Kinetic resolution of racemic planar-chiral vinylcymantrenes by molybdenum-catalyzed asymmetric metathesis dimerization

• Haruna Imazu,
• Hitoshi Izu,
• Yasuhiro Ohki and
• Masamichi Ogasawara

Beilstein J. Org. Chem. 2026, 22, 568–574, doi:10.3762/bjoc.22.42

• benzene at the indicated temperature in the presence of an appropriate chiral Mo-precatalyst (10 mol %), which was generated in situ from the Mo-precursor, (pyrrolyl)2Mo(=CHCMe2Ph)(=N-C6H3-2,6-iPr2) [36], and an axially chiral biphenol ligand. The chiral Mo/(R)-L1 precatalyst [21] facilitated the

Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• information for a better understanding of the NMR spectra. In contrast to the planar benzene ring of melifoliones, the para quinol ring in 4 adopts a flat but rigid boat conformation. However, the sp3-hybridized C-10b leads to greater flexibility of the whole molecule. Therefore, it is easier for the

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• benzene (see Supporting Information File 1, Figure S1). The absorption spectra have essentially the same key features, specifically absorption maxima at around 209 nm, 240 nm, and 273 nm, with a long-wavelength absorption onset at 350 nm. Both maxima and onset absorptions are hypsochromically shifted

• sensitized photocycloaddition reaction [48] A solution of the norbornadiene (4.02–25.0 mg, 10.0–62.1 mmol) and the sensitizer Ir(ppy)3 or [Ru(phen)3](PF6)2 (5–10 mol %) in deaerated benzene or MeCN was irradiated with light (λex = 420 or 520 nm) for 0.5–3 h. The solvent was removed under reduced pressure at

• benzene (4 mL) was irradiated with λex = 420 nm at rt for 3 h. The product was obtained as an opaque viscous liquid (24.6 mg, 61.1 µmol, >95%). 1H NMR (500 MHz, CDCl3) δ 1.54–1.57 (m, 1H), 1.67 (ddd, 3J = 6.0 Hz, 3J = 4.5 Hz, 3J = 2.2 Hz, 1H), 1.73–1.78 (m, 1H), 1.84–1.89 (m, 1H), 2.10 (dt, 2J = 11.1 Hz

Modern synthetic pathways towards eribulin and its subunits

• Sebastian Dominik Graf

Beilstein J. Org. Chem. 2026, 22, 495–526, doi:10.3762/bjoc.22.37

Recent advances in the stereoselective synthesis of distal biaxially chiral molecules

• Fanxing Zhou,
• Chen Zhang,
• Lingyu Sun,
• Yiyun Fang,
• Siming Zheng,
• Lina Hu,
• Mengyang Shen,
• Zhen Zhao,
• Wei Xu,
• Yunqiang Sun and
• Zi-Qiang Rong

Beilstein J. Org. Chem. 2026, 22, 461–479, doi:10.3762/bjoc.22.34

• carboxylic acid derivatives (Scheme 2b) [43]. They revealed that ortho-alkoxy substitution on the benzene-derived alkyne markedly enhanced both reactivity and enantioselectivity, while incorporation of a naphthyl substituent into the diyne enabled access to remote biaxially chiral molecules. Subsequent

A facile and practical method for the synthesis of trans-(±)-taxifolin and its derivatives via Darzens reaction

• Bo Peng,
• Panpan Yang,
• Maaz Khan,
• Xiaotong Lin,
• Jiang Wu,
• Peng Fu and
• Qingqing Wu

Beilstein J. Org. Chem. 2026, 22, 443–450, doi:10.3762/bjoc.22.31

• (Supporting Information File 1, Table S1, entries 3–5, and 7). When NaHCO3 was used as an additive to neutralize HBr in the reaction mixture that was responsible for the cleavage of MOM, bromination with PTT was also unsuccessful in that the bromination occurred at the benzene ring and MOM was partially

• . The stereochemical outcome of the Darzens reaction may produce the α,β-epoxycarbonyl products with either the substituents on the same side or opposite side of the epoxy functionality, i.e., as cis/trans isomers. In this work, the α,β-epoxycarbonyl product contains bulky multiple-substituted benzene

Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene

• Yukiho Hashimoto,
• Yuuya Kawasaki,
• Kazunobu Igawa and
• Katsuhiko Tomooka

Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30

• X-ray crystallographic analysis was performed (CCDC 2513894). The solid-state structure of 1ac shows that the phenyl group on the E-alkene is directed antiparallel to the fused benzene ring. The dihedral angle of the alkene moiety (∠C4–C5–C6–C7) of 1ac is 146.4°, which is distorted by 33.6° from an

Cone p-aminocalix[4]arenes enriched with ‘clickable’ alkyne or azide functionalities

• Ilia Korniltsev,
• Vasily Bazhenov,
• Alexander Gorbunov,
• Dmitry Cheshkov,
• Stanislav Bezzubov,
• Vladimir Kovalev and
• Ivan Vatsouro

Beilstein J. Org. Chem. 2026, 22, 399–415, doi:10.3762/bjoc.22.28

• complexation processes were obtained in these cases either; adding excess salt to solutions of these calixarenes in CDCl3 or in CDCl3/benzene-d6 mixtures resulted in the formation of insoluble precipitates containing the entire portions of the hosts, thus indicating a complexation process but the

Dialkylaminoalkylation of β-ketosulfones via ring-opening of 3-sulfonylpyrrolidines

• Evgeny M. Buev,
• Alexander V. Pavlushin,
• Vladimir S. Moshkin and
• Vyacheslav Y. Sosnovskikh

Beilstein J. Org. Chem. 2026, 22, 383–389, doi:10.3762/bjoc.22.26

• results. Refluxing a mixture of ketosulfone 1, a two-fold excesses of N-methylglycine and paraformaldehyde in benzene with a Dean–Stark trap for 4 h yields incomplete conversion of the substrate (Scheme 1, product 2a, 60%). However, we did not observe the resinification of the reaction media and hence we

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

• attributed to magnetic coupling between the face-to-face terminal rings, in line with the Johnson–Bovey model, given the inter-ring distances of approximately 3.75–3.79 Å [59]. On the other hand, the aromaticity of the pyrrole rings (A and A′) and benzene rings G and G′ in 5a and 5b decreases, which can be

• resulting plots show a clockwise diatropic current along the fused heterocycles and benzene rings, in agreement with the ring-current patterns reported for other helicene scaffolds [27] (Figure 2B). Enantiomerization barriers of oxaza[7]helicenes To investigate the enantiomerization (P/M) barriers of oxaza

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

• 4-membered ring (see Scheme 23B). Finally, acetal formation on the novel carbaldehyde furnished the structure of pepluacetal (89). An interesting example for both the ring expansion and contraction of benzene rings in nature was unveiled during investigations into the biosynthesis of xenovulene A

• natural product liphagal (104). A ring contraction from 6→5 was suggested for the biosynthesis of taiwaniaquinol natural products and is depicted in Scheme 27 [151][152][153][154][155][156]. The precursor to this family of natural products, 6,7-dehydroferruginol (107), is oxidised both at the benzene core

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

• ; Introduction Aromaticity has intrigued chemists since Michael Faraday’s isolation of benzene in 1825, marking the beginning of a concept that has shaped much of modern chemical thinking [1][2]. Despite its fundamental importance, aromaticity remains an abstract notion [3]. It is central to understanding

• molecular structure and reactivity, yet it cannot be measured directly [4]. This inherent elusiveness contributed to decades of debate over the structure of benzene, the prototypical aromatic molecule, until August Kekulé proposed his venerable representation: a six-membered carbon ring with alternating

• 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

• isopropanol as the solvent under the established conditions. This resulted in a mixture of the open-chain isopropyl ester and the corresponding cyclic product, with the latter predominating. When a mixture of isopropanol and benzene (1:1.5) was employed as the solvent, no isopropyl ester was formed

Configuration–packing synergy enabling integrated crystalline-state RTP and amorphous-state TADF

• Ruiyan Wang and
• Yunan Wu

Beilstein J. Org. Chem. 2026, 22, 224–236, doi:10.3762/bjoc.22.16

• -tris(1-phenyl-1H-benzoimidazol-2-yl)benzene, is the electron-transport material, and CBP – 4,4′-N,N′-dicarbazolebiphenyl is used as the host material mixed with 1 to form the emissive layer. As illustrated in Figure 9a, the electroluminescence peak of the fabricated OLED is observed at 533 nm. This

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

• mutually compatible, and rationalized facial selectivity through insights from asymmetric styrene hydrogenation. In 2024, Glorius and co-workers developed a chemoselective hydrogenation strategy capable of selectively reducing benzene rings in the presence of pyridine rings (Scheme 4) [47]. Supported by

• hydrogenation of the polycyclic aromatic compound PyBQ to PyBTHQ using this catalyst in HFIP (Scheme 5) [50]. Under the optimized conditions, only the heteroaromatic part of quinoline was reduced selectively, while the benzene ring and pyridine remained unchanged. In 2020, Beller and co-workers used a manganese

• 53 while retaining the benzene ring structure using an iridium catalyst to selectively hydrogenate indoles and benzofurans (Scheme 7) [59]. The hydrogenated products were obtained in 90% yield with 98% ee on average. In 2024, Yin and co-workers reported an innovative palladium-catalyzed asymmetric

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

• available materials, in benzene afforded the Zr(RCNN)2 complex 18. Investigation of the photoredox properties of the synthesized complex revealed trends similar to those of known photosensitizers, suggesting its potential utility as a photosensitizer [15]. Accordingly, the Zr(MeCNN)2 complex was employed as

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

• vary widely across the literature, with solvents ranging from neat conditions to cyclohexane, hexanes, toluene, benzene, carbon tetrachloride, dichloromethane, and diethyl ether. Reaction temperatures span from −10 °C to 100 °C. The first detailed investigation of this transformation was reported by

• Kagan and co-workers [48], who demonstrated that the reaction of acetophenone (1) with PCl5 in refluxing benzene affords a complex product mixture (Scheme 2). A second, very detailed investigation of this reaction was presented by Jung and Kwon [49]. Focusing on the synthesis of efavirenz (21), a potent

Synthesis of new tetra- and pentacyclic, methylenedioxy- and ethylenedioxy-substituted derivatives of the dibenzo[c,f][1,2]thiazepine ring system

• Gábor Berecz,
• András Dancsó,
• Mária Tóthné Lauritz,
• Loránd Kiss,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2645–2656, doi:10.3762/bjoc.21.205

• Group, Magyar tudósok krt. 2, H-1117 Budapest, Hungary 10.3762/bjoc.21.205 Abstract New tetra- and pentacyclic derivatives of the dibenzo[c,f][1,2]thiazepine ring system have been synthesized. The target compounds contain methylenedioxy or ethylenedioxy substituents linked to the benzene ring. The key

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

• followed by reaction with CH(OMe)3 afforded acetal 17, which was then subjected to a CH2Cl2 solution of TMSOTf and iPr2NEt. A mixture of enol methyl ethers 18 were thus produced by an elimination reaction. Eventually, a site-selective bromination of the double bond over the electron-rich benzene rings with

Pentacyclic aromatic heterocycles from Pd-catalyzed annulation of 1,5-diaryl-1,2,3-triazoles

• Kaylen D. Lathrum,
• Emily M. Hanneken,
• Katelyn R. Grzelak and
• James T. Fletcher

Beilstein J. Org. Chem. 2025, 21, 2524–2534, doi:10.3762/bjoc.21.194

• with ortho-bromo(trimethylsilylethynyl)benzene produced 1,5-diaryl-1,2,3-triazole products 25–30, each possessing an ortho-bromoaryl reactive site necessary for the annulation step. The tandem deprotection/click reaction was used to successfully prepare 1,5-diaryl-1,2,3-triazoles 25–30 in yields

Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• difference can be attributed to a subtle discrepancy between the spin localizations of IN4 and TS2. As depicted in Figure 2b, the spin density of IN4 is predominantly concentrated at the benzene ring, whereas in TS2 it is primarily localized at C19, C12, C3, and N9 (Figure 2a) [32]. Therefore, the

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

• ]undec-7-ene (DBU) in benzene resulted in high yield of β-hydroxyaldehyde 6. Through a series of synthetic transformations, the target products (−)-taiwaniaquinones A (7), F (8), G (9), and H (11), (−)-taiwaniaquinol B (10) and (−)-dichroanone (12) were obtained from intermediate 6 (Scheme 2). An

• -Ethylformylation of compound 35 and subsequent oxidation of ketoenol 36 with 30% aqueous H2O2 in the presence of a 28% MeONa/MeOH solution resulted in the formation of a diacid, which was then converted into dimethyl ester 37 with a yield of 55%. Refluxing ester 37 with an excess of t-BuOK in benzene gave acid 39

• ethylenedioxy fragment (see below) are attractive substrates for studying the possibility of a photochemically induced contraction of the cyclohexane ring. Photoirradiation of keto oxirane 146 [76] in benzene containing 1% methanol afforded cyclopentane annulated derivative 147a along with keto ester 148a, a

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

• , the conventional solvents that are typically employed as reaction media encompass a range of options, including tetrahydrofuran (THF) (a problematic solvent, p), dioxane (considered hazardous, h), benzene (designated as highly hazardous, hh), toluene (p), chloroform (hh), acetonitrile (p), sulfolane

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• fluorescence quenching efficiency upon iodide binding compared to the rigid WDG (KPBG/KWDG = 22.78), demonstrating its potential as a highly sensitive optical probe and offering a novel strategy for engineering dynamic supramolecular receptors. Two carbazole-based macrocyclic probes, PBG (flexible benzene ring

• variations in fluorescence properties, leading to deviations from the linear Stern–Volmer relationship governing the quenching mechanism. The flexible benzene ring of the PBG allows the cavity to be conformationally adjusted to fit the size of I−, while the rigid fluorenyl group of the WDG results in steric

• computational schematic (Figures S16 and S17 in Supporting Information File 1), the anions are positioned within the macrocycle cavity, exhibiting close contacts to hydrogen atoms on the bridging benzene rings, peripheral substituted phenyl groups, and carbazole moieties. These spatial interactions suggest a

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

• environmental concern. We report the design, synthesis, and characterization of a series of methylene-bridged glycoluril dimers G2W1–G2W4 that are insoluble in water and that differ in the nature of their aromatic sidewalls (G2W4: benzene, G2W3: naphthalene, G2W1 and G2W2: triphenylene). We tested G2W1–G2W4

• glycoluril tetramer-derived acyclic CB[n] (e.g., M1) containing benzene, naphthalene, and anthracene aromatic sidewalls bearing O(CH2)3SO3Na water-solubilizing groups and found that the hosts with larger sidewalls displayed higher affinity toward hydrophobic alicyclic cationic guests [42][43]. Conversely, we

•  1). The removal efficiency was calculated using Equation 1, where c0 is the initial dye concentration, and ct is the dye concentration after sequestration. The results of these experiments are shown in Figure 4. Quite disappointingly, Figure 4 shows that the benzene, naphthalene, and triphenylene