these compounds. The results of the in vitro and in silico study suggest that the triazole incorporated benzothiazinone may possess the ideal structural requirements for further development of novel therapeutic agents.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Arkile, Manisha,Khedkar, Vijay M.,Jadhav, Nandadeep,Sarkar, Dhiman,Shingate, Bapurao B.
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supporting information
p. 561 - 569
(2016/01/09)
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- Structure-based optimization leads to the discovery of NSC765844, a highly potent, less toxic and orally efficacious dual PI3K/mTOR inhibitor
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The phosphoinositide 3-kinase (PI3K) family is one of the most frequently activated enzymes in a wide range of human cancers; thus, inhibition of PI3K represents a promising strategy for cancer therapy. Herein, a series of benzylamine substituted arylsulfonamides were designed and synthesized as dual PI3K/mTOR inhibitors using a strategy integrating focused library design and virtual screening, resulting in the discovery of 13b (NSC765844). The compound 13b exhibits highly potent enzyme inhibition with IC50s of 1.3, 1.8, 1.5, 3.8 and 3.8?nM for PI3Kα, β, γ, δ, and mTOR, respectively. 13b was further evaluated in NCI by an in?vitro cytotoxic screening program. Broad-spectrum antitumor activities with mean GI50value of 18.6?nM against approximately 60 human tumor cell lines were found. 13b displayed favorable physicochemical properties and superior pharmacokinetic profiles for animal studies. It significantly inhibited tumor growth when administered orally in an A549 non-small-cell lung carcinoma xenograft and BEL7404 human hepatocellular carcinoma xenograft models. On the basis of its excellent in?vivo efficacy and superior pharmacokinetic profiles, 13b has been selected for further preclinical investigation as a promising anticancer drug candidate.
- Han, Jinsong,Chen, Ying,Yang, Chao,Liu, Ting,Wang, Mingping,Xu, Haojie,Zhang, Ling,Zheng, Canhui,Song, Yunlong,Zhu, Ju
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p. 684 - 701
(2016/07/21)
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- Synthesis and biological evaluation of aryloxyacetamide derivatives as neuroprotective agents
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A series of new aryloxyacetamide derivatives 10a-s and 14a-m are designed and synthesized. Their protective activities against the glutamate-induced cell death were investigated in differentiated rat pheochromocytoma cells (PC12 cells). Most compounds exhibited neuroprotective effects, especially for 10m, 10r, 14b and 14c, which showed potential protection of PC12 cells at three doses (0.1, 1.0, 10 μM). MTT assay, Hoechst 33342/PI double staining, and high content screening (HCS) revealed that pretreatment of the cells with 10m, 10r, 14b and 14c has significantly decreased the extent of cell apoptosis in a dose-dependent manner. The results of western blot analysis demonstrated these compounds suppressed apoptosis of glutamate-induced PC12 cells via caspase-3 pathway. These compounds can be lead compounds for further discovery of neuroprotective agents for treating cerebral ischemic stroke. Basic structure-activity relationships are also presented.
- Zhong, Yan,Xu, Yi,Zhang, Ai-Xia,Li, Xiao-Feng,Xu, Zhao-Ying,Li, Ping,Wu, Bin
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p. 2526 - 2530
(2016/07/07)
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- Dual roles for promoting monomers to polymers: A conjugated sulfonium salt photoacid generator as photoinitiator and photosensitizer in cationic photopolymerization
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An efficient strategy for comprehensive utilization of the conjugated sulfonium salt photoacid generator (PAG), namely, 3-{4-[4-(4-N,N′-diphenylamino)-styryl]phenyl}phenyl dimethyl sulfonium hexafluoroantimonate, was developed through photoinitiated cationic photopolymerization (CP) of epoxides and vinyl ether upon exposure to near-UV and visible light-emitting diodes (LEDs; e.g., 365, 385, 405, and 425 nm). Photochemical mechanisms were investigated by UV–vis spectra, molecular orbital calculations, fluorescence, cyclic voltammetry, and electron spin resonance spin-trapping analyses. Compared with commercial PAGs, the prepared conjugated sulfonium salt generated H+, which can be used as photoinitiator. Moreover, the fluorescent byproducts from photodecomposition can be used as photosensitizer of commercial iodonium salt in the photoinitiating systems of CP. These novel D-π-A type sulfonium-based photoinitiating systems are efficient (epoxide conversion = 85–90% and vinyl conversion >90%; LEDs upon exposure to 365–425 nm) even in low-concentration initiators (1%, w/w) and low curing light intensities (10–40 mW cm?2).
- Jin, Ming,Wu, Xingyu,Malval, Jean Pierre,Wan, Decheng,Pu, Hongting
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p. 2722 - 2730
(2016/07/28)
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- Conjugated type sulfonium salt photoinitiator with double functions of photoinitiator and photosensitizer, preparation method and application of conjugated type sulfonium salt photoinitiator
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The invention relates to a conjugated type sulfonium salt photoinitiator with double functions of a photoinitiator and a photosensitizer, a preparation method and an application of the conjugated type sulfonium salt photoinitiator. The conjugated type sulfonium salt photoinitiator is applicable to excitation from near ultraviolet regions with wavelength of 313 nm, 365 nm, 385 nm, 405 nm and 425 nm to a visible region, so that efficient polymerization of various monomers is initiated; synthesis steps of the photoinitiator are simple, the purification is easy, the yield is high, and in the region of 300 nm-425 nm, the optical absorption property is good and the initiation efficiency is high; a product obtained after decomposition can further be taken as the photosensitizer and combined with commercial photoinitiators such as iodonium salt, sulfonium salt and the like to form an efficient photosensitization-initiated binary polymerization system, and the polymerization efficiency is higher; according to the application of the conjugated type sulfonium salt photoinitiator and photosensitizer to a photopolymerization system, cheap LEDs can be taken as excitation light sources in the near ultraviolet region-visible region, the initiating system has the advantages of low addition quantity, high initiation efficiency and wide light source application range, and resource conservation can be realized.
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Paragraph 0021
(2016/12/01)
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- Clay-Supported Cu(II) Catalyst: An Efficient, Heterogeneous, and Recyclable Catalyst for Synthesis of 1,4-Disubstituted 1,2,3-Triazoles from Alloxan-Derived Terminal Alkyne and Substituted Azides Using Click Chemistry
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A novel series of alloxan-derived 1,4-disubstituted 1,2,3-triazoles was synthesized in excellent yields under catalytic conditions using a click reaction strategy through 1,3-dipolar cycloaddition. Their structures have been ascertained on the basis of spectroanalytical and elemental analysis data. Synthesis of hybrid compounds with varying substitutions in the triazole ring was achieved by reaction between alloxan-derived terminal alkyne and a pertinent azide derivative in the presence of clay-Cu(II) as the catalyst in methanolic medium. Also, comparative evaluation of various catalytic systems [viz., CuI, CuSO4, CuI-zeolite, K10Ti, and clay-Cu(II)] was investigated. Of these catalytic systems, clay-Cu(II) was observed to be the best. The catalyst was recyclable for several runs without showing significant loss in its activity. The good selectivity, cost-efficiency, short reaction time, milder reaction conditions, and simple workup procedure are the added salient features of this synthetic protocol.
- Dubey, Nitin,Sharma, Pratibha,Kumar, Ashok
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p. 2608 - 2626
(2015/11/28)
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- 1,2,3-Triazole derivatives as antitubercular agents: synthesis, biological evaluation and molecular docking study
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Searching for new active molecules against Mycobacterium tuberculosis (MTB) H37Ra, a small focused library of 1,2,3-triazoles has been efficiently prepared via a click chemistry approach. The newly synthesized compounds were tested against drug-sensitive MTB. Several derivatives were found to be promising inhibitors of MTB characterized by lower MIC values (5.8-29.9 μg mL-1). Among all the synthesized 31 compounds, 15e was the most active compound against MTB. Based on the results from the anti-tubercular activity, SAR for the synthesized series has been developed. The active compounds from the anti-tubercular study were further tested for anti-proliferative activity against THP-1, A549 and PANC-1 cell lines using MTT assay and showed no significant cytotoxic activity against these three cell lines except THP-1 at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antioxidant activities with an IC50 range of 10.1-37.3 μg mL-1. The molecular docking study of the synthesized compounds was performed against the DprE1 enzyme of MTB to understand the binding interactions. Moreover, the synthesized compounds were also analysed for ADME properties and all the experimental results promote us to consider this series as a starting point for the development of novel and more potent anti-tubercular agents in the future.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Nawale, Laxman,Sarkar, Dhiman,Kalam Khan, Firoz A.,Sangshetti, Jaiprakash N.,Shingate, Bapurao B.
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p. 1104 - 1116
(2015/06/25)
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- Application of "click" chemistry in solid phase synthesis of alkyl halides
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A convenient and highly selective microwave assisted procedure for the conversion of allylic, benzylic and aliphatic alcohols to their corresponding halides using polymer-bound triphenylphosphine and iodine is presented. In case of symmetrical diols, mono-iodination product is obtained in very high yield. Additionally, highly regioselective behavior is observed in our procedure. Simplicity in operation, no column chromatography required for the purification of the products, recyclability of the reagents used, short reaction times and good to excellent yields are the advantages of our protocol. Most functional groups remain unaffected under our reaction condition.
- Das, Diparjun,Chanda, Tridib,Rokhum, Lalthazuala
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p. 775 - 783
(2016/01/20)
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- Generation of α-imino gold carbenes through gold-catalyzed intermolecular reaction of azides with ynamides
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The generation of α-imino gold carbenes via gold-catalyzed intermolecular reaction of azides and ynamides is disclosed. This new methodology allows for highly regioselective access to valuable 2-aminoindoles and 3-amino-β-carbolines in generally good to excellent yields. A mechanistic rationale for this tandem reaction, especially for the observed high regioselectivity, is supported by DFT calculations.
- Shu, Chao,Wang, Yong-Heng,Zhou, Bo,Li, Xin-Ling,Ping, Yi-Fan,Lu, Xin,Ye, Long-Wu
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supporting information
p. 9567 - 9570
(2015/08/18)
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- P(NMe2)3-Mediated Umpolung Alkylation and Nonylidic Olefination of α-Keto Esters
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A commercial phosphorus-based reagent (P(NMe2)3) mediates umpolung alkylation of methyl aroylformates with benzylic and allylic bromides, leading to either Barbier-type addition or ylide-free olefination products upon workup. The reaction sequence is initiated by a two-electron redox addition of the tricoordinate phosphorus reagent with an α-keto ester compound (Kukhtin-Ramirez addition). A mechanistic rationale is offered for the chemoselectivity upon which the success of this nonmetal mediated C-C bond forming strategy is based.
- Wang, Sunewang Rixin,Radosevich, Alexander T.
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supporting information
p. 3810 - 3813
(2015/08/18)
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- Synthesis and photophysical properties of triphenylamine-based multiply conjugated star-like molecules
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Novel triphenylamine-based star-like molecules 11 were synthesized and characterized using FT-IR, 1H, 13C, and DEPT-135 NMR spectroscopy, and MALDI-TOF mass spectrometry. The absorption and emission spectra of star-like molecules were studied in different solvents. The effect of solvent polarity and aggregation studies on the absorption and emission spectra has also been studied. The new star-like molecules are found to exhibit broad absorption and emission band along with intramolecular charge transfer character. The fluorescence spectra of triphenylamine derivatives shift from blue to green wavelength on increasing the extended conjugation of the molecule. The experimental results indicate that there is cooperative enhancement originating from the inter-branch coupling and an increase in the light-harvesting ability upon increasing the conjugated molecule size.
- Balasaravanan, Rajendiran,Duraimurugan, Kumaraguru,Sivamani, Jayaraman,Thiagarajan, Viruthachalam,Siva, Ayyanar
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p. 7472 - 7480
(2015/09/02)
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- Method of manufacturing hydroxybenzenesulfonic deriv. Halomethylation
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PROBLEM TO BE SOLVED: To provide a method for producing a halomethylbenzene derivative by halogenating a methylbenzene derivative at the benzyl position, which is industrially achievable. SOLUTION: In the method for producing a halomethylbenzene derivative represented by formula (2) (wherein R1-R5are each independently a hydrogen atom, tert-butyl, phenyl or the like; X, Y and Z are each independently a halogen atom; p and q are each independently 0, 1 or 2; z is 1, 2 or 3 and p+q+z is 1, 2 or 3) by halogenating a methylbenzene derivative by light or heat, halogenation is carried out in a chain fluorine-containing hydrocarbon or cyclic fluorine-containing hydrocarbon. COPYRIGHT: (C)2011,JPOandINPIT
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-
Paragraph 0034; 0043
(2016/10/20)
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- CuI-catalyzed coupling of gem-dibromovinylanilides and sulfonamides: An efficient method for the synthesis of 2-amidoindoles and indolo[1,2-a] quinazolines
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A Cu(I)-catalyzed, intermolecular protocol for the synthesis of 2-amidoindoles and tetrahydroindolo[1,2-a]quinazolines in shorter time and high yields is reported. The key highlight of this disclosure is the formation of 2-amidoindole and tetrahydroindolo[1,2-a]quinazoline moieties directly from gem-dibromovinylanilides and sulfonamides in a one-pot fashion through the in situ formation of ynamides followed by a base-promoted intramolecular hydroamidation.
- Kiruthika, Selvarangam E.,Perumal, Paramasivan Thirumalai
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p. 484 - 487
(2014/04/03)
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- Synthesis of pyrrolo-/indolo[1,2-a ]quinolines and naphtho[2,1- b ]thiophenes from gem -dibromovinyls and sulphonamides
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A highly efficient and simple route for the synthesis of pyrrolo-/indolo[1,2-a]quinolines and naphtho[2,1-b]thiophenes from gem-dibromovinyls and sulphonamides is reported. The noteworthy feature of this report is that the methodology involves a two-step protocol to synthesize tri- and tetracyclic heterocycles in a one-pot fashion through the Cu(I)-catalyzed formation of ynamide followed by a Ag(I)-assisted intramolecular hydroarylation. The photophysical properties of representative examples of pyrrolo- and indolo[1,2-a]quinolines in solid and solution states have also been studied.
- Kiruthika, Selvarangam E.,Nandakumar, Avanashiappan,Perumal, Paramasivan Thirumalai
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p. 4424 - 4427
(2015/02/05)
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- Rasta resin-triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions
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Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as reagent precursors in a wide range of halogenation reactions. The rasta resin-triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form halogenated products in high yields after simple purification. The polymersupported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity.
- Xia, Xuanshu,Toy, Patrick H.
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supporting information
p. 1397 - 1405
(2014/07/22)
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- Nuclear versus side-chain bromination of 4-methoxy toluene by an electrochemical method
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GRAPHICAL ABSTRACT The electrochemical bromination of 4-methoxy toluene by two-phase electrolysis yields 3-bromo 4-methoxy toluene at first, which subsequently undergoes side-chain bromination to give 3-bromo 4-methoxy benzyl bromide as a final product in 86% yield. The two-phase electrolysis consists of 25-50% NaBr as aqueous electrolyte and CHCl3 containing aromatic compound as organic phase. The reaction temperature is maintained at 10-25 °C. The probable orientation of bromine atom in an alkyl aromatic compound (nuclear versus side chain) is explained from the experimental result.
- Kulangiappar,Anbukulandainathan,Raju
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p. 2494 - 2502
(2014/08/05)
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- A scalable procedure for light-induced benzylic brominations in continuous flow
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A continuous-flow protocol for the bromination of benzylic compounds with N-bromosuccinimide (NBS) is presented. The radical reactions were activated with a readily available household compact fluorescent lamp (CFL) using a simple flow reactor design based on transparent fluorinated ethylene polymer (FEP) tubing. All of the reactions were carried out using acetonitrile as the solvent, thus avoiding hazardous chlorinated solvents such as CCl4. For each substrate, only 1.05 equiv of NBS was necessary to fully transform the benzylic starting material into the corresponding bromide. The general character of the procedure was demonstrated by brominating a diverse set of 19 substrates containing different functional groups. Good to excellent isolated yields were obtained in all cases. The novel flow protocol can be readily scaled to multigram quantities by operating the reactor for longer time periods (throughput 30 mmol h-1), which is not easily possible in batch photochemical reactors. The bromination protocol can also be performed with equal efficiency in a larger flow reactor utilizing a more powerful lamp. For the bromination of phenylacetone as a model, a productivity of 180 mmol h -1 for the desired bromide was achieved.
- Cantillo, David,De Frutos, Oscar,Rincon, Juan A.,Mateos, Carlos,Oliver Kappe
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supporting information
p. 223 - 229
(2014/01/17)
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- One-pot transformation of methylarenes into aromatic aldehydes under metal-free conditions
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On the basis of studies of the transformation of benzylic bromides into the corresponding aromatic aldehydes by treatment with N-methylmorpholine N-oxide, various methylarenes were treated either with DBDMH in the presence of AIBN in acetonitrile at reflux (Method A) or with NBS in CCl4 under irradiation with a tungsten lamp at 30 °C (Method B), followed by treatment with N-methylmorpholine N-oxide to provide aromatic aldehydes in good yields. These methods could be adopted in one-pot transformations of methylarenes into aromatic aldehydes under conditions free of less toxic reagents and transition metals. Copyright
- Tabata, Masayuki,Moriyama, Katsuhiko,Togo, Hideo
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p. 3402 - 3410
(2014/06/09)
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- Enabling nucleophilic substitution reactions of activated alkyl fluorides through hydrogen bonding
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It was discovered that the presence of water as a cosolvent enables the reaction of activated alkyl fluorides for bimolecular nucleophilic substitution reactions. DFT calculations show that activation proceeds through stabilization of the transition structure by a stronger F···H 2O interaction and diminishing C-F bond elongation, and not simple transition state electrostatic stabilization. Overall, the findings put forward a distinct strategy for C-F bond activation through H-bonding.
- Champagne, Pier Alexandre,Pomarole, Julien,Therien, Marie-Eve,Benhassine, Yasmine,Beaulieu, Samuel,Legault, Claude Y.,Paquin, Jean-Francois
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supporting information
p. 2210 - 2213
(2013/06/26)
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- Synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters from arylmethyl azides via a domino process
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A convenient synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters via a domino process is described. The synthesis employs arylmethyl azides as the precursor which undergoes an acid-promoted rearrangement to give an N-aryl iminium ion. Following the addition with ethyl 3-ethoxyacrylate, intramolecular electrophilic aromatic substitution, elimination and subsequent oxidation, the quinoline products were obtained in moderate to excellent yields.
- Tummatorn, Jumreang,Thongsornkleeb, Charnsak,Ruchirawat, Somsak,Gettongsong, Tanita
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supporting information
p. 1463 - 1467
(2013/05/08)
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- Direct oxidative conversion of methylarenes into aromatic nitriles
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A variety of methylarenes were successfully converted into the corresponding aromatic nitriles in good to moderate yields by the treatment with NBS or DBDMH in the presence of a catalytic amount of AIBN or BPO, followed by the reaction with molecular iodine in aq NH3 in a one-pot procedure. The present reaction is a useful and practical transition-metal-free method for the preparation of aromatic nitriles from methylarenes.
- Tsuchiya, Daisuke,Kawagoe, Yuhsuke,Moriyama, Katsuhiko,Togo, Hideo
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supporting information
p. 4194 - 4197
(2013/09/12)
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- Polyvinylpyrrolidone-bromine complex: An efficient polymeric reagent for selective preparation of benzyl bromides in the presence of hexamethyldisilane
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Benzylic bromides were conveniently obtained in high yields via the reaction of the corresponding alcohols with crosslinked polyvinylpyrrolidone- bromine complex (PVPP-Br2)/hexamethyldisilane in chloroform at reflux condition. Selective conversion of benzyl alcohol to benzyl bromide in the presence of primary aliphatic alcohols, e.g. 2-phenylethanol was also achieved.
- Mokhtary, Masoud,Lakouraj, Moslem M.
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p. 305 - 309
(2012/10/29)
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- X-Ray structure determinations of bromo and/or bromomethylsubstituted benzenes: C-H···Br, C-Br···Br, and C-Br···p interactions
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The structures of seven benzene derivatives [1,2,3-tri(bromomethyl)benzene, (1); 3,5-di(bromomethyl)bromobenzene, (2); 2,5-di(bromomethyl)bromobenzene, (3); 4-(bromomethyl)-2,5-dibromotoluene, (4); 4-(bromomethyl)bromobenzene, (5); 2,3-di(bromomethyl)bromobenzene, (6) and (bromomethyl)-p-dibromobenzene, (7)] with bromo and bromomethyl (and in one case methyl) substituents are presented and analysed in terms of Br···Br interactions up to 4.0 A , supported by hydrogen bonds H···Br. Some interactions of the type Br···π and π·· · π are encountered and play a subordinate role in the packing. Despite the close chemical similarity of the compounds, some of which are isomers with permuted substituent positions, the packing motifs are highly variable. Compounds 2-5 are based on layer structures with Brn (n=3, 4) and/or mixed Br/C rings. Compounds 1, 6 and 7 display three-dimensional packings of differing complexity, but with interpretable substructures; 1 can be analysed in terms of ribbons of linked Br3 and Br4 rings; 6 displays chains of linked Br3 triangles; 7 consists of ribbons of linked Br4 quadrilaterals.
- Jones, Peter G.,Kus, Piotr,Dix, Ina
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p. 1273 - 1281
(2013/02/23)
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- Microwave-assisted benzyl mono- and dibromination in diethyl carbonate as environmentally friendly alternative to radical bromination in carbon tetrachloride
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An environmentally friendly benzyl mono- and di-bromination synthetic procedure was developed that is superior to the classic carbon tetrachloride bromination procedure in both reaction time and isolated yield. This new reaction was performed in diethyl carbonate as reaction media using microwave instead of conventional heating. Both the solvent and the brominating reagent N-bromosuccinimide (prepared from succinimide obtained from the reaction mixture) are recyclable. Practically, the preparation of our target compounds was completed in less than two hours. The Royal Society of Chemistry.
- Pingali, Subramanya R. K.,Upadhyay, Sunil K.,Jursic, Branko S
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experimental part
p. 928 - 933
(2011/05/15)
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- N-Halosuccinimide/SiCl4 as general, mild and efficient systems for the α-monohalogenation of carbonyl compounds and for benzylic halogenation
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Combinations of N-halosuccinimide and tetrachlorosilane in acetonitrile were found to be efficient systems for the selective α-monohalogenation of carbonyl compounds as well as for benzylic halogenation under mild conditions.
- Salama, Tarek A.,Novák, Zoltán
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experimental part
p. 4026 - 4029
(2011/08/09)
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