Article
Chemistry, Physical
Kuohong Chen, Jiaming Zhang, Qianqian Shi, Lili Han, Dongmin Fu, Donghui Wei, Yanyan Zhu
Summary: Understanding the mechanisms and origin of regio- and stereoselectivities in N-heterocyclic carbene (NHC)-catalyzed radical reactions of enals and pyridinium salts remains a significant challenge in radical chemistry. This study used density functional theory calculations to explore the possible mechanisms and the factors controlling selectivities. The findings shed light on the detailed steps involved in these reactions and provide valuable insight for theoretical investigations on radical reactions.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Ludivine Delfau, Samantha Nichilo, Florian Molton, Julie Broggi, Eder Tomas-Mendivil, David Martin
Summary: This study reported the synthesis of acyl azolium salts from various types of carbenes and the generation of their corresponding radicals and enolates, revealing the role of additives in the redox behavior of these compounds and correcting misconceptions about radical transformations of aldehyde derivatives. The reducing ability of enolates derived from certain carbenes was found to be underestimated, and catalytic intermediates were shown to transfer electrons efficiently at room temperature. Enol derivatives of certain carbenes were identified as powerful reducing agents.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Kenta Tanaka, Mami Kishimoto, Yuta Tanaka, Yusuke Kamiyama, Yosuke Asada, Mayumi Sukekawa, Naoya Ohtsuka, Toshiyasu Suzuki, Norie Momiyama, Kiyoshi Honda, Yujiro Hoshino
Summary: New moderately oxidizing thioxanthylium photoredox catalysts have been developed that can efficiently promote radical-cation Diels-Alder reactions under green light irradiation. These catalysts have relatively moderate excited-state reduction potentials and can tolerate beta-halogenostyrenes, producing synthetically useful halocyclohexenes.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Abhishek Koner, Bernd Morgenstern, Diego M. Andrada
Summary: A new N-heterocyclic carbene-stabilized phosphaborene has been synthesized and isolated, which is a room-temperature-stable crystalline solid. It exhibits remarkable reactivity and can undergo P-centre metathesis reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Bowen Zhu, Kexuan Wang, Haili Gao, Qinhua Wang, Xiaofeng Pan, Mizi Fan
Summary: The interaction between organic molecules and MXene surface depends on the type of functional groups, while the strength of the interaction is determined by the type of surface functional groups and the number of hydrogen bonds. MXene saturated with -OH or -F groups can form strong chemical and hydrogen bonds with organic molecules, leading to strong adsorption energy and charge transfer, while MXene saturated with -F or -O groups mainly exhibits physical interactions, with low adsorption energy and minimal charge transfer.
Review
Chemistry, Organic
Sandeepan Maity
Summary: Samarium diiodide (SmI2) is a versatile single electron transfer reagent used in organic synthesis for stereoselective reactions. However, its stoichiometric usage poses environmental concerns limiting its broader applicability. Recent studies have focused on developing catalytic methods to rejuvenate the applications of SmI2 in synthetic organic chemistry.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Review
Chemistry, Applied
Shivani Sharma, Jitender Singh, Anuj Sharma
Summary: The novel concept of radical-polar crossover (RPCO) and polar-radical crossover (PRCO) reactions has emerged in recent years as a valuable tool bridging the gap between polar and radical reactions, overcoming their limitations, and improving the green quotient of reactions. The development and transformation of this area into synthetically important reactions is summarized in this review.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Physical
Shu Cai, Qi Zhang, Ziqian Wang, Sheng Hua, Dahu Ding, Tianming Cai, Ruihong Zhang
Summary: The study found that nitrogen configurations doped in the carbon matrix play a key role in activating persulfates, and successfully prepared pyrrolic N-rich biochar BDK900 with ultra-high specific surface area by converting waste bean dregs. BDK900 exhibited superior catalytic activity in persulfate activation, efficiently removing BPA. Surface-bound radicals and electron-transfer mechanism were discovered to contribute to BPA oxidation.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2021)
Review
Chemistry, Applied
Xi Sun, Xu Dong, Hui Liu, Yuying Liu
Summary: Great improvements have been made in palladium-catalyzed radical reactions in recent years, offering more effective strategies for constructing complex heterocyclic compounds and applications in drug discovery. Reactions mediated by Pd(0)/(II)/(IV) typically undergo two-electron transfer processes, while those involving Pd(I) and Pd(III) usually occur via single electron transfer processes. Numerous methodologies involving palladium radical have emerged in the past five years since the publication of the review.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Multidisciplinary
Wouter A. A. Remmerswaal, Thomas Hansen, Trevor A. A. Hamlin, Jeroen D. C. Codee
Summary: Oxocarbenium ions play a key role in organic chemistry and their reactions with allyltrimethylsilane were investigated in this study. The researchers found that the preference for the chair conformation of the oxocarbenium ion influences the stereochemical outcome of the reaction. The introduction of alkoxy substituents on the ions also affects their conformational preference and stereoselectivity.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Beauty K. Chabuka, Igor V. Alabugin
Summary: In order to use holes as catalysts, the oxidation potential along the reaction path must increase, leading to hole upconversion. This study provides guidelines for the rational design of hole-catalyzed Diels-Alder (DA) reactions. The occurrence and magnitude of hole upconversion depend strongly on the placement and nature of substituents in the reactants, and stereoelectronic effects can activate or deactivate upconversion via conformational changes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Beatriz G. del Rio, Brandon Phan, Rampi Ramprasad
Summary: In this study, a machine learning model is proposed to emulate the essence of density functional theory (DFT) by mapping the atomic structure to the electronic charge density and predicting other properties. This model bypasses the computational cost of solving the central Kohn-Sham equation and maintains chemical accuracy.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Multidisciplinary Sciences
Clorice R. Reinhardt, Daniel Konstantinovsky, Alexander Soudackov, Sharon Hammes-Schiffer
Summary: This article presents a kinetic model that describes the reversible radical transfer in the enzyme ribonucleotide reductase (RNR). The model is based on experimental studies and provides insights into the time evolution and factors influencing radical transport in RNR.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Engineering, Environmental
Meng Li, Yu-Ting Jin, Jian-Fang Yan, Zhang Liu, Nai-Xian Feng, Wei Han, Long-Wei Huang, Qin-Ke Li, King-Lun Yeung, Shao-Qi Zhou, Ce-Hui Mo
Summary: Polyfluoroalkyl and perfluoroalkyl chemicals (PFCs) widely used in various industries pose great risks to human health and eco-environments. This study demonstrates that electrochemical oxidation process coupled with peroxymonosulfate (PMS) reaction can efficiently degrade PFCs through electron transfer and generation of active radicals. The findings provide insights and technical support for the removal of multiple organic contaminants.
Article
Chemistry, Physical
Daniele Loco, Isabelle Chataigner, Jean-Philip Piquemal, Riccardo Spezia
Summary: Modeling chemical reactions using Quantum Chemistry is a widely used predictive strategy that complements experimental studies to understand reaction mechanisms. This research benchmarked various computational approaches for predicting energy barriers in six Diels-Alder reactions of increasing complexity. The results showed that using economical Density Functional Theory methods combined with empirical dispersion corrections can provide high-quality results with minimal computational effort. This simulation protocol opens new prospects for studying Diels-Alder reactions with explicit solvent using hybrid QM/MM molecular dynamics simulations.
Article
Chemistry, Multidisciplinary
Simon Osswald, Christoph Zippel, Zahid Hassan, Martin Nieger, Stefan Braese
Summary: A new versatile method for C-P bond formation of (hetero)aryl halides with trimethyl phosphite via UV-induced photo-Arbuzov reaction has been developed. This method allows the synthesis of diverse phosphonate-grafted compounds without the need for catalyst, additives, or base. The reaction conditions are mild and transition metal-free, making it potentially useful for synthesizing pharmaceutically relevant compounds and precursors of supramolecular nanostructured materials.
Article
Chemistry, Multidisciplinary
Stephan Hagspiel, Felipe Fantuzzi, Merle Arrowsmith, Annalena Gaertner, Maximilian Fest, Jonas Weiser, Bernd Engels, Holger Helten, Holger Braunschweig
Summary: The reaction of a cyclic alkyl(amino)carbene (CAAC)-stabilized thiazaborolo[5,4-d]thiazaborole (TzbTzb) with strong Bronsted acids results in the protonation of both TzbTzb nitrogen atoms. The coordination of counteranions or solvent molecules to the doubly protonated fused heterocycle via hydrogen-bonding interactions influences the visible and fluorescence colors of these salts. DFT calculations show that the hydrogen bonding affects the charge transfer character, enabling fine-tuning of absorption and emission spectral features.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Jan Fassbender, Niklas Volk, Antonio Garcia Alcaraz, Selvakumar Balasubramaniam, Arturo Espinosa Ferao, Rainer Streubel
Summary: After more than 160 years of research, scientists have finally synthesized an oxaphosphirane, a phosphorus analogue derivative of oxirane. Reactions with various compounds have shown that increasing the coordination number at phosphorus causes destabilization, which supports previous findings. Theoretical studies have provided insights into ring strain energy, ring/ring interconversion, and oxidation pathways.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Applied
Miriam Mas-Montoya, Antonio Garcia Alcaraz, Arturo Espinosa Ferao, Delia Bautista, David Curiel
Summary: Two four-coordinate boron complexes, compounds 5 and 7, were synthesized using similar benzophenanthridine-based ligands but with different conformational constraints, and their optical properties were investigated. Ligand design considering expansion of pi-conjugation and structural desymmetrization was found to be effective in obtaining fluorophores with large Stokes shifts. The incorporation of a conformationally free substructure increased the geometry relaxation in the first excited state (S1) and the ground state (S0), resulting in enhanced Stokes shift. Solvatochromism showed divergent behavior in emission and absorption spectra, attributed to the different stabilization degrees of the S0 and S1 states compared to the Franck-Condon states. Aggregation-induced emission (AIE) was observed in molecule 7, which was attributed to blocking the motion of peripheral rotor based on solid state packing determined by X-ray diffraction.
Article
Chemistry, Multidisciplinary
Xujun Qiu, Julian Brueckel, Christoph Zippel, Martin Nieger, Frank Biedermann, Stefan Braese
Summary: In this article, a multifunctionalisable aryl azide, tris(4-azidophenyl)methanol, is reported. It can be used as a protecting group for thiols in peptoid synthesis and can be cleaved under mild reaction conditions via a Staudinger reduction. Additionally, the easily accessible aryl azide can be functionalised through copper-catalysed cycloaddition reactions, offering more possibilities for materials chemistry applications.
Article
Chemistry, Multidisciplinary
Arturo Espinosa Ferao, Alicia Rey Planells
Summary: Accurate ring strain energy (RSE) values were reported for sixty-six parent pnictogeniranes with two other identical p-block elements, El(2)Pn. A decrease in RSE was found to be correlated with an increase in the p character of the AO used in endocyclic bonds, particularly in groups 15 and 16. The higher -NICS(1) values also parallel the presence of atom-centred diatropic currents, mostly arising from the lone pairs. Only in the case of pnictogenaditrieliranes Tr(2)Pn (Tr=B, Al, Ga), the decrease of -NICS(1) is related to lower Huckel-type 2 pi-electron aromaticity in group 13.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Matthias Maier, Johannes Chorbacher, Anna Hellinger, Jonas Klopf, Julian Guenther, Holger Helten
Summary: This study focuses on oligo- and poly(arylene iminoborane)s with a backbone of phenylene or thiophene moieties linked via B=N units. The researchers successfully prepared various polymers and oligomers with tailored electronic properties using a modular synthetic approach. The compounds exhibited effective pi-conjugation, solid-state emission, and aggregation-induced emission behavior.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Editorial Material
Chemistry, Inorganic & Nuclear
Holger Helten, Rory Waterman
Summary: This special collection has been created to honor Prof. Streubel on his retirement, showcasing his significant contributions to the field of low-valent phosphorous chemistry, with a central theme on the beauty of inorganic chemistry.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Matthias Maier, Vivien Zeh, Nadine Munker, Julian Glock, Kai Oberdorf, Ozan Ayhan, Crispin Lichtenberg, Holger Helten
Summary: The incorporation of BN units into organic scaffolds by isoelectronic/isosteric substitution has proven effective in producing new materials. However, the knowledge about BN-doped inorganic-organic hybrid polymers is limited, especially for linear or cyclolinear macromolecules with longer inorganic chains. In this study, 1,2,5-azadiborolane was introduced as a novel building block for polymers. By coupling it with a p-phenylene diamine-based co-monomer, a hybrid polymer with a B2N3 chain and a considerable molecular weight was obtained. The UV-vis spectra revealed a red-shift in the longest-wavelength absorption band with increasing number of BN units in the chain.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Jere K. Mannisto, Ljiljana Pavlovic, Johannes Heikkinen, Tony Tiainen, Aleksi Sahari, Norbert M. Maier, Kari Rissanen, Martin Nieger, Kathrin H. Hopmann, Timo Repo
Summary: We developed a mildsuperbase-catalyzed carboxylation method for the synthesis of drug-like O-alkyl carbamates. Our mechanistic study reveals that when superbases interact with indoles and azoles, uncharged hydrogen-bonded complexes are formed instead of ionic salts. These complexes can be converted into carbamate salts upon exposure to CO2. The carbamate salts can be further classified into stable and fluxional types, with the latter being poor substrates for alkylation. We also identified the substrate-specific factors responsible for the fluxional behavior and proposed strategies to stabilize the carbamate salts for efficient alkylation.
Article
Chemistry, Multidisciplinary
Arturo Espinosa Ferao
Summary: This study explores the deoxygenation of parent and substituted oxiranes using lambda(3)sigma(3)-phosphorus reagents and reveals mechanistic aspects, as well as regio- and stereochemical consequences. It shows that attack to a ring C atom is usually preferred over direct P-to-O attack for one-step deoxygenation. The study also investigates the use of heavier derivatives AsMe3 and SbMe3 as oxirane deoxygenating reagents. The thermodynamic tendencies of lambda(3)sigma(3)-phosphorus reagents to act as oxygen or carbene acceptors are theoretically studied.
Article
Chemistry, Medicinal
Lamya H. Al-Wahaibi, Essmat M. El-Sheref, Alaa A. Hassan, S. Braese, M. Nieger, Bahaa G. M. Youssif, Mahmoud A. A. Ibrahim, Hendawy N. Tawfeek
Summary: 2,3,4-trisubstituted thiazoles 3a-i were successfully synthesized and their structures were determined. These compounds showed excellent antiproliferative activity without exhibiting cytotoxicity. The most potent derivatives, compounds 3a, 3c, 3d, and 3f, demonstrated strong antiproliferative activity against human cancer cell lines and also exhibited potent inhibition against EGFR and BRAF(V600E).
Article
Chemistry, Multidisciplinary
Johannes S. S. Schneider, Ivo Krummenacher, Holger Braunschweig, Holger Helten
Summary: In this study, various linear oligo(p-phenylene iminoboranes) with pendent ferrocene groups were synthesized from oligo(p-phenylene vinylenes) by BN modification. The formation of the unprecedented macrocycle was achieved through a stoichiometric reaction of bis-silylamine with a bisborane, without the need for a template.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Inorganic & Nuclear
Arif Ali Khan, Tim Kalisch, Arturo Espinosa Ferao, Rainer Streubel
Summary: The reaction of a transient terminal phosphinidene complex with triethylamine resulted in the formation of an sp(3) C-H insertion product, as confirmed by P-31 NMR spectroscopy. The product was isolated as a semi-solid compound. However, after 24 hours of reaction, a primary phosphane complex was obtained. The compounds were characterized using NMR spectroscopy and mass spectrometry. Formation of the final products is explained by a mechanistic proposal based on DFT calculations.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Vivien Zeh, Johannes S. Schneider, Jonas Bachmann, Ivo Krummenacher, Holger Braunschweig, Holger Helten
Summary: This study presents the first poly(ferrocenylene iminoborane), a polyferrocene-based metallopolymer, and a series of monodisperse ferrocenylene iminoborane oligomers, shedding light on the structural and electronic nature of this novel class of hybrid materials.
CHEMICAL COMMUNICATIONS
(2023)
