Article
Chemistry, Multidisciplinary
Alisa S. Sunagatullina, Andreas Hess, Alexander Kremsmair, Yifan Li, Yi-Hung Chen, Paul Knochel
Summary: We present a novel electrophilic amination method for primary, secondary, and tertiary alkyl, benzylic, and allylic zinc and magnesium organometallics using O-2,4,6-trimethylbenzoyl hydroxylamines (O-TBHAs) with yields ranging from 52-99%. These O-TBHAs exhibit excellent long-term stability and can be conveniently synthesized from various highly functionalized secondary amines through a three-step procedure. The amination reactions demonstrate remarkable chemoselectivity without the need for transition-metal catalysts, and are typically completed within 1-3 hours at 25 degrees Celsius. Furthermore, this electrophilic amination process enables the synthesis of enantioenriched tertiary amines (up to 88% ee) using optically enriched secondary alkylmagnesium reagents of the type s-AlkylMgCH(2)SiMe(3).
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Wei-Can Dai, Bo Yang, Shi-He Xu, Zhong-Xia Wang
Summary: The reaction of aryl 2-pyridyl ethers with arylzinc reagents catalyzed by NiCl2(PCy3)(2) can achieve aryl-aryl cross-coupling with a wide range of substrates and good functional group compatibility. It was found that beta-H-free alkylzinc reagents are more suitable as nucleophiles in this transformation.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Alexander Kremsmair, Simon Grassl, Christoph J. B. Seifert, Edouard Godineau, Paul Knochel
Summary: Various substituted and unsubstituted N-heteroaryl chlorides have been efficiently transformed into organozinc species using zinc dust, zinc pivalate, and CoCl2 in benzonitrile at 25 degrees C. The resulting heteroarylzinc reagents can react with a wide range of electrophiles to produce functionalized heteroarenes in high yields and short reaction times.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Organic
Pinaki Bhusan De, Sobi Asako, Laurean Ilies
Summary: This short review discusses the recent emergence of organosodium chemistry driven by the need for sustainability in modern synthetic chemistry. Methods for preparing organosodium compounds using sodium dispersion and their applications in synthesis are presented, along with a brief discussion of sodium amides and phosphides.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Multidisciplinary
Agonist Kastrati, Alexander Kremsmair, Alisa S. Sunagatullina, Vasilii Korotenko, Yusuf C. Guersoy, Saroj K. Rout, Fabio Lima, Cara E. Brocklehurst, Konstantin Karaghiosoff, Hendrik Zipse, Paul Knochel
Summary: Straightforward calculations have led to the development of a set of organometallic reactions for the regioselective functionalization of the underexplored fused N-heterocycle imidazo[1,2-a]pyrazine. These reactions provide a way to access polyfunctionalized imidazopyrazine heterocycles.
Article
Microbiology
Chrysi Sergaki, Saba Anwar, Martin Fritzsche, Ryan Mate, Robert J. Francis, Kirsty MacLellan-Gibson, Alastair Logan, Gregory C. A. Amos
Summary: This study developed a whole cell reference reagent specific to the gut microbiome and proposed a two-step reporting framework to validate choices of DNA extraction, sequencing, and bioinformatic pipelines in microbiome research.
Article
Chemistry, Multidisciplinary
Cynthia C. Fernandez, Matthias Franke, Hans-Peter Steinrueck, Ole Lytken, Federico J. Williams
Summary: Research has shown that porphyrin molecules at the solid-liquid interface are less likely to lose their metal center, possibly due to either incoming protons provided by the solution or outgoing metal ions being unable to be solvated while passing through the hydrophobic porphyrin multilayers. These results are important for the design of molecular devices based on porphyrin molecules adsorbed on solid surfaces.
Review
Biochemistry & Molecular Biology
Stephane Boissinot
Summary: Transposable elements have a base composition different from the genomic average and host genes. They are often AT-rich, which may affect the transcription and translation of encoded proteins. The cause of this unusual composition is still unclear and requires further investigation.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Christian F. F. Pantoja, Alain Ibanez de Opakua, Maria-Sol Cima-Omori, Markus Zweckstetter
Summary: Liquid-Liquid phase separation is a fundamental process in the formation of biomolecular condensates. However, the complex composition and dynamics of these condensates make it difficult to gain insights into their structure. In this study, an improved spatially-resolved NMR experiment is introduced to quantitatively analyze the physico-chemical composition of multi-component biomolecular condensates in equilibrium and label-free. The application of spatially-resolved NMR to condensates formed by the Alzheimer's disease-associated protein Tau reveals changes in water content, molecular crowding, and specific chemical environment, as well as a significant increase in Tau concentration inside the condensate. These findings highlight the potential of spatially-resolved NMR in understanding the composition and physical chemistry of biomolecular condensates.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Qian He, Jian-Liang Ye, Fang-Fang Xu, Hui Geng, Ting-Ting Chen, Hang Chen, Pei-Qiang Huang
Summary: The research findings demonstrated that Tf2O/TTBP can be an alternative amide activation system for the direct transformation of both secondary and tertiary amides, generally obtaining higher or comparable yields. Additionally, the combination of Tf2O/TTBP was also effective in promoting various important reactions, leading to concise and high-yield syntheses of natural products.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Microbiology
Andrea Unzueta-Martinez, Heather Welch, Jennifer L. Bowen
Summary: The study identified a strong population-specific signal in the microbial community composition of oysters sampled in the wild, and found that even oysters reared in a common garden environment maintained distinct gill-associated microbial communities reflecting their wild population of origin. The majority of gill-associated microbes were resident members specific to each oyster population, but a small portion of the microbial communities was transient and moved among oyster populations, suggesting stochastic assembly also contributes to the oyster gill microbiome.
FRONTIERS IN MICROBIOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Michael P. Crockett, Jeanette Pina, Achyut Ranjan Gogoi, Remy F. Lalisse, Andrew Nguyen, Osvaldo Gutierrez, Andy A. . Thomas
Summary: The effects of Lewis basic phosphoramides on the aggregate structure of t-BuLi have been investigated using NMR and DFT methods. It was found that hexamethylphosphoramide (HMPA) can shift the equilibrium of t-BuLi to form a triple ion pair with HMPA4Li+, which in turn allows for the deprotonation of remote sp3 C-H bonds. These newly accessed lithium aggregation states were then leveraged to develop a simple protocol for the lithiation and capture of chromane heterocycles with alkyl halide electrophiles in good yields.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Yifan Mao, Mehdi A. Abed, Nathan B. Lee, Xuedan Wu, Gengyu Du, Lin Pu
Summary: A chemoselective and enantioselective fluorescent probe has been developed to accurately determine the concentration and enantiomeric composition of the biologically important amino acid histidine by measuring fluorescence responses at two different wavelengths.
CHEMICAL COMMUNICATIONS
(2021)
Article
Environmental Sciences
Vittoria Curcio, Rachele Macirella, Settimio Sesti, Abdalmoiz I. M. Ahmed, Federica Talarico, Roberto Pizzolotto, Antonio Tagarelli, Marcello Mezzasalma, Elvira Brunelli
Summary: This study investigated the morphological and morphometric alterations induced by lead in early zebrafish development and revealed that the severity of malformations increased with increasing lead dose and exposure time. The study emphasizes the effectiveness of morphological biomarkers in detecting threatening situations and highlights the high sensitivity of zebrafish during the initial stages of development. Zebrafish embryos and larvae play a crucial role in risk assessment and environmental monitoring.
Article
Materials Science, Multidisciplinary
Cuong Ly, Cody A. Nizinski, Ada Toydemir, Clement Vachet, Luther W. McDonald, Tolga Tasdizen
Summary: The proposed approach uses convolutional neural networks to determine the composition of a mixed material, reducing costs by generating synthetic data instead of collecting mixed material images. The study demonstrates the scalability of the method through two datasets, showing that it accurately determines the presence of materials and estimates the composition of a mixed material. Additionally, analyses are provided to further validate and highlight the benefits of the proposed approach.
MICROSCOPY AND MICROANALYSIS
(2021)
Article
Chemistry, Physical
Andrew W. J. Platten, Andryj M. Borys, Eva Hevia
Summary: In this study, the use of potassium magnesiate complex as a catalyst for the hydrophosphinylation of styrenes was reported. The bimetallic approach showed higher catalytic activity and selectivity compared to single-metal components. Stoichiometric studies helped to determine the constitution of the active catalytic species and understand the influence of donors on catalytic activity. Mechanistic investigations suggested that the olefinic substrate insertion is the rate determining step.
Article
Chemistry, Multidisciplinary
Neil R. Judge, Leonie J. Bole, Eva Hevia
Summary: This study advances the understanding of using alkali-metal alkoxides as additives to organomagnesium reagents in Mg-Br exchange reactions. A series of mixed-ligand alkyl/alkoxide alkali-metal magnesiates has been prepared and their reactivity towards 2-bromoanisole has been evaluated. The alkali-metal effect on the reaction efficiency has been observed, with potassium magnesiate being the most efficient. Furthermore, the constitution of the exchange product has been studied, revealing the importance of reaction components in the stability of metalated intermediates.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
David E. Anderson, Andreu Tortajada, Eva Hevia
Summary: Deaggregation of alkyl sodium NaCH2SiMe3 with polydentate nitrogen ligands allows the preparation and characterization of new, hydrocarbon soluble chelated alkylsodium reagents. These systems, equipped with significantly enhanced metalating power, can promote controlled sodiation of weakly acidic benzylic C-H bonds from a series of toluene derivatives under mild stoichiometric conditions. The successful isolation and determination of the structures of key organometallic intermediates provide useful mechanistic insights into these new sodium-mediated transformations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Inorganic & Nuclear
Andryj M. Borys, Eva Hevia
Summary: In this study, a new family of alkyne supported alkali-metal nickelates was reported. These compounds were synthesized through the combination of Ni(COD)(2), Ph-CuC-Ph, and the corresponding lithium aryl in a 2:1:4 ratio. They exhibited structural diversity and showed potential in catalyzing cyclotrimerization reactions.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Neil R. R. Judge, Eva Hevia
Summary: By adding two molar equivalents of KOtBu to Zn(TMP)(2) (TMP=2,2,6,6-tetramethylpiperidide), the mild zinc bis-amide base is transformed into a powerful metalating agent capable of regioselective zincation of sensitive fluoroarenes. The intermediates formed during Zn-H exchange are structurally verified, showing the activation of TMP groups to generate higher order bis-aryl potassium zincates. This bimetallic KOtBu/Zn(TMP)(2) partnership exhibits the ability to zincate toluene and benzene at room temperature.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Andryj M. Borys, Eva Hevia
Summary: Recent advances in heterobimetallic chemistry have shown that mixed-metal systems can enable reactions that are not achievable with single-metal components. This perspective explores the combination of nickel(0) complexes with organo-alkali-metal reagents, leading to highly reactive alkali-metal nickelates. These previously understudied systems have re-emerged as a promising research area, with recent studies uncovering their unique bonding and structural motifs. Additionally, the discovery of nickelates as potential intermediates in cross-coupling reactions has laid the groundwork for the development and mechanistic understanding of stoichiometric and catalytic transformations.
Article
Chemistry, Multidisciplinary
Andreu Tortajada, Eva Hevia
Summary: Alkali-metal amides, especially lithium analogues, are widely used non-nucleophilic bases in synthetic chemistry. By studying the coordination effects of Lewis donor molecules, a new application of sodium amides in the functionalization of arenes has been discovered. These findings demonstrate the enhanced reactivity and potential of sodium amides for the development of new transformations.
News Item
Chemistry, Multidisciplinary
Andreu Tortajada, Eva Hevia
Summary: Organolithium reagents can be encapsulated within an organogel, providing enhanced stability and enabling their use and storage under ambient conditions.
Article
Chemistry, Multidisciplinary
Andreu Tortajada, Leonie J. Bole, Manting Mu, Martin Stanford, Marconi N. Penas-Defrutos, Max Garcia-Melchor, Eva Hevia
Summary: By using a sodium base in combination with the tridentate Lewis donor PMDETA and the sterically demanding electrophilic trap B(CH2SiMe3)(3), the deprotonative borylation of arenes can be achieved, resulting in the formal borylation of two equivalents of the relevant arene. The first B-C bond formation occurs through a sodiation/borylation sequence, while the second borylation step is facilitated by the formation of a borata-alkene intermediate.
Review
Chemistry, Physical
Andreu Tortajada, Eva Hevia
Summary: The preparation of deuterium or tritium labelled compounds is essential in various research fields. Hydrogen isotope exchange (HIE) provides a direct synthesis route for these compounds by introducing the isotopes at a late stage. Apart from transition metal catalysis, alkali-metal bases have emerged as a viable alternative for HIE processes. This minireview discusses the latest advances, synthetic potential, challenges, and possible mechanistic pathways of alkali-metal bases in HIE processes.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Andryj M. M. Borys, Tim Kunzmann, Jose M. M. Gil-Negrete, Eva Hevia
Summary: By combining the Lewis acid Zn(C6F5)(2) with nucleophilic diarylzinc (ZnAr2) reagents, the arylation of N-tosylimines under mild conditions was achieved. Mechanistic studies revealed the cooperative activation of the imine substrate and regeneration of the ZnAr2 reagent by the two zinc species, allowing for a limited usage of only 50 mol%.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Andryj M. Borys, Eva Hevia
Summary: By utilizing the high aggregation of aliphatic lithium acetylides, researchers have achieved the synthesis and structural analysis of polynuclear lithium nickelate clusters, where up to 10 equivalents of organolithium can co-complex per Ni(0) center. The exposure of the Ni(0)-ate clusters to dry air presents an alternative pathway for the formation of homoleptic Ni(ii)-ates.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Pasquale Mastropierro, Andrew W. J. Platten, Alan R. Kennedy, Eva Hevia, Marina Uzelac
Summary: By exploiting the bimetallic cooperation of alkali-metal manganate (II) complexes, oxidative homocoupling of terminal alkynes can be efficiently promoted to form conjugated 1,3-diynes. The influence of alkali-metal on these bond forming processes has been studied, and it has been found that initial metalation of the alkyne is required for the homocoupling to occur. The tetra(alkyl) alkali-metal manganates behave as polybasic reagents, easily deprotonating the alkynes.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Alessandra Logallo, Eva Hevia
Summary: Heterobimetallic base NaCo(HMDS)(3) [HMDS = N(SiMe3)(2)] enables regioselective di-cobaltation of activated polyfluoroarenes under mild reaction conditions. For 1,3,5-C6H2X3 (X= Cl, F), NaCo(HMDS)(3) in excess at 80 degrees C impressively induces the collective cleavage of five bonds (two C-H and three C-X) of the substrates via a cascade activation process that cannot be replicated by LiCo(HMDS)(3) or KCo(HMDS)(3).
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Pasquale Mastropierro, Alan R. Kennedy, Eva Hevia
Summary: A new mixed K/Zn heteroleptic base has been developed for regioselective zincation of fluoroarenes, allowing for trapping and structural authentication of the first intermediates of direct Zn-H exchange. This provides mechanistic insights into the processes involved.
CHEMICAL COMMUNICATIONS
(2022)
