Click chemistry‐inspired design, synthesis, and molecular docking studies of biscoumarin derivatives using carbon‐based acid catalyst

Click chemistry‐inspired design, synthesis, and molecular docking studies of biscoumarin derivatives using carbon‐based acid catalyst

Abstract

A green and eco‐benign synthesis of biscoumarin derivatives using carbon sulfonic acid, a solid support catalyst has been described. The reaction involved a one‐pot two‐component reaction of 4‐hydroxycoumarin and aldehyde using carbon sulfonic acid involving Knoevenegal‐Michael condensation. A series of aromatic (bearing electron withdrawing and releasing group) and heteroaromatic aldehydes has been converted to biscoumarins with excellent isolated yields. The reaction is in compliance with green principles, that is, inexpensive catalyst, easy to prepare, nontoxic, easy handling, reusable up to five recycle runs, easy separation, short reaction time, no need of time consuming column purification, high yielding, and so on. The synthesized catalyst and biscoumarin derivatives were well characterized by spectral analysis. The molecular modeling studies showed that the designed molecular scaffolds (3a‐j) showed outstanding interaction with methylenetetrahydrofolate reductase (MTHFR) and cytochrome P450 3A4 (CYP3A4) proteins. It was noticed that 3f (−17.55 kJ/mol) and 3d (−26.23 kJ/mol) showed the highest docking score against CYP3A4 and MTHFR proteins, respectively.

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Sulfur‐Modified Oxygen Vacancies in Iron–Cobalt Oxide Nanosheets: Enabling Extremely High Activity of the Oxygen Evolution Reaction to Achieve the Industrial Water Splitting Benchmark

Sulfur‐Modified Oxygen Vacancies in Iron–Cobalt Oxide Nanosheets: Enabling Extremely High Activity of the Oxygen Evolution Reaction to Achieve the Industrial Water Splitting Benchmark

The defective iron–cobalt oxide nanosheet is developed into a highly efficient OER catalyst through modulating its electron structure by oxygen vacancy creation and sulfur atom modification. Pairing with CoP3/Ni2P, its current density can reach up to 406.0 mA cm−2 at 2.3 V, meeting well with the industrial water splitting requirement.

Abstract

The oxygen vacancies of defective iron–cobalt oxide (FeCoOx ‐Vo) nanosheets are modified by the homogeneously distributed sulfur (S) atoms. S atoms can not only effectively stabilize oxygen vacancies (Vo), but also form the Co−S coordination with Co active site in the Vo, which can modulate the electronic structure of the active site, enabling FeCoOx ‐Vo‐S to exhibit much superior OER activity. FeCoOx ‐Vo‐S exhibits a mass activity of 2440.0 A g−1 at 1.5 V vs. RHE in 1.0 m KOH, 25.4 times higher than that of RuO2. The Tafel slope is as low as 21.0 mV dec−1, indicative of its excellent charge transfer rate. When FeCoOx ‐Vo‐S (anode catalyst) is paired with the defective CoP3/Ni2P (cathode catalyst) for overall water splitting, current densities of as high as 249.0 mA cm−2 and 406.0 mA cm−2 at a cell voltage of 2.0 V and 2.3 V, respectively, can be achieved.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Linzhou Zhuang, Yi Jia, Hongli Liu, Zhiheng Li, Mengran Li, Longzhou Zhang, Xin Wang, Dongjiang Yang, Zhonghua Zhu, Xiangdong Yao
doi.org/10.1002/anie.202006546

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Design of Bowl‐Shaped N‐Hydroxyimide Derivatives as New Organoradical Catalysts for Site‐Selective C(sp3)−H Bond Functionalization Reactions

Design of Bowl‐Shaped N‐Hydroxyimide Derivatives as New Organoradical Catalysts for Site‐Selective C(sp3)−H Bond Functionalization Reactions

A series of new bowl‐shaped N‐hydroxyimide derivatives has been designed and used as selective organoradical catalysts. A number of these bowl‐shaped N‐hydroxyimide derivatives exhibit high to excellent site‐selectivity in the amination of benzylic C(sp3)−H bonds in aromatic hydrocarbon substrates.

Abstract

A series of new bowl‐shaped N‐hydroxyimide derivatives has been designed and used as selective organoradical catalysts. A number of these bowl‐shaped N‐hydroxyimide derivatives exhibit excellent site‐selectivity in the amination of benzylic C(sp3)−H bonds in aromatic hydrocarbon substrates.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Terumasa Kato, Keiji Maruoka
doi.org/10.1002/anie.202003982

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A Synthetic Chlorophyll Dimer Appending Fullerene: Effect of Chlorophyll Pairing on (Photo)redox Properties

A Synthetic Chlorophyll Dimer Appending Fullerene: Effect of Chlorophyll Pairing on (Photo)redox Properties

Imitation game : A charge‐separating chlorophyll dimer with a structure resembling natural chlorophyll pairs in photosynthetic reaction centers is reported. Structural, electrochemical, and spectrometric analyses revealed the similarity between the artificial and natural pair. Pairing the chlorophyll‐a derivatives with an N‐alkylamide group provided geometry and properties that duplicate those of the natural chlorophyll pair.

Abstract

Accurately mimicking structure and function of natural chlorophyll (Chl) assemblies is very challenging. Herein, we report the synthesis of a fullerene‐appended Chl dimer being capable of intramolecular photoinduced charge separation (CS) with a unique structure reminiscent of reaction centers (RCs) in phototrophs. Structural analyses revealed that the Chl dimer adopts a bird‐like structure in which two Chl components overlapped partially with one of the four pyrrole rings in a Chl ring similar to in a Chl pair in the natural RC complexes. A comparative study including voltammetry and spectrometric analyses using the Chl dimer and its corresponding monomer with and without a fullerene moiety was performed to gain insight into the effect of Chl pairing on (photo)redox properties. Our results suggest that the present dimer motif that closely resemble the Chl pair in natural RCs lead to more facile oxidation and lower energy of the CS state of the Chl dimer than those of the Chl monomer, resulting in its photoredox behavior different from that of the monomer Chl.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Yoshinao Shinozaki, Chiasa Uragami, Hideki Hashimoto, Hitoshi Tamiaki
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000614

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Effect of an Aromatic Solvent on Hydrogen‐Bond‐Directed Supramolecular Polymerization Leading to Distinct Topologies

Effect of an Aromatic Solvent on Hydrogen‐Bond‐Directed Supramolecular Polymerization Leading to Distinct Topologies

Adding complexity : The use of aromatic and nonpolar solvent mixtures for supramolecular polymerization of hydrogen‐bonded supermacrocycles results in complex paths attributed to the formation of competing extended hydrogen‐bonded motifs.

Abstract

Beyond phenomenon, self‐assembly of synthetic molecules, is now becoming an essential tool to design supramolecular materials not only in the thermodynamically stable state but also in kinetically trapped states. However, an approach to design complex self‐assembly processes comprising different types of self‐assembled states remains elusive. Herein, an example of such systems is demonstrated based on a unique supramolecular polymer mediated by supermacrocyclization of hydrogen‐bonding π‐conjugated molecules. By adding an aromatic solvent into nonpolar solutions of the monomer, spontaneous nucleation triggered by supermacrocyclization was suppressed so that isothermal supramolecular polymerization could be achieved from kinetically formed topological variants and amorphous agglomerates to afford helicoidal structures hitherto obtainable only with very slow cooling of a hot solution. By increasing the proportion of aromatic solvent further, another self‐assembly path was found, based on competing extended hydrogen‐bonded motifs affording crystalline nanowires.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Atsushi Isobe, Deepak D. Prabhu, Sougata Datta, Takumi Aizawa, Shiki Yagai
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202001344

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Planar, Stair‐Stepped, and Twisted: Modulating Structure and Photophysics in Pyrene‐ and Benzene‐Fused N‐Heterocyclic Boranes

Planar, Stair‐Stepped, and Twisted: Modulating Structure and Photophysics in Pyrene‐ and Benzene‐Fused N‐Heterocyclic Boranes

Polycyclic aromatic hydrocarbons (PAHs) have become a significant building block in molecular materials chemistry. Fusion or doping of boron into PAHs is known to improve the optoelectronic properties by reducing the LUMO energy level. A comprehensive study on the syntheses, structures, and photophysical properties of a new class of fused N‐heterocyclic boranes (NHBs) is reported (see figure).

Abstract

Because of their rigidity, polycyclic aromatic hydrocarbons (PAHs) have become a significant building block in molecular materials chemistry. Fusion or doping of boron into PAHs is known to improve the optoelectronic properties by reducing the LUMO energy level. Herein, we report a comprehensive study on the syntheses, structures, and photophysical properties of a new class of fused N‐heterocyclic boranes (NHBs), pyrene‐ and benzene‐linked in a “Janus‐type” fashion (2 4 , 6 9 , and 11 ). Remarkably, these examples of fused NHBs display fluorescent properties, and collectively their emission spans the visible spectrum. The pyrene‐fused NHBs all display blue fluorescence, as the excitations are dominated by the pyrene core. In notable contrast, the emission properties of the benzene‐fused analogues are highly tunable and are dependent on the electronics of the NHB fragments (i.e., the functional group directly bound to the boron atoms). Pyrene‐fused 2 4 and 11 represent the only molecules in which the K‐region of pyrene is functionalized with NHB units, and while they exhibit distorted (twisted or stair‐stepped) pyrene cores, benzene‐fused 6 9 are planar. The electronic structure and optical properties of these materials were probed by computational studies, including an evaluation of aromaticity, electronic transitions, and molecular orbitals.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Kelsie E. Krantz, Sarah L. Weisflog, Nathan C. Frey, Wenlong Yang, Diane A. Dickie, Charles Edwin Webster, Robert J. Gilliard
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202002118

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Facile Construction of Furanoacenes by a Three‐Step Sequence Going through Disilyl‐exo‐cyclic Dienes

Facile Construction of Furanoacenes by a Three‐Step Sequence Going through Disilyl‐exo‐cyclic Dienes

Furanoacenes : Facile synthesis of various benzonaphthofurans was achieved from 1,4‐disilyl‐2‐aryloxy‐1,3‐enynes by hydroarylation, cycloaddition with arynes or alkenes, and desilylated aromatization. These three reactions could be operated sequentially in one‐pot, being highly effective and providing a range of furanoacene products easily.

Abstract

Facile synthesis of various benzonaphthofurans was achieved by intramolecular hydroarylation of 1,4‐disilyl‐2‐aryloxy‐1,3‐enynes followed by cycloaddition with arynes or alkenes and finally desilylaromatization. The three‐step transformation can be operated sequentially in one‐pot, providing with a range of furanoacenes easily and highly effectively.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Yasunori Minami, Yuki Furuya, Tamejiro Hiyama
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202001119

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Reactivity of Diarylnitrenium Ions

Reactivity of Diarylnitrenium Ions

Nitrenium conundrum : When exploring synthetic‐scale generation of stable diarylnitrenium ions, Ar2N+, we find products quite different to those derived from photochemical generation.

Abstract

Hydride abstraction from diarylamines with the trityl ion is explored in an attempt to generate a stable diarylnitrenium ion, Ar2N+. Sequential H‐atom abstraction reactions ensue. The first H‐atom abstraction leads to intensely colored aminium radical cations, Ar2NH.+, some of which are quite stable. However, most undergo a second H‐atom abstraction leading to ammonium ions, Ar2NH2+. In the absence of a ready source of H‐atoms, a unique self‐abstraction reaction occurs when Ar=Me5C6, leading to a novel iminium radical cation, Ar=N.+Ar, which decays via a second self H‐atom abstraction reaction to give a stable iminium ion, Ar=N+HAr. These products differ substantially from those derived via photochemically produced diarylnitrenium ions.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Agnes Kütt, Gunnar Jeschke, Lauri Toom, Jaak Nerut, Christopher A. Reed
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000930

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Organocatalyzed Kabbe condensation reaction for mild and expeditious synthesis of 2,2‐dialkyl and 2‐spiro‐4‐chromanones

Organocatalyzed Kabbe condensation reaction for mild and expeditious synthesis of 2,2‐dialkyl and 2‐spiro‐4‐chromanones

Abstract

An expeditious Kabbe condensation reaction for the synthesis of 2,2‐dialkyl and 2‐spiro‐chroman‐4(1H )‐ones has been developed using pyrrolidine‐butanoic acid in DMSO as bifunctional organocatalyst. Unlike existing methods, this reaction proceeds at room temperature with high yields, rendering it an attractive method to synthesize a vast variety of privileged 4‐chromones.

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Hydrochromic CsPbBr3 Nanocrystals for Anti‐Counterfeiting

Hydrochromic CsPbBr3 Nanocrystals for Anti‐Counterfeiting

Now you see me, now you don‘t : CsPbBr3 nanocrystals embedded in porous SiO2 are hydrochromic. Upon exposure/removal of water, reversible transformation between luminescent CsPbBr3 and non‐luminescent CsPb2Br5 can be achieved. This hydrochromic material can be laser‐jet printed on substrates and used for anti‐counterfeiting.

Abstract

Hydrochromic materials that can reversibly change color upon water treatment have attracted much attention owing to their potential applications in diverse fields. Herein, for the first time, we report that space‐confined CsPbBr3 nanocrystals (NCs) are hydrochromic. When CsPbBr3 NCs are loaded into a porous matrix, reversible transition between luminescent CsPbBr3 and non‐luminescent CsPb2Br5 can be achieved upon the exposure/removal of water. The potential applications of hydrochromic CsPbBr3 NCs in anti‐counterfeiting are demonstrated by using CsPbBr3 NCs@mesoporous silica nanospheres (around 100 nm) as the starting material. Owing to the small particle size and negatively charged surface, the as‐prepared particles can be laser‐jet printed with high precision and high speed. We demonstrate the excellent stability over repeated transformation cycles without color fade. This new discovery may not only deepen the understanding of CsPbX3, but also open a new way to design CsPbX3 materials for new applications.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xiaoya Yu, Linzhong Wu, Di Yang, Muhan Cao, Xing Fan, Haiping Lin, Qixuan Zhong, Yong Xu, Qiao Zhang
doi.org/10.1002/anie.202005120

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Synthesis of a Stable N‐Hetero‐RhI‐Metallacyclic Silanone

Synthesis of a Stable N‐Hetero‐RhI‐Metallacyclic Silanone

A N‐hetero‐RhI‐metallacyclic silanone has been synthesized. This silanone is stable in solution at 60 °C and only slowly isomerizes at 120 °C, via an intramolecular C(sp3)−H bond insertion. This RhI‐substituted silanone can react either on the Si=O function or the Rh center, depending on the type of reagents.The reaction with H2, resulting in the hydrogenation of silanone moiety, proceeds via cooperative involvement of both sites.

Abstract

A novel N‐hetero‐RhI‐metallacyclic silanone 2 has been synthesized. The silanone 2 , showing an extremely large dimerization energy (ΔG =+86.2 kcal mol−1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular Csp3−H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5 . The exceptional stability of 2 , related to the unusual electronic and steric effects of RhI‐substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H2 starts with the hydrogenation of RhI center leading to the corresponding RhIII‐dihydride complex 7 and it undergoes a cis /trans‐isomerization via a particular mechanism, demonstrating that addition‐elimination processes can also happen for silanones just like for their carbon analogues!

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shintaro Takahashi, Kazuki Nakaya, María Frutos, Antoine Baceiredo, Nathalie Saffon‐Merceron, Stéphane Massou, Norio Nakata, Daisuke Hashizume, Vicenç Branchadell, Tsuyoshi Kato
doi.org/10.1002/anie.202006088

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Synthesis, Characterization, and Computational Investigation of Bright Orange‐Emitting Benzothiadiazole [10]Cycloparaphenylene

Synthesis, Characterization, and Computational Investigation of Bright Orange‐Emitting Benzothiadiazole [10]Cycloparaphenylene

Moving towards the red : For the first time, the fluorescence of a cycloparaphenylene was dramatically red‐shifted without sacrificing quantum yield. This novel cycloparaphenylene has a strong absorption, high quantum yield and shows host–guest complexation with C60. Experimental and computational investigations explain its superior fluorescence properties compared to other red‐shifted nanohoops.

Abstract

Conjugated aromatic macrocycles are attractive due to their unique photophysical and optoelectronic properties. In particular, the cyclic radially oriented π‐system of cycloparaphenylenes (CPPs) gives rise to photophysical properties unlike any other small molecule or carbon nanomaterial. CPPs have tunable emission, possess large extinction coefficients, wide effective Stokes shifts, and high quantum yields. However, accessing bright CPPs with emissions beyond 500 nm remains difficult. Herein, we present a novel and bright orange‐emitting CPP‐based fluorophore showing a dramatic 105 nm red‐shift in emission and striking 237 nm effective Stokes shift while retaining a large quantum yield of 0.59. We postulate, and experimentally and theoretically support, that the quantum yield remains large due to the lack of intramolecular charge transfer.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Terri C. Lovell, Zachary R. Garrison, Ramesh Jasti
doi.org/10.1002/anie.202006350

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Quantitative Assessment of Tip Effects in Single‐Molecule High‐Speed Atomic Force Microscopy Using DNA Origami Substrates

Quantitative Assessment of Tip Effects in Single‐Molecule High‐Speed Atomic Force Microscopy Using DNA Origami Substrates

Heed the speed : A DNA origami‐based assay for the quantitative evaluation of tip effects in high‐speed atomic force microscopy (HS‐AFM) is presented. Using streptavidin–biotin as a model system, it is shown that the rapidly scanned AFM tip may disrupt even strongly binding biomolecular complexes with dissociation constants in the femtomolar range.

Abstract

High‐speed atomic force microscopy (HS‐AFM) is widely employed in the investigation of dynamic biomolecular processes at a single‐molecule level. However, it remains an open and somewhat controversial question, how these processes are affected by the rapidly scanned AFM tip. While tip effects are commonly believed to be of minor importance in strongly binding systems, weaker interactions may significantly be disturbed. Herein, we quantitatively assess the role of tip effects in a strongly binding system using a DNA origami‐based single‐molecule assay. Despite its femtomolar dissociation constant, we find that HS‐AFM imaging can disrupt monodentate binding of streptavidin (SAv) to biotin (Bt) even under gentle scanning conditions. To a lesser extent, this is also observed for the much stronger bidentate SAv–Bt complex. The presented DNA origami‐based assay can be universally employed to quantify tip effects in strongly and weakly binding systems and to optimize the experimental settings for their reliable HS‐AFM imaging.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Charlotte Kielar, Siqi Zhu, Guido Grundmeier, Adrian Keller
doi.org/10.1002/anie.202005884

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Wide‐Range Color‐Tunable Organic Phosphorescence Materials for Printable and Writable Security Inks

Wide‐Range Color‐Tunable Organic Phosphorescence Materials for Printable and Writable Security Inks

Multicolor swap shop : A facile doping approach for color‐tunable organic phosphorescence materials is enabled through hosts that not only restrict the molecular motion and avoid the triplet quenching from the oxygen, but also interact with the guests for the realization of phosphorescence. Color tunable, temperature dependent, and time‐resolved anti‐counterfeiting techniques are achieved by the printable and writable materials.

Abstract

Organic materials with long‐lived, color‐tunable phosphorescence are potentially useful for optical recording, anti‐counterfeiting, and bioimaging. Herein, we develop a series of novel host–guest organic phosphors allowing dynamic color tuning from the cyan (502 nm) to orange red (608 nm). Guest materials are employed to tune the phosphorescent color, while the host materials interact with the guest to activate the phosphorescence emission. These organic phosphors have an ultra‐long lifetime of 0.7 s and a maximum phosphorescence efficiency of 18.2 %. Although color‐tunable inks have already been developed using visible dyes, solution‐processed security inks that are temperature dependent and display time‐resolved printed images are unprecedented. This strategy can provide a crucial step towards the next‐generation of security technologies for information handling.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yunxiang Lei, Wenbo Dai, Jianxin Guan, Shuai Guo, Fei Ren, Yudai Zhou, Jianbing Shi, Bin Tong, Zhengxu Cai, Junrong Zheng, Yuping Dong
doi.org/10.1002/anie.202003585

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Maximization of Spatial Charge Density: An Approach to Ultrahigh Energy Density of Capacitive Charge Storage

Maximization of Spatial Charge Density: An Approach to Ultrahigh Energy Density of Capacitive Charge Storage

A spatial charge density (SCD) maximization strategy is developed to improve the energy density of capacitive charge storage, where ionic charges are densely and neatly packed in electrode materials. By balancing the valance and size of charge‐carrier ions and matching the ion sizes with the pore structure of electrode materials, a record high SCD of about 550 C cm−3 was achieved, nearly 5× conventional ones.

Abstract

Capacitive energy storage has advantages of high power density, long lifespan, and good safety, but is restricted by low energy density. Inspired by the charge storage mechanism of batteries, a spatial charge density (SCD) maximization strategy is developed to compensate this shortage by densely and neatly packing ionic charges in capacitive materials. A record high SCD (ca. 550 C cm−3) was achieved by balancing the valance and size of charge‐carrier ions and matching the ion sizes with the pore structure of electrode materials, nearly five times higher than those of conventional ones (ca. 120 C cm−3). The maximization of SCD was confirmed by Monte Carlo calculations, molecular dynamics simulations, and in situ electrochemical Raman spectroscopy. A full‐cell supercapacitor was further constructed; it delivers an ultrahigh energy density of 165 Wh L−1 at a power density of 150 WL−1 and retains 120 Wh L−1 even at 36 kW L−1, opening a pathway towards high‐energy‐density capacitive energy storage.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Hongyun Ma, Hongwu Chen, Mingmao Wu, Fengyao Chi, Feng Liu, Jiaxin Bai, Huhu Cheng, Chun Li, Liangti Qu
doi.org/10.1002/anie.202005270

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Correlating Glycoforms of DC‐SIGN with Stability Using a Combination of Enzymatic Digestion and Ion Mobility Mass Spectrometry

Correlating Glycoforms of DC‐SIGN with Stability Using a Combination of Enzymatic Digestion and Ion Mobility Mass Spectrometry

Uncovering stability of DC‐SIGN glycoforms with native mass spectrometry : A combined strategy of exoglycosidase sequencing, native mass spectrometry, ion mobility, and gas‐phase unfolding uncovered the occupancy and structural detail of O‐glycans present on the carbohydrate binding domain of DC‐SIGN. Collision‐induced unfolding by ion mobility revealed differences in stability among glycoforms, independent of glycoprotein mass.

Abstract

The immune scavenger protein DC‐SIGN interacts with glycosylated proteins and has a putative role in facilitating viral infection. How these recognition events take place with different viruses is not clear and the effects of glycosylation on the folding and stability of DC‐SIGN have not been reported. Herein, we report the development and application of a mass‐spectrometry‐based approach to both uncover and characterise the effects of O‐glycans on the stability of DC‐SIGN. We first quantify the Core 1 and 2 O‐glycan structures on the carbohydrate recognition and extracellular domains of the protein using sequential exoglycosidase sequencing. Using ion mobility mass spectrometry, we show how specific O‐glycans, and/or single monosaccharide substitutions, alter both the overall collision cross section and the gas‐phase stability of the DC‐SIGN isoforms. We find that rather than the mass or length of glycoprotein modifications, the stability of DC‐SIGN is better correlated with the number of glycosylation sites.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Hsin‐Yung Yen, Idlir Liko, Joseph Gault, Di Wu, Weston B. Struwe, Carol V. Robinson
doi.org/10.1002/anie.202005727

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Targeting an Interaction Between Two Disordered Domains by Using a Designed Peptide

Targeting an Interaction Between Two Disordered Domains by Using a Designed Peptide

Towards peptide therapeutics : The peptide p53 linkTer has been designed based on the p53 linker disordered domain, derived from its two termini. It binds the disordered RT loop in iASPP with the same affinity as the parent p53 linker peptide, thereby inhibiting the interaction between iASPP and p53, leading to cancer cell death. This peptide, comprising only the intrinsically disordered part of a parent peptide sequence, binds its target protein without pre‐folding to a defined conformation.

Abstract

Intrinsically disordered regions in proteins (IDRs) mediate many disease‐related protein–protein interactions. However, the unfolded character and continuous conformational changes of IDRs make them difficult to target for therapeutic purposes. Here, we show that a designed peptide based on the disordered p53 linker domain can be used to target a partner IDR from the anti‐apoptotic iASPP protein, promoting apoptosis of cancer cells. The p53 linker forms a hairpin‐like structure with its two termini in close proximity. We designed a peptide derived from the disordered termini without the hairpin, designated as p53 LinkTer. The LinkTer peptide binds the disordered RT loop of iASPP with the same affinity as the parent p53 linker peptide, and inhibits the p53–iASPP interaction in vitro. The LinkTer peptide shows increased stability to proteolysis, penetrates cancer cells, causes nuclei shrinkage, and compromises the viability of cells. We conclude that a designed peptide comprising only the IDR from a peptide sequence can serve as an improved inhibitor since it binds its target protein without the need for pre‐folding, paving the way for therapeutic targeting of IDRs.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Guy Mayer, Zohar Shpilt, Shachar Bressler, Orly Marcu, Ora Schueler‐Furman, Edit Y. Tshuva, Assaf Friedler
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000465

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Rhodium‐Catalyzed Reductive Esterification Using Carbon Monoxide as a Reducing Agent

Rhodium‐Catalyzed Reductive Esterification Using Carbon Monoxide as a Reducing Agent

A rhodium‐catalyzed reductive esterification of carboxylic acids with carbonyl compounds was developed. This protocol fits a variety of carboxylic acids and aldehydes, opening the short way from industrial bulk compounds to valuable esters.

Carbon monoxide used to have a limited number of applications in organic chemistry, but it gradually increases its role as a mild and selective reducing agent. It can be applied for the carbon–heteroatom single bond formation via the reductive addition of hydrogen‐containing nucleophiles to carbonyl compounds. In this paper, rhodium‐catalyzed reductive esterification is described, and a comparative study of the rhodium and ruthenium catalysis in the reductive addition reactions is provided. Rhodium performs better on highly nucleophilic substrates and ruthenium is better for compounds with less nucleophilicity.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Vladimir S. Ostrovskii, Sofiya A. Runikhina, Oleg I. Afanasyev, Denis Chusov
doi.org/10.1002/ejoc.202000438

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Facile Synthetic Route to [3.n]Thiacyclophanes through Ring‐Closing Metathesis and their Structural Studies

Facile Synthetic Route to [3.n]Thiacyclophanes through Ring‐Closing Metathesis and their Structural Studies

Here, we are reporting a simple synthetic strategy for the synthesis of thiacyclophanes by using the Grignard reaction and ring‐closing metathesis as key steps. The structures are confirmed by single‐crystal XRD diffraction studies and compared with computationally optimized structures.

We report a useful synthetic strategy to assemble constrained [3.n] thiacyclophanes using Grignard reaction and Ti(Oi Pr)4 assisted ring‐closing metathesis (RCM). This method is viable to access para, metapara, and meta isomers of thiacyclophanes. The structures of thiacyclophanes were confirmed unambiguously by single‐crystal X‐ray diffraction studies and compared with computationally optimized structures. It is implied that out of four methods (ab initio and DFT), MP2/6‐31G (d,p) is reasonably a better method for predicting structural parameters for this class of thiacyclophanes.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Sambasivarao Kotha, Naveen Kumar Gupta, Saima Ansari
doi.org/10.1002/ejoc.202000697

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Total Synthesis of the Antitumor Depsipeptide FE399 and Its S‐Benzyl Derivative: A Macrolactamization Approach

Total Synthesis of the Antitumor Depsipeptide FE399 and Its S‐Benzyl Derivative: A Macrolactamization Approach

The total synthesis of a novel antitumor cyclic depsipeptide FE399 was achieved mainly through the MNBA‐mediated macrolactamization. A combination of MNBA and a catalytic amount of DMAPO in the presence of triethylamine as coupling agents was found to be effective for the synthesis of the macrolactam core of FE399.

An efficient and practical method for the synthesis of (9R ,14R ,17R )‐FE399, a novel antitumor bicyclic depsipeptide, was developed. A 2‐methyl‐6‐nitrobenzoic anhydride (MNBA)‐mediated dehydration condensation reaction was effectively employed for the formation of the 16‐membered macrocyclic depsipeptide moiety of FE399. FE399 was found to exist as an inseparable equilibrium mixture of conformational isomers; the mixture was quantitatively transformed into the corresponding S‐benzyl product and isolated as a single isomer. Thus, we could confirm that the molecular structure of FE399 obtained by this method is identical to that of the natural product.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Takayuki Tonoi, Miyuki Ikeda, Teruyuki Sato, Takehiko Inohana, Ryo Kawahara, Takatsugu Murata, Isamu Shiina
doi.org/10.1002/ejoc.202000459

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Metal‐Catalyzed Regiospecific (4+3) Cyclization of 2‐Indolylmethanols with ortho‐Quinone Methides

Metal‐Catalyzed Regiospecific (4+3) Cyclization of 2‐Indolylmethanols with ortho‐Quinone Methides

The first metal‐catalyzed C3‐nucleophilic (4+3) cyclization of 2‐indolylmethanols with stable ortho‐quinone methides has been established, which was used to construct indole‐based seven‐membered heterocycles in high yields (up to 98 %) with regiospecificity.

The first metal‐catalyzed C3‐nucleophilic (4+3) cyclization of 2‐indolylmethanols with stable ortho‐quinone methides has been established, which constructed indole‐based seven‐membered heterocycles in high yields (70 %‐98 %) with regiospecificity. This reaction has tackled the challenges in exploring the C3‐nucleophilicity of 2‐indolylmethanols, which will contribute to the chemistry of 2‐indolylmethanols, especially to metal‐catalyzed cyclizations of 2‐indolylmethanols. In addition, this approach will provide a useful method for constructing indole‐based seven‐membered heterocycles with high efficiency and regioselectivity.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Si‐Jia Zhou, Meng Sun, Jing‐Yi Wang, Xian‐Yang Yu, Han Lu, Yu‐Chen Zhang, Feng Shi
doi.org/10.1002/ejoc.202000693

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From Rare Reagents to Rare Products: Regiospecific Silver‐Catalyzed [3+2] Cycloaddition of Aryl‐, Alkyl‐ and Aminosulfonyl Diazomethanes with Arenediazonium Tosylates

From Rare Reagents to Rare Products: Regiospecific Silver‐Catalyzed [3+2] Cycloaddition of Aryl‐, Alkyl‐ and Aminosulfonyl Diazomethanes with Arenediazonium Tosylates

A AgI‐catalyzed [3+2] cycloaddition between diazomethyl sulfones and sulfonamides with arenediazonium tosylates provides regiospecific access to novel tetrazoles. The reaction products can be obtained in moderate to good yields.

The scope of silver nitrate‐catalyzed cycloaddition of arenediazonium salts has been expanded to include aryl‐ and alkylsulfonyl diazomethanes as well as the recently introduced diazomethyl sulfonamides. The reliance on these two classes of diazo compounds led to a new synthetic approach to the rare 2‐aryltetrazol‐5‐yl sulfones as well as to the synthesis of hitherto not described 2‐aryltetrazol‐5‐yl sulfonamides.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Ekaterina Levashova, Olga Bakulina, Dmitry Dar’in, Andrey Bubyrev, Sergey Chuprun, Mikhail Krasavin
doi.org/10.1002/ejoc.202000619

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Steering Site‐Selectivity in Transition Metal‐Catalyzed C−H Bond Functionalization: the Challenge of Benzanilides

Steering Site‐Selectivity in Transition Metal‐Catalyzed C−H Bond Functionalization: the Challenge of Benzanilides

Full control of the site‐selectivity in C−H bond functionalization is as desirable as challenging in transition‐metal catalysis. This is especially true for benzanilide derivatives, which are one of the most important building blocks in organic synthesis. The developments of these methodologies are discussed emphasizing the action mode that the transition metal‐based catalysts display in order to reach a given site‐selectivity.

Abstract

Selective C−H bond functionalization catalyzed by metal complexes have completely revolutionized the way in which chemical synthesis is conceived nowadays. Typically, the reactivity of a transition metal catalyst is the key to control the site‐, regio‐ and/or stereo‐selectivity of a C−H bond functionalization. Of particular interests are molecules that contain multiple C−H bonds prone to undergo C−H bond activations with very similar bond dissociation energies at different positions. This is the case of benzanilides, relevant chemical motifs that are found in many useful fine chemicals, in which two C−H sites are present in chemically different aromatic fragments. In the last years, it has been found that depending on the metal catalyst and the reaction conditions, the amide motif might behave as a directing group towards the metal‐catalyzed C−H bond activation in the benzamide site or in the anilide site. The impact and the consequences of such subtle control of site‐selectivity are herein reviewed with important applications in carbon‐carbon and carbon‐heteroatom bond forming processes. The mechanisms unraveling these unique transformations are discussed in order to provide a better understanding for future developments in the field of site‐selective C−H bond functionalization with transition metal catalysts.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Rafael Gramage‐Doria
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202000672

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Oxidation of cis‐Diamminediacetato PtII with Hydrogen Peroxide Can Give Rise to Two Isomeric PtIV Products

Oxidation of cis‐Diamminediacetato PtII with Hydrogen Peroxide Can Give Rise to Two Isomeric PtIV Products

Oxidation of PtII diamminediacetato with H2O2 gives rise to two PtIV isomers. Carboxylation of the OH groups with anhydrides yields two isomeric dual‐action PtIV prodrugs that than can be isolated and differ in lipophilicity and cytotoxicity. With phenylbutyrate as the bioactive ligand, the symmetric ctc‐[Pt(NH3)2(OH)2(OAc)2] was more cytotoxic than the nonsymmetric isomer in four cancer cell lines.

Abstract

The oxidation of cis‐[Pt(NH3)2(OAc)2] with H2O2 yields a mixture of two isomers: ctc‐[Pt(NH3)2(OH)2(OAc)2] and ctc‐[Pt(NH3)2(OH)(OAc)(OH)(OAc)]. Following modification with 4‐phenylbutyric (PhB) anhydride, two isomers were separated and characterized; the symmetric ctc‐[Pt(NH3)2(PhB)2(OAc)2] (1 ) and the nonsymmetric ctc‐[Pt(NH3)2(PhB)(OAc)(PhB)(OAc)] (2 ). They differ in their log P values and despite having similar cellular uptake and similar DNA platination levels, the symmetric ctc‐[Pt(NH3)2(OH)2(OAc)2] is more than 4‐fold more potent than the nonsymmetric isomer in a panel of 4 cancer cell lines.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: D. Khattib, M. Ishan, S. Karmakar, H. Kostrhunova, V. Brabec, D. Gibson
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202001472

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The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone

The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone

No co‐ligands required : The precipitation and solubility behavior of lanthanide complexes with pyrroloquinoline quinone (PQQ), is presented. Complexes with early lanthanides are preferentially formed with PQQ and rapidly precipitate out of aqueous solutions. The first molecular structure of a biorelevant europium PQQ complex outside a protein environment is reported and shows a Eu2PQQ2 dimer.

Abstract

Lanthanides (Ln) are critical raw materials, however, their mining and purification have a considerable negative environmental impact and sustainable recycling and separation strategies for these elements are needed. In this study, the precipitation and solubility behavior of Ln complexes with pyrroloquinoline quinone (PQQ), the cofactor of recently discovered lanthanide (Ln) dependent methanol dehydrogenase (MDH) enzymes, is presented. In this context, the molecular structure of a biorelevant europium PQQ complex was for the first time elucidated outside a protein environment. The complex crystallizes as an inversion symmetric dimer, Eu2PQQ2, with binding of Eu in the biologically relevant pocket of PQQ. LnPQQ and Ln1Ln2PQQ complexes were characterized by using inductively coupled plasma mass spectrometry (ICP‐MS), infrared (IR) spectroscopy, 151Eu‐Mössbauer spectroscopy, X‐ray total scattering, and extended X‐ray absorption fine structure (EXAFS). It is shown that a natural enzymatic cofactor is capable to achieve separation by precipitation of the notoriously similar, and thus difficult to separate, lanthanides to some extent.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Henning Lumpe, Annika Menke, Christoph Haisch, Peter Mayer, Anke Kabelitz, Kirill V. Yusenko, Ana Guilherme Buzanich, Theresa Block, Rainer Pöttgen, Franziska Emmerling, Lena J. Daumann
chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202002653

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