Rh(III)-catalyzed chelation-assisted C–H activation/annulation of 2-arylimidazolines with cyclic diazo-1,3-dicarbonyl compounds: a novel approach to tetracyclic annulated derivatives of 2,3-dihydroimidazo[2,1-a]isoquinoline

• Ivan Lyutin,
• Grigory Kantin,
• Olga Bakulina and
• Dmitry Dar'in

Beilstein J. Org. Chem. 2026, 22, 997–1003, doi:10.3762/bjoc.22.78

• with ring sizes from 5 to 7 atoms were chosen as key building blocks. This strategy [17] has already proven to be a powerful tool for the synthesis of diverse fused polycyclic compounds using functionalized benzenes or six-membered aryl-substituted heterocycles as substrates, but there were only a few

The role of spacer length and flexibility in peptide self-assembly

• Julian Link,
• Albin Lahu,
• Manfred Wagner,
• Tanja Weil and
• David Y. W. Ng

Beilstein J. Org. Chem. 2026, 22, 986–996, doi:10.3762/bjoc.22.77

• peptide domain [27][28]. Such peptide amphiphiles have emerged as powerful building blocks to engineer highly-ordered nanostructures in biomedicine [29], nanoscience [30], and cosmetics [31]. While extensive efforts have focused on varying peptide sequences [32] and hydrophobic motifs [33], the role of

• -yl)-1H,3H-benzo[de]isochromene-1,3-dione (2) with good yield (79%, Figures S1–S6 in Supporting Information File 1) after purification through recrystallization from ethanol [36]. Compound 2 was used as the precursor for the synthesis of the C6-/C3-, and C0-spacer building blocks 3, 4, and 5. To

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

• desymmetrized building blocks avoid the dense packing commonly observed in rigid planar systems. As a proof of concept, these precursors were converted into methylene-alternating copolymers that exhibit high solubility and measurable carbon dioxide adsorption, highlighting their potential for the development of

• with modular ring sizes and peripheral groups. Incorporating either one or two BINOL units, these molecules represent highly versatile, nonsymmetric building blocks as promising candidates for further application in enantioselective chemosensing or organocatalysis. Providing a comprehensive biomedical

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

• essentially binary synthetic building blocks consisting of a highly strained small ring and an active functional group that are capable of reacting in domino or orthogonal modes. This dual reactivity allows their use in the syntheses of monocyclic heterocycles [11][12][13][14], fused heterocycles [15][16][17

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

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

• . Key synthetic challenges including the stereoselective construction of the 1,2-cis glycosidic linkage on the galacturonic acid core and the inherently low reactivity of elongated oligosaccharide intermediates were addressed employing orthogonally protected building blocks. The resulting library of

• assembly and subsequent functionalization of long oligosaccharide chains are hampered by their intrinsically low reactivity [29]. Overcoming these challenges relying on a linear strategy employing four key building blocks 1–4, we describe the first chemical synthesis of the hexasaccharide repeating unit

• . The total synthesis commenced with the preparation of the orthogonally protected monosaccharide building blocks 1–4 (Scheme 1). Galactoside 1 was synthesized starting from the β-selective glycosylation of thioglycoside 5 [30] with aminopentyl linker 6. This reaction was promoted by N-iodosuccinimide

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

• also provided us with several abundant chiral building blocks which are normally referred to as the ‘chiral pool’ to start with [4][5]. Representative terpenoid products, such as (−)-carvone, (+)-3-carene, and (+)-sclareolide that are typically isolated from renewable resources (Figure 1a), continue to

• pathway, have been adopted to provide the two key five-carbon building blocks DMAPP and IPP. With the recent advancement in the field of synthetic biology, more chiral terpenes (e.g., guaia-6,10(14)-diene [7][8], drimenol [9][10], and ent-atiserenoic acid [11] as shown in Figure 1b) became easily

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

• 181. Both building blocks from Scheme 17 and Scheme 18 were fused together via HWE reaction to construct 182 (Scheme 19). Treatment with HF·pyridine led to cleavage of the acetonide- and TBDMS-protecting groups, which induced the oxy-Michael cyclization towards 183. Notably, during this cyclization

• , Nicolaou and co-workers merged both building blocks within a Ni(II)/Cr(II)-catalyzed NHK reaction using chiral ligand 206 (Scheme 23) [95]. Upon treatment with DBU, 3-methylenetetrahydrofuran 201 was obtained in 56% yield over two steps. PMB-deprotection, iodination and selective reduction of the ester

• , Mitsunobu inversion of the secondary alcohol and TES-protection yielded allene 305 in 48%. The assembly of all building blocks is shown in Scheme 36. 306 was derived from the TBDPS-protection and DIBAL-H reduction of 92 (see Scheme 9). Deprotonated 41 (see Scheme 6) was added to 306`s aldehyde motif, before

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

• herein report on the synthesis approaches to a series of cone p-aminocalix[4]arenes having propargyl or 2-azidoethyl groups at the narrow rims (Figure 1). The newly synthesized compounds may be thus treated as novel building blocks in calixarene chemistry capable of step-wise orthogonal transformations

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

• modifications and the use of the obtained compounds as building blocks. We also examined other nucleophiles suitable for the described domino-sequence. Thus, application of ethanol as solvent resulted in a mixture of the desired product 4b with the corresponding intermediate C (NMR ratio 88:12), however, longer

• , that allows a broad functionalization of the 3-(sulfonyl)butan-1-amine with various substituents and their utilization as building blocks. We believe this approach has promising features for further development and pharmaceutical applications. Valuable amino sulfonic acids and aminosulfones. Selected

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

• 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

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

• , offering high atom economy, operational simplicity, and remarkable versatility [9][10][11][12][13]. Owing to their flexibility in combining diverse building blocks, MCRs have found widespread application in the synthesis of biologically active compounds. This versatility significantly shortens synthetic

Symmetrical D–π–A–π–D indanone dyes: a new design for nonlinear optics and cyanide detection

• Ergin Keleş,
• Alberto Barsella,
• Nurgül Seferoğlu,
• Zeynel Seferoğlu and
• Burcu Aydıner

Beilstein J. Org. Chem. 2026, 22, 131–142, doi:10.3762/bjoc.22.6

• ) efficiency [14][15][16]. Indanones are highly conjugated with a planar structure, which favors overlap between the molecules. They are building blocks for many compounds, such as organic materials for optoelectronic and NLO applications [17][18]. Research shows that the absorption wavelength of the region

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

• building blocks used in natural product syntheses are often difficult to prepare or scale-up, constrained by subtle chemical reactivity, functional group compatibility, and control of stereoselectivity. Together, these factors continue to shape the pursuit of concise and practical synthetic routes to

• catalysts, they synthesized 2-substituted quinoxalines 52 in high yield. For benzofuran, indole and other heteroarenes, hydrogenation of these easily accessible building blocks is rare. In 2020, Ding and co-workers demonstrated the selective reduction of benzoannelated five-membered heteroaromatic compounds

Tandem hydrothiocyanation/cyclization of CF₃-iminopropargyl alcohols with NaSCN in the presence of AcOH

• Ruslan S. Shulgin,
• Ol’ga G. Volostnykh,
• Anton V. Stepanov,
• Igor’ A. Ushakov,
• Alexander V. Vashchenko and
• Olesya A. Shemyakina

Beilstein J. Org. Chem. 2025, 21, 2694–2702, doi:10.3762/bjoc.21.207

• nucleophilic center – imino group or an imino and OH groups. The synthesized compounds are potential drug precursors, synthons, and multipurpose building blocks for fine organic synthesis. We believe that the present method will be of significant interest to synthetic and medicinal chemists due to the

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

• that the diarylmethine stereocenter at C7′ in 6 could be formed by an Evans’ auxiliary-induced asymmetric conjugate addition of α,β-unsaturated acyl oxazolidinone 7 with 3,4,5-trimethoxyphenylmagnesium bromide (8). Both of these two building blocks could be conveniently prepared from commercially

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

• chemotherapy and achieving targeted treatments [18][19][20]. In the era of nanotechnology, a promising strategy for developing more effective treatments against cancer [21][22], calixarene derivatives are also emerging as valid building blocks for the development of nanoscale multivalent constructs [23]. Due

Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• robust approach to a wide range of 3-substituted thiophene-2,5-dicarboxylates. These intermediates are of interest as valuable building blocks for the synthesis of more complex thiophene derivatives in both materials and medicinal chemistry contexts. The synthetic routes to 3-hydroxy-substituted TT

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

• involves a formal 1,3-C shift. Keywords: Aspidosperma alkaloids; [2 + 2]-cycloaddition/retro-Mannich reaction; DFT study; photoinduced electron transfer; Introduction Photochemical reactions, which enable the construction of topologically complex architectures from simple building blocks, have attracted

• valuable strategy for synthesizing natural and unnatural products from simple building blocks [4]. Three distinct photoinitiated approaches have been established for the formation of the [2 + 2] cycloadducts: direct irradiation [5][6], energy transfer (EnT) [7], and photoinduced electron transfer (PET, or

Ex-situ generation of gaseous nitriles in two-chamber glassware for facile haloacetimidate synthesis

• Nikolai B. Akselvoll,
• Jonas T. Larsen and
• Christian M. Pedersen

Beilstein J. Org. Chem. 2025, 21, 2465–2469, doi:10.3762/bjoc.21.188

• used building blocks in glycosylations. For the synthesis chamber (A) was loaded with trifluoroacetamide (6 equiv) in pyridine. In the other chamber (B), the hemiacetal (ca. 500 mg, 1 equiv) was dissolved in CH2Cl2 together with a catalytic amount of DBU. Upon addition of trifluoroacetic anhydride

The intramolecular stabilizing effects of O-benzoyl substituents as a driving force of the acid-promoted pyranoside-into-furanoside rearrangement

• Alexey G. Gerbst,
• Sofya P. Nikogosova,
• Darya A. Rastrepaeva,
• Dmitry A. Argunov,
• Vadim B. Krylov and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2025, 21, 2456–2464, doi:10.3762/bjoc.21.187

• development of a new methodology for the synthesis of galactofuranoside building blocks, we encountered an unexpected predominance of the furanoside form in the equilibrium mixture of benzoylated β-galactosides. Since the furanoside form is typically less stable and is usually present only in minor amounts

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

• aldol condensation of the resulting dialdehyde. This strategy is widely used at the key stage in the formation of a cyclopentane ring in the synthesis of various building blocks, including echinopine A (3) [10][11][12] (Scheme 1). The ozonolysis–cyclization sequence was used by Alvarez-Manzaneda et al

• simple building blocks [72]. The main feature of light-induced transformations is the involvement of electronically excited states that occur during photon absorption, leading to the formation of reactive intermediates causing significant changes in chemical compound reactivity. As a result, light energy

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• protection as ketal and nitrile reduction. The two building blocks (76 and 81) were then merged through the desired formal [3 + 3]-cycloaddition to generate N-desmethyl-α-obscurine (82), presumably via in situ-generated intermediates 76a and 81a, respectively. Subsequent Boc protection of the cyclic amine in

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

The application of desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds in the total synthesis of terpenoid and alkaloid natural products

• Dong-Xing Tan and
• Fu-She Han

Beilstein J. Org. Chem. 2025, 21, 2085–2102, doi:10.3762/bjoc.21.164

• The desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds is a powerful tool for the construction of ring systems bearing multiple stereocenters including all-carbon quaternary stereocenters, which are widely useful chiral building blocks for the total synthesis of structurally