Electrosynthetic access to unsymmetrical oxaza[8]helicenes with high chiral stability and strong circularly polarized luminescence (CPL)

• Tin Zar Aye,
• Rubal Sharma,
• Muthu Karuppasamy,
• Daiya Suzuki,
• Haruka Nakajima,
• Yoshitane Imai,
• Mitsuhiro Arisawa,
• Mohamed S. H. Salem and
• Shinobu Takizawa

Beilstein J. Org. Chem. 2026, 22, 372–382, doi:10.3762/bjoc.22.25

• products were detected under the optimized conditions (Scheme 2). Based on our previous reports [48][56], DFT calculations, and cyclic voltammetry (CV) analyses (Figure 1), anodic single-electron transfer (SET) is expected to occur first from 3, generating the electrophilic radical cation [3]·+ as 3 (Eox

• intense chiroptical responses, including mirror-image CD and strong CPL with |glum| values up to 0.0026 and CPL brightness approaching 30.8 M−1 cm−1. A plausible reaction mechanism: cyclic voltammetry (CV) analyses of hydroxycarbazole derivative 3 and 2-naphthol derivatives 4; DFT-based calculations of

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• bioactive compounds underwent smooth esterification with TFE to give the corresponding 2,2,2-trifluoroethyl esters 82–85 in high yields. To elucidate the reaction mechanism, cyclic voltammetry experiments, control reactions, and DFT calculations were conducted. At the anode, bromide ions are oxidized to

• equivalents of LiHMDS, N-alkyl- and N-arylanilides were efficiently cleaved to afford the corresponding amides 64 and 162–165 in high yields. A broad range of N,N-dialkylamides, cyclic amides, and heterocyclic amides were also compatible, all delivering amide products 3, 4, and 166–172 in good to excellent

• amide using aniline hydrochloride salt. CO2-catalyzed transamidation of amides. Transamidation of formamides using cyclic dihydrogen tetrametaphosphate. BF3·OEt2-mediated transamidation of primary amides. Acyl iodide intermediate 121 generation from amides for the transamidation using HOTf and KI

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

• reaction, starting with a Schenck ene reaction of cholesterol to form the highly reactive hydroperoxide species 112a was the operational pathway [159][160][161][162]. Carbon bond migration in a process called Hock cleavage leads to a cyclic hemiacetal 112b which ring-opens and aldolises (112c) to give the

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• synthesis of spirobarbiturates via a [3 + 2] cycloaddition reaction of azomethine ylides, we present for the first time a three-component diastereoselective synthesis of hybrid systems containing spiro-fused cyclic fragments of barbituric acid and pyrrolo[3,4-a]pyrrolizidine. It was found that azomethine

• preferential formation of the endo-adduct (upper pathway). The predominance of exo-isomers in some cases probably reflects insufficient stabilization due to secondary orbital interactions in the transition state [43]. It should be noted separately that secondary cyclic amino acids such as azetidine-2

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• single and double bonds (Figure 1A) [5]. However, despite its strength in representing a planar cyclic arrangement of tetravalent carbon atoms, this formalism fails to accurately depict the observed reactivity, structure, and stability of benzene. It implies three rapidly equilibrating, localized double

A mild and atom-efficient four-component cascade strategy for the construction of biologically relevant 4-hydroxyquinolin-2(1H)-one derivatives

• Dmitrii A. Grishin,
• Kseniia I. Sharkovskaia,
• Ilya G. Kolmakov,
• Daria A. Ipatova,
• Rostislav A. Petrov,
• Nikolai D. Dagaev,
• Dmitry A. Skvortsov,
• Maria G. Khrenova,
• Valeriy V. Andreychev,
• Sergei A. Evteev,
• Yan A. Ivanenkov,
• Roman L. Antipin,
• Olga А. Dontsova and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2026, 22, 244–256, doi:10.3762/bjoc.22.18

• acids followed by sequential Michael-type addition and subsequent cascade transformations. This versatile one-pot protocol delivers structurally diverse open-chain 3-arylpropanoate esters in moderate to good yields (46–69%), while cyclic pyranoquinolinones are formed under kinetically controlled

• Fe3O4@SiO2–SO3H nanoparticles [39]. However, all previously reported multicomponent protocols inevitably terminate at the formation of the cyclic pyranoquinolinone scaffold, and no controlled access to open-chain quinolinone esters has been demonstrated so far. Herein, building upon previous studies and

• reactions of α,β-unsaturated aldehydes with 2a–c afforded only minor amounts of the 1,4-addition product, while the cyclic 1,2-addition product predominated (Scheme 4C). The reaction of α,β-unsaturated cyanoacrylate with 2c also failed to yield the desired product (Scheme 4D). For the reaction of α,β

Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

•  1A) [15][16]. Oxidative rearrangements of carbonyl compounds are based on Dakin [17] and Baeyer–Villiger reactions [18] and their modifications. Cyclic and acyclic ketones were oxidized to afford lactones and esters, accordingly, involving catalytic reactions with hydrogen peroxide [19][20][21][22

Highly electrophilic, gem- and spiro-activated trichloromethylnitrocyclopropanes: synthesis and structure

• Ilia A. Pilipenko,
• Mikhail V. Grigoriev,
• Olga Yu. Ozerova,
• Igor A. Litvinov,
• Darya V. Spiridonova,
• Aleksander V. Vasilyev and
• Sergey V. Makarenko

Beilstein J. Org. Chem. 2026, 22, 123–130, doi:10.3762/bjoc.22.5

• -Petersburg 199034, Russia 10.3762/bjoc.22.5 Abstract New highly electrophilic gem- and spiro-activated trichloromethylnitrocyclopropanes were obtained by the Michael-initiated ring closure (MIRC) reaction of 1-bromo-1-nitro-3,3,3-trichloropropene with linear and cyclic CH-acids catalyzed by bases

• nitro group upon breaking the C–C bond [16][17]. Substituted nitrocyclopropanes in reactions with various nucleophiles form linear precursors for the synthesis of γ-substituted α-aminobutyric acids [18][19], cyclic nitropyrrolines [20] and isoxazoline N-oxides [18]. The nitrocyclopropane fragment is a

• Michael-initiated ring closure (MIRC) reaction of gem-halonitroalkenes and CH-acids [37][38]. Thus, 2-nitrocyclopropanecarboxylates were obtained based on the tandem reactions of cyclic CH-acids with alkyl 3-bromo-3-nitroacrylates [39]. Despite the structural proximity and high activity of 1-bromo-1-nitro

Total synthesis of natural products based on hydrogenation of aromatic rings

• Haoxiang Wu and
• Xiangbing Qi

Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4

• of axially chiral cyclic compounds with high enantioselectivity could be synthesized. In addition, the authors also obtained central chiral cyclic compounds by asymmetric hydrogenation of phenanthrene with directing groups. In 2022 and 2024, Chirik and co-workers reported the use of molybdenum as a

• mechanistic hypothesis. Based on this stereochemical control, the Stoltz team successfully obtained the asymmetric hydrogenation product 176, which spontaneously underwent intramolecular cyclization to furnish the bridged cyclic compound 177. With compound 177 in hand, a series of three transformations

Advances in Zr-mediated radical transformations and applications to total synthesis

• Hiroshige Ogawa and
• Hugh Nakamura

Beilstein J. Org. Chem. 2026, 22, 71–87, doi:10.3762/bjoc.22.3

• formation to give the cyclic acetal 33. This transformation was applicable to a range of oxetanes 30a–c bearing benzylic alcohol derivatives, each affording the corresponding cyclic acetals in good yields. In 2023, Ota and Yamaguchi et al. reported the hydrogenation of alkyl chlorides via halogen atom

• method applied to secondary alkyl chlorides, both acyclic (44h) and cyclic (44i and 44j), as well as to benzyl chlorides derived from bioactive molecules such as fenofibrate (44k) and celestoride (44l), all of which furnished the corresponding dimers in excellent yields. The proposed reaction mechanism

Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review

• Daniel S. Müller

Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1

Sustainable electrochemical synthesis of aliphatic nitro-NNO-azoxy compounds employing ammonium dinitramide and their in vitro evaluation as potential nitric oxide donors and fungicides

• Alexander S. Budnikov,
• Nikita E. Leonov,
• Michael S. Klenov,
• Andrey A. Kulikov,
• Igor B. Krylov,
• Timofey A. Kudryashev,
• Aleksandr M. Churakov,
• Alexander O. Terent’ev and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2025, 21, 2739–2754, doi:10.3762/bjoc.21.211

• (Table 1, entry 11). Under optimized reaction conditions (Table 1, entry 1), the scope of the electrochemical nitro-NNO-azoxylation protocol was tested (Scheme 2). The reaction proceeds in moderate to good yields for cyclic aliphatic nitroso compounds 1b–d, affording nitro-NNO-azoxy compounds 2b–d. The

• nucleophilic substitution of –ONO2 groups. To clarify the reaction mechanism, cyclic voltammetry (CV) studies were conducted. CV curves of cyclohexanone oxime (S1), 1-bromo-1-nitrosocyclohexane (S2), 1-chloro-1-nitrosocyclohexane (S3), 1-nitrosocyclohexyl acetate (S4), 1-nitro-1-nitrosocyclohexane (1c), 1

• calculations were performed [93] on ωB97X-3c [94] /CPCM(MeCN) level of theory (Figure 3). Based on cyclic voltammetry data, control experiments, and our previous study, the mechanism of the electrochemical synthesis of nitro-NNO-azoxy compounds 2 was proposed (Figure 3, Scheme 5). The reaction starts from

Total synthesis of asperdinones B, C, D, E and terezine D

• Ravi Devarajappa and
• Stephen Hanessian

Beilstein J. Org. Chem. 2025, 21, 2730–2738, doi:10.3762/bjoc.21.210

• metabolite and cyclic dipeptide consisting of a 7-prenylated ʟ-tryptophan and ʟ-alanine was isolated from the liquid cultures of S. teretispora containing potato broth in the medium. Its structure was based on extensive spectroscopic studies (Figure 1). Terezine D (6) exhibited modest in vitro antifungal

Mechanistic insights into hydroxy(tosyloxy)iodobenzene-mediated ditosyloxylation of chalcones: a DFT study

• Jai Parkash,
• Sangeeta Saini,
• Vaishali Saini,
• Omkar Bains and
• Raj Kamal

Beilstein J. Org. Chem. 2025, 21, 2703–2715, doi:10.3762/bjoc.21.208

• ) compounds in polar nucleophilic or non-nucleophilic solvents [10][11][12][20][29][30][31][32][33][34][35][36]. Fujita discusses typical pathways of alkene oxidation with hypervalent iodine in great detail including the stereochemical course of reaction involving a cyclic iodonium ion [30]. In the literature

• = -OCH3, -SCH3 a three-membered cyclic carbocation (Int4) is involved. This distinction can be attributed to the substituent on the phenyl ring. The positive charge on the three-membered cyclic carbocation will be stabilized by an electron-donating substituent (X) while the electron-withdrawing groups, X

• which leads to the formation and stabilization of the three-membered cyclic carbocation (Int4). The electron-donating group provides electron density to the carbocation, which stabilizes the positive charge. As a result, Int4 is observed when electron-donating groups are present (Scheme 2). In Int4, the

Tandem hydrothiocyanation/cyclization of CF₃-iminopropargyl alcohols with NaSCN in the presence of AcOH

• Ruslan S. Shulgin,
• Ol’ga G. Volostnykh,
• Anton V. Stepanov,
• Igor’ A. Ushakov,
• Alexander V. Vashchenko and
• Olesya A. Shemyakina

Beilstein J. Org. Chem. 2025, 21, 2694–2702, doi:10.3762/bjoc.21.207

• carried out a further derivatization experiment. The product 2a could be oxidized with H2O2 to produce a mixture of 3-hydroxy- and 3-hydroperoxy-2,3-dihydroisothiazole 1,1-dioxides 4 and 5 in a ratio of 4:1, respectively (Scheme 3). Such cyclic sulfonamides (sultams) are of interest in the field of

Efficient solid-phase synthesis and structural characterization of segetalins A–H, J and K

• Liangyu Liu,
• Wanqiu Lu,
• Quanping Guo and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2025, 21, 2612–2617, doi:10.3762/bjoc.21.202

• (Caryophyllaceae), are head-to-tail cyclic oligopeptides comprising 5–9 amino acid residues [5][6][7][8][9][10][11][12][13]. These natural products exhibit a significant diversity of pharmacological activities [14][15][16], including estrogen-like activity (1, 2, 7, 8), antitumor effects (5), and antimicrobial

• , successful macrocyclization was achieved by employing benzotriazol-1-yloxytripyrrolidinophosphonium hexafluorophosphate (PyBOP) as the coupling reagent in DMF at a concentration of 10−3 M. After cleavage from the resin and global side-chain deprotection, the crude cyclic peptides were purified by preparative

• electrospray ionization mass spectrometry (HRESIMS) data for all compounds matched the calculated exact masses for their respective molecular formulas. NMR spectroscopic analysis in appropriate deuterated solvents (e.g., DMSO-d6, D2O) fully corroborated the amino acid sequence and cyclic connectivity

Ni-promoted reductive cyclization cascade enables a total synthesis of (+)-aglacin B

• Si-Chen Yao,
• Jing-Si Cao,
• Jian Xiao,
• Ya-Wen Wang and
• Yu Peng

Beilstein J. Org. Chem. 2025, 21, 2548–2552, doi:10.3762/bjoc.21.197

• the tropical rain forests of the Kalimantan region (Indonesia) [1][2]. These cyclic ether natural products belong to the typical aryltetralin lignans, which have already attracted broad attention from the synthetic community [3][4][5]. Zhu and co-workers disclosed a concise synthesis of (±)-aglacins B

Synthesis and characterization of a isothiouronium-calix[4]arene derivative: self-assembly and anticancer activity

• Giuseppe Granata,
• Loredana Ferreri,
• Claudia Giovanna Leotta,
• Giovanni Mario Pitari and
• Grazia Maria Letizia Consoli

Beilstein J. Org. Chem. 2025, 21, 2535–2541, doi:10.3762/bjoc.21.195

• [7], cyclic peptides [8], cucurbiturils [9], resorcinarenes [10], pillarenes [11], prismarenes [12], and calix[n]arenes have proven to be particularly valuable. Calix[n]arenes, a family of polyphenolic macrocyclic oligomers, are widely utilized in applications ranging from materials science to life

Catalytic enantioselective synthesis of selenium-containing atropisomers via C–Se bond formations

• Qi-Sen Gao,
• Zheng-Wei Wei and
• Zhi-Min Chen

Beilstein J. Org. Chem. 2025, 21, 2447–2455, doi:10.3762/bjoc.21.186

• phenyl-substituted benzoisoquinoline derivatives. Two plausible reaction mechanisms were proposed in the study: one involving oxidative addition of Int 4, a five-membered rhodium cyclic intermediate, followed by reductive elimination and the other proceeding via a bimolecular nucleophilic substitution

Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds

• Natalya Akhmetdinova,
• Ilgiz Biktagirov and
• Liliya Kh. Faizullina

Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185

• [52] achieved high regioselectivity and stereospecific construction of contiguous all-carbon quaternary centers through an oxidative ring contraction of cyclic α-formyl ketones by the action of H2O2. This reaction is easy to perform, environmentally friendly, and does not require expensive catalysts

• ], the mechanism and factors controlling the selectivity of the oxidative ring contraction in cyclic α-formyl ketones under the action of H2O2 were studied in detail. Due to their complex architecture and diverse biological activities, including antiviral, antitumor, antimalarial, and antifungal activity

• formation of a mixture of ketone 194 and cyclic diene 195. Regio- and stereoselectivity was observed in the case of the epoxide 189. The cyclopentane derivative 194 was obtained stereoselectively and in high yield during the reaction with BF3·Et2O. An alternative example of the tandem epoxide rearrangement

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• for the preparation of such cyclic compounds and/or their fused cyclic systems typically necessitate the use of toxic solvents, including chloroform, benzene, toluene etc. [32][53][54][55][56][57][58][59]. Indeed, the selection of conventional organic solvents, including benzene, toluene and

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• (C6F5)3B triggered a Meinwald rearrangement, generating aldehyde 66. Nucleophilic addition, oxidation of the resulting alcohol, and base-promoted epimerization at C6 of 67' delivered 67. Subsequent dihydroxylation of the alkene in 67 and protection of the resulting 1,2-diol as a cyclic carbonate

• protection as ketal and nitrile reduction. The two building blocks (76 and 81) were then merged through the desired formal [3 + 3]-cycloaddition to generate N-desmethyl-α-obscurine (82), presumably via in situ-generated intermediates 76a and 81a, respectively. Subsequent Boc protection of the cyclic amine in

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• discern the effect of smaller aromatic sidewalls. The synthesis of acyclic CB[n]-type receptors follows a building block approach involving the reaction of a glycoluril bis(cyclic) ether with an activated aromatic wall by a double electrophilic aromatic substitution process [30]. Scheme 2 shows the

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• isomerization reactions of cyclic meso-epoxides as part of a bimetallic titanium/cobalt catalytic system [64]. Photoredox catalysis in radical reactions The ability of a photocatalyst (organic small molecule or transition-metal complex) to undergo single electron transfer (SET) to a variety of organic

• . Melchiorre and co-workers reported a dual catalytic system that involves photoredox and chiral organocatalysts for the construction of all-carbon quaternary centers. The authors studied radical additions to β,β-disubstituted cyclic enones (Scheme 7) [29]. The dual catalytic system of tetrabutylammonium

• decatungstate (TBADT) and chiral amine 33 was able to catalyze the reaction between benzodioxoles 32 and cyclic β,β-disubstituted enones 31. Cyclic ketones 34 bearing all-carbon quaternary stereocenters at the β-position were obtained in good yields and high enantioselectivity. Enzyme-catalyzed radical

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• allene intermediate 141, which subsequently underwent 5-exo-trig cyclization to construct polysubstituted furan compounds 142. Liu et al. discovered that the regioselectivity of cyclization could be completely altered by introducing a cyclic structure to modify the bond angle of the enol ether

• , affording the eight-membered benzo[b]azocin-2-one product 165. This methodology was distinguished by operational simplicity, high efficiency, and scalable synthesis. Moreover, temperature modulation achieved rapid access to cyclic compounds with distinct ring sizes. In 2022, biphenyl-embedded 1,3,5-trien-7