- In Situ Synthesized Silica-Supported Co@N-Doped Carbon as Highly Efficient and Reusable Catalysts for Selective Reduction of Halogenated Nitroaromatics
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Silica-supported Co@N-doped carbon (Co@CN/SiO2) catalysts were first prepared by a one-step impregnation with a mixed solution of cobalt nitrate, glucose and urea, followed by in situ carbonization and reduction. The Co@CN/SiO2 catalysts were investigated for the selective reduction of nitro aromatics to the corresponding anilines using hydrazine hydrate. The Co@CN/SiO2-500 carbonized at 500 °C exhibited the highest catalytic activity and excellent stability without any decay of activity after 6 cycles for the reduction of nitrobenzene. Both metallic Co atoms and Co?N species formed in the Co@CN/SiO2 catalysts were active, but the Co?N species were dominant active sites. The high activities of the Co@CN/SiO2 catalysts were attributed to the synergistic effect between the Co and N atoms, promoting heterolytic cleavage of hydrazine to form H+/H? pairs. Representative examples demonstrated that the Co@CN/SiO2-500 could completely transform various halogen-substituted nitro aromatics to the corresponding halogenated anilines with high TOFs and selectivity of '99.5 percent.
- Sheng, Yao,Wang, Xueguang,Yue, Shengnan,Cheng, Gonglin,Zou, Xiujing,Lu, Xionggang
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p. 4632 - 4641
(2020/07/30)
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- Novel cathepsin K inhibitors block osteoclasts in vitro and increase spinal bone density in zebrafish
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Cathepsin K (Cat K) is a predominant cysteine protease and highly potent collagenase expressed in osteoclasts. Cat K inhibitors are anti-resorptive agents to treat osteoporosis. A novel scaffold of cathepsin K inhibitors, exemplified by lead compound 1x, was used as the template for designing and synthesizing a total of 61 derivatives that have not been reported before. An exploratory structure-activity relationship analysis identified the potent Cat K inhibitor A22, which displayed an IC50 value of 0.44 μM against Cat K. A22 was very specific for Cat K and caused a significantly higher in vitro inhibition of the enzyme as compared to that of lead compound 1x. A surface plasmon resonance analysis confirmed in vitro binding of A22 to Cat K. Molecular docking studies indicated several favourable interaction sites for A22 within the active pocket of Cat K. Furthermore, A22 also blocked active osteoclasts in vitro and increased spinal bone density in zebrafish, in which it showed an activity that was higher than that of the marketed therapeutic bone metabolizer etidronate disodium. A22 represents a very promising lead compound for the development of novel antiresorptive agents functioning as orthosteric inhibitors of Cat K.
- Xue, Si-Tu,Wang, Ya-Li,Han, Xiao-Wan,Yi, Hong,Jiang, Wei,Si, Shu-Yi,Guo, Hui-Fang,Li, Zhuo-Rong
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p. 8600 - 8607
(2019/03/21)
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- Preparation of Well-Ordered Mesoporous-Silica-Supported Ruthenium Nanoparticles for Highly Selective Reduction of Functionalized Nitroarenes through Transfer Hydrogenation
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MCM-41-type mesoporous silica (OMS-IL) was prepared by using an ionic liquid (1-hexadecyl-3-methylimidazolium bromide) as a template. The XRD and TEM results demonstrated that OMS-IL was more stable than the MCM-41 material. Ru nanoparticles were supported on OMS-IL (Ru/OMS-IL) by impregnating OMS-IL with a RuCl3 aqueous solution, and the resulting material was used for the selective reduction of nitroarenes. The effects of the components of the catalysts and the reaction conditions on the catalytic behavior of the prepared catalysts were investigated in detail. Ru/OMS-IL exhibited high catalytic activity and chemoselectivity for the reduction of various substituted nitroarenes to the corresponding aromatic amines in ethanol with hydrazine hydrate as a hydrogen donor under mild conditions. The Ru/OMS-IL catalysts were highly stable and could easily be recovered by simple filtration over at least six recycling reactions without any observable loss in catalytic performance.
- Wei, Ning,Zou, Xiujing,Huang, Haigen,Wang, Xueguang,Ding, Weizhong,Lu, Xionggang
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supporting information
p. 209 - 214
(2018/01/26)
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- N-doped graphitic carbon-improved Co-MoO3 catalysts on ordered mesoporous SBA-15 for chemoselective reduction of nitroarenes
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Metallic Co-MoO3 catalysts supported on ordered mesoporous SBA-15 were first prepared through in situ reaction of SBA-15-supported Co-Mo oxides with 1,10-phenanthroline. The resulting Co-MoO3/NC@SBA-15 catalysts with N-doped carbon (NC) exhibited high catalytic activity and chemoselectivity for selective reduction of various functionalized nitroarenes to the corresponding arylamines in ethanol with hydrazine hydrate at near room temperature (30 °C). For reduction of all tested substrates (28 examples), the catalyst could afford a conversion of >99% and arylamine selectivity of >99%. The excellent catalytic performance of the Co-MoO3/NC@SBA-15 was attributed to the Co-Nχ(C)-Mo active sites generated through the interaction between the surface Co-Nχ(C) and MoO3 species, promoting the dissociation of hydrazine molecule into the active H* species for the reduction of nitro groups. After the seventh cycle for reduction of 4-methoxylnitrobenzene, the 2%Co-MoO3/NC@SBA-15 showed little change in catalytic performance, textural properties, size and dispersion of metal species and valence states of elements, indicating high stability and recyclability.
- Huang, Haigen,Liang, Xiangcheng,Wang, Xueguang,Sheng, Yao,Chen, Chenju,Zou, Xiujing,Lu, Xionggang
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p. 127 - 137
(2018/05/04)
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- Fluorine-18 labeling of ML04 - Presently the most promising irreversible inhibitor candidate for visualization of EGFR in cancer
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Overexpression of the EGFR has been linked to cell malignancy, metastasis and poor prognosis thus making it a target for several FDA approved drugs such as Gefitinib and Erlotinib. Unfortunately, these drugs have yielded suboptimal clinical results. In order to evaluate and monitor EGFR-targeted treatment response at the molecular level, several PET biomarkers have been developed. One of the lead irreversible inhibitors (1) has been labeled with carbon-11, however the short half-life of this radioisotope limited the time window for in vivo studies. Compound 1 was successfully labeled with fluorine-18 via a multi-step radiosynthesis with 14% decay-corrected overall radiochemical yield, 98% radiochemical purity, specific activity of 1800 Ci/mmol (n = 10) at end of bombardment, and a total radiosynthesis time of 4h including purification and formulation. [18F]-1 will allow for prolonged in vivo studies including Micro-PET analysis of EGFR tumor-bearing animal models. Copyright
- Dissoki, Samar,Laky, Desideriu,Mishani, Eyal
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p. 533 - 543
(2007/10/03)
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- Synthesis and antiparasitic activity of 2-(Trifluoromethyl)benzimidazole derivatives
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2-(Trifluoromethyl)benzimidazole derivatives substituted at the 1-, 5-, and 6-positions have been synthesized and in vitro tested against the protozoa Giardia lamblia, Entamoeba histolytica, and the helminth Trichinella spiralis. Results indicate that all the compounds tested are more active as antiprotozoal agents than Albendazole and Metronidazole. One compound (20) was as active as Albendazole against T. spiralis. These compounds were also tested for their effect on tubulin polymerization and none inhibited tubulin polymerization.
- Navarrete-Vazquez, Gabriel,Cedillo, Roberto,Hernandez-Campos, Alicia,Yepez, Lilian,Hernandez-Luis, Francisco,Valdez, Juan,Morales, Raul,Cortes, Rafael,Hernandez, Manuel,Castillo, Rafael
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p. 187 - 190
(2007/10/03)
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- Design, synthesis, and antiviral evaluations of 1-(substituted benzyl)- 2-substituted-5,6-dichlorobenzimidazoles as nonnucleoside analogues of 2,5,6- trichloro-1-(β-D-ribofuranosyl)benzimidazole
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We have recently reported that certain ribosylated polyhalogenated benzimidazoles are potent and selective inhibitors of HCMV replication at noncytotoxic concentrations. To extend the structure-activity relationship beyond these first-generation compounds, we alkylated 5,6dichloro-2- substituted-benzimidazoles with either a series of substituted benzyl halides or (2bromoethyl)benzene to obtain five series of nonnucleoside analogues. Evaluation of these compounds for activity against herpes viruses revealed that the new compounds were less active than the benzimidazole ribonucleosides against human cytomegalovirus (HCMV) and inactive against herpes simplex virus type 1 (HSV-1). However, as part of our broader antiviral testing, we found that some of these compounds were active against HIV. Comparisons of the biological data revealed that a chloro or bromo group was required at the 2-position for the best separation of activity against HIV and cytotoxicity. Evaluation of the most active compounds against drug- resistant HIV suggested that they act by a mechanism other than inhibition of reverse transcriptase.
- Porcari, Anthony R.,Devivar, Rodrigo V.,Kucera, Louis S.,Drach, John C.,Townsend, Leroy B.
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p. 1252 - 1262
(2007/10/03)
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- Synthesis and antiviral evaluation of 2-mercapto-5,6- dichlorobenzimidazole-β-D-ribofuranonucleoside derivatives
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2-Mercapto-5,6-dichlorobenzimidazole β-D-ribofuranonucleoside derivatives 8 - 10 have been synthesized and their antiviral properties examined. According to the glycosylation procedure used, the β-D-N-1 isomer (and the N,N-bis-riboside) or the β-D-S2-isomer have been obtained. All the prepared compounds were tested for their activity against a variety of RNA and DNA viruses, but they did not show significant antiviral activity.
- Mathe,Perigaud,Gosselin,Imbach
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p. 437 - 446
(2007/10/02)
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- Process for the manufacture of benzimidazolones-(2)
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Process for the manufacture of benzimidazolones-(2) wherein an o-phenylenediamine is reacted with optionally alkylated urea in the ratio of 1 to 1.3 moles per mole o-phenylenediamine in an organic solvent which has a solubility in water of not more than 5 g/l and has a boiling point above 100° C, at a temperature between 100° and 200° C.
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- Alkyl 4-(o-aminophenyl)-3-thioallophanates
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Various alkyl 4-(o-aminophenyl)-3-thioallophanates and alkyl 4-(o-alkylaminophenyl)-3-thioallophanates are useful as fungicides and mite ovicides. The compounds are prepared by reacting an o-phenylenediamine with the appropriate alkoxycarbonylisothiocyanate and an exemplary species is methyl 4-(o-aminophenyl)-3-thioallophanate.
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