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

• macrocycles: from synthesis to supramolecular function”. The aim of this collection is to highlight recent advances in the design, synthesis, and functional applications of macrocyclic supramolecular receptors. The issue opens with the work of Isaacs and co-workers [33], who report the synthesis of a new

• functional soft materials. Asymmetric frameworks are also central to the research reported by Niemeyer and co-workers [36], who focused on the synthesis of crown ethers bearing one or two BINOL units. Their paper outlines highly practical synthetic routes to open a diverse library of chiral architectures

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

• ; electroorganic synthesis; reaction mechanism; 3d transition metals; unsaturated C–C bonds; Introduction Reductions of unsaturated C–C bonds Reduction of unsaturated C–C bonds, most notably, alkynes and alkenes, is a synthetic method that has been widely and extensively discussed with a long and rich history

• -based systems [38][39]. In sharp contrast, electroorganic synthesis provides a fundamentally distinct mode of reactivity compared to conventional thermochemical approaches, in which electric current serves as the terminal reductant, thereby enabling unconventional mechanistic pathways for alkyne

• reduction while circumventing the need for molecular hydrogen or stoichiometric reducing agents. Consequently, the merger of 3d transition-metal catalysis with electroorganic synthesis represents a conceptual shift beyond traditional reagent-driven approaches, enabling precise control over redox events

Synthesis of sterically shielded piperidine nitroxides via acid-catalyzed heterocyclization of β-aminoketone derivatives with ketones

• Mark M. Gulman,
• Yurii I. Glazachev and
• Sergey A. Dobrynin

Beilstein J. Org. Chem. 2026, 22, 948–954, doi:10.3762/bjoc.22.74

• Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia 10.3762/bjoc.22.74 Abstract The capabilities of modern methods for the synthesis of sterically shielded piperidine nitroxides with acyclic substituents are largely limited to symmetrical

• -tetraethylpiperidine (TEEPONE). Keywords: heterocyclization; piperidine nitroxide; TEEPONE synthesis; Introduction Since their discovery in 1959 by Lebedev and Kazarnovsky, stable nitroxides of the piperidine series (2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives) hold a prominent position as compounds of

• of nitroxides and increases their lifetimes in biological systems [12], which makes these radicals promising MRI contrast agents [13], spin probes for in vivo EPRI [14][15] and antioxidant tissue protectors [16]. Existing methods for the synthesis of such sterically hindered piperidine nitroxide

Recent advances in copper-catalyzed direct hydroamination of alkenes with (hetero)aromatic amines

• Hyejeong Lee and
• Yunmi Lee

Beilstein J. Org. Chem. 2026, 22, 925–947, doi:10.3762/bjoc.22.73

• remains a primary objective of modern organic synthesis [5][6]. Among the diverse strategies available for C–N bond formation, the direct addition of an N–H bond across a C–C double bond, known as hydroamination, is an ideal transformation considering atom and step economy [7][8][9][10][11][12

• nucleophilicity, facilitating conjugate addition to electron-deficient alkenes. The formation of such well-defined copper–amido complexes provides valuable mechanistic insights into copper-catalyzed hydroamination and conjugate addition reactions. Pioneering studies by Gunnoe et al. describe the synthesis and

• imination-alkynylation-aza-Michael cascade for the enantio- and diastereoselective synthesis of 1,3-disubstituted isoindolines and tetrahydroisoquinolines 24 via a three-component coupling reaction involving 2-formylphenyl acrylates or 2-formylphenylcrotonates 21, arylalkynes 22, and anilines [46]. In this

A practical CO₂-mediated synthesis of 5,6-carboxylated silicon-rhodamines for targeted probe development

• Dongjie Hou,
• Shaowei Wu,
• Ning Xu,
• Pengjun Bao,
• Wenhao Jia,
• Qinglong Qiao and
• Zhaochao Xu

Beilstein J. Org. Chem. 2026, 22, 915–924, doi:10.3762/bjoc.22.72

• challenging synthesis of 5,6-carboxylated SiR derivatives, which are essential intermediates for bioconjugation. Here, we report a practical CO2-mediated strategy for the synthesis of 5,6-carboxylated SiRs from brominated SiR precursors via lithium–halogen exchange and direct carboxylation. Using n-BuLi and

• synthesis of 5,6-carboxylated SiRs generally rely on the prior installation of protected carboxy-containing precursors (Figure 1b), followed by cyclization to construct the SiR framework and subsequent deprotection [41][42][43][44]. In these routes, the strong electron-withdrawing effect of the carboxy

• practical utility. In addition, the preparation of protected carboxy-group containing substrates is often cumbersome [46], especially in the synthesis of (hydroxymethyl)rhodamine intermediates, thereby further increasing synthetic complexity [41]. To overcome these limitations, Butkevich developed an

Palladium-catalyzed benzocyclization reactions of quinoline-2-carboxamides via sequential C–H/N–H functionalization

• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2026, 22, 905–914, doi:10.3762/bjoc.22.71

• University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan 10.3762/bjoc.22.71 Abstract A novel benzocyclization protocol has been developed for the synthesis of quinoline-fused lactams by palladium-catalyzed sequential C–H/N–H functionalization of quinoline-2-carboxamides and 1,2-dihaloarenes. The reaction

• corresponding heterocycle-fused compounds. The high chemoselectivity of the 1,2-dihaloarene functional groups is confirmed in this reaction, thus enabling divergent synthesis of various multifused heterocyclic systems. Keywords: C–H activation; chemodivergent synthesis; C–N coupling; fused-ring system

• intriguing moiety in biologically active compounds (e.g., natural products used for medicines, quinine, and quinidine [5][6][7]) and synthesized pharmaceutical agents (e.g., quinolone antibiotics [8]). Moreover, quinoline-2-carboxamide derivatives are used as ligands in organic synthesis owing to their high

Cascade transformation of 2-(diazoacetyl)-2H-azirines to 2-aroyl-3-hydroxy-1H-pyrroles via condensation with aromatic aldehydes

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2026, 22, 897–904, doi:10.3762/bjoc.22.70

• [4.1.0]heptan-5-one derivative. The acid-catalyzed transformation of which leads to 2-aroyl-3-hydroxy-1H-pyrroles. Keywords: azirines; condensation; cyclization; diazo compounds; pyrroles; Introduction Diazo compounds play a significant role in the synthesis of heterocyclic compounds, which explains

• the ever-growing structural diversity of such molecules and the variety of their transformation pathways [1][2][3][4][5][6][7][8][9][10]. Azirinyl-substituted diazo compounds, which we have recently introduced into the heterocyclic synthesis arsenal [11][12][13][14][15][16][17][18][19], are

• Gibbs free energies for the acid-catalyzed transformation of the bicyclic intermediate (1RR,3SR,6RR)-Phe-4 to pyrrole 5 (in kcal/mol, 298 K, DFT B3LYP-D3/6-311+G(d,p) level of theory with a SMD solvent model for MeCN). Synthesis of pyrroles 5. Isolated yield calculated for two synthetic steps based on

Chiral cyclopropenimine-catalyzed enantioselective Michael reactions of phenol and benzofuran-derived α,β-unsaturated pyrazolamides with benzophenone-imine of glycine esters

• Ya Bai,
• Xue-Ying Wang,
• Si-Kai Zhu,
• Yan-Ting Shen,
• Sheng-Yong Zhang and
• Ping-An Wang

Beilstein J. Org. Chem. 2026, 22, 888–896, doi:10.3762/bjoc.22.69

• in organic synthesis. Many medicines and intermediates contain these two motifs and show diverse functions and bioactivities [1][2]. The esterification and etherification of phenols are some of their common modifications. 2-Substituted benzofurans are backbones for many medicines such as amiodarone

• synthesis, neurotransmitter function, and regulation of acid-base balance, metabolic intermediates, and promotion of nutrient absorption [4]. Therefore, the synthesis of substituted glutamic and pyroglutamic acid derivatives is vital to medicinal chemistry. In our previous reports, we have synthesized a

• catalyst [7][8]. Due to the importance of unnatural amino acids in the development of new medicines [9], we want to introduce phenol and benzofuran motifs to glutamic acids. For our continuous interest on the synthesis of chiral 3-substituted glutamic and pyroglutamic acids, herein, we present Michael

Diastereodivergent electrophilic trapping of α-boryl lithium derivatives

• Tereza Pavlíčková,
• Noam Orbach and
• Ilan Marek

Beilstein J. Org. Chem. 2026, 22, 882–887, doi:10.3762/bjoc.22.68

• in a stereodefined manner would achieve the synthesis of polysubstituted organoboron compounds with adjacent stereocenters. The latter are highly valuable building blocks, given the pivotal role of organoboron compounds in contemporary chemistry as stable, yet reactive, intermediates that enable

• reaction. We were particularly interested in examining cases with alkyl (5) instead of aryl substituents in 2 on C2 (Scheme 2). We initiated the investigation into the selectivity of the transformation with the synthesis of a library of cyclopropylmethyl iodides 5a–i, using our previously reported

• regioselectivity. The use of various electrophiles enabled the synthesis of acyclic boronic esters featuring vicinal tri- and tetrasubstituted stereocenters. Cyclopropylmethyl iodide starting materials. Synthesis and reactivity of α-boryl lithium species. Diastereodivergent electrophilic trapping of α-boryl

Site-specific labelling of native peptides and proteins: chemical and enzymatic strategies

• Antonio Angelastro,
• Jonathan Bargh,
• Subhajit Guria,
• Victor Laserna and
• Louis Luk

Beilstein J. Org. Chem. 2026, 22, 857–881, doi:10.3762/bjoc.22.67

• therapeutics, advances in protein modification have the potential to partially replace solid-phase peptide synthesis (SPPS), reducing environmental impact by minimising protecting groups and harmful solvents. Driven by scientific innovation, clinical demand and sustainability goals, the global protein

• mass intensity (PMI). Reagents should be near-stoichiometric, purification steps minimal, and catalysts effective in substoichiometric quantities. Compatibility with one-pot system and automation, such as flow chemistry and robotic synthesis, further enhance scalability. Existing tools and techniques

• -molecule modifications provide powerful strategies for site-selective modification of otherwise intractable residues, as summarised in a comprehensive review [109]. However, most new conjugation reagents are not yet commercially available, requiring in-house synthesis, and the resulting conjugates often

The trans-influence in gold chemistry from a catalytic perspective

• Manfred Bochmann

Beilstein J. Org. Chem. 2026, 22, 838–856, doi:10.3762/bjoc.22.66

• Manfred Bochmann School of Chemistry, University of East Anglia, Norwich Research Park, NR4 7TJ, Norwich, United Kingdom 10.3762/bjoc.22.66 Abstract Gold catalysis has developed into an increasingly important method in organic synthesis. Especially the potential of gold(I,III) redox systems and

• ]. Since these complexes are a means of facilitating oxidative addition reactions to gold by chelate formation, they have become a mainstay in Au(I,III) redox catalysis. The use of P^N and related ligands in synthesis has recently been reviewed [79]. A good way of assessing the trans-influence in these

• been claimed to explain the (MeDalPhos)Au-catalysed synthesis of Heck-type olefins, including migratory alkene 2,1-insertion into a Au–aryl bond, followed by β-H elimination, to give non-conjugated benzyl alkenes [94]. This reactivity scenario has been extended to include chain walking [95]. The main

Unsymmetrical sulfoxides with sterically hindered catechol fragment: synthesis, structure, electrochemical properties, and antiradical activity

• Daria A. Burmistrova,
• Vasiliy A. Fokin,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Maxim V. Arsenyev,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2026, 22, 828–837, doi:10.3762/bjoc.22.65

• electrochemical properties, and to establish how the hydrocarbon substituent influences antiradical activity upon conversion from thioethers to sulfoxides. Results and Discussion Synthesis The starting unsymmetrical thioethers 1–7 were obtained according to a previously described procedure based on the Michael

• ). Synthesis of catechol-contained thioethers 1–7 and sulfoxides 1a–7a. Proposed mechanism of electrochemical transformations of catechol sulfoxides (path a – for 1a, 3a, 4a, 6a, and 7a; path b – for 2a and 5a). Proposed mechanism of the reduction of electrogenerated o-benzoquinone. Peak (Epox) potentials of 1

Total synthesis of the capsular polysaccharide repeating unit towards the development of a glycoconjugate vaccine against Klebsiella pneumoniae ST512

• Shuo Zhang,
• Ondřej Daněk and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2026, 22, 821–827, doi:10.3762/bjoc.22.64

• emerging multidrug-resistant pathogen whose capsular polysaccharide represents a prime target for vaccine development. Here, we report the first total synthesis of the branched hexasaccharide repeating unit of the K. pneumoniae ST512 CPS, together with four structurally related oligosaccharide analogues

• . Keywords: glycoconjugate vaccines; glycosylation; oligosaccharides; selectivity control; total synthesis; Introduction The emergence and rapid spread of multidrug-resistant bacteria represent a critical threat to global health [1][2][3][4]. Among these pathogens, Klebsiella pneumoniae has surfaced as a

• currently available [24][25][26][27]. The identification of immunogenic epitopes is a key step toward the development of efficacious semi-synthetic vaccines [19][28]. Herein, we report the first total synthesis of a series of conjugation-ready oligosaccharides related to the CPS repeating unit of K

Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine

• Irene Moreno-Gutiérrez,
• Josefa L. López-Martínez,
• Sonia Berenguel-Gómez,
• Irene Torres-García,
• Duane Choquesillo-Lazarte,
• Manuel Muñoz-Dorado,
• Miriam Álvarez-Corral and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2026, 22, 813–820, doi:10.3762/bjoc.22.63

• , the design and synthesis of spiro-heterocycles – especially spirooxindoles – has continued to expand due to their broad pharmacological relevance and the wide array of modern synthetic strategies now available for their construction, including metal-free, organocatalytic, and transition-metal-mediated

• Olex2 [22]. The structure was solved by intrinsic phasing with SHELXT [23] and refined by full-matrix least-squares methods on F2 using SHELXL [24]. Commercially available chemicals were obtained from Scharlau, TCI and Acros and used as received. Synthesis of 25: Isatin (1, 2.98 g, 19.85 mmol, 1 equiv

• -1223-336033; E-mail: deposit@ccdc.cam.ac.uk. Synthesis of 24. Ethylenediamine (0.33 mL, 5 mmol, 1 equiv) was added dropwise to a solution of isatin (1, 1.47 g, 10 mmol, 2 equiv) in MeOH (50 mL). The mixture was heated at reflux for 5 h, cooled to 0 °C, and acidified with 1 M HCl (to pH ≈ 1), leading to

Knoevenagel condensation of 4,5- and 1,8-diazafluorenes

• Darya S. Cheshkina,
• Christina S. Becker,
• Alina A. Sonina and
• Maxim S. Kazantsev

Beilstein J. Org. Chem. 2026, 22, 803–812, doi:10.3762/bjoc.22.62

• . However, there are currently only limited methods for their synthesis, which are complicated and typically based on modifications of 4,5-diazafluorenone. Herein, we systematically studied the Knoevenagel condensation of both 4,5- and 1,8-diazafluorenes with aromatic aldehydes and evaluated the

• for their synthesis involves coupling reactions of diazafluoren-9-one [4][6][7] or diazafluoren-9-diazomethane [17][18] with thiones yielding the products in moderate yields (20–70%). However, these routes require the preliminary synthesis of malodorous thiones and diazomethane derivatives from the

• we applied this approach for the synthesis of 1,4-bis((9H-(1,8-diazafluoren)-9-ylidene)methyl)phenylene (4е, Scheme S1 in Supporting Information File 1) which resulted in 65% yield significantly surpassing the previously reported 11% using the TiCl4 system [15]. The method shown here, in contrast to

Synthetic study of vic-bromination of diarylacetylenes, easy purification and separation

• Akane Togo,
• Hiyono Suzuki,
• Yuto Akai,
• Makoto Matsumoto,
• Yoshinori Suzuma,
• Hidehiko Kodama and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2026, 22, 795–802, doi:10.3762/bjoc.22.61

• ; Introduction The addition reaction of bromine to diphenylacetylene is one of basic reactions and is recognized as important, because resulting 1,2-dibromo-1,2-diphenylethylene can serve as a precursor for various molecular transformations in organic synthesis [1][2]. This reaction seems to be simple, but some

• -diphenylethylenes (Scheme 1c) [5]. Previous studies reported the selective synthesis of (E)-1,2-dibromo-1,2-diphenylethylene and related compounds, but Br2 or expensive reagent, which was difficult to handle, was often used [6][7][8][9][10][11][12][13][14][15]. Based on these research backgrounds, we have also been

• interested in the selective synthesis of the E isomer of 1,2-dibromo-1,2-diphenylethylene, together with simple purification and separation toward process chemistry, because the compound is an attractive synthetic intermediate for further transformations. During the course of our studies, we have found that

Halogenated azobenzene acrylates: from efficient solution photoswitching to stable solid-state photochromic materials

• Martina Vachtlová,
• Michaela Fecková,
• Vítězslav Zima,
• Jan Podlesný,
• Milan Klikar,
• Oldřich Pytela,
• Patrik Pařík,
• Jakub Opršal,
• Eliška Juhaňáková,
• Veronika Chrtová and
• Filip Bureš

Beilstein J. Org. Chem. 2026, 22, 782–794, doi:10.3762/bjoc.22.60

• . Neumanna 1316, Pardubice, 53002, Czech Republic Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 53210, Czech Republic 10.3762/bjoc.22.60 Abstract The design, synthesis, and comprehensive characterization of six novel

• polyacrylate or polystyrene materials. Results and Discussion Synthesis of azobenzene monomers The target azobenzene monomers 1a–f were obtained using a facile three-step synthetic route as shown in Scheme 1. The first step represents an azo-coupling reaction between phenol and the corresponding diazonium

• designed and prepared in a straightforward three-step synthesis. Their fundamental properties were investigated in solution and polymeric matrix. TGA and DSC studies revealed different thermal behavior of mono- and disubstituted derivatives, which most likely results from their (non)planar arrangement as

Design, synthesis, and biological evaluation of FXR/ASK1 dual-target modulators

• Xi Zhang,
• Jingyan Wang,
• Ziqiang Zhao,
• Caiyi Wang,
• Zenghui Ye,
• Wei-Yuan Ma,
• Jian-Xing Xu and
• Fengzhi Zhang

Beilstein J. Org. Chem. 2026, 22, 771–781, doi:10.3762/bjoc.22.59

• , inflammation, and myofibroblast activation [18][19][20]. Conversely, intestinal FXR agonism has been demonstrated to promote the release of fibroblast growth factor 19 (FGF19) [21][22], which in turn has been shown to downregulate hepatic bile acid synthesis, lipogenesis, and gluconeogenesis [23][24][25]. A

• MASH. Results and Discussion Chemistry The synthetic routes to the target compounds are outlined in Schemes 4–8. The synthesis of isoxazole intermediate 2 commenced with the condensation of commercially available benzaldehyde I with hydroxylamine to afford oxime intermediate II. Subsequent treatment of

• LiOH or lithium aluminum hydride to obtain compounds Z4–7. The synthesis of compounds Z8–15 followed a similar preparation procedure as for Z1–7. The synthesis of target compounds Z16–29 is illustrated in Scheme 7. Intermediates 8 and 10 were synthesized by the Suzuki cross-coupling reaction using

Preparation of 3-(alkylamino)imidazo[1,2-a]pyridine-2-carbaldehydes via Kornblum oxidation and unexpected ring-opening reactions of the corresponding alcohols under oxidative conditions

• Sandile J. Mkhize,
• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2026, 22, 763–770, doi:10.3762/bjoc.22.58

• Sandile J. Mkhize Memory Zimuwandeyi Manuel A. Fernandes Amanda L. Rousseau Moira L. Bode Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, PO WITS, 2050, South Africa 10.3762/bjoc.22.58 Abstract The first synthesis of 3-(alkylamino)imidazo[1,2-a

• ester. In this paper, we describe the synthesis of a library of derivatives of 8, whose imidazo[1,2-a]pyridine core could be accessed via the Groebke–Blackburn–Bienayme (GBB) multicomponent coupling reaction [20][21][22][23]. Results and Discussion In order to access our initial target compounds 7, the

• to obtain the desired aldehydes led to a modification of the planned synthesis. A decision was made to convert alcohols 17 into the corresponding tosylate derivatives 19 (Scheme 6) and then react these with anilines to obtain the desired products 8. To our complete surprise, reaction of 17b and 17d

Synthesis and biological evaluation of new brassinosteroid analogs with C-22 benzoate function

• María Núñez,
• Camila Escobar,
• Mario Párraga,
• Mauricio Soto,
• Luis Espinoza-Catalán,
• Katy Díaz and
• Andrés F. Olea

Beilstein J. Org. Chem. 2026, 22, 753–762, doi:10.3762/bjoc.22.57

• , MEDING. Laboratorio de Biología molecular. Escuela de Medicina, Universidad de Valparaíso, Chile Instituto de Ciencias Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Av. del Valle Sur 534, Santiago 8580640, Chile 10.3762/bjoc.22.57 Abstract The synthesis and structural

• be possible to evaluate the contribution of different functions attached to ring A. Thus, herein the synthesis of analogs 17–22, starting from the precursor 16, is described. All compounds have been fully characterized by spectroscopic techniques (IR, 1D, 2D NMR and HRMS). The biological activities

• The synthesis of new BR analogs 17–22 (Figure 2) and compounds 23–28 has been carried out using the olefinic precursor 16 according to previously described procedures (Scheme 1) [28][29]. Treatment of olefine 16 with p-R-PhCOCl in DMAP/py/CH2Cl2, leads to compounds 23–28 with high yields (78.0–96.7

Rongalite addition to dienones: diastereoselectivity in cyclic sulfone synthesis; stereochemical rationalization and prospects as a general conjugate nucleophile

• Melina Goga,
• Hao Zong,
• James Franco,
• Jazmine Prana,
• Rudolph Michel,
• Antonia Muro,
• Elana Rubin,
• Janet Brenya,
• Henk Eshuis and
• Magnus W. P. Bebbington

Beilstein J. Org. Chem. 2026, 22, 742–752, doi:10.3762/bjoc.22.56

• experimental and computational study of the diastereoselectivity of cyclic sulfone synthesis by reaction of Rongalite with doubly electrophilic dienones is presented. Computational methods, including density functional theory, conformational search methods, and internal reaction coordinate methods, have been

• molecules are desirable, particularly in the light of the general need for more sustainable chemical synthesis. Recently, there has been significant progress in the use of SO2 equivalents and bulk inorganic high oxidation state sulfur compounds for the direct incorporation of sulfones [2][3]. Despite these

• used as a bleaching agent in the dyeing industry for more than a century [5][6]. Over the last 10 years particularly, it has begun to join the toolbox of reagents in organic synthesis, and shows diverse reactivity. It has been employed in reductions, radical processes and as a reagent for C1 transfer

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

• compounds; catalysis; (3 + 2) cycloaddition; decarboxylation; dipolarophiles; iminoesters; polycyclic compounds; spirocyclic compounds; stereoselectivity; Introduction The 1,3-dipolar cycloaddition is one of the most popular pericyclic reactions in organic synthesis, in which a dipole molecule interacts

• ]. The use of azomethine ylides as dipoles is necessary for the synthesis of pyrrolidine systems, which are often found in natural products and are important structural fragments of pharmaceuticals [5]. This method is also used to obtain pyrrolizidine derivatives, which are the structural basis of

• strategy is that the synthesis is often carried out under mild conditions without the use of a catalyst, and despite this, the resulting cycloadducts exhibit pronounced regio- and stereoselectivity [9][10][11]. In the second case, the generation of azomethine ylides from iminoesters is often realized using

Anti-invasive and cytotoxic evaluation of a (+)-pinoresinol-based semisynthetic library against glioblastoma

• Chen Zhang,
• Kah Yean Lum,
• Jonathan M. White,
• Paul I. Forster,
• Nicholas Booth,
• Sunita A. Ramesh and
• Rohan A. Davis

Beilstein J. Org. Chem. 2026, 22, 691–704, doi:10.3762/bjoc.22.54

• purity (>95%). Semisynthetic analogues 3−5 are known compounds [25][26]. However, some of these compounds have not been fully characterized. Regarding compound 5, this molecule had previously been reported as an intermediate in the total synthesis of racemic pinoresinol [25]. Through a bromination

• collected on a Rigaku XtaLAB synergy diffractometer using Cu Kα radiation at 100.0(1) K using an Oxford Cryostream cooling device. The structure was solved by direct methods and difference Fourier synthesis [36]. Hydrogen atoms bound to the carbon atom were placed at their idealized positions and included

Synthesis of depressin, cryptomeridiol and 4-epi-cryptomeridiol enabled by a terpenoid chiral pool-producing platform

• Yao Kong,
• Tao Wang,
• Chen Wang,
• Pengcheng Zhang,
• Yuanning Liu,
• Kaibiao Wang,
• Fen Liu,
• Hongli Jia and
• Zhengren Xu

Beilstein J. Org. Chem. 2026, 22, 683–690, doi:10.3762/bjoc.22.53

• skeleton and a C5-keto group. Key strategies for the synthesis of depressin, as well as its casbene skeleton reported so far focused on the formation of the challenging 14-membered ring system. Cryptomeridiol (2) and 4-epi-cryptomeridiol (3) are two eudesmane-type sesquiterpene diols produced by a variety

• of different plants with broad biological activity. Most of the syntheses focused on the transformation of chiral pool substrates into their trans-6/6-fused ring system. We herein report the synthesis of compounds 1–3 by taking advantage of an expanded chiral pool strategy, in which the terpenoid

• hydroxy group allowed the synthesis of compound 1 from 4 in nine steps. Selective acid-mediated 5,10-transannular cyclization of 5 followed by hydration reaction furnished both products 2 and 3 in two steps. Keywords: chemoenzymatic synthesis; chiral pool; isopentenol utilization pathway; terpene

Harnessing light energy with molecules

• Grace G. D. Han,
• Mogens Brøndsted Nielsen and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2026, 22, 680–682, doi:10.3762/bjoc.22.52

• article by Wahl and co-workers [21], ring-opening of photogenerated azetidinols was used as a strategy for the convenient synthesis of aminodioxolanes. Photochemical denitrogenation reactions of bicyclic azoalkanes present a way to prepare strained bicyclic compounds. Further, Gomes and Lopez [22] report