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

• further coordination thus giving rise to a relatively strong π–cation interaction with the phenyl group. In the case of complex 17c (n = 3) stemming from 18-crown-6, the barium cation remains within the average molecular plane determined by the macrocyclic moiety. The larger ΔGiso value for 15c results in

Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer

• Yusuke Matsuo,
• Aoi Nakagawa,
• Shu Seki and
• Takayuki Tanaka

Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119

• , Japan 10.3762/bjoc.21.119 Abstract The intramolecular oxidative fusion reaction of macrocyclic heteroaromatic arrays has provided strained polycyclic heteroaromatic macrocycles as promising functional molecules. In this study, we prepared an ortho-phenylene-pyrrole-thiophene hybrid icosamer, as the

• in detail. Keywords: cyclophane; fluorescence; heterohelicene; intramolecular oxidative coupling; Introduction Conjugated macrocyclic polyarenes have attracted significant attention due to their stimuli-responsive optoelectronic properties, dynamic structural changes, and host–guest interactions [1

•  1) [6][7][8][9][10][11][12]. Nevertheless, partially fused macrocyclic intermediates are also important as they exhibit structural strain associated with both the polycyclic segments and the inherent strain stemming from the macrocyclic structure. For instance, cyclic chrysenylenes [13][14][15][16

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• ruled out. The structures of compounds 3, 4, and 5 were determined by X-ray diffraction analysis (Figure 2). Mono-olefin 3 and bis-olefin 5 adopt a bathtub-like chiral macrocyclic structure rather than figure-eight conformation. Both compounds crystallize as a racemic pair of enantiomers with P21/c and

Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers

• Kenichi Kato,
• Tatsuki Hiroi,
• Seina Okada,
• Shunsuke Ohtani and
• Tomoki Ogoshi

Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95

• widely adopted to improve the solubility and modulate the molecular assemblies [4][5][6][7][8][9]. By contrast, the presence of sp3-hybridized atoms in core π-skeletons can lead to three-dimensional (3D) structures with appropriate rigidity, thereby giving macrocyclic arenes [10][11], molecule-based

• interactions between the naphthalene units. The monoformyl products are reduced to corresponding alcohols, which are then reacted under Friedel–Crafts conditions. Amorphous methylene-alternating copolymers are obtained without particular macrocyclic oligomers. Due to the 3D components, the linear copolymers

• . Despite the stereocontrolled substrate, the resonances in the 1H NMR spectrum of the product remained broad. Therefore, we concluded that these systems were difficult to give specific macrocyclic oligomers but instead provided linear polymers composed of fully π-fused propellanes. After the reactions

Synthetic approach to borrelidin fragments: focus on key intermediates

• Yudhi Dwi Kurniawan,
• Zetryana Puteri Tachrim,
• Teni Ernawati,
• Faris Hermawan,
• Ima Nurasiyah and
• Muhammad Alfin Sulmantara

Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91

• results were obtained when compound 155b was used. Addition of 5 mol % catalyst produced the expected macrocyclic product and dimer 157 in yields of 24 and 22%, respectively, while a significant amount of unreacted 155b (26%) remained under these conditions. Conclusion In summary, this review has examined

Supramolecular assembly of hypervalent iodine macrocycles and alkali metals

• Krishna Pandey,
• Lucas X. Orton,
• Grayson Venus,
• Waseem A. Hussain,
• Toby Woods,
• Lichang Wang and
• Kyle N. Plunkett

Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87

• hypervalent iodine-based macrocyclic complex. Furthermore, we have experimentally and computationally compared the association constants of lithium tetrakis(pentafluorophenyl)borate ethyl etherate LiBArF20 and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate NaBArF24 in the phenylalanine HIM system

• projecting outward denoted by an asterisk. Furthermore, the resulting crystal structure reveals that 1 is also a distorted planar macrocyclic system consisting of the amino acids carbonyl oxygens facing inside the ring. All three benzyl groups are located above a single plane (more figures are provided in

• cavity is highlighted by blue color in the chemical structure of phenylalanine HIM as shown in Figure 3 (left) (more figures are provided in Supporting Information File 1). Despite the core's composition of six electron-rich oxygen atoms, we hypothesized that the bowl-like macrocyclic cavity is electron

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

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

• alkyldiamines proceeded with solvent-independent regioselectivity, exclusively furnished [2 + 2] macrocyclic adducts. Strikingly, when 37 was combined with 2,2’-oxybis(ethylamine) (38), the reaction pathway exhibited pronounced solvent dependency. Reactions in methanol, ethanol, or chloroform selectively

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• were synthesized via a one-pot strategy starting from macrocyclic precursors. Host–dicarboxylate binding was investigated using 1H NMR titrations, revealing that B4aH exhibits strong binding affinities toward a series of dicarboxylates, with association constants reaching up to 6896 M−1. The

• than 50 atoms in the macrocyclic skeleton are denoted as ultracycles [1]. These very large macrocycles are prevalent in nature and exhibit unique functions. For instance, the archaeal lipid GDGT-0 enables archaea to thrive in extreme environments [2]; cycloamyloses enhance the stability of drug

• , synthetic ultracycles remain relatively unexplored due to the significant synthetic challenges [9][10][11][12][13][14][15][16][17][18][19]. Among these, very large macrocycles constructed from smaller macrocyclic building units are particularly underexplored. Such macrocycle-containing ultracycles are

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

• supramolecular chemistry involves the synthesis of macrocyclic hosts and studies of their molecular recognition properties. The most widely studied macrocyclic host systems include those created entirely by covalent bonds (crown ethers, cyclodextrins, calixarenes, cyclophanes, pillararenes, cucurbit[n]urils (CB

• ][22][23][24][25][26]. Within these families of macrocyclic hosts, CB[n] molecular containers have proven particularly versatile because they form high affinity CB[n]–guest complexes in aqueous solution that are responsive to various stimuli (e.g., photochemical, electrochemical, chemical) [27][28][29

• ][30]. For this reason, macrocyclic CB[n] have been used as key elements of separations processes [31][32], sensing systems [33][34], in pharmaceutical applications [35][36][37][38], in bioimaging systems [39][40], and even in household deodorizing products [41]. An important subclass of CB[n] hosts

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

• macrocyclic picenophadiene [51]. As the solid-state fluorescence bands of the F8-phenacenes were observed in the similar wavelength region of the picenophadiene, the solid-state F8-phenacene molecules have excimeric character in the fluorescing state. It is critical to know the crystal packing of the F8

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• binds free tryptophan selectively in aqueous media. Furthermore, it is capable of binding to tryptophan within model tripeptides. The naphthalene functionality in the glucose-derived receptor enables the study of guest binding using fluorescence spectroscopy. Keywords: amino acids; macrocyclic

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• imprinted polymers (MIPs) [60] has been discussed elsewhere and will not be covered. Perspective Cavity catalysis: current state of the art Functionalized macrocycles Since Cramer’s work with cyclodextrins [61][62][63], there has been significant interest in using macrocyclic confinement to modulate

• combinations of macrocyclic cavities adorned with functional groups (Figure 3A) [97][98]. These grand “set-piece” enzyme models typically showed only modest catalytic enhancements for enzyme-relevant reactions like the hydrolysis of activated esters, and so mostly contributed to the view that enzymes do not

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• properties of metal complexes. Phthalocyanins, porphyrins, and their derivatives exemplify this, as their rigid macrocyclic structures enable strong absorption in the visible to NIR regions, making them appealing for photoredox catalysis applications. For instance, ruthenium phthalocyanin complexes have

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• cucurbituril [18], cyclodextrin [19], and calix[4]pyrrole [20], as well as flexible crown ethers [10][21]. Few two-dimensional (2D) shape-persistent macrocyclic compounds are used for this purpose. One difficulty in realizing 2D macrocycle-based orthogonal assembly is that the construction motif must be

• polymers (Scheme 1). The terpyridyl group and the pyridinium cation in the AB-type monomer G2 each function as a “sticker” to enable supramolecular polymerization in the presence of the macrocyclic component and zinc ions. The driving force for the recognition involves multiple cooperative interactions

• adopted a nonplanar conformation, with one aromatic residue protruding out of the macrocyclic skeleton plane. Adopting such a conformation rendered it possible for the π-electron-rich phenyl ring to interact strongly with π-electron-deficient guest molecules G1 by means of charge–transfer interactions and

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• , photocatalysts, and electrocatalysts are presented here. The effect of macrocyclic structural modifications such as their functionalization with different substituents, distortion from planarity, conformational flexibility and rigidity towards catalytic activity are presented, highlighting the potential of these

• and separation technology [3][4][5][6][7][8]. Conversely, porphyrins are connected via methine (=CH-) bridges, resulting in an 18 π-electron macrocyclic system affording macrocyclic planarity as well as unique photophysical and electrochemical properties (Figure 1b). While corroles share similarities

• these macrocyclic catalysts is in a very nascent stage. In this review, the recent advancement in the field of metal-free macrocycles for catalysis will be summarized; mainly focused on porphyrins and calix[4]pyrroles and in the field of organocatalysis, photocatalysis, and electrocatalysis. Review 1

Deciphering the mechanism of γ-cyclodextrin’s hydrophobic cavity hydration: an integrated experimental and theoretical study

• Stiliyana Pereva,
• Stefan Dobrev,
• Tsveta Sarafska,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2024, 20, 2635–2643, doi:10.3762/bjoc.20.221

• light on the mechanism of the γ-CD hydration and to address some unanswered questions: (i) what are the preferable locations for water molecules in the macrocyclic cavity (“hot spots”); (ii) what are the major factors contributing to the stability of the water cluster in the CD interior; (iii) what type

• characteristic; Introduction Cyclodextrins (CDs), the remarkable macrocyclic molecules with significant impact on our daily life, have completed their 130th anniversary in 2021 [1]. These cavitands are made of 6–9 glucose fragments, linked with 1-4 α-glycosidic bonds. Most common is the β-CD with 7 glucose

• substituted/modified CDs. Recent studies combining experimental methods with molecular modeling have revealed that the maximum number of water molecules entrapped inside the macrocyclic cavity is 6 for α-CD [13] and 10 for β-CD [14]. Notably, the exact number of the encapsulated water molecules by γ-CD and

HFIP as a versatile solvent in resorcin[n]arene synthesis

• Hormoz Khosravi,
• Valeria Stevens and
• Raúl Hernández Sánchez

Beilstein J. Org. Chem. 2024, 20, 2469–2475, doi:10.3762/bjoc.20.211

• -shaped conformation it precipitates out of solution acting as a thermodynamic sink [5][6]. Shortly after, Cram et al. recognized the potential of resorcin[n]arenes as compounds large enough to encapsulate other simple molecules or ions and group them with other known macrocyclic arene compounds, e.g

• reported herein may impact the synthesis of other macrocyclic arene species, e.g., calix[n]arenes, calix[4]pyrroles, pillar[n]arenes, and cucurbit[n]urils [90][91][92]. Perspective Supramolecular chemistry is a mature field that has crossed boundaries into many other scientific areas. However, the work

• area to analyze ingrained synthetic protocols towards macrocyclic arenes and challenge them as there may be many gems awaiting discovery. Conclusion Introduction of HFIP to the synthesis of resorcin[n]arenes accelerates their reaction time significantly to under one hour for simple and commonly used

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• using an enzyme or at what stage in a synthesis the enzyme is employed: 1) regio- and stereoselective late-stage functionalization of core scaffolds, 2) in situ generation of highly reactive intermediates, and 3) the one-step construction of macrocyclic or fused multicyclic scaffolds via regio- and

• carboxylic acids followed by intramolecular condensation. As a chemo-enzymatic complementary strategy, thioesterase (TE) domains of NRPS and PKS gene clusters have been utilized as enzymes for macrolactone formation to produce a wide range of natural/non-natural macrocyclic compounds [58][59][60][61][62][63

• categorized into three distinct classifications based on the type of enzymatic conversions: 1) regio- and stereoselective late-stage functionalization of core scaffolds, 2) in situ generation of highly reactive intermediates, and 3) one-step construction of macrocyclic or fused multicyclic scaffolds. This

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• modifications have been observed during the maturation of different RiPPs. One example is the biosynthesis of thiopeptide GE2270, which is produced by the actinomycete Planobispora rosea ATCC53733 as a complex of related metabolites that differ in the number of methyl groups installed on the macrocyclic core

• aspartimide intermediates (Figure 6). The activity of most PAMTs depends on a cyclised precursor peptide. Modification of the aspartate/isoaspartate residue was found only in a hairpin-like or the macrocyclic region [71][78]. The underlying purpose of this structural requirement of PAMTs has not yet been

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• Guoqing Cheng Naoki Komatsu Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan 10.3762/bjoc.20.113 Abstract We have been working with carbon nanotube separation through host–guest chemistry. Herein, a new macrocyclic host molecule, Cu-tethered

• , recently, a rigid metal-tethered macrocyclic host molecule “M-nanobrackets” (M = Cu, Co and Pd) [11]. While the concept of the mechanically interlocked carbon nanotubes (MINTs) has been established by Pérez and López [12][13], Cu-tethered tetragonal nanobrackets 1a not only interlocked SWNTs, but also

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• Koki Ikemoto Hiroyuki Isobe Department of Chemistry, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan 10.3762/bjoc.20.103 Abstract Cyclo-meta-phenylenes doped with nitrogen atoms at the periphery were designed and synthesized. The syntheses of the macrocyclic structures were

• nitrogen-doped [n]CMPs (3) containing outward-radiating nitrogen dopants. The properties and structures were investigated with UV–vis spectroscopy and X-ray crystallography, which revealed the fundamental properties of the nitrogen dopants in the macrocyclic structures. Results and Discussion Nitrogen

• structural features of nitrogen-doped [n]CMPs. The crystal molecular structures of 3a and 3b are shown in Figure 3. The hexagonal macrocyclic structure of 3a showed a chair-like conformation with alternating biaryl dihedral angles showing +/– values. The octagonal structure of 3b exhibited a saddle-like

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases

• Min Li and
• Hui Tao

Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86

• terpenoids. LcTPS2 from Leucosceptrum canum was characterized as a versatile TS that generated six macrocyclic sesterterpenoids (11–16) and two macrocyclic diterpenoids (17,18), representing the first macrocyclic terpenoids isolated from plants (Table 1, Figure 2) [19]. In addition to linear prenyl

Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• , achieving 52.5% higher production than controls without pH shock [67]. Conversely, the present authors were able to increase the production of antarlides, which have a 22-membered ring macrocyclic structure, by adding disodium hydrogen phosphate to the culture medium of Streptomyces sp. BB47 to prevent the