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272 results on '"Mao, Guojiang"'

62. Direct Synthesis of Fused Thienoindoles via Base Promoted Double C−H Sulfuration with Elemental Sulfur.

Author

Chen, Shanping, Hu, Kai, Feng, Wei, Mao, Guojiang, Li, Yuxia, and Deng, Guo‐Jun

Subjects
SULFURATION, SULFUR, DOUBLE bonds, SCHIFF bases, INDOLE, PHARMACEUTICAL industry, INDOLE compounds
Abstract

A direct strategy for the preparation of fused thienoindoles from substituted indoles and elemental sulfur has been reported. The present approach produces a range of structurally valuable fused thienoindoles in 51–78% yield under transition‐metal‐free conditions, which may have potential applications in pharmaceutical industry and organic functional materials. In this work, the double C−S bonds formation is achieved via base promoted direct sulfuration of C−H bonds with elemental sulfur. [ABSTRACT FROM AUTHOR]

Published
2023
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63. Rhodium(III)-catalyzed mild and regioselective dearomative spirocyclization of 2-aryl-3-nitrosoindoles with alkynes.

Author

Li, Cheng, Zhao, Bin, Mao, Guojiang, and Deng, Guo-Jun

Subjects
ALKYNES, RHODIUM, RING formation (Chemistry), OXIMES
Abstract

Herein, we develop a Rh(III)-catalyzed intermolecular regioselective dearomative spirocyclization of 2-aryl-3-nitrosoindoles with alkynes, featuring the redox-neutral and atom-economic construction of spiroindoline-3-one oximes bearing a C2 spirocyclic quaternary carbon center under mild conditions. Both aryl alkyl alkynes and 1,3-diynes generally proceeded smoothly in the reaction with moderate to good regioselectivities. DFT calculations provided in-depth insights into the reaction mechanism and disclosed the origins of the regioselectivities. [ABSTRACT FROM AUTHOR]

Published
2023
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70. Four-Component Synthesis of 9 H -Pyrimido[4,5- b ]indoles Using Ammonium Iodide as the Nitrogen Source.

Author

Chen, Yufeng, Yang, Ruitong, Xiao, Fuhong, Li, Tong, Mao, Guojiang, and Deng, Guo-Jun

Subjects
INDOLE compounds, INDOLE, IODIDES, AROMATIC aldehydes, AMMONIUM, NITROGEN
Abstract

A four-component synthesis of 2-phenyl-9H-pyrimido[4,5-b]indoles was developed using indole-3-carboxaldehydes, aromatic aldehyde and ammonium iodide as the raw materials under transition-metal-free conditions. The pyrimidine ring was formed in one pot through [4 + 2] annulation reaction. Four C–N bonds were formed in one pot promoted by iodine and iodide additives. This work is highlighted by using two ammonium iodides as the sole nitrogen source. [ABSTRACT FROM AUTHOR]

Published
2023
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87. Polarization engineering of porous organic polymers for superior photocatalytic synthesis of disulfides and CO2 reduction.

Author

Huang, Xiaoyan, Lu, Yanling, Mao, Guojiang, Yin, Shiheng, Long, Bei, Deng, Guo-Jun, Ali, Atif, and Song, Ting

Abstract

The coupling of benzyl mercaptans to disulfide compounds is an important reaction in the production of pharmaceuticals, life medicine and other valuable fine chemicals. However, the coupling of benzyl mercaptans to disulfide compounds under aerobic and mild conditions remains a great challenge. Herein, we use cyclotriphosphazene as the basic skeleton to connect pyrimidine rings through ether bonds to form porous organic polymers (OBCPs). Research shows that OBCP samples not only exhibit fast carrier mobility, but also build up more negative reduction potential as well as low oxidation potential. In the photocatalytic reaction of benzyl mercaptans, OBCP sample generates the coupling of benzyl mercaptan to disulfide compounds rather than thiol oxidation products. Meanwhile, OBCPs also showed excellent photocatalytic reduction of CO2 to produce CH4. This work highlights that the dipole modulation of monomer molecules is important for designing polymers for excellent photocatalytic reactions. [ABSTRACT FROM AUTHOR]

Published
2022
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88. Determination of β-glucosidase activity using single-particle enumeration with Au@CeO2 nanoparticles.

Author

Yuan, Xiang, Zhang, Huiling, Cao, Huijuan, Mao, Guojiang, and Wei, Lin

Subjects
HYDROLASES, NANOPARTICLES, MICROSCOPY, DETECTION limit, NANOPARTICLES analysis, HYDROQUINONE
Abstract

A visible and sensitive assay for the quantitative detection of β-glucosidase (β-glu) activity based on Au@CeO2 core-shell nanoparticles (Au@CeO2 NPs) is described. As a hydrolytic enzyme, β-glu can promote the hydrolysis of β-arbutin to hydroquinone (HQ), which can trigger the decomposition of the CeO2 shell. With the single-particle enumeration (SPE) strategy coupled with dark field optical microscopy (DFM), an obvious color alteration of single Au@CeO2 NPs during the etching process can be observed in real-time. By statistically calculating the number of the etched nanoparticles, the β-glu activity level can be quantified accurately. This assay displays a broad linear range from 0.5 to 50 mU⋅mL−1 and low detection limit of 0.12 mU⋅mL−1. In addition, this method was successfully used to determine β-glu in real samples and acquires satisfactory recoveries in the range of 97.1-102.0%. This study provides a visualization analysis method for β-glu, which may be helpful for monitoring other targets in the future. [ABSTRACT FROM AUTHOR]

Published
2022
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89. CuBr2-Catalyzed Annulation of 2-Bromo-N-Arylbenzimidamide with Se/S8Powder for the Synthesis of Benzo[d]isoselenazole and Benzo[d]isothiazole

Author

Wang, Quanyuan, Xiao, Fuhong, Huang, Zhi, Mao, Guojiang, and Deng, Guo-Jun

Abstract

A CuBr2-catalyzed annulation of 2-bromo-N-arylbenzimidamide with selenium/sulfur powder for the synthesis of benzo[d]isoselenazole and benzo[d]isothiazole in generally good yields was investigated. This synthetic strategy features good substrate scope and functional group tolerance. Furthermore, the corresponding products could be converted into N-aryl indoles viarhodiumIII-catalyzed orthoC–H activation of the N-phenyl ring, providing an efficient approach for axial aromatic molecules.

Published
2023
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90. Ultrafast carrier transport in ultrafine porous 2D polymers for the highly selective photocatalytic reduction of CO2 to CH4.

Author

Tang, Guoen, Zhang, Huicong, Song, Ting, Yin, Shiheng, Mao, Guojiang, Long, Bei, Ali, Atif, and Deng, Guo-Jun

Abstract

The generation of high-calorific-value hydrocarbon fuels is still limited by poor photoinduced carrier transport in organic polymers. Herein, 2D polymers with different porous structures were synthesized by adopting a good-solvent/poor-solvent control strategy, and the photocatalytic CO2 reduction behavior was further compared. It was verified that the ultrafine porous structure in the 2D polymer (D1M4-PC) is responsible for the selective formation of CH4. The CH4 yield of the D1M4-PC sample reached 6733 μmol g−1, and the CH4 selectivity was near 100%. Experiments and theoretical calculations show that the ultrafine porous structure can provide an extremely short carrier transport distance and has accessible active sites, which enables the photoinduced carrier migration to the trapped CO2 molecules rapidly, enabling high selectivity photocatalytic CO2 conversion. This work offers a promising strategy for designing polymers for the conversion of CO2 into high-calorific-value hydrocarbon fuels with high selectivity and activity. [ABSTRACT FROM AUTHOR]

Published
2022
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91. Synthesis of Indenoquinolinones and 2-Substituted Quinolines via[4 + 2] Cycloaddition Reaction

Author

Yang, Gang, Yao, Lin, Mao, Guojiang, Deng, Guo-Jun, and Xiao, Fuhong

Abstract

We have reported a metal-free protocol for the synthesis of indenoquinolinones and 2-substituted quinolines via[4 + 2] cycloaddition reaction using readily available 2-aminobenzaldehydes and ketones as starting materials. Different quinoline derivatives can be selectively synthesized by changing the type of ketones. O2and dimethyl sulfoxide (DMSO) as co-oxidants play an important role in the synthesis of indenoquinolinones. This condensation/oxidation strategy involves the formation of C–N, C–C, and C–O bonds, with the advantages of high yields and a broad substrate range.

Published
2022
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95. Fabricating a wettable microwells array onto a nitrogen plasma-treated ITO substrate: high-throughput fluorimetric platform for selective sensing of ammonia in blood using polymer-stabilized NH2-MIL-125.

Author

Li, Pan, Zhang, Lixiang, Zhang, Sheng, Xu, Chenchen, Li, Yinuo, Qu, Juan, Li, Shuai, Mao, Guojiang, and Wang, Hua

Abstract

A high-throughput and selective fluorimetric platform has been constructed for the analysis of ammonia in blood by using a polymer-stabilized metal–organic framework (MOF) of porous NH2-MIL-125, which was coated onto a wettable microwells array constructed on an indium tin oxide (ITO) substrate. It was found that the nitrogen plasma treatment for the ITO substrate could create a super-hydrophilic interface that combined with the hydrophobic pattern yielded a wettable microwells array, enabling the condensation-based enrichment of targets from the sample droplets. Moreover, the NH2-MIL-125 MOF encapsulated using polymers could be firmly coated onto the microwells to act as fluorescent probes for sensing NH3 with enhanced responses. In addition, the use of the polymer polyvinyl pyrrolidone could protect and stabilize the crystals of NH2-MIL-125 probe in aqueous media, revealing the improved hydrophilicity and significantly depressed signal background. The as-developed fluorimetric platform, containing a MOF-coated microwells array, can enable the detection of ammonia in blood, with concentrations ranging linearly from 0.10 to 300 μM. More importantly, this plasma treatment-based fabrication route may hold promise for designing different wettable microwells arrays for the high-throughput detection of multiple targets in the fields of biomedical analysis and environmental monitoring. [ABSTRACT FROM AUTHOR]

Published
2021
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96. A near-infrared fluorescent probe based on photostable Si-rhodamine for imaging hypochlorous acid during lysosome-involved inflammatory response

Author

Hong-Min Meng, Suling Feng, Hua Zhang, Mao Guojiang, Jingjing Bi, Yi-Jun Gong, Liang Zhenzhen, Guisheng Zhang, and Li Su

Subjects
Hypochlorous acid, Mice, Nude, Biochemistry, Lyso, Fluorescence, Analytical Chemistry, Rhodamine, chemistry.chemical_compound, Mice, Limit of Detection, Escherichia coli, Environmental Chemistry, Animals, Humans, Spectroscopy, Fluorescent Dyes, Detection limit, Inflammation, Rhodamines, Photobleaching, Hypochlorous Acid, Autofluorescence, RAW 264.7 Cells, chemistry, Microscopy, Fluorescence, Luminescent Measurements, Biophysics, Phototoxicity, Lysosomes, HeLa Cells
Abstract

Hypochloric acid (HClO) is mainly distributed in acidic lysosomes of phagocytes and closely associated with numerous physiological and pathological processes, especially inflammatory response. Fluorescent probe has become an important tool for imaging HClO in lysosomes, but suffered from interference from autofluorescence in vivo , phototoxicity to biosamples and photobleaching phenomenon due to their short-wavelength excitation and emission. Unfortunately, up to now, no near-infrared (NIR) lysosome-targetable fluorescent probe has been reported for imaging HClO. In this paper, a near-infrared fluorescent probe Lyso - NIR - HClO for imaging lysosomal HClO was reported for the first time. Lyso - NIR - HClO based on Si-rhodamine is consisted of a morpholine unit as a lysosome-targetable group and a HClO-mediated cyclization reaction site as a response group, which was applied for highly selective and sensitive detection and imaging for endogenous and exogenous HClO in lysosomes, with a linear range from 5.0 × 10 −8 to 1.0 × 10 −5 M and a detection limit of 2.0 × 10 −8 M in vitro . Attributed to NIR emission and excellent photostability of Si-rhodamine, Lyso - NIR - HClO exhibits excellent performances in vivo , such as low interference from intracellular autofluorescence, stable and persistent fluorescence signal and good tissue penetration, which are in favor of accurate, time-lapse and long-term imaging for HClO. Finally, we applied the probe Lyso - NIR - HClO to visualize endogenous HClO during lysosome-involved inflammatory response including bacteria-infected cells and inflamed mouse model with satisfactory results. The above results proved that Lyso - NIR - HClO would be a potentially useful tool for the study of biological functions and pathological roles of HClO in lysosomes, especially role of lysosome in the inflammatory response.

Published
2018

98. General Defluoroalkylation of Trifluoromethylarenes with Both Electron-Donating and -Withdrawing Alkenes

Author

Zhu, Mengqi, Wang, Qiao-Lin, Huang, Huawen, Mao, Guojiang, and Deng, Guo-Jun

Abstract

The incorporation of gem-difluoromethylene units into organic molecules remains a formidable challenge. Conventional methodologies for constructing aryldifluoromethyl derivatives relied on the use of high-functional fluorinating regents under harsh conditions. Herein, we report general and efficient photoredox catalytic systems for defluoroalkylation of readily available trifluoromethylarenes through selective C–F cleavage to deliver gem-difluoromethyl radicals which proceed through reductive addition to both electron-donating and withdrawing alkenes under transition-metal free conditions. Mechanistic studies reveal that thiol serves as both photocatalyst and HAT reagent under visible light irradiation. This synergistic photocatalysis and HAT catalysis protocol exhibits ample and salient features such as high chemo- and regioselectivity, broad substrate scope, amenable gram-scale synthesis and late-stage modification of bioactive molecules.

Published
2024
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99. Enzyme-Responsive Fluorescent Labeling Strategy for In VivoImaging of Gut Bacteria

Author

Lang, Wenchao, Shu, Dunji, Liu, Songhan, Sun, Caixia, Liu, Huihong, Huang, Qianqian, Mao, Guojiang, Yang, Sheng, and Xing, Bengang

Abstract

Myrosinase (Myr), as a unique β-thioglucosidase enzyme capable of converting natural and gut bacterial metabolite glucosinolates into bioactive agents, has recently attracted a great deal of attention because of its essential functions in exerting homeostasis dynamics and promoting human health. Such nutraceutical and biomedical significance demands unique and reliable strategies for specific identification of Myr enzymes of gut bacterial origin in living systems, whereas the dearth of methods for bacterial Myr detection and visualization remains a challenging concern. Herein, we present a series of unique molecular probes for specific identification and imaging of Myr-expressing gut bacterial strains. Typically, an artificial glucosinolate with an azide group in aglycone was synthesized and sequentially linked with the probe moieties of versatile channels through simple click conjugation. Upon gut bacterial enzymatic cleavage, the as-prepared probe molecules could be converted into reactive isothiocyanate forms, which can further act as reactive electrophiles for the covalent labeling of gut bacteria, thus realizing their localized fluorescent imaging within a wide range of wavelength channels in live bacterial strains and animal models. Overall, our proposed method presents a novel technology for selective gut bacterial Myr enzyme labeling in vitroand in vivo. We envision that such a rational probe design would serve as a promising solution for chemoprevention assessment, microflora metabolic mechanistic study, and gut bacterium-mediated physiopathological exploration.

Published
2024
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