Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• considered ways to further enhance this activity. We first explored the effects of structural modifications to berberine itself. The cationic iminium within berberine and its derivatives is susceptible to nucleophilic attack [10][14]. Through use of an acetone enolate, as well as partial or full reduction by

Unraveling the role of prenyl side-chain interactions in stabilizing the secondary carbocation in the biosynthesis of variexenol B

• Moe Nakano,
• Rintaro Gemma and
• Hajime Sato

Beilstein J. Org. Chem. 2023, 19, 1503–1510, doi:10.3762/bjoc.19.107

• affected by hyperconjugation (C9–C10: 1.54 Å, C10–C11: 1.54 Å, C11–C1: 1.57 Å). We have also done a comparative analysis of the charge distribution in scenarios with and without cation–π interactions. In cases where the interaction is absent, the cationic character at C10 is pronounced. Conversely, in the

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• dihydropyrazoles 54 as products (Scheme 22) [59]. A credible pathway for the production of isoxazole 53 is illustrated in Scheme 23. The interaction of 1 with BF3·Et2O resulted in intermediate I that is in balance with I’. Cleavage of the N–S bond of I afforded cationic species PhS+ II, which activated the double

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• electron-donating substituents in the aromatic ring gave oligomeric materials. Presumably, in these cases, after dehydration and formation of the corresponding enone 2, the latter underwent subsequent cationic oligomerization. Next we studied the intramolecular cyclization of compounds 1 and 2 in TfOH. It

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• [(6-NHC)CuMes] with t-BuOH. It was found that the diaminocarbene derivative was more thermally stable whereas the diamido derivative underwent both thermal and hydrolytic ring-opening reactions (Scheme 13). Demir Atli and co-worker, in 2018, synthesized a cationic (NHC)2Cu(I) complex 39 in very good

• explored as catalysts for the hydrosilylation of ketones. Besides the type of the ligand in the NHC–Cu(I) complex, the counter anions (BF4 and PF6) also influenced the catalytic activity. Furthermore, the cationic complexes were found to be more efficient than the neutral analogues under similar conditions

• and co-workers [68] developed a new series of heteroleptic bis(NHC)–Cu(I) complexes and a mixed NHC–Cu–phosphine complex and employed these complexes as catalysts for azide–alkyne [3 + 2] cycloaddition (Scheme 50). These cationic heteroleptic bis(NHC)–Cu complexes 131 are highly active for this

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• either through diphosphate abstraction (for type I terpene synthases) or protonation of the substrate (type II terpene synthases). The resulting cationic species can then react in a cascade reaction via a series of cationic intermediates involving cyclisations, hydride or proton shifts, and skeletal

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• oxidant to generate an oxygen-radical cationic intermediate, which undergoes abstraction of a hydrogen radical (or loses a proton first, followed by an electron) to afford an oxonium ion intermediate. Finally, the oxonium ion is attacked by various nucleophiles to obtain the target functionalized product

• involves a hydride abstraction from the benzylic site of isochroman to generate a cationic species A, whereas the malonate is activated by the In/Cu catalyst (B). Subsequently, the coupling of the two intermediates yields the desired product and regenerates the catalyst. Alternatively, In(III) may be

• form cationic intermediate C and Fe(II) through a single electron transfer (SET) process. Subsequent abstraction of a proton from species C by a basic tert-butoxy anion generated from DTBP affords the product. Li et al. reported Fe-catalyzed CDC reactions of C(sp2)–H bonds of indoles and C(sp3)–H bonds

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• dehydration to generate isoxazolium cation 80 paired with a phosphate anion. This chiral phosphate is engaged in H-bonding with the free NH of the heteroarene ring to ease the stereoselective 1,2-addition to in situ generate the cationic heterocyclic scaffold 81. The reaction proceeded faster with pyrroles

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• of all ergot alkaloids, specifically the decarboxylative cyclization of DMAT, is still a puzzle even though a radical mechanism has been proposed (Figure 1a) [72][73]. Results and Discussion Herein, we propose that visible light irradiation of the cationic iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• using a cationic zirconium complex under a H2 atmosphere in 1989 and the work done by Bergman and Ellmann [49] in 2010 for the ortho-C–H alkylation of pyridines under Rh(I) catalysis at high temperature, in 2011 Hou and Guan reported an atom economical method for the selective ortho-alkylation of

• pyridines by C–H addition to olefins under cationic half-sandwich rare-earth catalysis [50]. They carried out the reaction in the presence of dialkyl complexes of scandium (Sc) or yttrium (Y) such as (C5Me5)Ln(CH2C6H4NMe2-o)2 (Ln = Sc, Y) in combination with B(C6F5)3 as an activator. The method demonstrated

• mechanism involves the coordination of pyridine to the metal center of the cationic catalyst and B(C6F5)3 promotes the ortho-C–H activation (deprotonation) of pyridine to afford pyridyl species 6. Next, the 2,1-migratory insertion of alkene 2 into the metal–pyridyl bond in 6 gives the intermediate 7, which

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