Article
Chemistry, Multidisciplinary
Euijae Lee, Yeongyu Hwang, Yeong Bum Kim, Dongwook Kim, Sukbok Chang
Summary: This study investigates the enantioselective access to chiral spirolactam products via nitrenoid transfer to aromatic ipso-carbons catalyzed by Ir, highlighting the importance of enhancing secondary interactions between chiral catalysts and substrates through the introduction of a traceless O-silyl achiral auxiliary, effectively differentiating two prochiral faces of the substrates based on arenol-derived 1,4,2-dioxazol-5-one.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Jeonghyo Lee, Bora Kang, Dongwook Kim, Jia Lee, Sukbok Chang
Summary: In this study, a novel amidative alkyl migration reaction catalyzed by Cp*Co(III)(LX) using 2,6-disubstituted phenyl azidoformates as substrates was reported. The reaction mechanism involves an alkyl-walking process facilitated by a quinolinol ligand of the cobalt catalyst system, enabling both [1,2]- and [1,4]-alkyl rearrangements to allow structural variations of N-heterocyclic compounds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Suhyeon Kim, Se Lin Song, Jianbo Zhang, Dongwook Kim, Sungwoo Hong, Sukbok Chang
Summary: A new method for the asymmetric C-H amidation of dioxazolones using a Cu(I) precursor with a chiral bisoxazoline ligand has been developed, allowing the synthesis of six-membered lactams with high selectivity (up to >19:1 rr and >99:1 er). Mechanistic studies suggest that the regioselective hydrogen atom abstraction and subsequent enantio-determining radical rebound of the resulting carbon radical intermediates are enabled by the open-shell character of the postulated Cu-nitrenoids. This asymmetric cyclization has demonstrated its synthetic utility in the diastereoselective introduction of additional functional groups into the chiral lactam skeleton and the rapid access to biorelevant azacyclic compounds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Seung Youn Hong, Dongwook Kim, Sukbok Chang
Summary: Carbocation intermediates are accessed catalytically via metal-nitrenoid transfer into alkenes, allowing for regiocontrolled elimination reactions. This method demonstrates high regioselectivity in the synthesis of valuable allylic lactams and offers the potential for enantioselective construction of gamma-lactams.
Article
Environmental Sciences
Yanhui Sun, Lin Liu, Ming Li, Xiaoxiao Chen, Fei Xu
Summary: Vanillin and vanillic acid are two lignin pyrolysis products generated by biomass combustion. The gas-phase oxidation mechanisms of vanillin and vanillic acid initiated by OH/NO3 radicals were investigated using density functional theory. The primary reactions involve OH/NO3 addition and H-atom abstraction, leading to the formation of various oxidation products. The total rate constants and atmospheric lifetimes of the oxidation processes were calculated, providing valuable information for further experimental research.
Article
Chemistry, Organic
Kazuma Nishimura, Ryohei Hanzawa, Tomoya Sugai, Haruhiko Fuwa
Summary: The intramolecular double hydro-functionalization of internal alkynes catalyzed by [RuCl2(p-cymene)](2)/AgNO3 resulted in the synthesis of a series of spirocyclic hemiaminal ether derivatives in good to excellent yields. The product spiro-hemiaminal ethers underwent Lewis acid-mediated chemoselective cleavage to generate in situ iminium/oxocarbenium ions that could be further reacted with nucleophiles to afford a range of nitrogen and oxygen heterocycles.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Biochemistry & Molecular Biology
Laura Machin, Martin Piontek, Sara Todhe, Katrin Staniek, Lianet Monzote, Werner Fudickar, Torsten Linker, Lars Gille
Summary: This study investigated the antileishmanial activity and selectivity of new anthracene-derived endoperoxides (EP) in model systems of Leishmania parasites and macrophages. The structural parameters of active compounds were correlated with their activity, and the mechanism of action in Leishmania was explored. The identified compounds serve as a promising starting point for further experiments in pathogenic Leishmania.
Article
Environmental Sciences
Yanhui Sun, Xiaoxiao Chen, Lin Liu, Fei Xu, Xiaochen Zhang
Summary: In this study, gas phase reaction mechanisms and kinetic parameters of eugenol with hydroxyl radicals and ozone molecules were calculated. The results suggest that eugenol has a short atmospheric lifetime. This work provides theoretical guidance for the photochemical reaction mechanisms of eugenol in the atmosphere and serves as a reference for future experimental research.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Chemistry, Physical
Monica Rodriguez, Aleksandr Y. Pereverzev, Jana Roithova
Summary: A novel octahedral non-heme iron-acyl-nitrenoid complex was presented, and its reactivity was studied using a flow chemistry setup with online mass spectrometry detection. It was found that the iron-acyl-nitrenoid complex can activate C-H bonds via hydrogen-atom transfer and form new N-S bonds in the reaction with thiophenol. However, the reaction with hydrocarbons results in the activation of C-H bonds without a subsequent rebound process.
Article
Pharmacology & Pharmacy
Yilue Zhang, Christian Schoneich
Summary: Pharmaceutical formulations are sensitive to light-induced degradation, which can be attributed to the presence of Fe(III) leachable from pharmaceutical containers. The leaching of Fe(III) from stainless steel can be promoted by histidine (His), especially at elevated storage temperatures. Our study investigates the photo-degradation mechanisms of Fe(III)-containing His buffer during exposure to near UV light, and suggests the formation of carbon dioxide radical anion and other photoproducts.
EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS
(2023)
Article
Materials Science, Multidisciplinary
Huaizhuang Luan, Jie Chen, Rutie Liu, Xiang Xiong, Fangping Ouyang, Junhao Yang
Summary: Pre-sintered Fe-WC-Mo2C-Cr3C2-VC-C alloy was studied for its microstructure and evolution of internal pores during the exhaust process. The gas produced by deoxidation significantly affected the densification process, resulting in expansion and shrinkage of the pre-sintered sample. The oxygen content was significantly reduced after the carbothermal reaction.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Chemistry, Multidisciplinary
Xue Han, Li-Xin Shan, Jin-Xin Zhu, Chang-Sheng Zhang, Xiao-Ming Zhang, Fu-Min Zhang, Hong Wang, Yong-Qiang Tu, Ming Yang, Wen-Shuo Zhang
Summary: A novel copper-nitrene-catalyzed desymmetric oxaziridination reaction was reported, producing a synthetically challenging chiral bicyclic lactam. This enriches the asymmetric reactions involving copper-nitrene and provides an alternative strategy for addressing the challenges of catalytic asymmetric Schmidt reactions. This unique reaction could inspire further investigation into novel copper-nitrene-catalyzed asymmetric transformations and their reaction mechanisms.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Engineering, Environmental
Yan Wang, Yuanguang Huang, Luming Ma
Summary: Activated carbon plays a role as an activator rather than a catalyst in catalytic ozonation. Its adsorption function improves the degradation of organic contaminants by concentrating them in the action zone. Furthermore, a quasi-complexation reaction may occur between activated carbon, oxalic acid, and oxygen.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Review
Biochemistry & Molecular Biology
Alexandra Barbouti, Nefeli Lagopati, Dimitris Veroutis, Vlasios Goulas, Konstantinos Evangelou, Panagiotis Kanavaros, Vassilis G. Gorgoulis, Dimitrios Galaris
Summary: The gradual accumulation of oxidatively damaged macromolecules in cells and organisms leads to cell and organ dysfunction, known as the free radical theory of aging. Lipofuscin, ceroid, or age pigment is formed through unregulated oxidative modifications induced by reactive free radicals. Modulating the distribution of labile iron pool could potentially hinder lipofuscin accumulation and cellular aging.
Article
Chemistry, Multidisciplinary
Gabriel Perez-Gonzalez, Victoria Melin, Camila Mendez-Rivas, Juan Diaz, Nataly Moreno, David Contreras
Summary: The chelator-mediated Fenton (CMF) chemistry is an important biological non-enzymatic system for generating oxygen-centered radicals. Our study found that a perhydroxyl radical (HO2 center dot) is generated as a secondary radical in all CMF systems, and there is also an HO2 center dot-independent pathway that contributes to the reduction of Fe3+. Additionally, we proposed that the singlet state (SQ) of the ED ligand contributes to the generation of HO2 center dot.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Physical
Yeong Bum Kim, Dongwook Kim, Shashikant U. Dighe, Sukbok Chang, Jung-Woo Park
Summary: This research describes a novel cobalt-catalyzed reaction for the synthesis of terminal branched allylsilanes under mild conditions. Mechanistic studies show the key intermediate and the order of bond migration involved in the process.
Article
Chemistry, Multidisciplinary
Wongyu Lee, Hyun Ji Jeon, Hoimin Jung, Dongwook Kim, Sangwon Seo, Sukbok Chang
Summary: A new relay process involving the slow in situ generation of a photoactive N-chloro species enables mild and selective access to N-centered radicals under visible light conditions, demonstrating high functional group tolerance and excellent applicability for late-stage functionalization.
Article
Chemistry, Physical
Seung Youn Hong, Dongwook Kim, Sukbok Chang
Summary: Carbocation intermediates are accessed catalytically via metal-nitrenoid transfer into alkenes, allowing for regiocontrolled elimination reactions. This method demonstrates high regioselectivity in the synthesis of valuable allylic lactams and offers the potential for enantioselective construction of gamma-lactams.
Article
Chemistry, Multidisciplinary
Suhyeon Kim, Dongwook Kim, Seung Youn Hong, Sukbok Chang
Summary: The article discusses the use of the Cp*Ir(kappa(2)-LX) system as a catalyst for alkene difunctionalization via a nitrenoid-mediated pathway, with a focus on tuning the orbital symmetry of key intermediates to improve catalytic activity. Through systematic engineering, a new catalyst system capable of stepwise nitrenoid transfer was developed, allowing for diastereoselective production of difunctionalized lactams with various nucleophiles. This mechanistic platform also enabled the development of asymmetric methods for introducing two-point chirality in (oxyallcyl)lactam products with excellent enantioselectivity.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Hyeyun Keum, Hoimin Jung, Jiwoo Jeong, Dongwook Kim, Sukbok Chang
Summary: In this study, an intramolecular C(sp(2))-H amidation of N-acyloxyamides under photoredox conditions was reported to produce delta-benzolactams with an aryl-alkyl sigma-bond relocation. Computational studies identified the N-[3,5-bis(trifluoromethyl)benzoyl] group as the most effective amidyl radical precursor, which led to the rationalization of radical-polar crossover for ring-expansion with C-C bond migration.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Seongho Jin, Jinwoo Kim, Dongwook Kim, Jung-Woo Park, Sukbok Chang
Summary: In this study, a Rh-catalyzed C-H acyloxylation under mild electrolytic conditions was developed, with anodic oxidation of a key rhodacyclic carboxylate intermediate enabling the product-releasing C-O bond-forming reductive elimination process. The accumulation of carboxylate near the electrode surface further induced the desired C-O bond formation, allowing ambient catalytic C-H oxygenation using stoichiometric amounts of readily accessible carboxylic acid coupling partners.
Article
Chemistry, Multidisciplinary
Jeonghyo Lee, Bora Kang, Dongwook Kim, Jia Lee, Sukbok Chang
Summary: In this study, a novel amidative alkyl migration reaction catalyzed by Cp*Co(III)(LX) using 2,6-disubstituted phenyl azidoformates as substrates was reported. The reaction mechanism involves an alkyl-walking process facilitated by a quinolinol ligand of the cobalt catalyst system, enabling both [1,2]- and [1,4]-alkyl rearrangements to allow structural variations of N-heterocyclic compounds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Jeonguk Kweon, Dongwook Kim, Seungju Kang, Sukbok Chang
Summary: In this study, an iron-catalyzed olefin oxyamidation using tethered dioxazolones as nitrenoid precursors was developed to produce valuable beta-lactam scaffolds with high diastereoselectivity. Mechanistic studies showed that the strong pi-accepting ability of the phthalocyanine ligand is critical in generating the key triplet iron-imidyl radical intermediate for efficient cyclization. The approach was also extended to the highly efficient synthesis of gamma-lactams with a TON > 300.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Manoj Kumar Sahoo, Dongwook Kim, Sukbok Chang, Jung-Woo Park
Summary: This study demonstrates the regioselective migratory hydrofunctionalization of alkynes to produce alpha-vinylsilanes and alpha-vinylgermanes using a cobalt hydride based system. The mechanism of alkyne pi-bond migration by the cobalt hydride species is supported by both experimental and computational studies, which elucidates the unique alpha-vinyl selectivity.
Article
Chemistry, Multidisciplinary
Zijun Zhou, Jeonguk Kweon, Hoimin Jung, Dongwook Kim, Sangwon Seo, Sukbok Chang
Summary: In this study, we report a photoinduced transition-metal-free C(aryl)-N bond formation method using 2,4,6-tri(aryl)boroxines or arylboronic acids as an aryl source and 1,4,2-dioxazol-5-ones as an amide coupling partner. The presence of chloride anion, either generated in situ by the photodissociation of chlorinated solvent molecules or added separately, plays a critical cooperative role in facilitating the synthesis of a wide range of synthetically versatile N-arylamides under mild photo conditions. Mechanistic investigations suggest the involvement of two distinctive photoexcitations in the process, enabling the activation of dioxazolones and the migration of aryl groups.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
Hoimin Jung, Jeonguk Kweon, Jong-Min Suh, Mi Hee Lim, Dongwook Kim, Sukbok Chang
Summary: To overcome the challenge of isolating and characterizing Rhodium (Rh) acylnitrene complexes, a chromophoric octahedral Rh complex with a bidentate dioxazolone ligand was designed. X-ray photocrystallographic analysis allowed structural elucidation of the Rh-acylnitrenoid and provided evidence that the singlet nitrenoid species is responsible for acylamino transfer reactions. In-crystallo reaction of a nucleophile with the in-situ-generated Rh-acylnitrenoid provided a traceable reaction system to capture mechanistic snapshots of nitrenoid transfer.
Article
Chemistry, Multidisciplinary
Youyoung Kim, Dongwook Kim, Sukbok Chang
Summary: An iridium(III)-catalyzed electrooxidative intramolecular dehydrogenative C-H/N-H coupling of unprotected 2-alkenyl anilines is described, allowing the synthesis of various 3-substituted N-H indole scaffolds under undivided electrolytic conditions. Mechanistic studies indicate that the reaction proceeds through an electro-oxidation induced reductive elimination pathway.
CHEMICAL COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Torben Rogge, Nikolaos Kaplaneris, Naoto Chatani, Jinwoo Kim, Sukbok Chang, Benudhar Punji, Laurel L. Schafer, Djamaladdin G. Musaev, Joanna Wencel-Delord, Charis A. Roberts, Richmond Sarpong, Zoe E. Wilson, Margaret A. Brimble, Magnus J. Johansson, Lutz Ackermann
Summary: C-H activation has emerged as a powerful platform for molecular syntheses in various fields including natural product syntheses, pharmaceutical industries, and material sciences. This Primer summarizes best practices for experimental set-up, data deposition, and key developments in C-H activation, as well as discussing its applications and limitations.
NATURE REVIEWS METHODS PRIMERS
(2021)
