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novembre 2022 – ChemDigest

Mois : novembre 2022

Iron‐catalyzed construction of cyanomethylated thiohydantoins by cross‐dehydrogenative C(sp3)‐C(sp3) coupling

Iron-catalyzed construction of cyanomethylated thiohydantoins by cross-dehydrogenative C(sp3)-C(sp3) coupling

Abstract

The efficient and novel approach for synthesizing cyanomethylated thiohydantoin from readily obtainable acetonitrile and 1,3-dibenzyl-2-thiohydantoin through iron(II)-catalyzed cross dehydrogenative coupling (CDC) protocol is documented here. The strategy displays extensive substrate scope, and provides an effectual construction of cyanomethylated thiohydantoins in moderate to good yield. Prominently, this new methodology represents hitherto unobserved reactivity pattern for the thiohydantoin.

Preparation and characterization of zinc oxide nanoparticles supported on reduced graphene oxide and using as an effective catalyst for synthesis of l,4‐dihydropyrimidinones under solvent‐free conditions

Preparation and characterization of zinc oxide nanoparticles supported on reduced graphene oxide and using as an effective catalyst for synthesis of l,4-dihydropyrimidinones under solvent-free conditions

In this research, it was presented a simple and easy method for the preparation of graphene oxide-supported ZnO nanoparticles with low cost, available precursor, and their application as nanocatalyst for the synthesis of l,4-dihydropyirimidinones.

Abstract

In this research, it was presented a simple and easy method for the preparation of graphene oxide (GO) supported ZnO nanoparticles with low cost, available precursor and their application as nanocatalyst for synthesis of l,4-dihydropyirimidinones. When GO combines with metal oxide nanoparticles such as ZnO shows very good properties. There is a wide range of chemical methods for the attachment of various functional groups. In this protocol, the GO was synthesized through Hummer’s method. The structure and morphology properties of ZnO NPs@rGO nanocomposite were investigated by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscope techniques. Also, the organic compounds were identified by melting point, FT-IR, and proton nuclear magnetic resonance analyses.

Efforts and Strategies for the Syntheses of Clavine‐Type Ergot Alkaloid Aurantioclavine

Efforts and Strategies for the Syntheses of Clavine-Type Ergot Alkaloid Aurantioclavine

This focus review presented recent advances in the synthesis of aurantioclavine, with a particular emphasis on synthetic strategies for building the azepino[5,4,3-cd]indole framework via three key intermediates: 4-substituted tryptamine/tryptophan derivatives, 4-substituted tryptophol derivatives, and aniline & analogues.

Abstract

Aurantioclavine, isolated by Kozlovskii from Penicillium aurantiovirens, is a unique member of the 3,4-disubstituted indole alkaloids distinguished by an azepino[5,4,3-cd]indole. As an essential intermediate in the biosynthesis of the complex polycyclic alkaloids of the fungal communesin, it has attracted considerable attention as a synthetic target. The development of various synthetic strategies for their application in total synthesis has been described. An overview focused on the synthesis of aurantioclavine from its first synthesis to the most recent one is present.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Cong‐Bin Ji, Xin Hu, Shi‐Zhi Jiang, Jin‐Hui Yang
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202201000

Two Directing Groups Used for Metal Catalysed Meta‐C−H Functionalisation Only Effect Ortho Electrophilic C−H Borylation

Two Directing Groups Used for Metal Catalysed Meta-C−H Functionalisation Only Effect Ortho Electrophilic C−H Borylation

Two templates used in metal catalysed directed meta functionalisation led to either no borylation, or only ortho borylation under electrophilic borylation conditions. In the absence of the complex template amide directed ortho borylation onto phenylacetyl groups is shown to be possible.

Abstract

Two templates used in meta-directed C−H functionalisation under metal catalysis do not direct meta-C−H borylation under electrophilic borylation conditions. Using BCl3 only Lewis adduct formation with Lewis basic sites in the template is observed. While combining BBr3 and the template containing an amide linker only led to amide directed ortho C−H borylation, with no pyridyl directed meta borylation. The amide directed borylation is selective for the ortho borylation of the aniline derived unit in the template, with no ortho borylation of the phenylacetyl ring – which would also form a six membered boracycle – observed. In the absence of other aromatics amide directed ortho borylation on to phenylacetyl rings can be achieved. The absence of meta-borylation using two templates indicates a higher barrier to pyridyl directed meta borylation relative to amide directed ortho borylation and suggests that bespoke templates for enabling meta-directed electrophilic borylation may be required.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Saqib A. Iqbal, Clement R. P. Millet, Jürgen Pahl, Kang Yuan, Michael J. Ingleson
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202200901

Visible Light Organo‐Photocatalytic Synthesis of 3‐Imidazolines

Visible Light Organo-Photocatalytic Synthesis of 3-Imidazolines

An efficient synthesis of tetrasubstituted 3-imidazolines under organo-photocatalytic conditions has been developed through formal [3+2]-cycloaddition between 2H-azirines and N-tosyl benzylidene imines. While the reaction exhibited complete regiocontrol, products were obtained as separable mixture of cis (major) and trans (minor) diastereoisomers in most of the cases.

Abstract

An efficient regioselective synthesis of tetrasubstituted 3-imidazolines under organo-photocatalytic conditions has been developed through formal [3+2]-cycloaddition between 2H-azirines and N-tosyl benzylidene imines. The products were isolated in high yields and as a separable mixture of diastereoisomers in most of the cases. The mild reaction conditions employing an organic dye as photocatalyst, excellent functional group tolerance, and high regioselectivity are notable features of the current protocol.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Poornima Mishra, Ipsha Shruti, Ruchir Kant, Tejender S. Thakur, Akhilesh Kumar, Namrata Rastogi
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202201079

Engineering Single-Atom Sites into Pore-Confined Nanospaces of Porphyrinic Metal–Organic Frameworks for the Highly Efficient Photocatalytic Hydrogen Evolution Reaction

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Qijie Mo, Li Zhang, Sihong Li, Haili Song, Yanan Fan, and Cheng-Yong Su
dx.doi.org/https://doi.org/10.1021/jacs.2c10801

Oxidative Desymmetrization Enables the Concise Synthesis of a trans‐Cyclooctene Linker for Bioorthogonal Bond Cleavage

Oxidative Desymmetrization Enables the Concise Synthesis of a trans-Cyclooctene Linker for Bioorthogonal Bond Cleavage

Bioorthogonal cleavage of trans-cyclooctene (TCO) linkers triggered by a click reaction with tetrazines has enabled new concepts in chemical biology and in vivo chemistry. We introduce a new dioxolane-fused cleavable TCO linker (dcTCO) with high stability and reduced lipophilicity that can be prepared in five steps and demonstrate its application in bioorthogonal prodrug activation, achieving a remarkable >1000-fold “turn-on” in cytotoxicity.

Abstract

Modified trans-cyclooctenes (TCO) are capable of highly efficient molecular manipulations in biological environments, driven by the bioorthogonal reaction with tetrazines (Tz). The development of click-cleavable TCO has fueled the field of in vivo chemistry and enabled the design of therapeutic strategies that have already started to enter the clinic. A key element for most of these approaches is the implementation of a cleavable TCO linker. So far, only one member of this class has been developed, a compound that requires a high synthetic effort, mainly to fulfill the multilayered demands on its chemical structure. To tackle this limitation, we developed a dioxolane-fused cleavable TCO linker (dcTCO) that can be prepared in only five steps by applying an oxidative desymmetrization to achieve diastereoselective introduction of the required functionalities. Based on investigation of the structure, reaction kinetics, stability, and hydrophilicity of dcTCO, we demonstrate its bioorthogonal application in the design of a caged prodrug that can be activated by in-situ Tz-triggered cleavage to achieve a remarkable >1000-fold increase in cytotoxicity.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Walter Kuba, Barbara Sohr, Patrick Keppel, Dennis Svatunek, Viktoria Humhal, Berthold Stöger, Marion Goldeck, Jonathan C. T. Carlson, Hannes Mikula
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202203069

Surface Modification, Topographic Design and Applications of Superhydrophobic Systems

Surface Modification, Topographic Design and Applications of Superhydrophobic Systems

Superhydrophobic surfaces with expanded wetting behaviors like tunable adhesion, hybrid surface hydrophobicity and smart hydrophobic switching, have attracted increasing attention due to their broad applications. This review mainly focuses on recent advances in surface modification, topographic design and the application of superhydrophobic systems.

Abstract

Superhydrophobic surfaces with expanded wetting behaviors, like tunable adhesion, hybrid surface hydrophobicity and smart hydrophobic switching have attracted increasing attention due to their broad applications. Herein, the construction methods, mechanisms and advanced applications of special superhydrophobicity are reviewed, and hydro/superhydrophobic modifications are categorized and discussed based on their surface chemistry, and topographic design. The formation and maintenance of special superhydrophobicity in the metastable state are also examined and explored. In addition, particular attention is paid to the use of special wettability in various applications, such as membrane distillation, droplet-based electricity generators and anti-fogging surfaces. Finally, the challenges for practical applications and future research directions are discussed.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Weinan Zhao, Yi Wang, Mei Han, Jiaxin Xu, Kam Chiu Tam
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202657

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

A dirhodium(II)/Xantphos catalyzed three-component reaction of N, N-disubstituted anilines, α-diazo esters, and allylic compounds was developed, affording various aniline derivatives with diaryl allylic quaternary centers in good yields under mild conditions. The reaction proceeds via para C(sp2)−H functionalization of aniline derivatives by Rh(II)-carbenoid intermediate, and subsequent [Rh2]/Xantphos-catalyzed allylic alkylation of the resulting α, α-diarylacetate intermediate.

Abstract

A three-component reaction of N, N-disubstituted aniline, α-diazo ester, and an allylic electrophile has been realized by [Rh(II)]2/Xantphos catalysis, providing a direct access to various aniline derivatives bearing diaryl allylic quaternary centers in good yields. The synthetic utility of this protocol was demonstrated by facile derivatization of the products for preparation of biologically relevant molecules and structural scaffolds, which offers a high potential for increasing the molecular diversity. Mechanistic studies identified α, α-diarylacetate species as an active intermediate, thereby revealing the presence of a C(sp2)−H functionalization of aniline derivatives/allylic alkylation cascade in this attractive catalytic transformation.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Zhaoliang Ge, Bin Lu, Huailong Teng, Xiaoming Wang
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202820

Rational Design and Synthesis of D‐galactosyl Lysophospholipids as Selective Substrates and non‐ATP‐competitive Inhibitors of Phosphatidylinositol Phosphate Kinases

Rational Design and Synthesis of D-galactosyl Lysophospholipids as Selective Substrates and non-ATP-competitive Inhibitors of Phosphatidylinositol Phosphate Kinases

New-to-Nature D-galactosyl lysophospholipids were rationally designed and synthesized to act as artificial substrates and non-ATP-competitive inhibitors of phosphatidylinositol phosphate kinases, which are validated drug targets for deadly human diseases including cancers, amyotrophic lateral sclerosis, and SARS-COVID-2 infection. Rational Design and Synthesis of D-galactosyl Lysophospholipids as Selective Substrates and non-ATP-competitive Inhibitors of Phosphatidylinositol Phosphate Kinases (X. Huang, J. Hu et al.)

Abstract

Phosphatidylinositol phosphate kinases (PIPKs) produce lipid signaling molecules and have been attracting increasing attention as drug targets for cancer, neurodegenerative diseases, and viral infection. Given the potential cross-inhibition of kinases and other ATP-utilizing enzymes by ATP-competitive inhibitors, targeting the unique lipid substrate binding site represents a superior strategy for PIPK inhibition. Here, by taking advantage of the nearly identical stereochemistry between myo-inositol and D-galactose, we designed and synthesized a panel of D-galactosyl lysophospholipids, one of which was found to be a selective substrate of phosphatidylinositol 4-phosphate 5-kinase. Derivatization of this compound led to the discovery of a human PIKfyve inhibitor with an apparent IC50 of 6.2 μM, which significantly potentiated the inhibitory effect of Apilimod, an ATP-competitive PIKfyve inhibitor under clinical trials against SARS-CoV-2 infection and amyotrophic lateral sclerosis. Our results provide the proof of concept that D-galactose-based phosphoinositide mimetics can be developed into artificial substrates and new inhibitors of PIPKs.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Mengxia Sun, Chi Zhang, Dexin Sui, Canchai Yang, Dohun Pyeon, Xuefei Huang, Jian Hu
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202083

Size Selectivity in Heterolanthanide Molecular Complexes with a Ditopic Ligand

Size Selectivity in Heterolanthanide Molecular Complexes with a Ditopic Ligand

A size selectivity in the coordination of different lanthanides ions to the two donor sites of the ditopic pyterpyNO ligand has been evidenced in heteronuclear complexes of formula RE2RE*2(tta)12(pyterpyNO)2, where smaller (larger) ions normally display a higher affinity for the eight (nine)-coordinated oxygen (nitrogen) site. The present results, obtained in solution and in the solid state with a multi-technique approach (X-ray diffraction, 19F NMR, magnetometry and photoluminescence), are independent of the employed synthetic route.

Abstract

The similar reactivity of lanthanides generally leads to statistically populated polynuclear complexes, making the rational design of ordered hetero-lanthanide compounds extremely challenging. Here we report on the site selectivity in hetero-lanthanide tetranuclear complexes afforded by the relatively simple ditopic pyterpyNO ligand (4’-(4-pyridil)-2,2’:6’,2”-terpyridine N-oxide). The sequential room temperature reaction of RE2(tta)6(pyterpyNO)2 (where RE=Y, (1); Eu, (2), Dy, (3) Htta=2-thenoyltrifluoroacetone) with La(tta)3dme (dme=dimethoxyethane) yielded Y2La2(tta)12(pyterpyNO)2 (4), Dy2La2(tta)12(pyterpyNO)2 (5) and Eu2La2(tta)12(pyterpyNO)2 (6). Single crystals X-ray diffraction studies showed that 4, 5 and 6 are isostructural, featuring a tetranuclear structure with two different metal coordination sites with coordination numbers 8 (CN8) and 9 (CN9). The two smaller cations are mainly bridged by the O-donor atoms of the NO groups of two pyterpyNO ligands (CN8), while the larger lanthanum centres are bound by a terpyridine unit (CN9). Size selectivity has been studied with structural and magnetic studies in the solid state and through 19F NMR and photoluminescence studies in solution, showing a direct dependence on the difference of ionic radii of the ions and yielding a 91 % selectivity for 4. Furthermore, 19F NMR, X-ray and PL studies pointed out that the nature of the product is independent from the synthetic route for compound Eu2Y2(tta)12(pyterpyNO)2 (7), keeping the ion selectivity also for a self-assembly reaction. Unexpectedly, these studies have evidenced that selectivity is not exclusively governed by electrostatic interactions related to size dimensions.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Luca Bellucci, Lorenzo Fioravanti, Lidia Armelao, Gregorio Bottaro, Fabio Marchetti, Francesco Pineider, Giordano Poneti, Simona Samaritani, Luca Labella
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202823

Activation of Ge−H and Sn−H Bonds with N‐Heterocyclic Carbenes and a Cyclic (Alkyl)(amino)carbene

Activation of Ge−H and Sn−H Bonds with N-Heterocyclic Carbenes and a Cyclic (Alkyl)(amino)carbene

Insertion of cAACMe into E−H bonds of EH2R2 (E=Ge, R=Mes; E=Sn, R=Me) to yield cAACMeH−EHR2 and the dehydrogenative coupling of EH2R2 using N-Heterocyclic Carbenes are reported.

Abstract

A study of the reactivity of several N-heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene 1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene (cAACMe) with the group 14 hydrides GeH2Mes2 and SnH2Me2 (Me=CH3, Mes=1,3,5-(CH3)3C6H2) is presented. The reaction of GeH2Mes2 with cAACMe led to the insertion of cAACMe into one Ge−H bond to give cAACMeH−GeHMes2 (1). If 1,3,4,5-tetramethyl-imidazolin-2-ylidene (Me2ImMe) was used as the carbene, NHC-mediated dehydrogenative coupling occurred, which led to the NHC-stabilized germylene Me2ImMe⋅GeMes2 (2). The reaction of SnH2Me2 with cAACMe also afforded the insertion product cAACMeH−SnHMe2 (3), and reaction of two equivalents Me2ImMe with SnH2Me2 gave the NHC-stabilized stannylene Me2ImMe⋅SnMe2 (4). If the sterically more demanding NHCs Me2ImMe, 1,3-di-isopropyl-4,5-dimethyl-imidazolin-2-ylidene (iPr2ImMe) and 1,3-bis-(2,6-di-isopropylphenyl)-imidazolin-2-ylidene (Dipp2Im) were employed, selective formation of cyclic oligomers (SnMe2) n (5; n=5–8) in high yield was observed. These cyclic oligomers were also obtained from the controlled decomposition of cAACMeH−SnHMe2 (3).

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Michael S. M. Philipp, Rüdiger Bertermann, Udo Radius
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202493

Orthogonal Crosslinking: A Strategy to Generate Novel Protein Topology and Function

Orthogonal Crosslinking: A Strategy to Generate Novel Protein Topology and Function

Intrigued by diverse non-disulfide crosslinks occurring naturally in bacterial adhesins and pili domains, scientists have endeavored to expand crosslinker structures by using a variety of approaches and transpose this unusual topology to other robust protein scaffolds such as domain antibodies. This Concept summarizes recent advances in this fertile intersection of organic chemistry, biochemistry, and protein science.

Abstract

Compared to the disulfide bond, other naturally occurring intramolecular crosslinks have received little attention, presumably due to their rarity in the vast protein space. Here we presented examples of natural non-disulfide crosslinks, which we refer to as orthogonal crosslinks, emphasizing their effect on protein topology and function. We summarize recent efforts on expanding orthogonal crosslinks by using either the enzymes that catalyze protein circularization or the genetic code expansion strategy to add electrophilic amino acids site-specifically in proteins. The advantages and disadvantages of each method are discussed, along with their applications to generate novel protein topology and function. In particular, we highlight our recent work on spontaneous orthogonal crosslinking, in which a carbamate-based crosslink was generated in situ, and its applications in designing orthogonally crosslinked domain antibodies with their topology-mimicking bacterial adhesins.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Zheng Wang, Johnathan D. Rabb, Qing Lin
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202828

Deaminative Arylation and Alkenyaltion of Aliphatic Tertiary Amines with Ary and Alkenylboronic Acids via Nitrogen Ylides

Deaminative Arylation and Alkenyaltion of Aliphatic Tertiary Amines with Ary and Alkenylboronic Acids via Nitrogen Ylides

An efficient and general deaminative arylation and alkenylation of tertiary amines with ary and alkenylboronic acids enabled by difluorocarbene under transition-metal-free conditions. This protocol represents a novel reaction mode which succeeded in the construction of Csp 3−Csp 2 bonds via an in situ formed nitrogen ylide from tertiary amines (propargyl amines, allyl amines and 1H-indol-3-yl methane amines) and difluorocarbene with aryl and alkenylboronic acids.

Abstract

Transition-metal-catalyzed Suzuki–Miyaura coupling has significantly advanced C−C bond formation and has been well recognized in organic synthesis, pharmaceuticals, materials science and other fields. In this rapid development, cross coupling without transition metal catalyst is a big challenge in this field, and using widely existing tertiary amines as electrophiles to directly couple with boronic acids has great hurdles yet significant application prospects. Herein, we report an efficient and general deaminative arylation and alkenylation of tertiary amines (propargyl amines, allyl amines and 1H-indol-3-yl methane amines) with ary and alkenylboronic acids enabled by difluorocarbene under transition-metal-free conditions. Preliminary mechanism experiments suggest that in situ formed difluoromethyl quaternary amine salt, nitrogen ylide and tetracoordinate boron species are the key intermediates, the subsequent 1,2-metallate shift and protodeboronation complete the new coupling reaction.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jianke Su, Chengbo Li, Xinyuan Hu, Yu Guo, Qiuling Song
onlinelibrary.wiley.com/doi/10.1002/anie.202212740

Photoredox‐Mediated Deoxygenative Radical Additions of Aromatic Acids to Vinyl Boronic Esters and gem‐Diborylalkenes

Photoredox-Mediated Deoxygenative Radical Additions of Aromatic Acids to Vinyl Boronic Esters and gem-Diborylalkenes**

Photoredox-mediate deoxygenation: In this work, we explore an efficient, general photoredox-mediated deoxygenated approach of abundant, simple, and commercially available carboxylic acids and vinyl boronic esters, which form the important β-keto-borylalkanes. Additionally, a protocol of the late-stage functionalization of naturally occurring bioactive carboxylic acids and drugs has been developed using this approach.

Abstract

A new method to access β-keto-gem-diborylalkanes, by direct deoxygenative radical addition of aromatic carboxylic acids to gem-dibortlalkenes, is described. The reaction proceeds under mild photoredox catalysis and involves the photochemical C−O bond activation of aromatic carboxylic acids in the presence of PPh3. It generates an acyl radical, which further undergoes an additional reaction with gem-diborylalkenes to form an α-gem-diboryl alkyl radical intermediate, which then reduces to the corresponding anion, which after protonation, affords the β-keto-gem-diborylalkane product. Moreover, the same scenario has been extended to the vinyl boronic esters, for example, gem-(Ar, Bpin)-alkenes, and gem-(Alkyl, Bpin)-alkenes. Importantly, this protocol provides a general platform for the late-stage functionalization of bio-active and drug molecules containing a carboxylic acid group.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Anugula Nagaraju, Tamer Saiaede, Nadim Eghbarieh, Ahmad Masarwa
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202646

Peptide Conjugated Dihydroazulene/Vinylheptafulvene Photoswitches in Aqueous Environment

Peptide Conjugated Dihydroazulene/Vinylheptafulvene Photoswitches in Aqueous Environment

A series of dihydroazulene/vinylheptafulvene (DHA/VHF) photoswitches was prepared and studied in various media regarding their photophysical, photochemical, and thermal properties. To pave the way towards the use of DHAs as building blocks in bio(macro)molecules, we synthesized peptide conjugates including the 17-amino acid ALFA peptide and found excellent switching properties of the biohybrid constructs in aqueous media. 

Abstract

Light-responsive molecules have seen a major advance in modulating biological functions in recent years. Especially photoswitches are highly attractive building blocks due to the reversible nature of their light-mediated reactivity. They are frequently used to affect both the properties of small bioactive compounds and biomacromolecules if incorporated suitably. Despite their success in a plethora of applications, only a limited set of photochromic core structures is routinely employed and a large number of photochromic couples are under-investigated in biological context. Broadening the toolbox of photoswitches available to modulate biological activity would open new avenues and unlock the full potential of photoswitchable molecules for biological studies. In this work, we explore the photochemical and thermal properties of the dihydroazulene/vinylheptafulvene photochromic couple as peptide conjugates in aqueous environment.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Brian P. Corbet, J. Malte Schlüter, Elena R. Cotroneo, Stefano Crespi, Nadja A. Simeth
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202201140

The Anionic Chemistry in Regulating the Reductive Stability of Electrolytes for Lithium Metal Batteries

The Anionic Chemistry in Regulating the Reductive Stability of Electrolytes for Lithium Metal Batteries

The participation of anions in the solvation sheath of lithium-ion promotes the reductive stability of solvents. Simultaneously, anions themselves tend to get reduced more willingly and induce the formation of inorganic-rich solid electrolyte interphase, which is beneficial to stabilizing lithium metal anodes.

Abstract

Advanced electrolyte design is essential for building high-energy-density lithium (Li) batteries, and introducing anions into the Li+ solvation sheaths has been widely demonstrated as a promising strategy. However, a fundamental understanding of the critical role of anions in such electrolytes is very lacking. Herein, the anionic chemistry in regulating the electrolyte structure and stability is probed by combining computational and experimental approaches. Based on a comprehensive analysis of the lowest unoccupied molecular orbitals, the solvents and anions in Li+ solvation sheaths exhibit enhanced and decreased reductive stability compared with free counterparts, respectively, which agrees with both calculated and experimental results of reduction potentials. Accordingly, new strategies are proposed to build stable electrolytes based on the established anionic chemistry. This work unveils the mysterious anionic chemistry in regulating the structure–function relationship of electrolytes and contributes to a rational design of advanced electrolytes for practical Li metal batteries.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Nan Yao, Shu‐Yu Sun, Xiang Chen, Xue‐Qiang Zhang, Xin Shen, Zhong‐Heng Fu, Rui Zhang, Qiang Zhang
onlinelibrary.wiley.com/doi/10.1002/anie.202210859

Total Synthesis of Arylnaphthalene Lignans through a Photochemical Key Step

Total Synthesis of Arylnaphthalene Lignans through a Photochemical Key Step

The total syntheses of arylnaphthalene lignans (ANL) Vitrofolal E (1), Noralashinol C (2), and Ternifoliuslignan E (3) are described. These natural products have in common a missing substituent in 2-position of the naphthalene skeleton (2HANL). The key step of the syntheses is the Photo-Dehydro-Diels-Alder (PDDA) reaction between arylalkyne moieties, which are connected by a suberate linker unit. The reasons for the regioselectivity of the photochemical ring closure were investigated by means of DFT methods.

Abstract

The total syntheses of three arylnaphthalene lignans (ANLs) were developed: Vitrofolal E (1), Noralashinol C (2), and Ternifoliuslignan E (3). These natural products have in common a missing substituent in 2-position of the naphthalene moiety (2H-ANLs). The key step of these syntheses is a regioselective intramolecular Photo-Dehydro-Diels-Alder (PDDA) reaction with (1,7)naphthalenophanes as primary products. A further improvement of the photochemical step was achieved by triplet sensitization with xanthone, allowing the use of more efficient UVA lamps. It should be noted that this work is a continuation of a previous publication about the total synthesis of lignans using the PDDA reaction.[1]

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Pablo Wessig, Dominik Badetko, Lukas Wichterich, Eric Sperlich, Alexandra Kelling
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202201234

Spectro‐Microscopic Techniques for Studying Nanoplastics in the Environment and in Organisms

Spectro-Microscopic Techniques for Studying Nanoplastics in the Environment and in Organisms

Nanoplastics (NPs) pose a threat to the environment and human health but are challenging to detect and characterize in environmental samples. This Minireview covers established imaging and characterization techniques, with a focus on micro-spectroscopic techniques. More exotic advanced techniques to measure NP morphology and chemical fingerprints simultaneously are discussed, and challenges in detection of NPs using high-resolution imaging are outlined.

Abstract

Nanoplastics (NPs), small (<1 μm) polymer particles formed from bulk plastics, are a potential threat to human health and the environment. Orders of magnitude smaller than microplastics (MPs), they might behave differently due to their larger surface area and small size, which allows them to diffuse through organic barriers. However, detecting NPs in the environment and organic matrices has proven to be difficult, as their chemical nature is similar to these matrices. Furthermore, as their size is smaller than the (spatial) detection limit of common analytical tools, they are hard to find and quantify. We highlight different micro-spectroscopic techniques utilized for NP detection and argue that an analysis procedure should involve both particle imaging and correlative or direct chemical characterization of the same particles or samples. Finally, we highlight methods that can do both simultaneously, but with the downside that large particle numbers and statistics cannot be obtained.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Laurens D. B. Mandemaker, Florian Meirer
onlinelibrary.wiley.com/doi/10.1002/anie.202210494

Gold(I) Multi‐Resonance Thermally Activated Delayed Fluorescent Emitters for Highly Efficient Ultrapure‐Green Organic Light‐Emitting Diodes

Gold(I) Multi-Resonance Thermally Activated Delayed Fluorescent Emitters for Highly Efficient Ultrapure-Green Organic Light-Emitting Diodes

A simple gold(I) coordination strategy affords highly efficient narrowband green and blue multi-resonance thermally activated delayed fluorescence with emission quantum yields of ca. 0.9 and considerably shortened lifetimes down to 5.5 μs. The resultant AuI emitters deliver ultrapure-green OLEDs with external quantum efficiencies of up to 30.3 %, alongside diminished roll-offs as low as 0.8 % and device lifetimes (LT60) of 1210 h at 1000 cd m−2.

Abstract

Acceleration of singlet-triplet intersystem crossings (ISC) is instrumental in bolstering triplet exciton harvesting of multi-resonance thermally activated delayed fluorescent (MR-TADF) emitters. This work describes a simple gold(I) coordination strategy to enhance the spin-orbit coupling of green and blue BN(O)-based MR-TADF emitters, which results in a notable increase in rate constants of the spectroscopically observed ISC process to 3×109 s−1 with nearly unitary ISC quantum yields. Accordingly, the resultant thermally-stable AuI emitters attained large values of delayed fluorescence radiative rate constant up to 1.3×105/1.7×105 s−1 in THF/PMMA film while preserving narrowband emissions (FWHM=30–37 nm) and high emission quantum yields (ca. 0.9). The vapor-deposited ultrapure-green OLEDs fabricated with these AuI emitters delivered high luminance of up to 2.53×105 cd m−2 as well as external quantum efficiencies of up to 30.3 % with roll-offs as low as 0.8 % and long device lifetimes (LT60) of 1210 h at 1000 cd m−2.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Siyuan Cai, Glenna So Ming Tong, Lili Du, Gary Kwok‐Ming So, Faan‐Fung Hung, Tsz‐Lung Lam, Gang Cheng, Hui Xiao, Xiaoyong Chang, Zong‐Xiang Xu, Chi‐Ming Che
onlinelibrary.wiley.com/doi/10.1002/anie.202213392

Tuning the Electro‐Optical Properties of Mixed‐Halide Trityl Radicals Bearing para‐Brominated Positions through Halogen Substitution

Tuning the Electro-Optical Properties of Mixed-Halide Trityl Radicals Bearing para-Brominated Positions through Halogen Substitution

Two new mixed-halide trityl radicals bearing p-brominated positions were synthesized in good yield from halogenated triphenylmethanes obtained by multistep Friedel-Crafts reactions. Their electrochemical and spectroscopic properties were reported as well as quantum-chemical calculations carried out to supplement the experimental investigation. The most blue-shifted emission among trityl radicals was achieved for the highly fluorinated trityl radical.

Abstract

In this work, the synthesis and characterization of two new trityl radicals bearing two p-brominated positions, i. e. the 2,2′-((perchlorophenyl)methylene)bis(1,3,5-tribromobenzene) radical and the 6,6′-((perchlorophenyl)methylene)bis(3-bromo-1,2,4,5-tetrafluorobenzene) radical, are presented. Slightly modifying the strategy typically used for the synthesis of non-symmetric mixed-halide trityl radicals, we were able to considerably increase the reaction yield for the radical precursors. In addition, for the first time the electro-optical properties of a highly fluorinated trityl radical were studied, achieving the most blue-shifted emission for a trityl radical reported up to now. Quantum-chemical calculations carried out to supplement the experimental investigation support the electrochemical and spectroscopic data as well as rationalize the observed blue shift of the highly fluorinated species.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Davide Mesto, Yasi Dai, Carlo N. Dibenedetto, Angela Punzi, Jozef Krajčovič, Marinella Striccoli, Fabrizia Negri, Davide Blasi
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202201030

α‐Acylation of Alkenes by a Single Photocatalyst

α-Acylation of Alkenes by a Single Photocatalyst

A reaction for the difunctionalization of terminal alkenes with an acyl group and a fluoromethyl, alkyl, sulfonyl, or thioether group was developed with acylation at the internal position by using a single photocatalyst. Key to success was a kinetic difference in the reactivity of the radical precursors with the excited photocatalyst, whereby the terminal position was first occupied by the more kinetically favorable radical precursor.

Abstract

A direct strategy for the difunctionalization of alkenes, with acylation occurring at the more substituted alkene position, would be attractive for complex ketone synthesis. We report herein a reaction driven by a single photocatalyst that enables α-acylation in this way with the introduction of a fluoromethyl, alkyl, sulfonyl or thioether group at the β-position of the alkene with high chemo- and regioselectivity under extremely mild conditions. Crucial to the success of this method are rate differences in the kinetics of radical generation through single-electron transfer (SET) between different radical precursors and the excited photocatalyst (PC*). Thus, the β-position of the alkene is first occupied by the group derived from the radical precursor that can be generated most readily, and α-keto acids could be used as an electrophilic reagent for the α-acylation of alkenes.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Yuan‐Yuan Cheng, Hong‐Yu Hou, Yu Liu, Ji‐Xin Yu, Bin Chen, Chen‐Ho Tung, Li‐Zhu Wu
onlinelibrary.wiley.com/doi/10.1002/anie.202208831