14 results on '"Chunsen Li"'
Search Results
2. Mechanistic insights into the crucial roles of Glu76 residue in nickel-dependent quercetin 2,4-dioxygenase for quercetin oxidative degradation
- Author
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Jinshuai Song, Qianqian Lu, Chunsen Li, and Xueyuan Yan
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010405 organic chemistry ,Chemistry ,Stereochemistry ,Mutant ,Protonation ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Residue (chemistry) ,chemistry.chemical_compound ,Dioxygenase ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Proton-coupled electron transfer ,Quercetin - Abstract
Combined QM/MM calculations and MD simulations are utilized to investigate the detailed mechanisms of reactions catalyzed by wild-type nickel-dependent quercetin 2,4-dioxygenase (Ni-QueD) and its Glu76Asp and Glu76Gln mutants. The conserved nickel-ligating Glu76 residue in the deprotonated form is found to be essential for initiating the catalytic reaction by proton coupled electron transfer process. The generated protonated Glu76 promotes the subsequent reaction by regulating hydrogen-bonding (H-bonding) interaction with the carbonyl groups of quercetin. Investigations of Glu76Gln and Glu76Asp mutants show that mutation of Glu76 suppresses such H-bonding interaction and results in the lower catalytic activity observed experimentally. Thus, our results reveal the critical role of Glu76 residue in steering the reactivity of Ni-QueD. This work is not only useful for better understanding the mechanisms of reactions catalyzed by other metal ion-dependent QueDs, but also provides insights into how enzymes achieve specific reactions by utilizing H-bonding interaction from the metal center-ligating residues.
- Published
- 2020
3. An Uncommon Hypervalent Fluorooxosilicophosphate
- Author
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Chunsen Li, Qingran Ding, Maochun Hong, Lina Li, Junhua Luo, Yusong Wang, Shuai Liu, Han Xiao, Sangen Zhao, and Yanqiang Li
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Silicon ,010405 organic chemistry ,Phonon ,Organic Chemistry ,Hypervalent molecule ,Species diversity ,chemistry.chemical_element ,Ionic bonding ,General Chemistry ,Conductivity ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,chemistry ,Chemical physics ,Ionic conductivity ,Species richness - Abstract
The species diversity of silicon (including traditional tetrahedral coordinated silicon and hypervalent penta- and hexa-coordinate silicon) gives rise to the structural richness and diverse properties of silicates. Among these silicon species, hypervalent silicon is very rare, not to mention almost unexplored mixed-anion hypervalent fluoroxosilicate species. In this work, we successfully obtained a mixed-anion fluorooxosilicophosphate Na4Si2PO4F9 consisting of two uncommon hypervalent fluoroxosilicate species, namely, trans-SiO2F4 species and SiOF5 species. To the best of our knowledge, such hypervalent silicon species are reported for the first time in inorganic compounds. Remarkably, the coexistence of two distinct hypervalent fluoroxosilicate species in one compound is somewhat conflicted with Pauling's parsimony rule, but it indeed achieves an unlikely connection by PO4 and our phonon dispersion calculation confirms the structure stability of Na4 Si2 PO4 F9 . Temperature-dependent conductivity measurements show that Na4 Si2 PO4 F9 is a promising solid ionic conductor with a high conductivity of 4.0×10-5 S⋅cm-1 at 700 K and a low active energy of about 53.1 KJ⋅mol-1 . This work will enrich the structure chemistry of silicates and may provide a new platform for solid ionic batteries.
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- 2019
4. Mechanistic Insights into the Directing Effect of Thr303 in Ethanol Oxidation by Cytochrome P450 2E1
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Peng Wu, Chunsen Li, Walter Thiel, Jinshuai Song, and Qianqian Lu
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chemistry.chemical_classification ,Ethanol ,biology ,010405 organic chemistry ,Cytochrome P450 ,Alcohol ,General Chemistry ,CYP2E1 ,010402 general chemistry ,Hydrogen atom abstraction ,01 natural sciences ,Combinatorial chemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Enzyme ,chemistry ,Alcohol oxidation ,biology.protein - Abstract
There is a long-standing mechanistic consensus that alcohol oxidation by cytochrome P450 enzymes is triggered by hydrogen abstraction from the α-C–H bond of the alcohol. Through combined molecular ...
- Published
- 2019
5. Optical Resolution of the Water-Soluble Ti4(embonate)6 Cages for Enantioselective Recognition of Chiral Drugs
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Lv-Bing Yuan, Chunsen Li, Guang-Hui Chen, Lei Zhang, Jian Zhang, Qipu Lin, Yan-Ping He, and Jinshuai Song
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Materials science ,010405 organic chemistry ,General Chemical Engineering ,Resolution (electron density) ,Enantioselective synthesis ,General Chemistry ,010402 general chemistry ,Quantitative Biology::Other ,01 natural sciences ,0104 chemical sciences ,Condensed Matter::Soft Condensed Matter ,Condensed Matter::Materials Science ,Crystallography ,Water soluble ,Enantiopure drug ,Physics::Atomic and Molecular Clusters ,Materials Chemistry ,Physics::Chemical Physics - Abstract
Synergetic optical resolution and chiral amplification of tetrahedral Ti4L6 cages by enantiopure coordination cations have been realized in this work. Anionic ΔΔΔΔ-[Ti4L6] and ΛΛΛΛ-[Ti4L6] cages (L...
- Published
- 2018
6. B‐Heterocyclic Carbene Arising from Charge Shift: A Computational Verification
- Author
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Zhimin Wang, Fan Fan, Yirong Mo, Jinshuai Song, Chunsen Li, and Congjie Zhang
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Tetracoordinate ,010405 organic chemistry ,Chemistry ,Ligand ,Organic Chemistry ,Ionic bonding ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Adduct ,Crystallography ,chemistry.chemical_compound ,Ab initio quantum chemistry methods ,Singlet state ,Lewis acids and bases ,Carbene - Abstract
1-Borabicyclo[1.1.0]but-2(3)-ene (1BB) is a singlet biradical with two single electrons that can form an ionic resonance structure through a charge shift. The ionic resonance structure is a B-heterocyclic carbene (BHC), which can act as a carbene, Lewis base, or L- and Z-type ligand, to give adducts and complexes. Through a range of quantum methods, four types of stable compounds (A-D) derived from 1BB have been designed. These compounds retain the unique features of 1BB. As a consequence, the structures, stability, and Wiberg bond indices of the Lewis adducts of A-D with Lewis acids (BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , and C13 BH9 ) and CuI , AgI , and AuI complexes have been investigated. Results show that A-D can indeed react as carbenes. Interestingly, compounds A-D, as L-type ligands, can attach to BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , C13 BH9 , and CuCl and form compounds with planar tetracoordinate carbon (ptC), whereas Z-type ligands A-D can bind to AgCl and AuCl to provide complexes with planar tetracoordinate boron (ptB). In addition, the binuclear complexes of ClX(1BB)CuCl (X=Ag, Au) have been studied and A-D behave as both L- and Z-type ligands, in which these complexes contain both ptC and ptB. Thus, a novel method for designing compounds with ptC and ptB is presented. These rationally designed compounds involve the elements of carbene, ptC, ptB, and L- and Z-type ligands, and are expected to be unique and useful in experimental chemistry once they are synthesized.
- Published
- 2018
7. HOTf-Catalyzed Alkyl-Heck-type Reaction
- Author
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Liang Ge, Yajun Li, Huan Zhou, Wujun Jian, Hongli Bao, Chunsen Li, and Jinshuai Song
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chemistry.chemical_classification ,Multidisciplinary ,Primary (chemistry) ,010405 organic chemistry ,Alkylation ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Heck reaction ,Organic chemistry ,Organic synthesis ,lcsh:Q ,lcsh:Science ,Alkyl - Abstract
Summary: The Heck reaction, along with other cross-coupling reactions, led to a revolution in organic chemistry. In the last 50 years, metal-catalyzed, photo-induced, or base-mediated Heck and Heck-type reactions have been elegantly developed. Brønsted acid-catalyzed Heck (or Heck-type) reactions are still unknown, however. By introducing alkyl peroxides as the key intermediates, primary, secondary, and tertiary aliphatic carboxylic acids are therefore applied here in a one-pot Brønsted acid-catalyzed Heck-type reaction, to deliver E-alkenes exclusively in most cases. The use of HOTf is vital to the reaction, whose mechanism is supported by both experimental and computational results. This method can be expanded to the direct alkylation of complex natural products. : Organic Synthesis; Organic Chemistry Methods; Natural Product Synthesis Subject Areas: Organic Synthesis, Organic Chemistry Methods, Natural Product Synthesis
- Published
- 2018
8. A theoretical study on the mechanism of hydrogenation of carboxylic acids catalyzed by the Saito catalyst
- Author
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Chunsen Li, Minyi Zhang, Jing Wei, Jinshuai Song, and Qianqian Lu
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chemistry.chemical_classification ,010405 organic chemistry ,Hydride ,Carboxylic acid ,chemistry.chemical_element ,Alcohol ,010402 general chemistry ,01 natural sciences ,Aldehyde ,Combinatorial chemistry ,Heterolysis ,0104 chemical sciences ,Catalysis ,Ruthenium ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Catalytic cycle - Abstract
The mechanism of the ruthenium carboxylate-catalyzed hydrogenation of carboxylic acids was investigated by using density functional theory (DFT) calculations. The novel mechanism including two hydrogenation cycles was proposed for this reaction. The first cycle is the hydrogenation of the carboxylic acid to an aldehyde, while the second cycle is the hydrogenation of the aldehyde to an alcohol. These two catalytic cycles share similar elementary steps, including H2 heterolysis, hydride migration of the carboxylic acid or aldehyde, and catalyst regeneration. In this hydrogenation mechanism, the carboxylic acid is not only a reactant, but also an important proton source. Furthermore, the noncovalent interaction (e.g. hydrogen bonding interaction) between the ligand and carboxylic acid substrate could promote the hydrogenation of the carboxylic acid through stabilizing the transition state of the most energy-demanding step (i.e., hydride migration in the first catalytic cycle). Besides, the strong electron-donating ability of the dppb ligand could also facilitate the hydride migration.
- Published
- 2018
9. Brønsted base-catalyzed annulation of allyl ketones and alkynyl 1,2-diketones
- Author
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Xinyue Zhan, Jinshuai Song, Xinqiang Fang, Shuang Yang, Miao Meng, Jian Liu, Xiangwen Kong, Chunsen Li, and Min Zeng
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Annulation ,010405 organic chemistry ,Chemistry ,organic chemicals ,Metals and Alloys ,food and beverages ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Important research ,Intramolecular force ,Electrophile ,Materials Chemistry ,Ceramics and Composites ,Organic synthesis ,Brønsted–Lowry acid–base theory ,Bond cleavage - Abstract
The discovery of new reaction modes mediated by easily available substrates is an important research topic in organic synthesis. Allyl ketones and related compounds have been demonstrated to undergo γ- or α-selective additions to different electrophiles. We disclose here the Brønsted base-catalyzed reaction of allyl ketones and alkynyl 1,2-diketones, which undergo a unique α-selective addition/intramolecular aldol-type annulation/C-C bond cleavage process, and a series of 2-acyloxycyclopent-3-enones can be obtained under very mild conditions.
- Published
- 2018
10. Rhodium-Catalyzed Azide–Alkyne Cycloaddition of Internal Ynamides: Regioselective Assembly of 5-Amino-Triazoles under Mild Conditions
- Author
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Yinghua Yu, Yun Liao, Chunsen Li, Xueliang Huang, Gui Chen, and Qianqian Lu
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chemistry.chemical_classification ,010405 organic chemistry ,chemistry.chemical_element ,Regioselectivity ,Alkyne ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Combinatorial chemistry ,Catalysis ,Cycloaddition ,0104 chemical sciences ,Rhodium ,chemistry.chemical_compound ,chemistry ,Click chemistry ,Structural isomer ,Organic chemistry ,Azide - Abstract
A rhodium-catalyzed azide–alkyne cycloaddition of internal ynamides is described. The reaction could be performed in a wide range of solvents, including aqueous media, under mild conditions without careful exclusion of air and moisture, giving a variety of 5-amino-triazoles as a single regioisomer. The mechanism of regioselective cycloaddition was rationalized by means of density functional theory calculations.
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- 2017
11. Highly Chemoselective and Enantioselective Catalytic Oxidation of Heteroaromatic Sulfides via High-Valent Manganese(IV)–Oxo Cation Radical Oxidizing Intermediates
- Author
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Shuang Gao, Wen Dai, Ying Lv, Guosong Li, Chunsen Li, and Sensen Shang
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010405 organic chemistry ,Sulfoxide ,General Chemistry ,Benzoxazole ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Heterolysis ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Benzothiazole ,Pyridine ,Organic chemistry ,Hydrogen peroxide ,Thiazole - Abstract
A manganese complex with a porphyrin-like ligand that catalyzes the highly chemoselective and enantioselective oxidation of heteroaromatic sulfides, including imidazole, benzimidazole, indole, pyridine, pyrimidine, pyrazine, sym-triazine, thiophene, thiazole, benzothiazole, and benzoxazole, with hydrogen peroxide is described, furnishing the corresponding sulfoxides in good to excellent yields and enantioselectivities (up to 90% yield and up to >99% ee) within a short reaction time (0.5 h). The practical utility of the method has been demonstrated in the gram-scale synthesis of chiral sulfoxide. Mechanistic studies, performed with 18O-labeled water (H218O), hydrogen peroxide (H218O2), and cumyl hydroperoxide, reveal that a high-valent manganese–oxo species is generated as the oxygen atom delivering agent via carboxylic acid assisted heterolysis of O–O bonds. Density functional theory (DFT) calculations were also carried out to give further insight into the mechanism of manganese-catalyzed sulfoxidation. O...
- Published
- 2017
12. Easy access to medium-sized lactones through metal carbene migratory insertion enabled 1,4-palladium shift
- Author
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Chunsen Li, Xueliang Huang, Lei Zhu, Pushkin Chakraborty, Jinshuai Song, and Yinghua Yu
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inorganic chemicals ,Science ,General Physics and Astronomy ,chemistry.chemical_element ,Synthetic chemistry methodology ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Metal ,Benzaldehyde ,chemistry.chemical_compound ,Molecule ,lcsh:Science ,Multidisciplinary ,010405 organic chemistry ,Chemistry ,Catalytic mechanisms ,Migratory insertion ,General Chemistry ,Homogeneous catalysis ,Combinatorial chemistry ,0104 chemical sciences ,Lactone synthesis ,visual_art ,visual_art.visual_art_medium ,lcsh:Q ,Carbene ,Palladium - Abstract
Reactions that efficiently construct medium-sized lactones are significant, as they overcome the unfavorable entropic factor and transannular interactions for ring closure, and the lactones produced are common structural motifs recurring in many biologically active compounds. Herein, we describe a valuable strategy for medium-sized lactone synthesis by accomplishing site-selective C–H bond functionalization via a palladium carbene migratory insertion enabled 1,4-palladium shift. The overall process achieves the formal dimerization of two readily available benzaldehyde derivatives, providing value-added products medium-sized lactones. Our method is amenable to late-stage modification of approved drugs and other complex molecules. Mechanistic studies including deuterium-labeling experiments and DFT calculation shed light on the reaction pathways., Transannular construction of medium-sized lactones is entropically unfavoured. Herein, the authors describe a strategy for valuable medium-sized lactone synthesis from available benzaldehydes by selective C-H bond functionalization via palladium carbene migratory insertion-enabled 1,4-palladium shift.
- Published
- 2019
13. Selective Chlorination of Substrates by the Halogenase SyrB2 Is Controlled by the Protein According to a Combined Quantum Mechanics/Molecular Mechanics and Molecular Dynamics Study
- Author
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Dina A. Sharon, Chunsen Li, Sason Shaik, Jing Huang, Binju Wang, and Wei Wu
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chemistry.chemical_classification ,Reaction mechanism ,010405 organic chemistry ,Ligand ,Chemistry ,Hydrogen bond ,Halogenation ,General Chemistry ,010402 general chemistry ,Hydrogen atom abstraction ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Molecular dynamics ,Computational chemistry ,Isomerization ,Alkyl - Abstract
The enzyme SyrB2 employs an FeIV–oxo species to achieve selective C–H halogenation of l-threonine. Herein, we use combined quantum mechanical/molecular mechanical (QM/MM) calculations and molecular dynamics (MD) simulations to decipher the mechanism of selective halogenation by SyrB2. Our QM/MM calculations show the presence of three Cl–FeIV–oxo isomers which interconvert, and only the one having its oxo ligand pointing toward the target C–H bond is active during the hydrogen atom abstraction (H-abstraction) process. The fate of the formed Cl–FeIII–OH/R• intermediate is determined by a hydrogen-bonding interaction between the Arg254 residue and the OH ligand of Cl–FeIII–OH. The hydrogen bond not only prevents the OH group from participating in the followup rebound step to form a hydroxylated product but also facilitates the isomerization of the Cl–FeIII–OH/R• intermediate so that the Cl is directed toward the alkyl radical. The role of Arg254 in regulating the selectivity of chlorination is further discus...
- Published
- 2016
14. Aminofluorination: transition-metal-free N-F bond insertion into diazocarbonyl compounds
- Author
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Chunsen Li, Xueliang Huang, Xuesong Luo, Yinghua Yu, Jinshuai Song, and Gui Chen
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010405 organic chemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Chemistry ,chemistry ,Transition metal ,Computational chemistry ,Fluorine ,Nitrogen source ,Potential mechanism - Abstract
Gem-aminofluorination of diazocarbonyl compounds has been achieved for the first time., Gem-aminofluorination of diazocarbonyl compounds has been achieved for the first time. This reaction proceeds under mild conditions and does not require any transition-metal promoter or catalyst. Treatment of diazoesters with N-fluorobenzenesulfonimide (NFSI), which serves as both a fluorine and nitrogen source, results in the facile construction of C–N and C–F bonds, providing aminofluorination products in moderate to excellent yields. Kinetic studies and DFT calculations have provided valuable insight into the potential mechanism for this novel N–F bond insertion.
- Published
- 2015
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