Review
Chemistry, Organic
Zhi-Hao Shang, Jun Pan, Zeyu Wang, Ze-Xin Zhang, Jingjing Wu
Summary: Organoboron compounds are versatile in various fields and their preparation usually requires reactive organometallic reagents or transition metals. However, recent developments in transition-metal-free borylation methodologies using radical chemistry have attracted much attention. Through thermochemical, photochemical, or electrochemical pathways, successful approaches from different radical precursors have been developed. This review provides an overview of recent advances in transition-metal-free radical borylation processes.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Panjie Xiang, Kai Sun, Shuang Wang, Xiaolan Chen, Lingbo Qu, Bing Yu
Summary: An S(N)2-based photochemical strategy using dithiocarbamate anion as catalyst has been developed for the activation of benzyl halides, allowing the benzylation (or cyanomethylation) of various heterocycles with high yields. This transition-metal-free and oxidant-free protocol also enables the synthesis of biologically relevant compounds under mild conditions.
CHINESE CHEMICAL LETTERS
(2022)
Article
Chemistry, Applied
Zhipeng Huang, Yang Yang, Junju Mu, Genheng Li, Jianyu Han, Puning Ren, Jian Zhang, Nengchao Luo, Ke-Li Han, Feng Wang
Summary: Radicals are key intermediates in reactions and their reactivity poses challenges to controlling reactions over heterogeneous catalysts. Metal nanoparticles can stabilize and manipulate free radical species generated from photo-excited TiO2, facilitating controlled radical reactions on catalyst surfaces. These insights are crucial for designing advanced heterogeneous catalytic systems.
CHINESE JOURNAL OF CATALYSIS
(2023)
Review
Chemistry, Inorganic & Nuclear
Pengcheng Gao, Michal Szostak
Summary: The catalytic addition of water to unsaturated C-C or C-N p bonds is an important and environmentally sustainable method for forming C-O bonds. Traditional acid-catalyzed hydration requires strong acids or toxic mercury salts, limiting its practical applications and posing safety and environmental concerns. Transition-metal-catalyzed hydration with NHC ligands has gained significant attention and has achieved major progress. This review provides a comprehensive overview of hydration reactions catalyzed by transition metal-NHC complexes and their applications in catalytic hydration.
COORDINATION CHEMISTRY REVIEWS
(2023)
Article
Chemistry, Physical
Roel F. J. Epping, David Vesseur, Minghui Zhou, Bas de Bruin
Summary: Discovered in the 1970s as organometallic curiosities, carbene radicals have become essential in modern homogeneous catalysis. These radicals exhibit nucleophilic reactivity different from electrophilic Fischer carbenes. The successful catalytic application of carbene radicals has led to the synthesis of diverse carbon and heterocyclic compounds. This Perspective provides an overview of the coordination chemistry, reactivity, and catalytic application of carbene radicals using transition metal complexes and catalysts since 2011.
Review
Biochemistry & Molecular Biology
Tomasz Bauer, Yusuf Zaim Hakim, Paulina Morawska
Summary: This review covers recent research on enantioselective synthesis using radical reactions, focusing on the synthesis of chiral molecules through metal catalysis, dual metal and organocatalysis, and pure organocatalysis including enzyme catalysis. The review highlights the synthetic aspects of the methodology and discusses the compounds that can be obtained in enantiomerically enriched forms.
Review
Chemistry, Physical
Jiapian Huang, Zhiyuan Chen, Jie Wu
Summary: Methylation is a crucial process in biology, and radical-type methylation protocols have been developed for late-stage modifications of privileged scaffolds in pharmaceutical research. The chemistry involving methyl-radical-involved conversions has significantly developed in recent years. Various pathways for methyl radical generation have been explored, including photo-/electro-catalysis, transition-metal catalysis, transition-metal-free methylations, and demethylation-triggered radical cyclization/cascade reactions. Representative methyl-containing molecules produced from these reactions have been analyzed.
Review
Chemistry, Organic
Yatao Lang, Chao-Jun Li, Huiying Zeng
Summary: Photoreactions have become powerful synthetic tools, but many require transition-metal catalysts and photosensitizers, which pose challenges to metal sustainability and complicates product purification. Developing transition-metal and photosensitizer-free photoreactions can reduce costs and contribute to sustainable development.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Multidisciplinary
Yongli Li, Dalong Shen, Hao Zhang, Zhenxing Liu
Summary: Due to the increasing demand for sustainable organic chemistry, the development of green and powerful methods for C-C and C-B bond formation is highly desired. Transition-metal-free coupling reactions of gem-diborylalkanes have emerged as valuable tools for organic chemists in the past decade. This review presents selected representative examples and compares these reactions to transition-metal-catalyzed reactions. The recent formation of alpha-boryl radicals from gem-diborylalkanes is also briefly discussed.
CHINESE CHEMICAL LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Brady J. H. Austen, Marissa L. Clapson, Marcus W. Drover
Summary: This report describes the use of metal-ligand cooperativity to convert unsaturated small molecules such as nitriles into reduced products. The study reveals the reactivity differences in nitrogen and phosphorus carbon triple bond systems and investigates the effect of SCS stabilization using nitrile dihydroboration as a model reaction.
Article
Engineering, Environmental
Dingren Ma, Ji Mei, Qiwen Liang, Yimu Jiao, Tianyu Hu, Jingchen Chen, Jiaming Wang, Hao Zhou, Qiyu Lian, Mingzhe Sun, Dehua Xia, Tianqi Wang
Summary: The heterogeneous catalytic activation of persulfate (PS) has been extensively studied for the removal of organic pollutants. This comprehensive review focuses on the latest advancements in the activation of PS using metal-based and carbon-based catalysts as well as photocatalysts. The interaction and surface reaction mechanisms between PS and catalysts are discussed, and the mechanisms underlying the degradation of organic pollutants by PS are summarized.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Article
Chemistry, Multidisciplinary
Avishek Guin, Subrata Bhattacharjee, Akkattu T. Biju
Summary: This study demonstrates the direct C2-functionalization of pyridines through a transition-metal-free protocol using aryne multicomponent coupling. The reaction allows for the synthesis of C2-substituted pyridine derivatives bearing the -CF3 group in good yields, with activated keto esters also being employed as third components in the formal 1,2-di(hetero)arylation of ketones. Performing the reaction under dilute conditions inhibits the competing pyridine-aryne polymerization pathway, leading to the desired products.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Karl Gruber, Vanessa Csitkovits, Christoph Kratky, Bernhard Kraeutler, Andrzej Lyskowski
Summary: This study reveals the activation mechanism of radical enzymes dependent on coenzyme B-12, by establishing a tight caged radical reaction space in the protein to control the entire reaction pathway.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Multidisciplinary Sciences
Yun Li, Bo Zhao, Jin-Peng Xue, Jing Xie, Zi-Shuo Yao, Jun Tao
Summary: This study reports a Zn-II complex that undergoes a giant single-crystal-to-single-crystal transformation induced by thermal elimination of ethylene glycol chelating ligands. The enormous structural change is characterized by single-crystal X-ray diffraction analyses, showcasing a unique material with both periodic crystal lattice and gel-like super-ductility. This research also suggests a potential solid-state reaction method for preparing chiral compounds by eliminating chelating ligands.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Jin Wang, Xiao-Qin Yang, Na Li, Li. -Li Wang
Summary: A green and general method for the direct transformation of aldehydes to nitriles has been developed. It features a broad scope of substrates and can be applied for the synthesis of various key cyano-containing molecules.
Article
Chemistry, Multidisciplinary
Manish Shetty, Huamin Wang, Feng Chen, Nicholas Jaegers, Yue Liu, Donald M. Camaioni, Oliver Y. Gutierrez, Johannes A. Lercher
Summary: The dehydration rates of alkanols catalyzed by hydronium ions are enhanced by the steric confinements of zeolite pores and intraporous intermolecular interactions. Different zeolite structures lead to varying activation enthalpies for alkanol dehydration, affecting the overall reaction rate.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Review
Chemistry, Applied
Guodong Zhang, Yihan Cheng, Matthias Beller, Feng Chen
Summary: The recent research focus on utilizing carbon dioxide for organic synthesis has led to advancements in carboxylations using visible light photoredox and transition-metal dual catalysis, creating new pathways for constructing carboxylates.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Physical
Feng Chen, Manish Shetty, Meng Wang, Hui Shi, Yuanshuai Liu, Donald M. Camaioni, Oliver Y. Gutierrez, Johannes A. Lercher
Summary: The rate of acid-base-catalyzed dehydration of alcohols depends strongly on the solvent and the environment of the acid sites. Brønsted acidic sites in large-pore zeolites catalyze cyclohexanol dehydration at significantly higher rates than hydrated hydronium ions in aqueous phase. The difference in turnover rates between the two solvents is much larger in large-pore zeolites compared to medium-pore zeolites. Additionally, the mechanism of cyclohexanol dehydration varies depending on the zeolite structure, with E1 elimination being dominant except for a monomer dehydration route on H-MFI which follows an E2-type mechanism.
Article
Chemistry, Organic
Pan Gao, Qingzheng Zhang, Feng Chen
Summary: A new protocol for vinyl sulfide synthesis has been developed using an alkoxy base without the need for metal catalysts. This method allows for the conversion of aryl and alkenyl sulfonium triflates with various functionalities into vinyl sulfides with excellent reactivity. The reaction conditions are mild and safe, without the use of catalysts, transition metals, high-pressure gases, or high temperatures, while still maintaining efficiency.
Article
Chemistry, Multidisciplinary
Guodong Zhang, Ye Tian, Chengyu Zhang, Xiang Li, Feng Chen
Summary: Herein, a new decarboxylative Minisci-type reaction of N-heteroarenes with silanecarboxylic acids under photo- or silver-mediated conditions is reported. This C-H silylation strategy provides efficient access to diverse N-heteroarylsilanes in moderate to excellent yields with high regioselectivity, among which Ag-catalysed decarboxylation of silanecarboxylic acids furnishes an unprecedented method for silyl radical generation.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Meiling Zhu, Haitao Tian, Sanxia Chen, Wenxuan Xue, Yanhong Wang, Hongcheng Lu, Ting Li, Feng Chen, Conghui Tang
Summary: Herein, we report a cobalt N,N-bidentate complex catalyzed reductive formylation of N-heteroarenes for the generation of N-formyltetrahydroquinoline (FTHQ) derivatives. Formic acid was used as a transfer hydrogenation reagent, which is safe, abundant, and easy to handle. This work represents the first homogeneous system for the reductive formylation of N-heteroarenes, where the metal ligand cooperated dehydrogenation is crucial for the success of this transformation. Deuteration labeling experiments and Hammett analysis were conducted, suggesting a plausible mechanism.
JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Physical
Guodong Zhang, Chengyu Zhang, Haijun Jiao, Feng Chen
Summary: The compatibility between photogenerated silyl radicals and transition metal catalysis in synthetic organic chemistry remains a challenge. Herein, we present a protocol for photoredox/nickel catalyzed allylic silylation of allyl acetates using a silyl radical intermediate. This method provides a modular synthesis of substituted allylsilanes from silanecarboxylic acids.
JOURNAL OF CATALYSIS
(2023)
Article
Chemistry, Organic
Guodong Zhang, Lei Wang, Liping Cui, Pan Gao, Feng Chen
Summary: Here, a novel photoredox-catalysed strategy is presented to synthesize gem-difluoroallylarenes from alpha-trifluoromethylalkenes with sterically hindered primary amines via C-N and C-F bond activation. This deaminative and defluorinative allylation exhibits broad compatibility with various functional groups and sterically hindered α-3° and 2° primary amines.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Guodong Zhang, Chengyu Zhang, Ye Tian, Feng Chen
Summary: In this study, a concise and efficient method for the synthesis of diverse nitrile compounds from ubiquitous carboxylic acids was achieved using an inexpensive iron catalyst. The method demonstrated compatibility with primary, secondary, tertiary, and aryl carboxylic acids, as well as various functional groups.
Article
Chemistry, Physical
Pan Gao, Liping Cui, Guodong Zhang, Feng Chen
Summary: A catalytic defluorosilylation method is developed, providing concise and modular synthetic routes for gem-difluoroallylsilanes. Trifluoromethylalkenes and silacarboxylic acids are used as easy-to-prepare and stable silyl radical precursors. This method utilizes photoredox catalysis and features a unique decarboxylation followed by defluorosilylation without extra hydrogen atom transfer catalysis, offering mild reaction conditions and a broad substrate scope applicable to diverse electron-rich and electron-poor groups.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Pan Gao, Qingzheng Zhang, Yicheng Li, Liping Cui, Xinting Fan, Guodong Zhang, Feng Chen
Summary: Radicals can be formed rapidly through direct irradiation of an electron donor-acceptor (EDA) complex. Here, we demonstrate a photocatalyst-free method for synthesizing gem-difluoroalkenes by photo-irradiating EDA complexes, which can be generated in situ between N-alkylpyridinium salts and Hantzsch ester without any additional additives. Various readily available alkylamines undergo deaminative defluoroalkylation to yield the corresponding gem-difluoroalkenes. This reaction system exhibits high reactivity, good tolerance towards different functional groups, and provides a practical and efficient approach to a wide range of alpha-alkyl-substituted gem-difluoroalkenes.
Review
Chemistry, Organic
Xinyin Wu, Pan Gao, Feng Chen
Summary: The utilization of aryl radicals as open-shelled intermediates is important in synthetic chemistry, but current methods for generating aryl radicals are inefficient. Sulfonium salts have emerged as appealing sources for generating aryl radicals due to their unique structure and chemical tendencies. This review focuses on the mechanisms of cleaving C-S bonds in sulfonium salts to generate aryl radicals. The development of synthetic applications using aryl sulfonium salts as precursors is also discussed.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Guodong Zhang, Kaiping Wang, Duo Zhang, Chengyu Zhang, Wei Tan, Zhanzhan Chen, Feng Chen
Summary: This study presents a visible-light-facilitated transition-metal-free allylic silylation reaction, which efficiently synthesizes substituted allylsilanes under mild conditions. The protocol utilizes an inexpensive organophotocatalyst and shows good compatibility with readily available allyl sulfones and stable silanecarboxylic acids. Furthermore, this strategy is also compatible with vinyl sulfones, allowing access to vinylsilanes. The silver catalytic system provides an alternative approach for the decarboxylative allylation of silanecarboxylic acids.
Article
Chemistry, Applied
Feng Chen, Sungmin Kim, Dushyant Barpaga, John. L. L. Fulton, Radha Kishan Motkuri, Oliver. Y. Y. Gutierrez, Donald. M. M. Camaioni, Johannes. A. A. Lercher
Summary: Bronsted-acid sites are introduced on the ZrO2 nodes of UiO-66 MOFs via -OSO3H groups. These sites exhibit strong Bronsted acidity and are active for cyclohexanol and ethanol dehydration reactions in different phases. The activity of Bronsted acid sites at nodes is improved by increasing sulfur concentration, which leads to the formation of two interacting groups [(&mu(3)-OSO3H)(2)] through hydrogen bonding. The catalytic activity can be manipulated by functionalizing zirconia nodes of the MOF framework.
TOPICS IN CATALYSIS
(2023)
Article
Chemistry, Physical
Xugang Yang, Zaihao Yuan, Minghao Zhou, Feng Chen, Bo-Qing Xu, Hui Shi
Summary: A quantitative assessment was conducted on four types of Zr catalysts for the Meerwein-Pondorf-Verley (MPV) reductions, revealing significant differences in the relative fraction of active sites (13-78% of total Zr) and turnover rates (>300-fold) among the catalysts. The results also showed that the hydride shift remained as the sole rate-limiting step, but the free energy barriers and kinetic isotope effects varied significantly among the catalysts, indicating diverse transition state structures and energetics.