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Search for "cationic" in Full Text gives 470 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

  • Merve Karaman,
  • Abhishek Kumar Gupta,
  • Subeesh Madayanad Suresh,
  • Tomas Matulaitis,
  • Lorenzo Mardegan,
  • Daniel Tordera,
  • Henk J. Bolink,
  • Sen Wu,
  • Stuart Warriner,
  • Ifor D. Samuel and
  • Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

Graphical Abstract
  • the non-doped device, at 2.0% demonstrated 100% exciton utilization efficiency in the device and efficient energy transfer from the host to the guest cyanine emitter. Deep blue emission in LEECs is challenging. We also reported a blue-emitting LEEC employing a cationic sulfone-based donor–acceptor
  • where the emissive layer also contained an inorganic salt and a conducting polymer. Recently, a step-change in device performance were achieved by He et al. who employed a cationic TADF compound that possesses low-lying through-space and through-bond charge transfer excited states [23]. The LEEC showed
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Published 22 Sep 2022

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

  • Mana Kitano,
  • Tsuyoshi Saitoh,
  • Shigeru Nishiyama,
  • Yasuaki Einaga and
  • Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

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  • propose a reaction mechanism (Table 2). First, we carried out the electrolysis of 1 in MeCN–MeOH to confirm whether the reaction intermediate is a radical or cationic species (Table 2, entry 1). As a result, methyl cumyl ether, a methoxy adduct to the benzyl position of 1, was obtained as the main product
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Letter
Published 07 Sep 2022

Enzymes in biosynthesis

  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1131–1132, doi:10.3762/bjoc.18.116

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  • proceed through multistep cationic cascade reactions and usually produce a polycyclic terpene hydrocarbon or alcohol with multiple stereogenic centers. While these transformations require only a single enzyme, polyketide and nonribosomal peptide biosyntheses are catalyzed by megasynthases that follow an
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Editorial
Published 30 Aug 2022

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene

  • Shani Zev,
  • Marion Ringel,
  • Ronja Driller,
  • Bernhard Loll,
  • Thomas Brück and
  • Dan T. Major

Beilstein J. Org. Chem. 2022, 18, 972–978, doi:10.3762/bjoc.18.97

Graphical Abstract
  • ), which is −18.5 kcal/mol more stable than A. The barrier for the 1,3-hydride transfer is 16.2 kcal/mol for B→C. Subsequently, the double bond on C14–C15 reacts with the cationic charge on C1 to form intermediate D, which is slightly less stable than C (−17.3 kcal/mol) In the enzyme environment
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Published 04 Aug 2022

DDQ in mechanochemical C–N coupling reactions

  • Shyamal Kanti Bera,
  • Rosalin Bhanja and
  • Prasenjit Mal

Beilstein J. Org. Chem. 2022, 18, 639–646, doi:10.3762/bjoc.18.64

Graphical Abstract
  • reaction. So, based on literature reports [53][54][55], we have proposed a reaction mechanism in Figure 5b. Initially, DDQ abstracts a hydride ion from substrate 1a to generate the intermediate A. Then intermediate A undergoes an electrophilic intramolecular cyclization to form the cationic intermediate B
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Published 01 Jun 2022

BINOL as a chiral element in mechanically interlocked molecules

  • Matthias Krajnc and
  • Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

Graphical Abstract
  • thread also leads to a desymmetrization of the BINOL-based macrocycle (loss of C2 symmetry), as seen by 13C NMR spectroscopy. Stoddart and co-workers also used their π–π-recognition approach for the synthesis of BINOL-containing cationic catenanes [47][48]. They employed BINOL-based macrocycles
  • pyridine axle, followed by ion exchange, gave rise to the cationic rotaxanes 64a/b in 23/37% overall yield, both of which feature four iodotriazoles as XB donors. While rotaxane (S)-64a only possesses the BINOL unit as a stereogenic element, the system (S,S,S)-64b features two additional chiral centers on
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Published 06 May 2022

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

  • Tommaso Lorenzetto,
  • Fabrizio Fabris and
  • Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

Graphical Abstract
  • promoting the protonation of the substrates leading to the formation of cationic intermediates that are stabilized within the cavity with consequent peculiar features in terms of acceleration and product selectivity. In all cases the catalytic activity displayed by the hexameric capsule is remarkable if
  • compared to many other strong Brønsted or Lewis acids. Keywords: cationic intermediates; encapsulation; organocatalysis; resorcin[4]arene hexamer; supramolecular catalysis; Introduction In enzymatic catalysis, the substrate is selected matching the size, shape and specific functional groups present in
  • 1375 Å3 that is accessible [23] for cationic guests [24] thanks to extended cation–π interactions [25] as well as other electron poor molecules [26][27]. After our seminal work on the use of 16 as a nanoreactor to bind an Au(I) catalyst and to impart unique product [28] as well as substrate [29
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Published 28 Mar 2022

Site-selective reactions mediated by molecular containers

  • Rui Wang and
  • Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

Graphical Abstract
  • ) [60]. The host in here was a water-soluble deep cavitand D with methylated urea groups on the rim, which had already been used to mediate other organic reactions [61]. The feet of the host were transformed to pyridinium cationic moieties to make it soluble in water, and in other examples, similar
  • cavitand hosts were also modified with imidazolium cationic or carboxylic anionic feet [29]. Before the reaction, NMR analysis of the host–guest complex indicated that the bound guest was in yo-yo motions time-averaged between unsymmetrical J-shaped conformations and symmetrical U-shaped ones. Treatment of
  • demonstrated a relatively high affinity towards cationic guests through cation–π interactions, which was crucial for the catalysis of many of the organic reactions. And similarly, the ionic form of the host made it water-soluble and reactions could be conducted in water. In this particular example, the
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Published 14 Mar 2022

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

  • Surendran Amrutha,
  • Sankaran Radhika and
  • Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

Graphical Abstract
  • cross-coupling reactions Homogeneous green protocols Tsai et al. discussed an efficient, simple and environmentally friendly method for the coupling of arylynols 3 with an aryl halide [21]. This strategy discloses a one pot reaction catalyzed by FeCl3 in an aqueous medium associated with the cationic
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Published 03 Mar 2022

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

  • Thaipparambil Aneeja,
  • Cheriya Mukkolakkal Abdulla Afsina,
  • Padinjare Veetil Saranya and
  • Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

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  • heteroarenes such as thiophenes, benzofurans, furans, and indoles were found suitable substrates and afforded the desired products with high chemo- and site-selectivity. A possible mechanism for the reaction was also described. The first step of the catalytic cycle involves the formation of a cationic complex
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Published 04 Jan 2022

Iron-catalyzed domino coupling reactions of π-systems

  • Austin Pounder and
  • William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

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  • authors propose the intramolecular cyclization proceeds via the nucleophilic attack of a brominated or cationic benzylic position rather than a radical cyclization. In 2021, Tang and Zhang demonstrated a similar radical annulation of unsaturated carboxylic acids with disulfides for the synthesis of γ
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Published 07 Dec 2021

Electrocatalytic C(sp3)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

  • Bin Guo and
  • Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

Graphical Abstract
  • through reversible reaction with this cationic species. Conclusion In summary, we have achieved the electrochemical dehydrogenation cross-coupling of tetrahydroisoquinolines with terminal alkynes in continuous flow through Cu/TEMPO relay catalysis. This work demonstrates that continuous-flow
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Published 28 Oct 2021

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

  • Yi Liu,
  • Puying Luo,
  • Yang Fu,
  • Tianxin Hao,
  • Xuan Liu,
  • Qiuping Ding and
  • Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

Graphical Abstract
  • trapped by Cu(II) to deliver the Cu(III) species 12, which undergoes intramolecular annulation and reductive elimination to afford the desired product 8 and regenerate the Cu(I) catalyst. Path b: vinyl radical intermediate 11 is oxidized by Cu(II) to give the cationic vinyl species 14. Finally, the
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Published 22 Sep 2021

Targeting active site residues and structural anchoring positions in terpene synthases

  • Anwei Hou and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

Graphical Abstract
  • attack of an olefinic double bond to the cationic centre Wagner–Meerwein rearrangements, and proton or hydride migrations [2]. These multistep cascade reactions ultimately result in terpene hydrocarbons that are often (poly)cyclic and contain several stereogenic centres [3][4]. In some cases, water is
  • incorporated by its nucleophilic attack at a cationic intermediate, leading to terpene alcohols [5][6] or sometimes ethers [7][8]. Substrate ionisation by TPSs is achieved through binding of the diphosphate portion to a trinuclear Mg2+ cluster in the active site that is itself bound to two highly conserved
  • synthases seem to be quite random, only the active site is lined with mostly non-polar residues. They contour the active site and force the substrate into a certain conformation which, after substrate ionisation, determines the reaction pathway that is taken by the cationic cascade. Here we present site
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Published 17 Sep 2021

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

  • Andrey I. Puzanov,
  • Dmitry S. Ryabukhin,
  • Anna S. Zalivatskaya,
  • Dmitriy N. Zakusilo,
  • Darya S. Mikson,
  • Irina A. Boyarskaya and
  • Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

Graphical Abstract
  • bond of these oxadiazoles quantitatively resulted in E/Z-vinyl triflates. The reactions of the cationic intermediates have been studied by DFT calculations and the reaction mechanisms are discussed. Keywords: acetylene-oxadiazoles; Friedel–Crafts reaction; hydroarylation; superelectrophilic activation
  • , as a hydride ion source, was conducted to achieve the ionic hydrogenation of intermediate cationic species. However, no products of ionic hydrogenation were obtained, only the product of the hydrophenylation of the acetylene bond 5a was quantitatively isolated (compare with data shown in Scheme 5
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Published 15 Sep 2021

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

  • Sumana Mandal,
  • Raju D. Chaudhari and
  • Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

Graphical Abstract
  • literature. Utilization of Hg(II) salts in the intramolecular cationic cyclization of olefinic, acetylenic, and allenic substrates having aromatic rings, nucleophiles, and heteroatoms in the neighborhood were well documented. Hg(II) reagents were also often employed in the important cyclization step during
  • Yamamoto et al [116]. The catalytic pathway was proved to involve the direct H-transfer to the vinylmercury complex from the aromatic ring. It involved Hg(OTf)2-catalyzed cyclization of aryl 1,1-disubstituted allenes with the formation of a quaternary carbon center followed by the formation of a cationic
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Published 09 Sep 2021

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

  • Janina-Miriam Noy,
  • Fan Chen and
  • Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

Graphical Abstract
  • peptides and proteins have been linked to nanotechnology. DQA and TPP are both cationic and lipophilic molecules and therefore able to easily pass the mitochondrial membrane [15][16][17][18][19]. TPP is the most-studied mitochondrial targeting agent and has shown to accumulate 1000 times more in the
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Published 03 Sep 2021

Halides as versatile anions in asymmetric anion-binding organocatalysis

  • Lukas Schifferer,
  • Martin Stinglhamer,
  • Kirandeep Kaur and
  • Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

Graphical Abstract
  • the cationic reactive species. Keywords: anion binding; asymmetric catalysis; halide anions; hydrogen donors; noncovalent interactions; Introduction Halogens and the respective anionic halides occupy an essential role in natural and chemical processes [1][2][3][4]. While in chemical syntheses
  • anion coordination and supramolecular chemistry [7][8][9][10][11], this field of research has attracted more attention within the past two decades. Immense efforts were made to identify small molecules that are able to productively bind anions via noncovalent hydrogen bonding, from which cationic
  • proton of the enolizable β-ketoester 49 and thus activating the nucleophilic species. This enolate then adds to the cationic substrate from in situ upon halide abstraction of α-chloro amino acid derivatives 48 by the thiourea moiety of the bifunctional catalyst (Scheme 10c, key intermediate), leading to
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Published 01 Sep 2021

Chemical syntheses and salient features of azulene-containing homo- and copolymers

  • Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

Graphical Abstract
  • , Fukutomi, and Nakayama [19] reported the synthesis of what they described as ‘true polyazulene’ through a cationic polymerization reaction. Their protocol involved heating the trifluoroacetic acid (TFA) solution of azulene (1) followed by treatment with triethylamine to obtain a brown polymeric product
  • ) complexes. Synthesis of ‘true polyazulene’ 3 or 3’ by cationic polymerization. Synthesis of 1,3-polyazulene 5 by Yamamoto protocol. Synthesis of 4,7-dibromo-6-(n-alkyl)azulenes 12–14. Synthesis of (A) 4,7-diethynyl-6-(n-dodecyl)azulene (16) and (B) 4,7-polyazulene 17 containing an ethynyl spacer. Synthesis
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Published 24 Aug 2021

Constrained thermoresponsive polymers – new insights into fundamentals and applications

  • Patricia Flemming,
  • Alexander S. Münch,
  • Andreas Fery and
  • Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

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Published 20 Aug 2021

Towards new NIR dyes for free radical photopolymerization processes

  • Haifaa Mokbel,
  • Guillaume Noirbent,
  • Didier Gigmes,
  • Frédéric Dumur and
  • Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

Graphical Abstract
  • process is expected with different NIR dyes [9]. Table 1 and Figure S2 (Supporting Information File 1) clearly show the exothermicity observed upon irradiation. The proposed NIR dye/iodonium combinations are able to generate free radicals and cationic species (Scheme 7 and Figure 4), and these two
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Published 16 Aug 2021

Progress and challenges in the synthesis of sequence controlled polysaccharides

  • Giulio Fittolani,
  • Theodore Tyrikos-Ergas,
  • Denisa Vargová,
  • Manishkumar A. Chaube and
  • Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

Graphical Abstract
  • . Cationic ROP of anhydrosugars was the pioneering approach for the preparation of synthetic, unnatural xylans. Polyxylofurans with (1–5) and (3–5) linkages were described [199][200]. In most cases, non-uniform polysaccharides were obtained, as in the case of α(1–5)-xylans, prepared in up to 93% yields and
  • , enabling the synthesis of a 32mer [272]. The construction of α(1–6)-mannans (up to 10mer) bearing α(1–2)-Man branches was also accomplished using phosphate, N-phenyltrifluoroacetimidate or n-pentenylorthoester donors [273][274]. An approach using a (cationic) ROP method using tricyclic orthoester Man BBs
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Published 05 Aug 2021

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

  • Mathias B. Danielsen and
  • Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

Graphical Abstract
  • strategy that has been employed to optimize the delivery profile of ASOs, is the functionalization of ASOs with cationic amine groups, either by direct conjugation onto the sugar, nucleobase or internucleotide linkage. The introduction of these positively charged groups has improved properties like
  • nuclease resistance, increased binding to the nucleic acid target and improved cell uptake for oligonucleotides (ONs) and ASOs. The modifications highlighted in this review are some of the most prevalent cationic amine groups which have been attached as single modifications onto ONs/ASOs. The review has
  • been separated into three sections, nucleobase, sugar and backbone modifications, highlighting what impact the cationic amine groups have on the ONs/ASOs physiochemical and biological properties. Finally, a concluding section has been added, summarizing the important knowledge from the three chapters
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Published 29 Jul 2021

Development of N-F fluorinating agents and their fluorinations: Historical perspective

  • Teruo Umemoto,
  • Yuhao Yang and
  • Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

Graphical Abstract
  • moisture, while HF seriously attacks human skin. The N-F fluorinating agents can be classified into two categories: these are neutral and cationic. This review covers the chronological advancement of these reagents regardless of their classification, as they advanced side by side. Review 1. Historical
  • gave higher yields of the protonated products 4-3. 1-5. N-Fluoropyridinium salts and their derivatives In 1986, Umemoto et al. reported N-fluoropyridinium triflate and its derivatives 5-4 as new stable cationic fluorinating agents. These possessed either electron-donating or -withdrawing substituents
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Published 27 Jul 2021

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

  • Nikita Brodyagin,
  • Martins Katkevics,
  • Venubabu Kotikam,
  • Christopher A. Ryan and
  • Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Graphical Abstract
  • phosphono-PNAs retained the stability against nucleases. In another study, conjugation with glutamine phosphonate or lysine bis-phosphonate amino acid derivatives introduced up to twelve negative charges (phosphonate moieties) into PNAs [91]. The negative charges allowed cationic lipid-mediated delivery of
  • cationic RNA binding compounds, perhaps, because the protonation event is coupled with the Hoogsteen hydrogen bond formation. As a result, the partially protonated M strengthens the triple helix without compromising the sequence specificity of recognition [28][30][31]. As discussed above, guanidine groups
  • triplex, most likely due to reduced ability of R to π-stack [103]. As expected, fluorescence microscopy showed improved cellular uptake of the cationic guanidinium-modified PNAs [103]. PNA nucleobases for Hoogsteen recognition of adenine: Because the T•A–T triplets are reasonably stable under
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Published 19 Jul 2021
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