Article
Chemistry, Multidisciplinary
Paul Zaby, Jan Blasius, Anna K. Mueller, Steven P. Nolan, Oldamur Holloczki
Summary: The formation mechanism of metal-N-heterocyclic carbene (NHC) complexes from imidazolium salts in the presence of weak bases was investigated through theoretical methods. Quantum chemical calculations revealed that both sodium acetate and trimethylamine facilitate complex formation. Molecular dynamics simulations showed that the ionic nature of the [AuCl2](-) and imidazolium ions, as well as the sodium acetate base, keep these species associated in the reaction mixture through ion pairing. The neutral amine, however, remains mostly separated from the other reaction partners, making it a significantly less effective base.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Zhi Hao Toh, Hendrik Tinnermann, Dinh Cao Huan Do, Han Vinh Huynh, Tobias Kramer, Rowan D. Young
Summary: We isolated and characterized the gold(i)-iron(0) adducts and found that the gold-iron interaction is predominantly a sigma-donation from iron to gold. The Pr-i(2)-bimy carbenic C-13 NMR signal can be used to gauge the relative donor strength of Fe(0) donors.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Qiuming Liang, Kasumi Hayashi, Longfei Li, Datong Song
Summary: The dioxygenation of mesoionic N-heterocyclic olefins (mNHOs) using molecular dioxygen has been reported. Depending on the presence of a vinyl proton and acidic C-H group, the mNHOs are oxidized into different products.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Kostiantyn P. Melnykov, Olha Tavlui, Artem Skreminskiy, Yuliya O. Kuchkovska, Oleksandr O. Grygorenko
Summary: The physicochemical properties of fluoroalkyl-substituted heterocyclic amines were analyzed to aid their rational application in medicinal chemistry research. The effects of introducing fluoroalkyl groups on the lipophilicity and aqueous solubility of compounds were complex and dependent on the fluorination pattern, ring size, and substituent conformation. The summarized data provide a useful guideline for fine-tuning compound properties in drug discovery.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Inorganic & Nuclear
Robin Guthardt, Hannes L. Jacob, Clemens Bruhn, Ulrich Siemeling
Summary: The use of bulky 1,3,2-diazaborolyl N-substituents allows the synthesis of a complete series of ferrocene-based N-heterocyclic tetrylenes. Silylene fc[(N{B})(2)Si] is less reactive than its N-aryl homologue fc[(NC6H3-2,6-Pr-i(2))(2)Si]. Computational investigation suggests that silylenes of this type may have superior ambiphilicity compared to fc[(NC6H3-2,6-Pr-i(2))(2)Si].
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Shahar Dery, Peter Bellotti, Tzipora Ben-Tzvi, Matthias Freitag, Tehila Shahar, Albano Cossaro, Alberto Verdini, Luca Floreano, Frank Glorius, Elad Gross
Summary: Adsorption of chiral molecules on heterogeneous catalysts is a simple approach for inducing an asymmetric environment to enable enantioselective reactivity. However, successful practical utilization of chiral induction is complex and understanding the factors behind it is crucial for the mechanism of chirality transfer. Adsorption geometry of OH-functionalized N-heterocyclic carbenes plays a key role in influencing enantioselectivity in a-arylation reactions on Pd nanoparticles.
Article
Chemistry, Inorganic & Nuclear
Michael S. M. Philipp, Mirjam J. Krahfuss, Krzysztof Radacki, Udo Radius
Summary: A systematic study on Lewis-acid/base adducts of N-heterocyclic carbenes and cyclic (alkyl)(amino)carbene with antimony(III) chlorides was conducted, revealing a series of products formation and thermal isomerization reactions.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2021)
Article
Materials Science, Multidisciplinary
Peng Luo, Sha Bai, Xin Wang, Jing Zhao, Zhen-Ning Yan, Ying-Feng Han, Shuang-Quan Zang, Thomas C. W. Mak
Summary: The study describes a series of bis-N-heterocyclic carbene (NHC)-protected gold nanoclusters obtained from direct reduction of Au-bis-NHC complexes. The composition and structures of these clusters are unequivocally determined by single crystal X-ray crystallography and electrospray ionization mass spectrometry. The Au-13 cluster exhibits high emission in solution and the luminescence properties are severely dependent on the substituent effects.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Chemistry, Organic
Zheng-Wang Qu, Hui Zhu, Rainer Streubel, Stefan Grimme
Summary: Extensive DFT calculations in this study show that the isomerization of unprotected C-5-position mesoionic N-heterocyclic olefins (mNHOs) can be efficiently catalyzed by weakly protic acidic species, including mNHOs themselves, their Lewis adducts, and polar H2O molecules, leading to the formation of more Lewis-basic mesoionic carbenes (MICs) and enabling catalytic isomerization and H-isotope exchange of mNHOs and their Lewis adducts.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Natesan Mannangatti Rajendran, Qi Lu, Jean Bouffard
Summary: A direct method for synthesizing N-heterocyclic olefins (NHOs) and their mesoionic congeners (mNHOs) from N-heterocyclic carbenes and N-aziridinylimines is reported. This reaction provides diverse functionalized (m)NHOs and pi-extended analogues. The prepared NHOs are capable of initiating the ring-opening polymerization of beta-butyrolactone and demonstrating the insertion of aldehyde and nitrile into an NHO-B(C6F5)(3) adduct.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Arne Merschel, Dennis Rottschaefer, Beate Neumann, Hans-Georg Stammler, Mark Ringenberg, Maurice Van Gastel, T. Ilgin Demirer, Diego M. M. Andrada, Rajendra S. S. Ghadwal
Summary: In this study, we have successfully synthesized and isolated two stable anions K[SIPrBp] (4 a-K) and K[IPrBp] (4 b-K). These anions, derived from classical N-heterocyclic carbenes (NHCs), exist as violet crystalline solids.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Bastiaan Kooij, Zhaowen Dong, Paul Varava, Farzaneh Fadaei-Tirani, Rosario Scopelliti, Laura Piveteau, Kay Severin
Summary: This study reports the preparation and structural characterization of vanadium complexes with N-heterocyclic vinylidene ligands, enabled by utilizing diazoolefins as ligand precursors. Structural and theoretical analysis show that N-heterocyclic vinylidenes can act as strong 6e(-) donor ligands, forming strong metal-carbon interactions.
CHEMICAL COMMUNICATIONS
(2022)
Article
Biochemistry & Molecular Biology
Domenique Herbstritt, Pooja Tomar, Thomas Braun
Summary: In this study, the greenhouse gas SF(5)CF(3) was photochemically activated with SIMes to generate various organic compounds. Additionally, the photochemical activation of SF(5)CF(3) in the presence of triphenylphosphine was also investigated.
Article
Chemistry, Organic
Yan Cao, Mohammad Reza Poor Heravi, Sepideh Habibzadeh, Abdol Ghaffar Ebadi, Seyed Mohammad Shoaei, Esmail Vessally
Summary: This theoretical research investigates the substituent effect and stability of singlet and triplet rNHGes, finding that singlet germylene is more stable than its corresponding triplet state. The stability order of rNHGe in fused rings is ortho-pyrrole > furan > thiophene > benzene > phosphole in a zigzag arrangement. The resonance effect and aromaticity of rNHGes depend on the electronegativity, size, and topology of the substituted heteroatoms.
JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Venkatachalam Pitchumani, Martin Breugst, David W. Lupton
Summary: This study demonstrates the enantioselective conversion of beta-substituted acrylamides to enantioenriched quinolones using electron-withdrawing protection and moderate nucleophilicity N-heterocyclic carbenes. The reaction shows complete diastereoselectivity, good yield, and modest enantioselectivity. Computational studies support the concept of decreased amide bond character with electron-withdrawing protection of the nitrogen.
Article
Chemistry, Multidisciplinary
Feng An, Biplab Maji, Elizabeth Min, Armin R. Ofial, Herbert Mayr
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2020)
Article
Chemistry, Multidisciplinary
Feng An, Harish Jangra, Yin Wei, Min Shi, Hendrik Zipse, Armin R. Ofial
Summary: The kinetics of the reactions of tributylphosphine with allenic and olefinic Michael acceptors were studied using photometric and NMR spectroscopic methods. The relevance of retroaddition barriers in phosphine-catalysed reactions was revealed when mixtures of allenic and olefinic substrates were used.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Jeremy T. Maddigan-Wyatt, Mitchell T. Blyth, Jhi Ametovski, Michelle L. Coote, Joel F. Hooper, David W. Lupton
Summary: A phosphine-catalyzed approach to pyrrolines has been developed, involving two mechanistically unlinked catalytic processes, and successfully synthesizing various pyrrolines. The reaction shows high sensitivity to the selection of catalysts.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Organic
Venkatachalam Pitchumani, Martin Breugst, David W. Lupton
Summary: This study demonstrates the enantioselective conversion of beta-substituted acrylamides to enantioenriched quinolones using electron-withdrawing protection and moderate nucleophilicity N-heterocyclic carbenes. The reaction shows complete diastereoselectivity, good yield, and modest enantioselectivity. Computational studies support the concept of decreased amide bond character with electron-withdrawing protection of the nitrogen.
Article
Chemistry, Organic
Manfred Hartnagel, Armin R. Ofial, Herbert Mayr
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Organic
Jose A. Forni, Milena L. Czyz, David W. Lupton, Anastasios Polyzos
Summary: A regioselective C(sp(3))-C(sp(2)) cross coupling reaction between inert gamma-C(sp(3))-H bonds in aliphatic amines and cyanoarenes under electrochemical conditions in flow is reported. The reaction utilizes a removable redox active auxiliary to trigger selective 1,7-hydrogen atom transfer for functionalization of a gamma-position aliphatic C-H bond. The cyanoarene radical anion acts both as a selective arylating reagent and a redox active mediator, enabling controlled one-electron reduction of the redox active auxiliary. This strategy provides a new approach for gamma-C(sp(3))-H bond functionalization to generate sterically crowded carbon centers under mild reaction conditions and without additional catalysts or radical initiators.
TETRAHEDRON LETTERS
(2022)
Article
Chemistry, Organic
Jeremy T. Maddigan-Wyatt, Jing Cao, Jhi Ametovski, Joel F. Hooper, David W. Lupton
Summary: Here, an enantioselective catalytic annulation of electron-poor allenes with aminocrotonates is reported. The reaction proceeds via umpolung gamma-amination and beta-umpolung intramolecular conjugate addition. The reaction provides ready access to chiral compounds with high yields and high enantiomeric ratios, and an assisted tandem-catalytic variant is also proposed.
Article
Chemistry, Multidisciplinary
Simon Cromwell, Randy Sutio, Changhe Zhang, Georgina K. Such, David W. Lupton
Summary: In this study, a reaction cascade involving the addition of C1-pyridinium enolate to thiocarbonyl compounds was reported, leading to the synthesis of a range of dihydrothiophenes and dihydrothiopyrans. Mechanistic investigations and experimental evidence supported the involvement of an activated acid intermediate and turnover limiting cyclization in the reaction pathway, with subsequent formation of β-thiolactone regenerating the catalyst.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Microbiology
Laura Perlaza-Jimenez, Kher-Shing Tan, Sarah J. Piper, Rachel M. Johnson, Rebecca S. Bamert, Christopher J. Stubenrauch, Alexander Wright, David Lupton, Trevor Lithgow, Matthew J. Belousoff
Summary: Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to human health, and its treatment often requires the use of last-line antibiotics like linezolid. This study identified linezolid-resistant mutants in MRSA strains and found that mutations in the ribosomal protein uL3 were responsible for the resistance. Cryo-electron microscopic analysis revealed structural rearrangements in the ribosome caused by these mutations.
MICROBIOLOGY SPECTRUM
(2022)
Article
Biochemistry & Molecular Biology
Suk Woo Kang, James Antoney, David W. Lupton, Robert Speight, Colin Scott, Colin J. Jackson
Summary: The stereoselective reduction of alkenes conjugated to electron-withdrawing groups has been extensively studied for the commercial production of fine chemicals. The old yellow enzyme (OYE) family and a subset of flavin/deazaflavin oxidoreductases (FDOR) have been shown to exhibit complementary enantioselectivity. This study explores several enzymes of the FDOR-A subgroup and identifies two enzymes (MSMEG_2027 and MSMEG_2850) that can selectively reduce a wide range of compounds. Protein crystallography and computational docking provide mechanistic insights into the observed stereoselectivity. These findings highlight the potential of FDOR and OYE families in asymmetric ene-reduction.
Article
Chemistry, Medicinal
Biljana Vujcic, Jessica Wyllie, Tania, Jed Burns, Keith F. White, Simon Cromwell, David W. Lupton, Jason L. Dutton, Tatiana P. Soares da Costa, Sevan D. Houston
Summary: The threat of a post-antibiotic era is caused by the rise of antibacterial resistance and depletion of effective antibiotic agents. One solution is to reengineer existing antibiotic drugs by covalently linking two pharmacophores using cage hydrocarbons like cubane, BCO, adamantane, and BCP as linkers. This report demonstrates the successful construction of dimers based on trimethoprim and tedizolid antibiotics using these hydrocarbons. The design strategy presented highlights the potential of this group as a platform for the rapid and modular construction of novel antibiotics.
BIOORGANIC & MEDICINAL CHEMISTRY LETTERS
(2023)
Article
Biochemistry & Molecular Biology
Suk Woo Kang, James Antoney, David W. Lupton, Robert Speight, Colin Scott, Colin J. Jackson
Summary: Asymmetric reduction by ene-reductases has been extensively studied, with the Old Yellow Enzyme (OYE) family being the most researched. However, the limited substrate range and stereocomplementary pairs of current ene-reductases necessitate the development of a complementary class. Flavin/deazaflavin oxidoreductases (FDORs) that use F-420 as a cofactor have gained attention due to their stereocomplementarity with OYEs. In this study, the activity of eight FDOR-B enzymes was investigated, comparing their specific activity, kinetic properties, and stereoselectivity with FDOR-A enzymes and OYE family.
Editorial Material
Multidisciplinary Sciences
Yuji Nakano, David W. Lupton
Review
Chemistry, Multidisciplinary
Yuji Nakano, Jeremy T. Maddigan-Wyatt, David W. Lupton
Summary: Conjugate acceptors are commonly used electrophilic functional groups in organic synthesis. Our research focuses on their ability to undergo polarity inversion through the conjugate addition of Lewis base catalysts. We have achieved cycloisomerizations and annulation reactions using simple conjugate acceptors and those embedded within more complicated substrates. However, significant challenges remain to be addressed before a universal approach to polarity inversion of all conjugate acceptors can be achieved.
ACCOUNTS OF CHEMICAL RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Jing Cao, Antonia Seitz, Jose A. Forni, Anastasios Polyzos, David W. Lupton
Summary: This article reports on a reaction design that avoids the facile oxidation of phosphine organocatalyst and combines traditional nucleophilic phosphine organocatalysis with photoredox catalysis to enable Giese coupling with ynoates. The approach exhibits good generality, and its mechanism is supported by cyclic voltametric, Stern-Volmer quenching, and interception studies.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
