Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• –2021, Kuduk and co-workers published three different tandem, one-pot methodologies towards complex polycyclic heterocycles [100][101][102]. All of them are two-step reactions consisting of an intermolecular coupling followed by an intramolecular, base-induced oxetane opening (Scheme 48). The first one

• utilised a HATU-promoted amide formation involving 3-(methylamino)oxetane (192) in the first step and the resulting bi- and tricyclic products 193 and 194 containing 6- and 7-membered rings were obtained in high yields (Scheme 48a). The second methodology generated similar polycyclic systems but used a

Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

• Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

• design beyond all-hexagon polycyclic aromatic hydrocarbons (PAHs). Among these, π-conjugated scaffolds featuring embedded azulene units have gained considerable attention due to their unique optical and electronic properties. This review provides an overview of representative azulene-embedded

• nanographenes, with a particular focus on the synthetic strategies. Additionally, it explores selected aspects of aromaticity and spectroscopic properties. Keywords: azulene; nanographenes; non-alternant; non-benzenoid; polycyclic aromatic hydrocarbons; Introduction The discovery of graphene and fullerenes

• benzenoid nanographenes, also known as polycyclic aromatic hydrocarbons (PAHs) [8][9]. PAHs can be considered molecular models of bulk graphene, offering invaluable insights into structure–property relationships in graphene and graphene-based materials. Structural defects appear to be inevitable in real

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

• as the photocatalyst (Scheme 27). The reaction was carried out under blue LED irradiation in DMSO as the solvent, yielding valuable polycyclic quinazolinones in satisfactory yields. Furthermore, a variety of substituents on the phenyl ring of N-cyanamide alkenes, as well as a series of difluorinated

Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes

• Linqiang Wang and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86

• desired products 3bc, 3bd, 3bi, and 3bk in relatively low yields and enantioselectivities. The strongly electron-deficient 4-nitrobenzaldehyde (2l) showed the highest enantioselectivity, affording the desired product 3bl in 63% yield and >99% ee. Polycyclic fused naphthalene-1-carbaldehyde (2m) and

Synthesis of pyrrolo[3,2-d]pyrimidine-2,4(3H)-diones by domino C–N coupling/hydroamination reactions

• Ruben Manuel Figueira de Abreu,
• Robin Tiedemann,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2025, 21, 1010–1017, doi:10.3762/bjoc.21.82

• . Electron-donating N,N-dimethylaminophenyl substituents led to bathochromically shifted absorption and emission spectra accompanied by strongly elevated fluorescence quantum yields (up to 83%). Further studies will be devoted to the synthesis of novel polycyclic uracil derivatives with potential biological

A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids

• Zhiyang Zhang,
• Jialei Hu,
• Hanfeng Ding,
• Li Zhang and
• Peirong Rao

Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75

• . A preliminary investigation revealed that krishnolide A (7) exhibited unique anti-human immunodeficiency virus (HIV) activity, representing the first report of anti-HIV activity in khayanolide-type limonoids. However, the highly oxygenated and polycyclic scaffolds pose substantial challenges toward

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• utilizing in situ-generated π-allylpalladium complexes to capture strained cyclic allene intermediates (Scheme 4) [22]. By modulating the ligands in the reaction system, two distinct polycyclic scaffolds, 13 or 14, could be synthesized with high selectivity. Mechanistically, the Pd(0) catalyst coordinates

• -García and Fernández-Rodríguez reported on the practicality of metal-free BCl3-catalyzed borylation cyclization reactions in synthesis (Scheme 16) [45]. Biphenyl-embedded 1,3,5-trienes-7-yne compounds 58 react with BCl3 under catalyst-free and additive-free conditions to form novel polycyclic boronated

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• electron-donating and electron-withdrawing groups produced products with yields ranging from 71% to 91%, and they were found to be effective in forming the corresponding polycyclic products (Scheme 15). Through cyclic voltammetry experiments, the researchers confirmed that since the oxidation potential of

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• acyclic CB[n] are not macrocycles, they are preorganized into a C-shaped geometry by virtue of their polycyclic chemical structure and display binding affinities approaching those of macrocyclic CB[n]. M1 and analogues display outstanding biocompatibility and have been used for a number of in vivo

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• , most likely due to different crystalline packing motifs. Keywords: fluorescence; fluorinated aromatics; phenacene; photoreaction; Introduction Polycyclic aromatic hydrocarbons (PAHs) have been subject of continuous interest not only from aspects of fundamental synthetic, structural, and physical

• the manipulation of the solid-state optoelectronic nature of polycyclic aromatic molecules to develop future functional materials in organic electronics. Chemical structures of phenacenes studied in this work. UV–vis and fluorescence spectra of F8PIC (a), F8FUL (b), and F87PHEN (c) (red lines) and the

Synthesis of new condensed naphthoquinone, pyran and pyrimidine furancarboxylates

• Kirill A. Gomonov,
• Vasilii V. Pelipko,
• Igor A. Litvinov,
• Ilya A. Pilipenko,
• Anna M. Stepanova,
• Nikolai A. Lapatin,
• Ruslan I. Baichurin and
• Sergei V. Makarenko

Beilstein J. Org. Chem. 2025, 21, 340–347, doi:10.3762/bjoc.21.24

• ). Polycyclic furan-3-carboxylates – alkyl 7-methyl-4,9-dioxo-4H,9H-furo[2,3-d]pyran[4,3-b]pyran-3-carboxylates 6a,b or alkyl 4,11-dioxo-4H,11H-furo[2',3':4,5]pyran[3,2-c]chromene-1-carboxylates 6c,d were obtained by reacting bromonitroacrylates 1a,b with 4-hydroxy-7-methyl-2H,5H-pyrano[4,3-b]pyran-2,5-dione

Molecular diversity of the reactions of MBH carbonates of isatins and various nucleophiles

• Zi-Ying Xiao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21

• diastereomeric ratios. The relative configurations of the various polycyclic compounds were clearly elucidated by determination of several single crystal structures. Keywords: allylic SN2 reaction; dimerization; isatin; MBH carbonate; 3-methyleneoxindole; Introduction Isatins (indoline-2,3-diones) possessing

• synthetic methodologies and in continuation of our aim to develop domino reactions based on MBH carbonates of isatins for efficient construction of diverse polycyclic spiroindolinones [42][43][44][45][46][47][48][49][50][51][52], herein, we wish to report the nucleophilic substitution reactions of various N

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• , National University of Singapore, 3 Science Drive 3, Singapore, Singapore 10.3762/bjoc.21.20 Abstract Oxidized states of polycyclic aromatic hydrocarbons are of importance as they represent charged conductive species in organic semiconductor substrates. In this work, we investigated the properties of

• systems in which charge defects are responsible for conductivity in their corresponding conducting polymers. Acenes are the archetypal structure of small polycyclic aromatic hydrocarbons with a π-electron structure expanded over a sequence of linearly fused benzenes [4]. Whereas acenes, up to substituted

• ], including [3]naphthylenes 1 and 2 in Figure 1 [18]. They are endowed by three aromatic naphthalenoid (NAP) moieties, fused by two antiaromatic CBD ones in two different topologies. Structurally, these polycyclic π-conjugated hydrocarbons consist of eight fused rings and thirty π-electrons. In this work, we

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• by scanning electron microscopy. The intriguing optical properties of BPP and its derivatives may lead to their application as fluorophores. Keywords: benzo[rst]pentaphene; intramolecular charge transfer; nanocrystals; photoluminescence; polycyclic aromatic hydrocarbon; Introduction Polycyclic

Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles

• Yujun Pang,
• Jinglan Yan,
• Nawaf Al-Maharik,
• Qian Zhang,
• Zeguo Fang and
• Dong Li

Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15

• , Palestine 10.3762/bjoc.21.15 Abstract An efficient and eco-friendly approach for synthesizing difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles was established via a visible-light-promoted radical cyclization reaction. This method employed the readily accessible and inexpensive

• target products in good to excellent yields. Mechanistic studies revealed that the reaction proceeds via a radical pathway. Keywords: cyclization; difluoromethylation; hypervalent iodine; polycyclic imidazole; visible light; Introduction Organofluorine compounds continue to play important roles in

• abstraction to yield the hydrodifluoromethylation product. Building upon this work, we hypothesized that if the newly formed alkyl radical could undergo intramolecular cyclization with an aromatic ring, instead of hydrogen abstraction, it could enable the construction of polycyclic structures. Thus, as part

Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• amidation Recently, Cao and co-workers reported the copper-catalyzed synthesis of 1,2,4-triazole derivatives via an N-acyl nitrene intermediate [76]. As illustrated in Scheme 3, dioxazolones 4 and N-iminoquinolinium ylides 5 served as reactive substrates, leading to the formation of various polycyclic 1,2,4

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• Michael-type addition of 5-aminoindazole to afford the first coupling product XXXVIII. The subsequent intramolecular amination and dehydration then leads to the final product (Scheme 31) [50]. Polycyclic spiroindoline-3,4’-pyrano[3,2-b]pyran-4-ones 43 were synthesized exploiting the three-component

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• Abstract The polycyclic skeleton of tris(4,5-dehydro-2,3:6,7-dibenzotropone) is a key structural fragment in carbon schwarzites, a theoretical form of negatively curved carbon allotrope. This report presents a new synthesis of this compound using a Ni-mediated Yamamoto coupling reaction and structural

• , expanding its π-skeleton through the Barton–Kellogg and Scholl reactions led to the successful synthesis of a curved polycyclic arene containing three heptagons and two pentagons. Keywords: carbon schwarzites; polycyclic arenes; Scholl reaction; seven-membered carbocycle; Yamamoto coupling; Introduction

• -tropone” in literature [1][2], although it should be named as 9H,18H,27H-hexabenzo[c,c′,c′′,f,f′,f′′]benzo[1,2-a:3,4-a′:5,6-a′′]triscycloheptene-9,18,27-trione according to the IUPAC nomenclature. We became interested in compound 1 because its polycyclic skeleton presents a key structural unit in carbon

Synthesis of acenaphthylene-fused heteroarenes and polyoxygenated benzo[j]fluoranthenes via a Pd-catalyzed Suzuki–Miyaura/C–H arylation cascade

• Merve Yence,
• Dilgam Ahmadli,
• Damla Surmeli,
• Umut Mert Karacaoğlu,
• Sujit Pal and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2024, 20, 3290–3298, doi:10.3762/bjoc.20.273

• total synthesis of the fungal natural product bulgarein. Keywords: acenaphthylene-fused heteroarenes; benzo[j]fluoranthenes; C–H arylation; fluoranthenes; heterocycles; Introduction An important subclass of polycyclic aromatic hydrocarbons (PAHs) [1] is comprised of fluoranthenes, which have been the

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• an effective tool for the design of liquid crystalline materials [3][4][5][6][7][8]. Rod-like liquid crystalline molecules with fluorine-substituted arenes are ubiquitous in the displays industry [12]. They are also gaining importance in the design of π-conjugated polycyclic aromatic discotic liquid

• . Photophysical properties: UV–vis absorption and photoluminescence UV–vis absorption and fluorescence spectra of the synthesized fluorine polycyclic aromatic hydrocarbons Fn and Gnm were measured in solution (in various solvents) and thin film and the results are summarized in Figure 6 and Table S7 in Supporting

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• under Brønsted base conditions. The authors claimed that the reactions to obtain the complex fused polycyclic diastereomeric products is proceeding through a cascade Michael addition–aza-Michael addition, however, they did not propose a plausible reaction pathway for the transformations. In order to

• indoles 52 via a (3 + 2) cyclization with azoalkenes 53 catalyzed by chiral phosphoric acid XIV (Scheme 20). This methodology enables the synthesis of a wide scope of pyrroloindolines 54, important privileged polycyclic indolines in high yields (72–99%) and high enantioselectivities (90–99%) [43]. The

• with different reaction partners such as azlactones, enecarbamates, vinylindoles, 3-isothiocyanatooxindoles, malononitrile, 3-chlorooxindoles or β,γ-unsaturated ketones lead to the synthesis of a great variety of polycyclic N-heterocycles. To summarize, the asymmetric cycloaddition of 1-azadienes is a

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• Ruben Manuel Figueira de Abreu Peter Ehlers Peter Langer Universität Rostock, Institut für Chemie, Albert-Einstein-Str. 3a, 18059 Rostock, Germany 10.3762/bjoc.20.228 Abstract We report the synthesis of polycyclic uracil derivatives. The method is based on palladium-catalysed Sonogashira–Hagihara

• investigation or modulation of desired properties. Conclusion In summary, we have developed the synthesis of novel polycyclic uracil-based compounds. Careful optimisation of the reaction conditions led to the isolation of the desired products in excellent to moderate yields. The developed methodology tolerates

• , bathochromically shifted absorption and emission spectra with elevated extinction coefficients and quantum yields up to 71%. Further studies will be directed to the synthesis to polycyclic, π-conjugated uracil derivatives. Experimental General information Nuclear magnetic resonance spectra (1H/13C/19F NMR) were

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• , Allostreptomyces was introduced as a new genus in the family Streptomycetaceae [21], and two species, A. psammosilenae [21] and A. indica [22], are currently known. Only two 22-membered macrolides were reported from this genus [23] until we recently isolated five polycyclic tetramate-class macrolactams from

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• popular structural motif of many biologically active alkaloids and other molecules of therapeutic interest [1][2][3][4]. Polycyclic N-heteroaromatics also often exhibit intercalating properties [5][6][7][8][9]. Pyridoindazolium salts can be considered as one of the typical representatives of polyfused N