Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• band around 350 nm was observed. This increase can be explained by deprotonation of the structures, which facilitates solvation effects by water molecules. The cause for the tautomerism effect at acidic pH may be due to the protonation of the basic site of the amino group present in the derivatives

• the electronic density towards the acceptor regions (Figure 10), which inhibits the intramolecular charge transfer upon excitation. It is important to note that protonation and deprotonation can significantly alter the HOMO–LUMO gap of a molecule by disrupting its electronic structure. In general

• , protonation of these compounds resulted in a lowering of the HOMO energy level, leading to an increase in the HOMO–LUMO gap and, consequently, greater molecular stability. In contrast, deprotonation led to an increase in the LUMO energy level, with little influence on the HOMO energy. Notably, the neutral

Recent advances in total synthesis of illisimonin A

• Juan Huang and
• Ming Yang

Beilstein J. Org. Chem. 2025, 21, 2571–2583, doi:10.3762/bjoc.21.199

• , deprotonation, and intramolecular addition to ketone. Treatment of the silacycle with MeMgCl cleaved the Si–O bond and subsequent intramolecular nucleophilic substitution of the chloride with the adjacent hydroxy group yielded TMS-epoxide 41. Protonic acid-mediated opening of the TMS-epoxide, accompanied by TES

• deketalization afforded carbonate 58. A palladium-catalyzed decarboxylative alkenylation reaction was then carried out across the less hindered face of the six-membered ring to connect C5 and C6. Selective deprotonation and triflation at the C4 carbonyl group provided enol triflate 59. An intramolecular

• epoxide ring-opening afforded 71. To install the all-carbon quaternary center at C5, compound 71 was treated with t-BuOK and MeI, enabling the deprotonation of the α,β-unsaturated aldehyde and methylation at C5; this step also facilitated protection of the secondary alcohol. The aldehyde was reduced in

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

• .1 initially engages substrate 7 through hydrogen bonding, forming intermediate Int 7. Subsequently, deprotonation of the naphthol group by quinuclidine yields intermediate Int 8. This intermediate then undergoes nucleophilic attack on the selenium atom in substrate 8, leading to the formation of the

Synthetic study toward vibralactone

• Liang Shi,
• Jiayi Song,
• Yiqing Li,
• Jia-Chen Li,
• Shuqi Li,
• Li Ren,
• Zhi-Yun Liu and
• Hong-Dong Hao

Beilstein J. Org. Chem. 2025, 21, 2376–2382, doi:10.3762/bjoc.21.182

• not proceed to form the all-carbon quaternary center and only decomposition of 21 was observed. The failure is likely due to the sterically hindered environment of the substituted β-lactone ring which precludes the C–H insertion or deprotonation of the β-lactone and interrupted the generation of the

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• base results in the deprotonation of the ammonium site and shuttling of the macrocycle to the urea site. Whereas, upon addition of acid, the macrocycle returns to the protonated BAA site. Notably, the rotaxane exhibited high fluorescence intensity due to aggregation in acetonitrile with high water

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• cyclization and subsequent deprotonation furnished 1,3-disubstituted or 1,2,3-trisubstituted naphthalenes 29 (Scheme 7, path a). When the alkyne terminus was iodo-substituted or unsubstituted, the 5-exo-dig cyclization pathway proceeded via selective activation of the iodoalkyne, generating 1-methyleneindene

• ]. Ph3PAuCl/AgOTf catalyzed a tandem 7-exo-dig cyclization followed by a cyclobutyl ring expansion process, yielding intermediate 84. The deprotonation followed by protonolysis-mediated gold elimination delivered the ring-expanded product 85 (Scheme 18, path a). When a bulkier ligand was used, steric

• featuring an isopropyl substituent was transformed to a carbene intermediate 121 via a gold-catalyzed 5-endo-dig cyclization. When the Ph3PAuCl/AgOTs system was used, indene derivative 122 was obtained by deprotonation (Scheme 25, path a). In contrast, 1,2-hydrogen migration was favored using the Ph3PAuCl

Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings

• Lifen Peng,
• Ting Wang,
• Zhiwen Yuan,
• Bin Li,
• Zilong Tang,
• Xirong Liu,
• Hui Li,
• Guofang Jiang,
• Chunling Zeng,
• Henry N. C. Wong and
• Xiao-Shui Peng

Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166

• ] generated [Cp2Fe]+ along with cathodic reduction of MeOH to H2 and MeO− acting as a base. Deprotonation of 1a using MeO− produced the anion A, which underwent single-electron transfer (SET) with [Cp2Fe]+ to give the nitrogen-centered radical B with regeneration of [Cp2Fe] [164][165][166][167][168][169][170

• formed H2 and HO−. The anti-nucleophilic attack of the N atom in A and the following HO− facilitated deprotonation and formed the corresponding 3-iodoindole 11a. Excessive-reduction (a minor side-reaction) of 11a took place as well in certain instances, resulting in the formation of 12a. And for the

• generation of 12a in Cu rod electrodes, the Cu anode was expected to liberate Cu+ into the reaction mixture. The reaction of this Cu+ with DMSO and I− afforded (DMSO)nCuI, which was coordinated with C≡C to give B. The intermediate C was obtained by cyclization of B and deprotonation. Further protonation of C

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

Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis

• Rasma Kroņkalne,
• Rūdolfs Beļaunieks,
• Armands Sebris,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154

• likely formed via the allylic cation intermediate Int-1 (Scheme 2), from where on two competing mechanistic pathways are possible. Deprotonation of the β-H and reductive elimination affords diene 10. Alternatively, an intramolecular cyclization leads to silylindenes 11. We were interested to see whether

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

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

• hydrophobic alkyl chain core. The assembly driving force directly relies on the host–guest interaction between WP6 and FC. Further studies have shown that by regulating the deprotonation/protonation state of the WP6 carboxyl groups through pH control, the reversible dissociation and reassembly of the vesicle

Approaches to stereoselective 1,1'-glycosylation

• Daniele Zucchetta and
• Alla Zamyatina

Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133

• ]. Diarylborinic acids have been shown to provide exclusive catalytic performance in the site-selective monofunctionalization of various 1,2- and 1,3-diols [60], as well as in the regioselective glycosylation of polyhydroxyglycosyl acceptors via base-promoted deprotonation of a specific hydroxy group involved in

pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality

• Ryota Kimura,
• Satoshi Ichikawa and
• Akira Katsuyama

Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120

• triggered by protonation and deprotonation [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. This class of molecules has the capacity to regulate three-dimensional structures and motions of molecules through simple acid–base stimuli. This provides a high degree of control over their

• clearly showed that the rotational barriers of ortho-disubstituted benzamidine can be modulated by the protonation or deprotonation of the amidine moiety. Next, we experimentally examined the C–N rotation of 2-bromo-N,N-diethyl-6-methylbenzimidamide (1). First, the effect of the protonation on the C–N

Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides

• Nadezhda M. Metalnikova,
• Nikita S. Antonkin,
• Tuan K. Nguyen,
• Natalia S. Soldatova,
• Alexander V. Nyuchev,
• Mikhail A. Kinzhalov and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110

• molecule from the reaction medium to X2 occurs culminating in the formation of the final product 2 after deprotonation and tautomerization. The proposed mechanistic pathway is formally supported by conducting the reaction in the presence of NaOAc as a base, which resulted in the formation of the acetoxy

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• OH functionality in compound 2 gives possibility to influence the tautomerism in this compound dynamically by protonation/deprotonation. The tautomeric and switching properties of compounds 1 and 2 have been revealed by using quantum-chemical calculations, UV–vis and NMR spectroscopy and UV

• group surrounded by fluorine atoms, which could spontaneously deprotonate in polar solvents, while the tautomeric OH/NH group is always a part of strong intramolecular hydrogen bonding and the possibility for deprotonation is low. The deprotonation of the phenyl OH group is also supposed by the

• computational quantum chemistry calculations. As seen from Table S2 in Supporting Information File 1, the deprotonation of the tautomeric proton requests substantially more energy, while the deprotonation of the phenyl OH group leads to a single E− tautomer. This fact is confirmed by a simple experiment. As

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

• after deprotonation of a suitably functionalised ether at the α-carbon. Therefore, a stabilising group must be incorporated to control regioselectivity of the deprotonation as well as to increase the acidity of the α-hydrogen. Mordini et al. showed that even weakly stabilising groups such as phenyl

• react through the terminal carbon and deliver tetrahydrooxepines, especially, if the oxirane is monosubstituted (58, R1 = H). The deprotonation step can also be enabled by employing classical electron-withdrawing groups such as esters, and a particularly powerful methodology was disclosed by Bull and

Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer

• Hao-Sen Wang,
• Lin Li,
• Xin Chen,
• Jian-Li Wu,
• Kai Sun,
• Xiao-Lan Chen,
• Ling-Bo Qu and
• Bing Yu

Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100

• PCET process, involving the oxidation of excited 4CzIPN* and deprotonation by a base. The resulting amidyl radical 20 smoothly abstracted a hydrogen atom from the substrate via a HAT process, generating a radical 4. This C-centered radical subsequently underwent Giese addition with activated alkenes

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

• optical absorption. The UV–vis absorption spectra, fluorescence properties and 1H NMR spectroscopy, indicate that 150 and 151 can be protonated to form the corresponding tropylium cation and consecutive dication under acidic conditions, with reversible protonation−deprotonation capabilities. Additionally

• , new OFET-based acid vapor sensors were developed from 150 by synergistically utilizing its charge transport and protonation−deprotonation properties. The solution-phase synthesis of a non-benzenoid nanoribbon from an azulene-containing polymer via alkyne benzannulation was reported by Morin and co

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

• either a 1,5-hydride shift to give D or a direct cyclization with the aryl ring via intermediate E, which upon deprotonation lead to the final products 16 and 17. In a 2016 study by Van der Eycken’s group (Scheme 9), an innovative copper-catalyzed alkylarylation of activated alkenes using isocyanides as

• radical C, which adds to the N-arylacrylamide, followed by intramolecular cyclization and deprotonation to form the final products 19. To further expand the radical difunctionalization toolbox, electrochemical approaches have emerged as a green and efficient alternative, offering precise redox control

• . Based on these results and previous studies, a detailed reaction mechanism was proposed as shown in Scheme 12. The process begins with the oxidation of Cp2Fe at the anode to form Cp2Fe+, which then facilitates the deprotonation of the α-C–H bond of the 1,3-dicarbonyl compound by methoxide, generated at

Optimized synthesis of aroyl-S,N-ketene acetals by omission of solubilizing alcohol cosolvents

• Julius Krenzer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2025, 21, 1201–1206, doi:10.3762/bjoc.21.97

• deprotonation, followed by chloride elimination/neutralization from the zwitterionic tetrahedral intermediate 5 to give the target molecule 1. The standard protocol for the synthesis of (hetero)aroyl-S,N-ketene acetals 8 from (hetero)aroyl chlorides 6 and 2-methylbenzothiazolium salts 7 employs a twofold excess

Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups

• Julius Seumer,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94

• metallation deprotonation mechanisms mediated by common catalysts like Pd(OAc)2. Our methodology not only identifies potential activation sites but also addresses the limitations of existing models by including a broader range of directing groups and reaction conditions while maintaining moderate

• activation, called concerted metal deprotonation (CMD) [5][6][7]. In a concerted mechanism, the Pd atom of the catalyst forms a sigma bond to an aromatic carbon, which increases the acidity of the adjacent (alpha) proton. This allows for the simultaneous abstraction of this proton by a carboxylate ligand. A

• does not generalize well. In this study, we rely on several key assumptions that we will outline below. First, we focus exclusively on the regioselective outcomes of reactions using the concerted metallation deprotonation (CMD) mechanism between the catalyst and the substrate. It is important to note

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 total synthesis of natural products leveraging a strategy of enamide cyclization

• Chun-Yu Mi,
• Jia-Yuan Zhai and
• Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

• of the resulting acyliminium [30]. Unlike the monocyclization, which involves deprotonation of the acyliminium ion, the success of this polycyclization relies on the interception of the acyliminium ion by an aryl nucleophile, resulting in the formation of N-heterocyclic fused[6,6,5]tricycles

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

• follows a concerted metalation–deprotonation (CMD) mechanism to generate ruthenium intermediate Int-75. Subsequently, diazo compound 78 or 79 coordinates with intermediate Int-75, followed by deazidation to form the ruthenium carbenoid species Int-76. The ruthenium–aryl bond in this intermediate migrates

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

• proceeded via the anodic oxidation of diarylphosphines to diarylphosphine oxides, followed by further anodic oxidation to give phosphine oxide radicals. In the subsequent step treatment of alkoxide radicals (formed via the deprotonation of alcohols with cesium carbonate and anodic oxidation), the phosphine

• oxidation of phosphines to phosphine oxides, followed by further anodic oxidation to give a phosphine oxide radical. In the subsequent step, treatment of the thiol radical (formed via the deprotonation of thiols with cesium carbonate and anodic oxidation) with the phosphine oxide radical gave the