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Your search keyword '"Yang, Huameng"' showing total 124 results
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124 results on '"Yang, Huameng"'

3. Controlled chemoselective defluorination and non-defluorination for [5 + 1] aromatic annulation via Meisenheimer-type nitrogen anion and radical intermediates† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c9sc03216a

Author

Qian, Jinlong, Zhang, Jinlong, Yang, Huameng, Kang, Lei, and Jiang, Gaoxi

Subjects
Chemistry
Abstract

A unique chemoselectivity to base-promoted defluorinative and Cu-catalyzed aerobic oxidative non-defluorinative [5 + 1] cycloaddition of fluoride unsaturated ketones with ammonium salts was demonstrated., Reported is a unique chemoselectivity approach to base-promoted defluorinative and Cu(i)-catalyzed aerobic oxidative non-defluorinative [5 + 1] condensation aromatizations of simple unsaturated ketones with ammonium salts via Meisenheimer-type nitrogen anion and radical intermediates. The CuBr/O2 catalysis provides a straightforward approach to diverse 3-fluoropyridines in high yields. The synthetic utility of the strategy is highlighted by the concise synthesis of several F-modified bioactive compounds.

Published
2019

14. Brønsted Acid Catalyzed Cyclization of Inert N-Substituted Pyrroles to Benzo[ f ]pyrrolo[1,2- a ][1,4]diazepines.

Author

Gao, Zeng, Qian, Jinlong, Yang, Huameng, Zhang, Jinlong, and Jiang, Gaoxi

Subjects
BRONSTED acids, DIAZEPINES, PYRROLES, RING formation (Chemistry), ACID catalysts, PHOSPHORIC acid, AZEPINES
Abstract

Two approaches involving intramolecular and intermolecular cyclization, respectively, have been developed for the direct and practical construction of a series of important benzo[ f ]pyrrolo[1,2- a ][1,4]azepines by using Brønsted acid catalysts. Upon catalysis by TsOH, the intramolecular dehydroxylation/ring closure of 3-hydroxy-2-[2-(1 H -pyrrol-1-yl)benzyl]isoindolin-1-ones provided various racemic benzo[ f ]pyrrolo[1,2- a ][1,4]azepines in high yields. Furthermore, enantioenriched benzo[ f ]pyrrolo[1,2- a ][1,4]azepines were also obtained by chiral phosphoric acid catalyzed intermolecular addition of [2-(1 H -pyrrol-1-yl)phenyl]methanamines to 2-formylbenzoates under mild conditions. [ABSTRACT FROM AUTHOR]

Published
2021
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15. Base-Catalyzed Intramolecular Defluorination/O-Arylation Reaction for the Synthesis of 3-Fluoro-1,4-oxathiine 4,4-Dioxide.

Author

Kang, Lei, Zhang, Jinlong, Yang, Huameng, Qian, Jinlong, and Jiang, Gaoxi

Subjects
MOLECULAR sieves, SCISSION (Chemistry), CATALYSIS
Abstract

A novel process involving base-catalyzed intramolecular defluorination/O-arylation of readily available α-fluoro-β-one-sulfones was realized and provided a series of 3-fluoro-1,4-oxathiine 4,4-dioxide derivatives in good to excellent yields. Unlike traditional defluorination reactions with stoichiometric base as the deacid reagent, this process is triggered by a catalytic amount of base (TMG: tetramethylguanidine) and molecular sieves serve as both an adsorbent to remove HF acid and an activator to assist C–F bond cleavage. [ABSTRACT FROM AUTHOR]

Published
2021
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42. From Palladium to Brønsted Acid Catalysis: Highly Enantioselective Regiodivergent Addition of Alkoxyallenes to Pyrazolones.

Author

Zhou, Hui, Wei, Zhao, Zhang, Jinlong, Yang, Huameng, Xia, Chungu, and Jiang, Gaoxi

Subjects
ALKOXY compounds, ENANTIOSELECTIVE catalysis, PYRAZOLONES, STEREOSELECTIVE reactions, HETEROCYCLIC compounds
Abstract

A highly enantioselective regiodivergent addition of alkoxyallenes to pyrazolones was developed to afford multiply functionalized alkylated products bearing a quaternary carbon stereocenter in high yields with excellent stereoselectivities. One approach is enabled by palladium catalysis, thus leading to branched allylic pyrazol-5-ones under mild reaction conditions. The other is catalyzed by a chiral Brønsted acid to give linear products exclusively. Moreover, the usefulness of this new method was highlighted by converting the allylic products into other interesting multifunctionalized pyrazolone derivatives which would be of great potential for the exploitation of pharmaceutically important molecules. [ABSTRACT FROM AUTHOR]

Published
2017
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43. AgNO3 as nitrogen source for rhodium(iii)-catalyzed synthesis of 2-aryl-2H-benzotriazoles from azobenzenes.

Author

Li, Jixing, Zhou, Hui, Zhang, Jinlong, Yang, Huameng, and Jiang, Gaoxi

Subjects
OXIDATIVE coupling, AZOBENZENE, NITROGEN, NITRATION, CATALYSIS
Abstract

A new approach has been established for Rh(iii)-catalyzed direct aza oxidative cyclization of non-prefunctionalized azobenzenes to provide 2-aryl-2H-benzotriazoles in good yields, in which AgNO3 instead of conventional azide reagents for the first time functions as the nitrogen source for the nitrogenation reaction. Preliminary mechanistic studies suggest that the Rh(iii)-catalyst could account for the nitration reaction, and subsequently cationic silver species might both play a vital role in the fission of the nitrogen–oxygen bonds in nitro groups and promote aza oxidative cyclization. [ABSTRACT FROM AUTHOR]

Published
2016
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47. Metal-Free Synthesis of ortho-CHODiaryl Ethers by a Three-Component Sequential Coupling.

Author

Liu, Fangliang, Yang, Huameng, Hu, Xinquan, and Jiang, Gaoxi

Subjects
*ETHER synthesis, *DIMETHYLFORMAMIDE, *CHEMOSELECTIVITY, *ARYNE, *METAL analysis, *COUPLING agents (Chemistry)
Abstract

A practical, metal-free, and highlychemoselective approach wasdeveloped for the synthesis of ortho-CHO diaryl ethersby a three-component sequential coupling of arynes, N,N-dimethylformamide (DMF), and diaryliodoniumsalts. Diverse functional groups including halo, nitryl, and bulkysubstituents and heteroaromatics are well tolerated. Mechanistically,isotopic tracer experiments reveal that the diaryliodonium salt servesas an electrophile to trap the transient intermediates generated fromthe [2 + 2] cyclization of an aryne and DMF. [ABSTRACT FROM AUTHOR]

Published
2014
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48. Brønsted Acid Accelerated Pd-Catalyzed DirectAsymmetric Allylic Alkylation of Azlactones with Simple Allylic Alcohols:A Practical Access to Quaternary Allylic Amino Acid Derivatives.

Author

Zhou, Hui, Yang, Huameng, Liu, Muwen, Xia, Chungu, and Jiang, Gaoxi

Subjects
*BRONSTED acids, *PALLADIUM catalysts, *ALLYLIC alkylation, *ALLYL alcohol, *AMINO acid derivatives, *ASYMMETRY (Chemistry), *CHEMICAL synthesis
Abstract

A Brønstedacid accelerated Pd-catalyzed asymmetric allylicalkylation of azlactones with simple allylic alcohols under mild reactionconditions has been realized, which provides a direct and readilyscalable approach for the synthesis of all-carbon quaternary allylicamino acid derivatives in excellent yields and good enantioselectivities. [ABSTRACT FROM AUTHOR]

Published
2014
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49. Cooperative and Enantioselective NbCl5Primary Amine Catalyzed Biginelli Reaction

Author

Cai, YongFeng, Yang, HuaMeng, Li, Li, Jiang, KeZhi, Lai, GuoQiao, Jiang, JianXiong, and Xu, LiWen

Abstract

A series of chiral organocatalysts and Lewis acids have been evaluated in the Lewis acidorganocatalystsbased cooperative catalytic Biginelli reaction, which resulted in the determination of a novel cooperative Lewis acidprimary amine catalyst system, NbCl5QNNH2. The synergistic effect of NbCl5and the quininederived primary amine is pronounced and gave dihydropyrimidiones DHPMs in moderate to good enantioselectivities up to 84  ee and good to excellent yields up to 99  yield under mild conditions.

Published
2010
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50. Brønsted acid-catalyzed aromatic annulation of alkoxyallenes with naphthols: a reaction sequence to larger π-conjugated naphthopyrans with aggregation-induced emission characters.

Author

Zhang J, Zhu L, Shen K, Yang H, Hang XC, and Jiang G

Abstract

A practical and readily scalable reaction sequence was developed for the straightforward synthesis of a new family of larger π-conjugated naphthopyrans by a Brønsted acid-catalyzed aromatic annulation of alkoxyallenes with inert naphthols. The cascade pathway involves allylation/cyclization/debenzyloxylation/isomerization/dehydration. The new class of solid state diphenylmethylene substituted naphthopyrans are fluorescent emissive and proved to have aggregation-induced emission (AIE) behavior.

Published
2018
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