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Electrochemical Dearomative Spirocyclization of N-Acyl Sulfonamides in a Continuous-Flow Cell

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Chinese Journal of Chemistry 2024年第9期42卷 980-984页

作者： Ting Liu Zhaojiang Shi Yaofeng Yuan Yuqi Lin Ke-Yin Ye Key Laboratory of Molecule Synthesis and Function Discovery(Fujian Province University) College of ChemistryFuzhou University FuzhouFujian350108China

The development of efficient and sustainable methods to obtain spirocyclic compounds is of significance as these structures are widely found in pharmaceuticals and agrochemicals.Herein,we disclose an electrochemical dearomative spirocyclization of N-acyl sulfonamides in a continuous-flow cell.The reaction is simple and efficient without external catalysts or supporting electrolytes and could be applied in a decagram-scale synthesis.

关键词： Electrochemistry Continuous-flow dearomatization Spirocyclization Sulfonamides Cyclization Methodology and reactions

Metal-free nucleophilic 7,8-dearomatization of quinolines:Spiroannulation of aminoquinoline protected amino acids

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Chinese Chemical Letters 2023年第2期34卷 219-223页

作者： Zhiguo Zhang Xiyang Cao Xiaoqing Song Gang Wang Bingbing Shi Xiang Li Nana Ma Lantao Liu Guisheng Zhang Key Laboratory of Green Chemical Media and Reactions Ministry of EducationCollaborative Innovation Centre of Henan Province for Green Manufacturing of Fine ChemicalsNMPA Key Laboratory for Research and Evaluation of Innovative DrugSchool of Chemistry and Chemical EngineeringHenan Normal UniversityXinxiang 453007China The College of Chemistry and Chemical Engineering Shangqiu Normal UniversityShangqiu 476000China

Atom-and step-economy in IBX assisted diversity-oriented synthesis is achieved with a versatile AQ auxiliary α-amino acid analogs offering rapid access to polycyclic spiro-quinolines featuring a quaternary stereocenter in 20%–91% yields under mild conditions via 7,8-dearomatization of quinolines. Free of a preinstalled activation group is highlight of this intramolecular oxidation spiroannulation tandem reaction. This type of N-heterospirocycles, traditionally difficult to access, may open the door to a potentially interest scaffold for synthetic and medicinal chemistry.

关键词： dearomatization Spiroannulation Aminoquinoline Amino acids Hypervalent iodine reagents

Asymmetric dearomatization of Electron-Deficient Heteroarenes by a Phosphine-Catalyzed[3+2]Annulation with Vinylcyclopropanes

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CCS Chemistry 2023年第9期5卷 2023-2032页

作者： Xuan Dai Fuhao Zhang Lei Dai Yixin Lu Department of Chemistry National University of SingaporeSingapore 117543 School of Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094

Asymmetric dearomatization reactions of various electron-deficient heteroarenes,including benzofurans,benzothiophenes,and indoles,have been described.Through a phosphine-catalyzed[3+2]annulation with vinylcyclopropanes,readily available heteroarene feedstocks undergo smooth dearomatization reactions,delivering a diverse array of valuable chiral cyclopentabenzodihydrofuran and cyclopentaindoline scaffolds in a highly diastero-and enantioselective manner.Notably,the employment of cyclopropanes in phosphine-mediated annulation for the dearomatization of electron-deficient arenes is unknown.

关键词： dearomatization enantioselectivity phosphine catalysis electron-deficient heteroarenes vinylcyclopropanes

Catalytic Asymmetric[4+1]Spiroannulation ofα-Bromo-βNaphthols with Azoalkenes by an Electrophilic dearomatization/S_(RN)1-Debromination Approach

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CCS Chemistry 2022年第3期4卷 1054-1064页

作者： Lu Bai Xin Luo Yicong Ge Hui Wang Jingjing Liu Yaoyu Wang Xinjun Luan Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry&Materials ScienceNorthwest UniversityXi’an 710127 State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071

An enantioselective[4+1]spiroannulation ofαbromo-β-naphthols with azoalkenes has been developed for the one-step construction of a new class of pyrazoline-based spirocyclic molecules.Using chiral Cu(II)/Box catalysts,asymmetric induction was achieved with high levels of enantioselectivity[up to 99:1 enantiomeric ratio(er)].Notably,α-chloroandα-iodo-substitutedβ-naphthols were also tolerated by this reaction.Mechanistic studies disclosed that this process was triggered by electrophilefacilitated dearomatization ofα-bromo-β-naphthols and followed by the debromination via SRN 1-subsitution with in situ-formed N-nucleophile.The chiral copper(II)-species,bound with azoalkene moiety,was assumed to control the enantiodiscrimination over the naphthoxy C-radical that was generated from the debromination step.Moreover,the potential utility of this protocol was greatly amplified by the derivatization of spirocyclic products through oxidative dearomatization of the other aromatic ring in the naphthyl fragment,providing a rather attractive route for the rapid generation of synthetically more valuable doubly dearomatized architectures.

关键词： dearomatization spiroannulation bromonaphthol azoalkene asymmetric catalysis

Electrochemical Oxidation dearomatization of Anisol Derivatives toward Spiropyrrolidines and Spirolactones

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CCS Chemistry 2022年第4期4卷 1199-1207页

作者： Cui Zhang Faxiang Bu Chulin Zeng Dan Wang Lijun Lu Heng Zhang Aiwen Lei College of Chemistry and Molecular Sciences Institute for Advanced Studies(IAS)Wuhan UniversityWuhanHubei 430072 State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032

Spiro compounds are widely prevalent in biological activities and natural products.However,developing new strategies for their efficient synthesis and derivatization remains a challenge.Outstanding progress has been made in the synthesis of spiro compounds through dearomatization of aromatic compounds,most of them are mediated by the hypervalent iodine reagents.Herein,we report a method of anodic oxidation spiroamination and spirolactonization of anisole derivatives with concomitant cathodic reduction of protons in the absence of hypervalent iodine reagents.A wide variety of spiropyrrolidines and spirolactones with diverse functional groups made useful scaffolds in this transformation,with yields up to 97%.Moreover,hectogram-scale synthesis could supply target product with 83% yield in a flow electrochemical cell using carbon paper as the anode and nickel plate as the cathode,demonstrating the potential application of this method.

关键词： electrochemical spiropyrrolidine spirolactone dearomatization spiro-cycle anisole derivatives hectogram synthesis flow cell

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO_(2) via Visible-Light-Induced Reductive dearomatization

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CCS Chemistry 2022年第5期4卷 1565-1576页

作者： Yuzhen Gao Hao Wang Zhuomin Chi Lei Yang Chunlin Zhou Gang Li Key Laboratory of Coal to Ethylene Glycol and Its Related Technology Center for Excellence in Molecular SynthesisFujian Institute of Research on the Structure of MatterUniversity of Chinese Academy of SciencesChinese Academy of SciencesFuzhouFujian 350002 College of Chemistry and Materials Science Fujian Normal UniversityFuzhouFujian 350117 Frontiers Science Center for Transformative Molecules Shanghai Jiao Tong UniversityShanghai 200240

Visible-light-induced reductive dearomatization of nonactivated arenes is a very challenging transformation and remains in its infancy.Herein,we report a novel strategy to achieve a visible-light-induced spirocyclizative remote arylcarboxylation of nonactivated arenes including naphthalenyl-and phenyl-bearing aromatics with CO_(2) under mild conditions through a radical-polar crossover cascade(RPCC).This reductive dearomatization protocol rapidly delivers a broad range of spirocyclic and valuable carboxylic acid derivatives from readily accessible aromatic precursors with generally good regioselectivity and chemoselectivity.

关键词： carbon dioxide utilization nonactivated arene dearomatization photocatalysis spirocyclization

Construction of highly congested quaternary carbon centers by NHC catalysis through dearomatization

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绿色合成与催化(英文)

绿色合成与催化(英文) 2023年第3期4卷 263-267页

作者： Lixia Liu Cong-Ying Zhou Chengming Wang College of Chemistry and Materials Science Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and ApplicationsJinan UniversityGuangzhou 510632China

A NHC-catalyzed hypervalent iodine reagents and transition-metal free redox-neutral dearomatization of phenols is reported.This protocol provides an efficient access for highly congested quaternatry carbon centers construction.It also features operationally simplicity,mild reaction conditions and good functional group tolerance.Moreover,the reported procedure can be easily emplified to 1 g scale.Mechanism study reveals the dearomative transformation possibly undergoes a single electron transfer process with NHC radical cation as a reactive intermediate.

关键词： NHC Quaternary carbon center dearomatization Radical SET

dearomatization of normal paraffin by adsorption process using synthesized NaX zeolite

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Petroleum Science 2013年第3期10卷 408-414页

作者： Hossein Faghihian Leila Riazi Department of Chemistry Shahreza Branch Islamic Azad University86145-311 Iran R&D Department I. C. I. I. C.Isfahan Iran

Linear alkyl benzenes （LABs） are the main materials for detergent production. The presence of aromatic compounds in this material can decrease the quality of the final product and enhance the deactivation rate of catalysts. In this research we used zeolite NaX for de-aromatization of the recycled paraffin from the alkylation unit of an LAB production complex. The effect of different parameters on the removal efficiency of adsorbent was studied and optimized. To study the re-usability of the adsorbent, the breakthrough curves were obtained by using a fixed bed column filled with the adsorbent. The results indicated that the adsorbent capacity remained unchanged after three regeneration cycles. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. It was concluded that the Langmuir model agreed well with the experimental data. The calculated thermodynamic parameters of the adsorption showed that the adsorption process was spontaneous and exothermic. The reaction rate was estimated by the pseudo-second order kinetic model.

关键词： dearomatization LAB zeolite adsorption separation

Br■nsted acid-catalyzed asymmetric dearomatization of indolyl ynamides: Practical and enantioselective synthesis of polycyclic indolines

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Chinese Chemical Letters 2023年第3期34卷 317-321页

作者： Zhi-Xin Zhang Xuan Wang Jia-Tian Jiang Jie Chen Xin-Qi Zhu Long-Wu Ye Key Laboratory for Chemical Biology of Fujian Province and State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Catalytic asymmetric dearomatization of indoles and alkynes has received much attention in the past decade because this strategy offers an attractive and alternative way for the efficient synthesis of valuable chiral polycyclic indolines. However, these reactions have been mostly limited to transition-metal catalysts, and the related chiral Br■nsted acid catalysis has been scarcely reported. Herein, we disclose a chiral phosphoric acid-catalyzed asymmetric dearomatization of indolyl ynamides by direct activation of alkynes. This metal-free method enables the practical and atom-economical construction of an array of valuable chiral polycyclic indolines in moderate to good yields with high enantioselectivities.

关键词： Br■nsted acid catalysis dearomatization Heterocycles Ynamides Stereoselectivity