Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• ” anion hangs over the cationic centers of both independent molecules, which are almost perpendicular to each other, while the “yellow” one participates mainly in the coordination with the hydrogen atoms of the NMe2 groups. Such a distribution of counterions apparently ensures mutually perpendicular

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• 1-(2-thiophenyl)pyrroles (Scheme 4). It includes intramolecular cationic π-cyclizations in 3-hydroxy-2-(2-sulfanylphenyl)-2,3-dihydro-1H-isoindol-1-ones (Scheme 4, entry 14) [9] and intramolecular cyclizations of 1-(2-(methylsulfinyl)phenyl)-1H-pyrroles under «interrupted Pummerer rearrangement

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• -induced emission (AIE) character [20][21]. Chitosan (CS) is a natural cationic polysaccharide, which is considered an ideal material for the construction of drug delivery systems due to its nontoxic, biocompatible, biodegradable, and easily functionalized properties [22]. Herein, we designed and

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• the alkoxy group which can finally reductively eliminate the isochromene product. Based on control reactions, the authors proposed the active catalytic species is cationic, as the use of the cationic precatalyst [Cp*Ru(CH3CN)3]PF6 in THF afforded the isochromene as the major product, suggesting a

• similar cationic species may be generated in MeOH [60]. In 2011, Tenaglia and co-workers investigated the Ru-catalyzed coupling of oxabenzonorbornene derivatives 30 with propargylic alcohols and ethers 106 to access benzonorcaradienes 107 (Scheme 19) [61]. While discriminating between the neutral and

• cationic active ruthenium species, the authors noted the use of [Cp*Ru(CH3CN)3]PF6 as the precatalyst produced the cyclopropanated bicyclic alkene adducts exclusively. This contrasts with Tam’s report (Scheme 18) [55] which found cationic Ru species formed the isochromene 100 preferentially which may be

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• protocol, complexes 7a–d were obtained with acceptable yields, with similar yields compared to previous methods. In some cases, the homoleptic cationic copper(I) complexes [(NHC)2Cu]+CuCl2− were observed as side products [48][53]. We decided to directly compare complex 5 from mechanochemical synthesis (5bm

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• conjugates. In addition to this, the fluorescence studies suggested that the energy transfer was not efficient in Zn(II) porphyrin-BODIPY and 21,23-dithiaporphyrin-BODIPY conjugates. Dalip Kumar and his co-workers reported a CuAAC click reaction to prepare novel water soluble triazole-linked cationic

• MeI in DMF to afford the cationic products 85 and 87 in good yields. The synthesized conjugates exhibited high photocytotoxicity towards A549 cancer cells as compared to a tumor-localizing and potent photosensitizing agent, TMPyP. Further, the authors discovered that the porphyrin-carboline conjugates

• -fluorescein dyad 73. Synthesis of meso-triazole-linked porphyrin-carborane conjugates 76a,b. Synthesis of meso-triazole-bridged porphyrin-BODIPY conjugates 78 and 80. Synthesis of meso-triazole-linked cationic porphyrin conjugates 85 and 87. Reaction conditions: (i) Zn(OAc)2, CHCl3, MeOH, reflux, 2 h (ii

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• biomedical applications in, e.g., drug delivery systems, tissue engineering and more. Commonly, the synthesis of poly(2-oxazoline)s involves problematic organic solvents that are not ideal from a safety and sustainability point of view. In this study, we investigated the cationic ring-opening polymerization

• . Size exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were performed to determine the molar mass of the resulting polymers. Our work shows clearly that the solvent is not inert under the conditions typically used for the cationic ring-opening

• antibodies [10][11][12][13], anaphylaxis [14][15], and vacuolization [12], drives the search for alternatives [4][8]. POx have attracted the attention of scientists and companies in recent years as a promising material for pharmaceutical applications [16][17]. POx are obtained via cationic ring-opening

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• farnesylfarnesyl diphosphate (FFPP) can serve as a precursor to triterpenes [5], a compound class that was believed to be solely derived from squalene. Terpene synthases convert these linear precursors through cationic cascade reactions into terpene hydrocarbons or alcohols [6][7][8]. For type I terpene synthases

• this multistep process is initiated by the abstraction of diphosphate to produce an allyl cation that subsequently undergoes typical cation reactions such as cyclisations by intramolecular attack of an olefin to the cationic centre, Wagner–Meerwein rearrangements, hydride or proton shifts. The process

• . Alternatively, reprotonation of 1 at C-10 can also induce the formation of the guaiane skeleton. Assuming anti addition to the C-4/C-5 double bond in 1, only four cationic intermediates (K1–K4) can be generated by reprotonation at C-4 (Scheme 14A). Similarly, reprotonation of 1 at C-10 leads by anti addition to

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• pH. Preliminary studies have evidenced pKa values in the 8.3 range for non-amphiphilic surrogates of these cationic CDs, supporting the cationic character of the resulting NPs [20]. We hypothesized that these polycationic CD NPs, which we designed in our previous studies, could protect the active and

• through either (i) the cationic nature of the CD such as poly-β-CD-C6 or (ii) coating of non-ionic 6-O-capro-β-CD with the cationic polymer chitosan (CS). Uncoated 6-O-capro-β-CD negatively charged NPs were used as control formulation. Results and Discussion Fabrication and in vitro characterization of

• with the cationic CD formulation. In our further research [8], it was also reported that the oral CPT-loaded poly-β-CD-C6 NPs showed antitumoral and antimetastatic effects in a colorectal tumor-bearing animal model. Drug release from amphiphilic CD nanoparticles In vitro release studies were performed

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• leaving group at the 3β-position, have a unique feature in their chemical reactions. In these steroids, the breaking of the C3–X bond is facilitated by the formation of a cationic strained cyclopropane intermediate, which is formed by translocation of the C5–π bond electrons to the homoallylic carbon atom

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

• range of structural types than the trivalent compounds. A number of the compounds required inclusion of several conformational isomers, and for the cationic compounds, the counterions were included, and the experimental chemical shifts included compounds as pure liquids and as CDCl3, CH2Cl2, CH3CN, DMSO

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• aromatic common intermediate 9 (Scheme 10). Despite the simplicity, the most obvious disconnections, such as an anionic enone conjugated addition and a direct cationic Friedel–Crafts reaction failed. Highlighting the power of radical disconnection, the group thought of utilizing a β-keto carbon-centered

• further oxidized, and thus producing the respective benzylic cation. Intramolecular cyclization in the cationic position under participation of the methyl ester function provided the core for (+)-grandilodine C (191) and (+)-lapidilectine B (192), while allylation of the benzylic position allowed

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• have a bicyclo[2.2.2]octane precursor, which can be obtained by a dearomatization/Diels–Alder cascade. For Luo, the 1,2-shift forms bond C12–C13 through a cationic Wagner–Meerwein-type rearrangement. The B ring is obtained by a key bridgehead carbocation trapping, while the skeleton arises from an A

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• -coupling involving aldehyde C–H bond cleavage. DABCO-derived cationic catalysts in inactivated C–H bond cleavage for alkyl radical addition to electron-deficient alkenes under photoredox catalysis conditions. Electrochemical diamination and dioxygenation of vinylarenes catalyzed by triarylamines

Formal total synthesis of macarpine via a Au(I)-catalyzed 6-endo-dig cycloisomerization strategy

• Jiayue Fu,
• Bingbing Li,
• Zefang Zhou,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2022, 18, 1589–1595, doi:10.3762/bjoc.18.169

• generated indicating cationic Au(I) was the true catalyst (Table 1, entry 16). A control experiment using 2,6-di-tert-butylpyridine as a proton scavenger in the IPrAuCl/AgSbF6 system provided the product in good yield, which excluded the influence of trace amounts of acids on the reaction (Table 1, entry 17

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• capsule can catalyze the cyclization of (S)-citronellal forming isopulegol. In this study it was exploited the ability of the resorcinarene capsule to work as a Brønsted acid catalyst, and its aptitude to stabilize cationic intermediates and transition states inside the cavity. Velmurugan, Hu and co

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• , for 5c, single-crystal X-ray crystallography (Figure 1a). The 13C NMR signals of the cationic carbon atoms of the three-membered ring appeared at about 145 ppm. Besides, the 1H NMR spectra of 5 were unremarkable and consistent with the suggested formulas. As a next step, we synthesized a series of

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

• 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

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

• 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

Enzymes in biosynthesis

• Jeroen S. Dickschat

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

• 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

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

• ), 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

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

• 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

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

• 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

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

• 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