Article
Chemistry, Multidisciplinary
Yaxin Zeng, Ying Xia
Summary: The direct synthesis of gem-difluorinated carbocyclic molecules has long been a challenge in organic chemistry. Here, a Rh-catalyzed [3+2] cycloaddition reaction between gem-difluorinated cyclopropanes and internal olefins has been developed, providing an efficient method to synthesize gem-difluorinated cyclopentanes with good functional group compatibility, excellent regioselectivity, and good diastereoselectivity. The resulting products can also be further transformed into various mono-fluorinated cyclopentenes and cyclopentanes, demonstrating the potential of this reaction as a strategy for synthesizing other gem-difluorinated carbocyclic molecules.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Tatiana Suarez-Rodriguez, angel L. Suarez-Sobrino, Alfredo Ballesteros
Summary: The Gold(I)-catalyzed formal [4+2] cycloaddition of O-aryl ynol ethers 1 and enol ethers 2 results in chromene derivatives with good yields under mild conditions. The reaction is completely regio- and stereoselective, and versatile for different reactants, including silyl enol ethers. Experimental results support a proposed mechanism involving the selective addition of the enol ether to the alkyne gold activated complex followed by an intramolecular aromatic electrophilic substitution, leading to the formation of a cationic oxonium intermediate prior to the aromatic substitution. This reaction introduces a new route to the chromene core.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
John M. Halford-McGuff, Alexandra M. Z. Slawin, Allan J. B. Watson
Summary: This article presents a predictive model for the reactivity and turnover of the Rh-catalyzed [2 + 2 + 2] cycloaddition of diynes and alkynes. Contrary to the proposed electronic model, this model suggests that the reaction is predominantly driven by steric effects, and turnover is proportional to alkyne steric parameters. The model allows for the prediction of catalyst loading, turnover, and reaction yield based on the assessment of the alkyne's steric parameter.
Article
Chemistry, Organic
Yujia Gao, Juan Zhang, Wenyu Shan, Weihong Fei, Jinzhong Yao, Weijun Yao
Summary: In this study, a trimerization reaction of gamma-aryl-3-butynoates was achieved through catalysis, leading to the formation of exocyclopentene derivatives with an allcarbon quaternary stereocenter. The reaction exhibited high stereoselectivity and enantioselectivity, delivering optically pure products with high enantiomeric excess values.
Article
Chemistry, Multidisciplinary
Ryota Shimotsukue, Kohei Fujii, Yu Sato, Yuki Nagashima, Ken Tanaka
Summary: We have developed a rhodium-catalyzed intermolecular [2+2+2] cycloaddition reaction with excellent selectivity, producing chiral cyclohexadienylamines. The reaction involves the reaction of two arylacetylenes with a cis-enamide or a silylacetylene to yield the desired products with complete regio- and diastereoselectivity and high yields and enantioselectivity. Mechanistic studies suggest the formation of a rhodacyclopentadiene intermediate from the terminal alkynes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Hao Zeng, Xiaojie Fang, Zhiyi Yang, Chuanle Zhu, Huanfeng Jiang
Summary: A general and practical method for the synthesis of 5-trifluoromethylpyrazoles has been reported, using a coupling reaction between hydrazonyl chlorides and the industrial feedstock 2-bromo-3,3,3-trifluoropropene (BTP). This catalyst-free [3 + 2] cycloaddition shows high regioselectivity, mild conditions, high yields, scalability, broad substrate scope, and tolerance for various functional groups, with application in synthesizing key intermediates for an active agonist of sphingosine 1-phosphate receptor.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Huai-Ri Sun, Lan Yang, Yu Li, Le Yu, Bo-Bo Gou, Atif Sharif, Qing-Song Jian, Jie Chen, Ling Zhou
Summary: A chiral phosphoric acid was used as a catalyst for the enantioselective [2 + 2] cycloaddition reaction between alkynylindols or alkynylnaphthols and quinones. The reaction produced a class of functionalized cyclobutenes with high yields and excellent diastereo- and enantioselectivities. Mechanistic studies revealed the involvement of dearomatization of indole or naphthol and intramolecular Michael addition in the reaction, while preventing competitive [2 + 3] cycloaddition. During the transformation of the product, an interesting conversion from central to axial chirality was achieved through a rearrangement process.
SCIENCE CHINA-CHEMISTRY
(2023)
Article
Chemistry, Physical
Sagar Arepally, Ponnusamy Nandhakumar, Gisela A. Gonzalez-Montiel, Alina Dzhaparova, Gyeongho Kim, Ahyeon Ma, Ki Min Nam, Haesik Yang, Paul Ha-Yeon Cheong, Jin Kyoon Park
Summary: Electrochemical access to organometallic redox reagents allows for selective synthesis of various benzene derivatives with different regioisomers. A unified electrochemical strategy is presented for the selective cyclotrimerization of terminal alkynes to access both 1,3,5- and 1,2,4-regioisomeric trisubstituted benzene derivatives. The regiocontrol can be switched by the addition of a carboxylic acid.
Article
Chemistry, Physical
Jordan L. Harper, Stephanie Felten, Ryan M. Stolley, Alexander S. Hegg, Paul H-Y Cheong, Janis Louie
Summary: The mechanistic investigation into the origins of regio- and chemoselectivities observed in iron/pyridine dialdimine (PDAI)-catalyzed intermolecular [2+2+2] cycloaddition reactions of terminal alkynes and cyanamides reveals the significant role of the hemilabile PDAI ligand in controlling the observed selectivity of the resultant products.
Article
Chemistry, Applied
Kai Wang, Xiangfeng Lin, Qian Li, Yan Liu, Can Li
Summary: This study developed a highly selective synthetic method for the direct synthesis of polycyclic coumarin compounds from simple and readily-available coumarin derivatives, achieving excellent yields and enantioselectivities. This asymmetric reaction was achieved using a Pd(0)/Cu(I) bimetallic catalytic system, where chiral Cu(I) and chiral Pd(0) played important synergistic roles.
CHINESE JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Organic
Yating Dai, Hongchun Huang, Shuangshuang Liang, Yanli Yin, Xu Ban, Xiaowei Zhao, Zhiyong Jiang
Summary: In this study, an enantioselective intermolecular [3 + 2] cycloaddition of N-arylcyclopropylamines with 2-aryl acrylates/ketones and cyclic ketone-derived terminal olefins via asymmetric photoredox catalysis was reported. A dual catalyst system involving DPZ and a chiral phosphoric acid was effective for the transformations, leading to a wide array of valuable cyclopentylamines with high yields, ee's, and drs. Elaborate modulation of the ester group of 2-aryl acrylates was shown to be effective in improving reactivity, thereby enabling the success of the transformations.
Article
Chemistry, Organic
Kelvin J. Y. Wu, Amy E. Benedetto, Andrew G. Myers
Summary: The regioselectivity of a [3+2] dipolar cycloaddition reaction between a stabilized azomethine ylide and an electron-deficient dipolarophile is contrary to a previous report in this journal.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Barry M. Trost, Zhijun Zuo
Summary: A novel Pd-0-catalyzed highly selective [3+2] spiroannulation reaction has been developed for rapid assembly of a new class of [5,5] spirocyclic carbo- and heterocycles. The regioselectivity of the reaction can be controlled by fine-tuning the Pd-pi-allyl intermediate, with excellent toleration of various coupling partners and enantioselectivities demonstrated through further transformations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Biochemistry & Molecular Biology
Igor Philippov, Yuriy Gatilov, Alina Sonina, Aleksey Vorob'ev
Summary: A method for the synthesis of pyrazolo[1,5-a]pyridine-3-ylphosphonates by oxidative [3+2]cycloaddition reaction was reported. Different substituents have an effect on the reaction activity, with 4-halogenated substituents showing lower reactivity.
Article
Chemistry, Organic
Hyo Seon Sim, Hari Datta Khanal, Yong Rok Lee
Summary: In this paper, a highly efficient and atom-economic iron(III)-catalyzed three-component heteroannulation reaction is described for the construction of multifunctionalized 2-pyridones. The protocol allows rapid access to a variety of 2-pyridones with an ortho-hydroxybenzoyl and a benzoyl scaffold under simple conditions. The synthetic utility of the synthesized 2-pyridone scaffolds is demonstrated by transforming them into biologically interesting complex heterocycles.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Inorganic & Nuclear
Joseph M. Mwansa, Matthew J. Stirling, Gemma Sweeney, Jiri Hanusek, Jiri Vana, Michael Page
Summary: A novel dimeric iodo-iridium(iii) complex with an amide moiety within the tetramethylcyclopentadiene ring has been synthesized and characterized. The presence of restricted rotation in the 2-substituted isomer leads to the existence of two distinguishable conformers. The relative acidities of Cp*CONMe2 and Cp* have been compared, and the study also focuses on the decrease in enantiomeric excess during the reduction reaction.
DALTON TRANSACTIONS
(2022)
Article
Chemistry, Analytical
Alona Usenko, Jaromira Chylkova, Renata Selesovska, Milos Sedlak, Jiroi Vana, Jan Bartacek, Tomas Mikysek
Summary: In this study, a direct electrochemical oxidation method was used to simultaneously determine growth regulator daminozide (DMZ) and its degradation product N,N-dimethylhydrazine (DMH). The oxidation mechanism of DMZ was proposed. A sensitive differential pulse voltammetric method was developed for the determination of both substances, and an extraction technique was utilized to enhance the detection limits. The presence of DMH significantly affected the results of DMZ analysis, and a method for DMH removal was also developed. Real samples were successfully analyzed.
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
A. Olshtrem, I. Panov, S. Chertopalov, K. Zaruba, B. Vokata, P. Sajdl, J. Lancok, J. Storch, V. Cirkva, V. Svorcik, M. Kartau, A. S. Karimullah, J. Vana, O. Lyutakov
Summary: The response of circularly polarized light sensitive materials can be achieved at plasmon wavelengths by combining non-chiral plasmonic nanostructures with chiral organic molecules. Different types of metal nanoparticles of various shapes and sizes are tested and show an obvious circular dichroism (CD) signal in both nanoparticle suspensions and after immobilization on a substrate. This work proposes the creation of plasmon-active 2D flakes of MXenes, which exhibit an apparent CD response at plasmon wavelength through coupling with helically shaped helicene enantiomers. This is the first demonstration of a chiral and plasmon-active 2D material that exhibits light absorption sensitive to intrinsic circular polarization even in the plasmon wavelength range. The induced CD signal is further confirmed through theoretical calculations. These flakes are then utilized for polarization sensitive conversion of light to heat, as well as for polarization dependent triggering of plasmon-assisted chemical transformations.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Organic
Lukas Marek, Jiri Vana, Jan Svoboda, Jiri Hanusek
Summary: In this study, the reactions of thiobenzamide or thioacetamide with different conditions were investigated. The influence of structure and medium features on product distribution was identified, including Eschenmoser coupling reaction, Hantzsch thiazole synthesis, and elimination to nitriles. The successful Eschenmoser coupling reaction relies on the optimum balance in acidity of nitrogen and carbon atoms of the intermediary alpha-thioiminium salts.
BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Analytical
Alona Usenko, Jaromira Chylkova, Jiri Vana, Oleksandr Matvieiev, Lenka Janikova, Renata Selesovska
Summary: The electrochemical oxidation of Paclobutrazol (PBZ) was investigated for the first time. PBZ showed an irreversible anodic peak on a boron-doped diamond electrode (BDDE) over a wide pH range. The mechanism of electrochemical oxidation of PBZ was proposed based on LC-MS analysis. A method for determination of PBZ using differential pulse voltammetry with BDDE was developed.
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Ian J. S. Fairlamb, Jan Lang, Ales Ruzicka, Milos Sedlak, Jiri Vana
Summary: In this study, it was found that N,N-dimethyl-fluoro-benzylamines can react directly with Pd-3(OAc)(6) to form higher-order cyclopalladated intermediates and produce two regioisomeric products. The regioselectivity can be subtly altered by changing the ratio of substrate:Pd-3(OAc)(6) and the solvent used.
Article
Chemistry, Physical
Anna Zabelina, Jakub Dedek, Olga Guselnikova, Denis Zabelin, Andrii Trelin, Elena Miliutina, Zdenka Kolska, Jakub Siegel, Vaclav Svorcik, Jiri Vana, Oleksiy Lyutakov
Summary: The conversion of CO2 to fine chemicals is an efficient tool for reducing environmental impact. This study demonstrates that CO2 capture and sunlight-based activation can be achieved at low temperatures using plasmon-assisted chemistry. A specific photocatalyst consisting of an organic shell and a plasmon-active metal nanoparticle core was proposed, facilitating the cycloaddition reaction. The plasmon-assisted CO2 cycloaddition was found to be only slightly temperature sensitive. The results suggest potential for utilizing the solar potential of Arctic and Antarctic regions.
Article
Chemistry, Organic
Martin Kocurik, Jan Bartacek, Pavel Drabina, Jirci Vana, Jan Svoboda, Lenka Husakova, Vladimir Finger, Michaela Hympanova, Milos Sedlak
Summary: This study presents an improved synthetic route for a ligand that can be used as a highly active and enantioselective catalyst. The immobilized catalyst exhibited stability and high turnover numbers, providing valuable insights into the development of continuous flow reactors for the synthesis of benzosultams.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Tereza Korabkova, Jan Bartacek, Lukas Marek, Jiri Hanusek, Ales Ruzicka, Jiri Vana
Summary: In this work, the possibility of switching the regioselectivity of C-H activation reactions by adding acids of different strengths was studied. The addition of no or weak acids causes the reaction to be controlled by a stronger directing group, while the addition of a strong acid leads to control by a weaker directing group. This approach enables the synthesis of non-symmetrical [2.2]-dipalladaparacyclophanes.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Physical
Anna Zabelina, Jakub Dedek, Olga Guselnikova, Denis Zabelin, Andrii Trelin, Elena Miliutina, Zdenka Kolska, Jakub Siegel, Vaclav Svorcik, Jiri Vana, Oleksiy Lyutakov
Summary: The conversion of CO2 to fine chemicals is efficiently achieved through plasmon-assisted chemistry, allowing for CO2 capture and activation at low temperatures. A specific photocatalyst with an organic shell for CO2 capture and a plasmon-active metal nanoparticle core for activation is proposed. The plasmon-assisted CO2 cycloaddition reaction is found to be slightly temperature sensitive, and the apparent activation barrier is significantly decreased under the plasmon-assisted mechanism. This research opens up new opportunities for utilizing the solar potential in the Arctic and Antarctic regions.
Article
Chemistry, Applied
Jaroslav Pochobradsky, Jan Bartacek, Jiri Vana, Jan Svoboda, Marketa Svobodova, Pavel Drabina, Jan Patocka, Milos Sedlak
Summary: This study investigates the development of recyclable heterogeneous catalysts for the palladium-catalysed additions of arylboronic acids to nitrostyrenes. Two strategies, direct copolymerization and post-modification, are explored for immobilizing chiral isoquinoline-oxazoline ligands onto polymer matrices. The incorporation of polar functional groups into the polymer matrix enhances catalytic properties, albeit with a decrease in reaction rate compared to the homogeneous system. Post-modification using a polystyrenepolyethylene glycol (PS-PEG) support shows promise, resulting in a moderate decrease in reaction rate and satisfactory performance over multiple reaction cycles. These findings provide valuable insights into the immobilization of chiral ligands and highlight the advantages and limitations of different polymer compositions. The results contribute to the development of advanced catalytic systems for the synthesis of biologically relevant compounds.
REACTIVE & FUNCTIONAL POLYMERS
(2023)
Article
Biochemistry & Molecular Biology
Qiuyun Yang, Jiri Vana, Petr Klan
Summary: Irradiation of coumarin-3-carboxylic acid in acetonitrile and methanol solutions results in complex multistep photochemical transformations. The reaction intermediates and final products were identified using various spectroscopic and analytical techniques. The study provides detailed insights into the complex phototransformations of coumarin derivatives, which are widely used in photophysical and photochemical applications.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2022)
