Novel macrocycles: from synthesis to supramolecular function

• Veronica Iuliano,
• Carmen Talotta,
• Margherita De Rosa,
• Paolo Della Sala,
• Konrad Tiefenbacher,
• Pablo Ballester and
• Carmine Gaeta

Beilstein J. Org. Chem. 2026, 22, 982–985, doi:10.3762/bjoc.22.76

• units connected through methylene bridges, pillararenes are generally regarded as representatives of a third generation of macrocyclic hosts. Unlike the cone-shaped architecture typically adopted by calix[4]arenes, pillararenes display a rigid pillar-like geometry with a preorganized cavity. Their

• distinctive structural features and supramolecular behavior stimulated the development of numerous related macrocycles, including biphenarenes [10], oxatubarenes [11], saucerarenes [12], pagodarenes [13], calix[2]naphth[2]arenes [14], naphthotubes [15], and finally prismarenes [16], all of which are

• directions for the clinical translation of these materials. Moving from broad biomedical overviews to therapeutic applications, Consoli and co-workers [38] exploit the synthetic versatility of calix[4]arenes to develop selective anticancer systems. By clustering bioactive isothiouronium groups on an

Electrochemical reduction of unsaturated carbon–carbon bonds via 3d transition-metal catalysis

• Geon Kang,
• Minki Jeon,
• Pooja Kumari Jat,
• Cheoljae Kim and
• Isaac Choi

Beilstein J. Org. Chem. 2026, 22, 955–981, doi:10.3762/bjoc.22.75

• previously established in Baran’s study (Scheme 6A) [103]. Redox-sensitive functionalities such as esters, ketones, epoxides, nitriles, and arylboronic esters remained intact, and both electron-rich and electron-poor arenes were fully compatible with the reaction conditions (Scheme 6B). Importantly, this

Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds

• Ekaterina V. Berezhnaya,
• Alexander I. Ponyaev,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55

• (hetero)arenes 16 were investigated as dipolarophiles in CuI- and AgI-catalyzed 1,3-dipolar cycloaddition reactions with various imines 1 (Scheme 19). It is noteworthy that when using the [Cu(CH3CN)4]PF6/(R)-DTBM-Segphos L11 catalytic system, exo-pyrrolidines 39 are formed with >98% ee and almost complete

Photoorganocatalytic trifluoromethylation of (het)arenes in green conditions

• Egor N. Boronin,
• Svetlana E. Kaurkina,
• Milena M. Svetlakova,
• Anton S. Bolshakov,
• Maxim V. Arsenyev,
• Vasilii F. Otvagin,
• Alexey Yu. Fedorov,
• Timothy Noël and
• Alexander V. Nyuchev

Beilstein J. Org. Chem. 2026, 22, 662–671, doi:10.3762/bjoc.22.50

• , Russia Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands 10.3762/bjoc.22.50 Abstract A sustainable photocatalytic protocol for the trifluoromethylation of (hetero)arenes is reported. The method operates under metal- and base-free

• conditions using an inexpensive and atom-efficient CF3 source, trifluoroacetic anhydride, in ethyl acetate as a green solvent. An organic cyanoarene photocatalyst enables efficient CF3 radical generation under blue-light irradiation, providing a broad range of trifluoromethylated arenes and heteroarenes. The

• trifluoromethyl-substituted compounds. Over the past decade, numerous photocatalytic protocols for the trifluoromethylation of arenes and heteroarenes have been developed, including approaches employing microflow techniques [6]. These transformations utilize a broad spectrum of catalysts, ranging from Ru- and Ir

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• incorporated on supramolecular architectures to explore their potential for the removal of uranium from aqueous media. For instance, it has been long known that hydroxamic acid derivatives of calix[4]arenes and calix[6]arenes act as excellent uranophiles as demonstrated in early studies from 1991 [33]. A calix

• extraction under weakly acidic conditions, while others perform better at higher pH values. For instance, an octa-functionalized calix[4]resorcinarenehydroxamic acid exhibits quantitative extraction of uranyl into ethyl acetate solution at pH value of 8 [34]. On the other hand, calix[4]arenes and calix[6

• ]arenes functionalized with hydroxamic acid groups show a marked increase in uranyl extractability from aqueous solution into chloroform at pH 3–4, reaching nearly 100% extractability at pH 5. The enhanced extraction efficiency observed in the acidic pH region has been attributed to the metal-ion-assisted

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

• first enantioselective C–H amination of arenes catalyzed by a chiral phosphoric acid. Thus, this nucleophilic aromatic substitution reaction not only enables the synthesis of compounds bearing two chiral N-aryl axes but also provides a viable alternative to metal-catalyzed C–N cross-coupling reactions

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

• ]arenes containing four amino groups at the wide rim and one, two or four propargyl or 2-azidoethyl groups at the narrow rim of the macrocycle, which can be used for expanding functionalization of the calixarene core in the well-known amine acylation (or similar reactions) and CuAAC ‘click’ reactions. Two

• were ipso-nitrated followed by reduction of the nitro groups. To prepare 2-azidoethylated macrocycles, the ipso-nitration/reduction sequence was applied to p-tert-butylcalix[4]arenes containing 2-tosyloxyethyl groups at the narrow rims followed by replacement of the tosyloxy groups with azide ones. In

• all cases, p-aminocalix[4]arenes were obtained as the readily cleavable tert-butoxycarbonyl (Boc) derivatives, which was crucial for certain transformation and purification steps. To confirm the functionalization capabilities of the five obtained multifunctional calixarenes, they were reacted with

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

• ]. Today, aromatic compounds are essential in both academic and industrial chemical applications (Figure 1B) [9][10]. Their ubiquity is the result of a decades-spanning effort devoted to leveraging aromatic stability in the development of methods that functionalize the periphery of arenes without

• disrupting the aromatic core, such as electrophilic and nucleophilic aromatic substitutions, transition metal-catalyzed cross-couplings [11], and C–H functionalizations [12]. Taken together with their natural abundance, these transformations have established arenes and heteroarenes as versatile synthetic

• building blocks in pharmaceuticals, agrochemicals, and materials science (Figure 1B). In contrast, direct modification of the central aromatic core, i.e., controlled disruption of aromaticity, remains a fundamental challenge in synthetic chemistry and leaves the vast potential of planar arenes as

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

• Haoxiang Wu Xiangbing Qi National Institute of Biological Sciences, Beijing. No. 7, Science Park Road, Zhongguancun Life Science Park, Changping District, 102206 Beijing, China 10.3762/bjoc.22.4 Abstract Arenes and heteroarenes are easily available building blocks in organic chemistry, and

• complex natural products [16][17]. Arenes and heteroarenes have long been readily accessible, as many can be obtained through industrial synthesis or microbial fermentation. The diverse reactivity of aromatic compounds has made them indispensable starting materials in synthetic and medicinal chemistry [18

• access these saturated frameworks, catalytic hydrogenation of unsaturated arenes stands out as the most efficient one: it directly transforms planar sp2 systems into three-dimensional sp3-rich scaffolds via the shortest possible synthetic route, embodying both step economy and atom economy (Scheme 1) [25

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

• group developed a one-step electrochemical approach to the synthesis of nitro-NNO-azoxy arenes employing ammonium dinitramide (ADN) [87]. The achieved use of ADN, known as prospective chlorine-free green oxidant for aerospace propulsion applications [89][90][91], as both a reagent and an electrolyte is

• very important, as it overcomes one of the major obstacles to the sustainability and scalability of organic electrosynthesis: the need for a supporting electrolyte in addition to reactants. The synthesized nitro-NNO-azoxy arenes were discovered as a novel class of fungicides, with in vitro activity

• synthesized nitro-NNO-azoxy compounds were tested for fungicidal activity against phytopathogenic fungi and for NO-release activity. Earlier we have demonstrated [87] that nitro-NNO-azoxy arenes were discovered as a novel class of fungicides, with in vitro activity against a broad range of phytopathogenic

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• used for late-stage modification of bioactive compounds, including natural products. These developments will find suitable applications in medicinal chemistry for introducible organosilyl groups (Scheme 5) [55]. A visible-light-induced Friedel–Crafts acylation of arenes and heteroarenes was reported by

• Studer et al., which belongs to the class of aryl and heteroaryl electrophilic substitutions and is a highly versatile synthetic transformation in traditional organic chemistry. A highly regioselective dual catalytic approach for the novel acylation of electron-rich benzo-fused arenes or heterocycles 15

• enables the highly regioselective formation of meta-acylated ketone products 16 through a radical pathway. The NHC-catalyzed novel acylation was achieved using acyl fluorides 4 and electron-rich arenes 15 in the presence of NHC (20 mol %), photocatalyst (5 mol %), and Cs2CO3 in CH3CN at room temperature

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

• , Via Paolo Gaifami 9, 95126 Catania, Italy 10.3762/bjoc.21.195 Abstract Calix[n]arenes are polyphenolic macrocycles known for their remarkable synthetic versatility, which supports their broad application in various areas, including drug discovery. Their unique conformational features, functionality

• [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

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

• observed for these annulated molecules, while their analogous non-annulated control compounds were not bioactive. Keywords: annulation; arenes; antimicrobials; fused-ring systems; UV–vis spectroscopy; Introduction Polycyclic aromatic heterocycles are a diverse class of small molecules with utility in a

• subunits connected at the triazole C5 position were non-emissive under the conditions utilized, while the majority of the N1-connected analogs showed weak but observable signals. Such influence of triazole connectivity on the emission intensity of attached arenes has been previously reported [54]. Within

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• gram-scale synthesis under the optimized conditions. The reaction of 1a was performed on a 4.1 mmol (1.0 g) scale, yielding the C1–H-nitrated carbazole product 2a in 49% (0.585 g, 2.02 mmol) isolated yield (Scheme 4a). Given the importance of nitro-functionalized (hetero)arenes, we sought to access the

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

• synthetic approaches for constructing selenium-containing atropisomers have been reported, such as C–H selenylation of arenes, selenosulfonylation of vinylidene o-quinone methides (VQM), and hydroselenation of alkynes. Nevertheless, a comprehensive review that systematically summarizes these advances is

Pd-catalyzed dehydrogenative arylation of arylhydrazines to access non-symmetric azobenzenes, including tetra-ortho derivatives

• Loris Geminiani,
• Kathrin Junge,
• Matthias Beller and
• Jean-François Soulé

Beilstein J. Org. Chem. 2025, 21, 2234–2242, doi:10.3762/bjoc.21.170

• hazardous diazonium salts and electron-rich arenes (mainly limited to phenols) [29][30][31], including metalated arenes [32][33]. The growing demand for structurally complex compounds across diverse applications has rendered the synthesis of non-symmetrical azoarenes with differently substituted azo bonds

Measuring the stereogenic remoteness in non-central chirality: a stereocontrol connectivity index for asymmetric reactions

• Ivan Keng Wee On,
• Yu Kun Choo,
• Sambhav Baid and
• Ye Zhu

Beilstein J. Org. Chem. 2025, 21, 1995–2006, doi:10.3762/bjoc.21.155

• , asymmetric synthesis of “inherently chiral” macrocycles have gained growing attention [22]. Practically, such reactions that yield “inherently chiral” macrocycles can be treated similarly as planar chirality (Scheme 6). The synthesis of calix[4]arenes via C–H arylation [23] is [31] (Scheme 6A), following the

• same procedure as in Scheme 5C. In analogy to Scheme 5B, the direct cyclization forging the planar chirality [24] in Scheme 6B is regarded as [31 10], in which two stereogenic arenes are proximate and the two distal arenes are considered diastereomeric. The desymmetrization cross-coupling of cavitands

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• that inherently lacks symmetry [8][9]. One of the most typical representatives are calix[4]arenes (Figure 1a), first reported by Böhmer in 1994 [10], where asymmetric substitutions on the macrocyclic rim induce inherent chirality. Subsequent advancements have identified other inherent chiral systems

• non-classical chiral macrocycles, providing insights into molecular design of chiral macrocycles with high emissions. (a) Representatives of inherent chiral calix[4]arenes. (b) Molecular skeletons of inherent chiral N-doped macrocycles in this work. Crystal structures of compounds (a) 3a, (b) MC2, and

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• chirality originating from the rigid conformation of molecules lacking symmetry, which do not fit into the aforementioned four categories, are termed inherent chirality. Notable examples include inherently chiral calix[4]arenes and saddle-shaped medium-sized cyclic compounds. Catalytic asymmetric synthesis

• [49] and the Liu group [50] independently reported the asymmetric synthesis of inherently chiral calix[4]arenes through an enantioselective desymmetrization strategy. Starting from the achiral aniline-containing calix[4]arenes 52, we employed the CPA 11-catalyzed asymmetric Povarov reaction [51] with

• enamide 6a and various aldehydes 7 to break the symmetry of substrates 52, which was followed by a one-pot oxidative aromatization mediated by DDQ to yield the quinoline-containing inherently chiral calix[4]arenes 53 (Scheme 15). Notably, the prochiral calix[4]arenes bearing a disubstitution pattern on

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• ) can interchange between tautomers to make a chalcogen bond with sulphur in the Z-isomer and a hydrogen bond in the E-isomer [64]. Extension of the conjugation with additional electron-rich arenes enables isomerisation with wavelengths up to >700 nm, with high PSS and high quantum yield. Electron-poor

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• characteristics, CAs hold potential for applications in drug delivery systems. 1.2 PAs: structure and properties Since Ogoshi et al. first introduced pillar[n]arenes in 2008, these macrocycles have become essential to the synthetic macrocyclic receptor field [74]. Research on PAs and their derivatives has become

• environment, which significantly enhances the density of π-electrons. This structural feature makes pillar[n]arenes particularly effective at encapsulating guest molecules that are either electron-deficient or neutral. For example, pillar[5]arene (PA5) has a strong binding affinity for neutral guest molecules

• superior performance in host–guest interactions. Creating functional and intelligent supramolecular nano-drug carriers for controlled drug delivery is promising. In this context, water-soluble carboxylated arenes are the primary host molecules for most pH-responsive nanosystems. The nanosystem is broken

On the aromaticity and photophysics of 1-arylbenzo[a]imidazo[5,1,2-cd]indolizines as bicolor fluorescent molecules for barium tagging in the study of double-beta decay of ¹³⁶Xe

• Eric Iván Velazco-Cabral,
• Fernando Auria-Luna,
• Juan Molina-Canteras,
• Miguel A. Vázquez,
• Iván Rivilla and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126

• decoupling between the para-phenylene and benzo[a]imidazo[5,1,2-cd]indolizine components that results in a blue shift upon Ba2+ coordination. Keywords: aromaticity; DFT-TDDFT calculations; double-beta decay; fluorescent sensors; polycyclic arenes; Introduction Double beta-decay [1] is a radioactive decay

3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles

• Julia I. Pavlenko,
• Pavel A. Sakharov,
• Anastasiya V. Agafonova,
• Derenik A. Isadzhanyan,
• Alexander F. Khlebnikov and
• Mikhail S. Novikov

Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123

• arenes with azirines. These include the [3 + 2] cycloaddition of azirines to arynes (Scheme 1, reaction 1) [10][11][12], Pd-catalyzed reaction of azirines with iodoarenes (Scheme 1, reaction 2) [13], and reaction of 2-aroylazirines with naphthols (Scheme 1, reaction 3) [8]. The [3 + 2] annulation

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

• )aryloxetanes 146 in moderate yields. Investigation of the reaction scope identified electron-rich, -neutral and -poor arenes as well as vinyl bromides as viable coupling partners, and the authors also applied this methodology for a novel, simplified synthesis of two medicinally relevant oxetane precursors. The