Chemistry

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11 pages, 1804 KiB

Open AccessArticle

On the Importance of the Thiazole Nitrogen in Epothilones: Semisynthesis and Microtubule-Binding Affinity of Deaza-Epothilone C

by Adriana Edenharter, Lucie Ryckewaert, Daniela Cintulová, Juan Estévez-Gallego, José Fernando Díaz and Karl-Heinz Altmann

Chemistry 2020, 2(2), 499-509; https://doi.org/10.3390/chemistry2020030 - 23 May 2020

Viewed by 3238

Abstract

Deaza-epothilone C, which incorporates a thiophene moiety in place of the thiazole heterocycle in the natural epothilone side chain, has been prepared by semisynthesis from epothilone A, in order to assess the contribution of the thiazole nitrogen to microtubule binding. The synthesis was [...] Read more.

Deaza-epothilone C, which incorporates a thiophene moiety in place of the thiazole heterocycle in the natural epothilone side chain, has been prepared by semisynthesis from epothilone A, in order to assess the contribution of the thiazole nitrogen to microtubule binding. The synthesis was based on the esterification of a known epothilone A-derived carboxylic acid fragment and a fully synthetic alcohol building block incorporating the modified side chain segment and subsequent ring-closure by ring-closing olefin metathesis. The latter proceeded with unfavorable selectivity and in low yield. Distinct differences in chemical behavior were unveiled between the thiophene-derived advanced intermediates and what has been reported for the corresponding thiazole-based congeners. Compared to natural epothilone C, the free energy of binding of deaza-epothilone C to microtubules was reduced by ca. 1 kcal/mol or less, thus indicating a distinct but non-decisive role of the thiazole nitrogen in the interaction of epothilones with the tubulin/microtubule system. In contrast to natural epothilone C, deaza-epothilone C was devoid of antiproliferative activity in vitro up to a concentration of 10 μM, presumably due to an insufficient stability in the cell culture medium. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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10 pages, 1301 KiB

Open AccessArticle

Combining the Sensitivity of LAMP and Simplicity of Primer Extension via a DNA-Modified Nucleotide

by Moritz Welter and Andreas Marx

Chemistry 2020, 2(2), 490-498; https://doi.org/10.3390/chemistry2020029 - 14 May 2020

Viewed by 3732

Abstract

LAMP is an approach for isothermal nucleic acids diagnostics with increasing importance but suffers from the need of tedious systems design and optimization for every new target. Here, we describe an approach for its simplification based on a single nucleoside-5′-O-triphosphate (dNTP) that is [...] Read more.

LAMP is an approach for isothermal nucleic acids diagnostics with increasing importance but suffers from the need of tedious systems design and optimization for every new target. Here, we describe an approach for its simplification based on a single nucleoside-5′-O-triphosphate (dNTP) that is covalently modified with a DNA strand. We found that the DNA-modified dNTP is a substrate for DNA polymerases in versatile primer extension reactions despite its size and that the incorporated DNA indeed serves as a target for selective LAMP analysis. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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17 pages, 3144 KiB

Open AccessArticle

Oxidative Repair of Pyrimidine Cyclobutane Dimers by Nitrate Radicals (NO₃^•): A Kinetic and Computational Study

by Tomas Haddad, Joses G. Nathanael, Jonathan M. White and Uta Wille

Chemistry 2020, 2(2), 453-469; https://doi.org/10.3390/chemistry2020027 - 9 May 2020

Viewed by 2877

Abstract

Pyrimidine cyclobutane dimers are hazardous DNA lesions formed upon exposure of DNA to UV light, which can be repaired through oxidative electron transfer (ET). Laser flash photolysis and computational studies were performed to explore the role of configuration and constitution at the cyclobutane [...] Read more.

Pyrimidine cyclobutane dimers are hazardous DNA lesions formed upon exposure of DNA to UV light, which can be repaired through oxidative electron transfer (ET). Laser flash photolysis and computational studies were performed to explore the role of configuration and constitution at the cyclobutane ring on the oxidative repair process, using the nitrate radical (NO₃^•) as oxidant. The rate coefficients of 8–280 × 10⁷ M⁻¹ s⁻¹ in acetonitrile revealed a very high reactivity of the cyclobutane dimers of N,N’-dimethylated uracil (DMU), thymine (DMT), and 6-methyluracil (DMU^6-Me) towards NO₃^•, which likely proceeds via ET at N(1) as a major pathway. The overall rate of NO₃^• consumption was determined by (i) the redox potential, which was lower for the syn- than for the anti-configured dimers, and (ii) the accessibility of the reaction site for NO₃^•. In the trans dimers, both N(1) atoms could be approached from above and below the molecular plane, whereas in the cis dimers, only the convex side was readily accessible for NO₃^•. The higher reactivity of the DMT dimers compared with isomeric DMU dimers was due to the electron-donating methyl groups on the cyclobutane ring, which increased their susceptibility to oxidation. On the other hand, the approach of NO₃^• to the dimers of DMU^6-Me was hindered by the methyl substituents adjacent to N(1), making these dimers the least reactive in this series. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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16 pages, 6443 KiB

Open AccessFeature PaperArticle

OH Group Effect in the Stator of β-Diketones Arylhydrazone Rotary Switches

by Silvia Hristova, Fadhil S. Kamounah, Aurelien Crochet, Nikolay Vassilev, Katharina M. Fromm and Liudmil Antonov

Chemistry 2020, 2(2), 374-389; https://doi.org/10.3390/chemistry2020024 - 4 May 2020

Cited by 5 | Viewed by 3156

Abstract

The properties of several hydrazon-diketone rotary switches with OH groups in the stators (2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-1-phenylbutane-1,3-dione, 2-(2-(2-hydroxyphenyl)hydrazono)-1-phenylbutane-1,3-dione and 2-(2-(4-hydroxyphenyl)hydrazono)-1-phenylbutane-1,3-dione) were investigated by molecular spectroscopy (UV-Vis and NMR), DFT calculations (M06-2X/TZVP) and X-ray analysis. The results show that, when the OH group is in ortho position, [...] Read more.

The properties of several hydrazon-diketone rotary switches with OH groups in the stators (2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-1-phenylbutane-1,3-dione, 2-(2-(2-hydroxyphenyl)hydrazono)-1-phenylbutane-1,3-dione and 2-(2-(4-hydroxyphenyl)hydrazono)-1-phenylbutane-1,3-dione) were investigated by molecular spectroscopy (UV-Vis and NMR), DFT calculations (M06-2X/TZVP) and X-ray analysis. The results show that, when the OH group is in ortho position, the E’ and Z’ isomers are preferred in DMSO as a result of a stabilizing intermolecular hydrogen bonding with the solvent. The availability, in addition, of a nitro group in para position increases the possibility of deprotonation of the OH group in the absence of water. All studied compounds showed a tendency towards formation of associates. The structure of the aggregates was revealed by theoretical calculation and confirmed by X-ray analysis. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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13 pages, 4224 KiB

Open AccessFeature PaperArticle

Size and Surface Charge Dependent Impregnation of Nanoparticles in Soft- and Hardwood

by David Bossert, Christoph Geers, Maria Inés Placencia Peña, Thomas Volkmer, Barbara Rothen-Rutishauser and Alke Petri-Fink

Chemistry 2020, 2(2), 361-373; https://doi.org/10.3390/chemistry2020023 - 2 May 2020

Cited by 4 | Viewed by 3491

Abstract

Recent progress in wood preservative research has led to the use of insoluble copper carbonate in the form of nano- to micron-sized particles in combination with known triazole fungicides to combat fungal decay and thus decrease physical material properties. Evidently, particle-based agents could [...] Read more.

Recent progress in wood preservative research has led to the use of insoluble copper carbonate in the form of nano- to micron-sized particles in combination with known triazole fungicides to combat fungal decay and thus decrease physical material properties. Evidently, particle-based agents could lead to issues regarding impregnation of a micro-structured material like wood. In this study, we analyzed these limitations via silicon dioxide particles in impregnation experiments of pine and beech wood. In our experiments, we showed that limitations already existed prior to assumed particle size thresholds of 400–600 nm. In pine wood, 70 nm sized particles were efficiently impregnated, in contrast to 170 nm particles. Further we showed that surface functionalized silica nanoparticles have a major impact on the impregnation efficiency. Silica surfaces bearing amino groups were shown to have strong interactions with the wood cell surface, whereas pentyl chains on the SiO₂ surfaces tended to lower the particle–wood interaction. The acquired results illustrate an important extension of the currently limited knowledge of nanoparticles and wood impregnation and contribute to future improvements in the field of particle-based wood preservatives. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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12 pages, 1397 KiB

Open AccessFeature PaperArticle

A Procedure for Computing Hydrocarbon Strain Energies Using Computational Group Equivalents, with Application to 66 Molecules ^†

by Paul R. Rablen

Chemistry 2020, 2(2), 347-360; https://doi.org/10.3390/chemistry2020022 - 30 Apr 2020

Cited by 27 | Viewed by 4548

Abstract

A method is presented for the direct computation of hydrocarbon strain energies using computational group equivalents. Parameters are provided at several high levels of electronic structure theory: W1BD, G-4, CBS-APNO, CBS-QB3, and M062X/6-31+G(2df,p). As an illustration of the procedure, strain energies are computed [...] Read more.

A method is presented for the direct computation of hydrocarbon strain energies using computational group equivalents. Parameters are provided at several high levels of electronic structure theory: W1BD, G-4, CBS-APNO, CBS-QB3, and M062X/6-31+G(2df,p). As an illustration of the procedure, strain energies are computed for 66 hydrocarbons, most of them highly strained. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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16 pages, 3401 KiB

Open AccessArticle

Towards a Real Knotaxane

by Torben Duden and Ulrich Lüning

Chemistry 2020, 2(2), 305-321; https://doi.org/10.3390/chemistry2020020 - 26 Apr 2020

Cited by 1 | Viewed by 3419

Abstract

Two classes of mechanically interlocked molecules, [3]rotaxanes and knotted [1]rotaxanes, were the subject of this investigation. The necessary building blocks, alkyne-terminated axles containing two ammonium ions and azide-terminated stoppers, and azide-containing substituted macrocycles, have been synthesized and characterized. Different [3]rotaxanes were synthesized by [...] Read more.

Two classes of mechanically interlocked molecules, [3]rotaxanes and knotted [1]rotaxanes, were the subject of this investigation. The necessary building blocks, alkyne-terminated axles containing two ammonium ions and azide-terminated stoppers, and azide-containing substituted macrocycles, have been synthesized and characterized. Different [3]rotaxanes were synthesized by copper-catalyzed “click” reactions between the azide stoppers and [3]pseudorotaxanes formed from the dialkyne axles and crown ethers (DB24C8). Methylation of the triazoles formed by the “click” reaction introduced a second binding site, and switching via deprotonation/protonation was investigated. In preliminary tests for the synthesis of a knotted [1]rotaxane, pseudorotaxanes were formed from azide-containing substituted macrocycles and dialkyne substituted diammonium axles, and copper-catalyzed “click” reactions were carried out. Mass spectral analyses showed successful double “click” reactions between two modified macrocycles and one axle. Whether a knotted [1]rotaxane was formed could not be determined. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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12 pages, 2726 KiB

Open AccessFeature PaperArticle

Topological Dynamics of a Radical Ion Pair: Experimental and Computational Assessment at the Relevant Nanosecond Timescale

by Helmut Quast, Georg Gescheidt and Martin Spichty

Chemistry 2020, 2(2), 219-230; https://doi.org/10.3390/chemistry2020014 - 31 Mar 2020

Viewed by 3131

Abstract

Chemical processes mostly happen in fluid environments where reaction partners encounter via diffusion. The bimolecular encounters take place at a nanosecond time scale. The chemical environment (e.g., solvent molecules, (counter)ions) has a decisive influence on the reactivity as it determines the contact time [...] Read more.

Chemical processes mostly happen in fluid environments where reaction partners encounter via diffusion. The bimolecular encounters take place at a nanosecond time scale. The chemical environment (e.g., solvent molecules, (counter)ions) has a decisive influence on the reactivity as it determines the contact time between two molecules and affects the energetics. For understanding reactivity at an atomic level and at the appropriate dynamic time scale, it is crucial to combine matching experimental and theoretical data. Here, we have utilized all-atom molecular-dynamics simulations for accessing the key time scale (nanoseconds) using a QM/MM-Hamiltonian. Ion pairs consisting of a radical ion and its counterion are ideal systems to assess the theoretical predictions because they reflect dynamics at an appropriate time scale when studied by temperature-dependent EPR spectroscopy. We have investigated a diketone radical anion with its tetra-ethylammonium counterion. We have established a funnel-like transition path connecting two (equivalent) complexation sites. The agreement between the molecular-dynamics simulation and the experimental data presents a new paradigm for ion–ion interactions. This study exemplarily demonstrates the impact of the molecular environment on the topological states of reaction intermediates and how these states can be consistently elucidated through the combination of theory and experiment. We anticipate that our findings will contribute to the prediction of bimolecular transformations in the condensed phase with relevance to chemical synthesis, polymers, and biological activity. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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10 pages, 1372 KiB

Open AccessFeature PaperArticle

Appropriate Buffers for Studying the Bioinorganic Chemistry of Silver(I)

by Lucille Babel, Soledad Bonnet-Gómez and Katharina M. Fromm

Chemistry 2020, 2(1), 193-202; https://doi.org/10.3390/chemistry2010012 - 22 Mar 2020

Cited by 10 | Viewed by 5498

Abstract

Silver(I) is being largely studied for its antimicrobial properties. In parallel to that growing interest, some researchers are investigating the effect of this ion on eukaryotes and the mechanism of silver resistance of certain bacteria. For these studies, and more generally in biology, [...] Read more.

Silver(I) is being largely studied for its antimicrobial properties. In parallel to that growing interest, some researchers are investigating the effect of this ion on eukaryotes and the mechanism of silver resistance of certain bacteria. For these studies, and more generally in biology, it is necessary to work in buffer systems that are most suitable, i.e., that interact least with silver cations. Selected buffers such as 4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid (HEPES) were therefore investigated for their use in the presence of silver nitrate. Potentiometric titrations allowed to determine stability constants for the formation of (Ag(Buffer)) complexes. The obtained values were adapted to extract the apparent binding constants at physiological pH. The percentage of metal ions bound to the buffer was calculated at this pH for given concentrations of buffer and silver to realize at which extent silver was interacting with the buffer. We found that in the micromolar range, HEPES buffer is sufficiently coordinating to silver to have a non-negligible effect on the thermodynamic parameters determined for an analyte. Morpholinic buffers were more suitable as they turned out to be weaker complexing agents. We thus recommend the use of MOPS for studies of physiological pH. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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Review

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20 pages, 4512 KiB

Open AccessReview

Giant Polymer Compartments for Confined Reactions

by Elena C. dos Santos, Alessandro Angelini, Dimitri Hürlimann, Wolfgang Meier and Cornelia G. Palivan

Chemistry 2020, 2(2), 470-489; https://doi.org/10.3390/chemistry2020028 - 12 May 2020

Cited by 7 | Viewed by 5830

Abstract

In nature, various specific reactions only occur in spatially controlled environments. Cell compartment and subcompartments act as the support required to preserve the bio-specificity and functionality of the biological content, by affording absolute segregation. Inspired by this natural perfect behavior, bottom-up approaches are [...] Read more.

In nature, various specific reactions only occur in spatially controlled environments. Cell compartment and subcompartments act as the support required to preserve the bio-specificity and functionality of the biological content, by affording absolute segregation. Inspired by this natural perfect behavior, bottom-up approaches are on focus to develop artificial cell-like structures, crucial for understanding relevant bioprocesses and interactions or to produce tailored solutions in the field of therapeutics and diagnostics. In this review, we discuss the benefits of constructing polymer-based single and multicompartments (capsules and giant unilamellar vesicles (GUVs)), equipped with biomolecules as to mimic cells. In this respect, we outline key examples of how such structures have been designed from scratch, namely, starting from the application-oriented selection and synthesis of the amphiphilic block copolymer. We then present the state-of-the-art techniques for assembling the supramolecular structure while permitting the encapsulation of active compounds and the incorporation of peptides/membrane proteins, essential to support in situ reactions, e.g., to replicate intracellular signaling cascades. Finally, we briefly discuss important features that these compartments offer and how they could be applied to engineer the next generation of microreactors, therapeutic solutions, and cell models. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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35 pages, 4076 KiB

Open AccessFeature PaperReview

Recent Studies on the Antimicrobial Activity of Transition Metal Complexes of Groups 6–12

by Sara Nasiri Sovari and Fabio Zobi

Chemistry 2020, 2(2), 418-452; https://doi.org/10.3390/chemistry2020026 - 9 May 2020

Cited by 82 | Viewed by 9642

Abstract

Antimicrobial resistance is an increasingly serious threat to global public health that requires innovative solutions to counteract new resistance mechanisms emerging and spreading globally in infectious pathogens. Classic organic antibiotics are rapidly exhausting the structural variations available for an effective antimicrobial drug and [...] Read more.

Antimicrobial resistance is an increasingly serious threat to global public health that requires innovative solutions to counteract new resistance mechanisms emerging and spreading globally in infectious pathogens. Classic organic antibiotics are rapidly exhausting the structural variations available for an effective antimicrobial drug and new compounds emerging from the industrial pharmaceutical pipeline will likely have a short-term and limited impact before the pathogens can adapt. Inorganic and organometallic complexes offer the opportunity to discover and develop new active antimicrobial agents by exploiting their wide range of three-dimensional geometries and virtually infinite design possibilities that can affect their substitution kinetics, charge, lipophilicity, biological targets and modes of action. This review describes recent studies on the antimicrobial activity of transition metal complexes of groups 6–12. It focuses on the effectiveness of the metal complexes in relation to the rich structural chemical variations of the same. The aim is to provide a short vade mecum for the readers interested in the subject that can complement other reviews. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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28 pages, 3474 KiB

Open AccessFeature PaperReview

Reactive Sterol Electrophiles: Mechanisms of Formation and Reactions with Proteins and Amino Acid Nucleophiles

by Ned A. Porter, Libin Xu and Derek A. Pratt

Chemistry 2020, 2(2), 390-417; https://doi.org/10.3390/chemistry2020025 - 6 May 2020

Cited by 20 | Viewed by 5752

Abstract

Radical-mediated lipid oxidation and the formation of lipid hydroperoxides has been a focal point in the investigation of a number of human pathologies. Lipid peroxidation has long been linked to the inflammatory response and more recently, has been identified as the central tenet [...] Read more.

Radical-mediated lipid oxidation and the formation of lipid hydroperoxides has been a focal point in the investigation of a number of human pathologies. Lipid peroxidation has long been linked to the inflammatory response and more recently, has been identified as the central tenet of the oxidative cell death mechanism known as ferroptosis. The formation of lipid electrophile-protein adducts has been associated with many of the disorders that involve perturbations of the cellular redox status, but the identities of adducted proteins and the effects of adduction on protein function are mostly unknown. Both cholesterol and 7-dehydrocholesterol (7-DHC), which is the immediate biosynthetic precursor to cholesterol, are oxidizable by species such as ozone and oxygen-centered free radicals. Product mixtures from radical chain processes are particularly complex, with recent studies having expanded the sets of electrophilic compounds formed. Here, we describe recent developments related to the formation of sterol-derived electrophiles and the adduction of these electrophiles to proteins. A framework for understanding sterol peroxidation mechanisms, which has significantly advanced in recent years, as well as the methods for the study of sterol electrophile-protein adduction, are presented in this review. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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24 pages, 2669 KiB

Open AccessReview

Natural and Engineered Electron Transfer of Nitrogenase

by Wenyu Gu and Ross D. Milton

Chemistry 2020, 2(2), 322-346; https://doi.org/10.3390/chemistry2020021 - 27 Apr 2020

Cited by 14 | Viewed by 6503

Abstract

As the only enzyme currently known to reduce dinitrogen (N₂) to ammonia (NH₃), nitrogenase is of significant interest for bio-inspired catalyst design and for new biotechnologies aiming to produce NH₃ from N₂. In order to reduce [...] Read more.

As the only enzyme currently known to reduce dinitrogen (N₂) to ammonia (NH₃), nitrogenase is of significant interest for bio-inspired catalyst design and for new biotechnologies aiming to produce NH₃ from N₂. In order to reduce N₂, nitrogenase must also hydrolyze at least 16 equivalents of adenosine triphosphate (MgATP), representing the consumption of a significant quantity of energy available to biological systems. Here, we review natural and engineered electron transfer pathways to nitrogenase, including strategies to redirect or redistribute electron flow in vivo towards NH₃ production. Further, we also review strategies to artificially reduce nitrogenase in vitro, where MgATP hydrolysis is necessary for turnover, in addition to strategies that are capable of bypassing the requirement of MgATP hydrolysis to achieve MgATP-independent N₂ reduction. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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12 pages, 1908 KiB

Open AccessFeature PaperReview

Before Radicals Were Free – the Radical Particulier of de Morveau

by Edwin C. Constable and Catherine E. Housecroft

Chemistry 2020, 2(2), 293-304; https://doi.org/10.3390/chemistry2020019 - 20 Apr 2020

Cited by 4 | Viewed by 5192

Abstract

Today, we universally understand radicals to be chemical species with an unpaired electron. It was not always so, and this article traces the evolution of the term radical and in this journey, monitors the development of some of the great theories of organic [...] Read more.

Today, we universally understand radicals to be chemical species with an unpaired electron. It was not always so, and this article traces the evolution of the term radical and in this journey, monitors the development of some of the great theories of organic chemistry. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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16 pages, 3713 KiB

Open AccessFeature PaperReview

Amino Acids and Peptides as Versatile Ligands in the Synthesis of Antiproliferative Gold Complexes

by Tina P. Andrejević, Biljana Đ. Glišić and Miloš I. Djuran

Chemistry 2020, 2(2), 203-218; https://doi.org/10.3390/chemistry2020013 - 27 Mar 2020

Cited by 9 | Viewed by 3410

Abstract

Gold complexes have been traditionally employed in medicine, and currently, some gold(I) complexes, such as auranofin, are clinically used in the treatment of rheumatoid arthritis. In the last decades, both gold(I) and gold(III) complexes with different types of ligands have gained considerable attention [...] Read more.

Gold complexes have been traditionally employed in medicine, and currently, some gold(I) complexes, such as auranofin, are clinically used in the treatment of rheumatoid arthritis. In the last decades, both gold(I) and gold(III) complexes with different types of ligands have gained considerable attention as potential antitumor agents, showing superior activity both in vitro and in vivo to some of the clinically used agents. The present review article summarizes the results achieved in the field of synthesis and evaluation of gold complexes with amino acids and peptides moieties for their cytotoxicity. The first section provides an overview of the gold(I) complexes with amino acids and peptides, which have shown antiproliferative activity, while the second part is focused on the activity of gold(III) complexes with these ligands. A systematic summary of the results achieved in the field of gold(I/III) complexes with amino acids and peptides could contribute to the future development of metal complexes with these biocompatible ligands as promising antitumor agents. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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13 pages, 3157 KiB

Open AccessFeature PaperReview

Addition of Heteroatom Radicals to endo-Glycals †

by Torsten Linker

Chemistry 2020, 2(1), 80-92; https://doi.org/10.3390/chemistry2010008 - 20 Feb 2020

Cited by 9 | Viewed by 4165

Abstract

Radical reactions have found many applications in carbohydrate chemistry, especially in the construction of carbon–carbon bonds. The formation of carbon–heteroatom bonds has been less intensively studied. This mini-review will summarize the efforts to add heteroatom radicals to unsaturated carbohydrates like endo-glycals. Starting [...] Read more.

Radical reactions have found many applications in carbohydrate chemistry, especially in the construction of carbon–carbon bonds. The formation of carbon–heteroatom bonds has been less intensively studied. This mini-review will summarize the efforts to add heteroatom radicals to unsaturated carbohydrates like endo-glycals. Starting from early examples, developed more than 50 years ago, the importance of such reactions for carbohydrate chemistry and recent applications will be discussed. After a short introduction, the mini-review is divided in sub-chapters according to the heteroatoms halogen, nitrogen, phosphorus, and sulfur. The mechanisms of radical generation by chemical or photochemical processes and the subsequent reactions of the radicals at the 1-position will be discussed. This mini-review cannot cover all aspects of heteroatom-centered radicals in carbohydrate chemistry, but should provide an overview of the various strategies and future perspectives. Full article

(This article belongs to the Special Issue Radically Different—A Themed Issue in Honor of Professor Bernd Giese on the Occasion of His 80th Birthday)

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