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

• extraction or column chromatography. On the other hand, upon performing the reaction with amines in acetonitrile we did not observe the formation of benzamides. Presumably, debenzoylation occurred in basic media with water traces and cesium benzoate was discarded upon work-up. The presumable mechanism of the

• % was used instead of methanol, heating at 80 °C for 36 h. bThe quaternization with AlkHal (1.5 equiv) was performed at 70 °C for 7 days. cTHIQ = 1,2,3,4-tetrahydroisoquinolin-2-yl. The presumable mechanism of the domino process. Reductive elimination of the nucleophiles. Synthetic sequence and

Electrosynthetic access to unsymmetrical oxaza[8]helicenes with high chiral stability and strong circularly polarized luminescence (CPL)

• Tin Zar Aye,
• Rubal Sharma,
• Muthu Karuppasamy,
• Daiya Suzuki,
• Haruka Nakajima,
• Yoshitane Imai,
• Mitsuhiro Arisawa,
• Mohamed S. H. Salem and
• Shinobu Takizawa

Beilstein J. Org. Chem. 2026, 22, 372–382, doi:10.3762/bjoc.22.25

• intense chiroptical responses, including mirror-image CD and strong CPL with |glum| values up to 0.0026 and CPL brightness approaching 30.8 M−1 cm−1. A plausible reaction mechanism: cyclic voltammetry (CV) analyses of hydroxycarbazole derivative 3 and 2-naphthol derivatives 4; DFT-based calculations of

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• bioactive compounds underwent smooth esterification with TFE to give the corresponding 2,2,2-trifluoroethyl esters 82–85 in high yields. To elucidate the reaction mechanism, cyclic voltammetry experiments, control reactions, and DFT calculations were conducted. At the anode, bromide ions are oxidized to

• reacted smoothly with p-methoxyphenyl (PMP) amine, p-methoxybenzyl (PMB) amine, N-benzyl-N-methylamine, and indole, generating the corresponding amides 99–102 in good to excellent yields. Based on kinetic studies, the authors proposed a plausible mechanism in which the dihydrogen tetrametaphosphate

• corresponding amides 108–115 in excellent yields. Beyond benzamides, a variety of α-alkylamides possessing primary, secondary, and tertiary moieties also underwent efficient transamidation with aniline, furnishing the amide products 116–120 in excellent yields. This transformation proceeds through a mechanism

Synthesis of tricyclic fused pyrrolidine nitroxides from 2-alkynylpyrrolidine-1-oxyls

• Mark M. Gulman,
• Yuliya F. Polienko,
• Sofia Yu. Trakhininа,
• Yuri V. Gatilov,
• Tatyana V. Rybalova,
• Sergey A. Dobrynin and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2026, 22, 344–351, doi:10.3762/bjoc.22.22

• that this methylene fragment has a more fixed conformation, consistent with the annulated structure (Figure 4). Nitroxides are known to decay in biological systems; the major mechanism is chemical reduction with cellular antioxidants (ascorbic acid and glutathione) and enzymatic systems [34]. The rate

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

• deliver the most common terpene frameworks. In some instances, these enzymes can also effect ring contraction or expansion directly during the initial cyclisation mechanism [19][20][21][22][23][24][25][26][27]. In many cases though, the ring-altering reaction instead takes place at a later stage of

• single, concerted step. This concerted mechanism allows the reaction to bypass a high-energy, non-stabilised secondary carbocation intermediate that would result from a stepwise migration. This pathway is facilitated by the enzyme's active site, where aromatic residues (e.g., Tyr564) are proposed to

• mechanism could be enabled by deprotonation through an active-site base (32b) and re-protonation of the cyclopropane moiety (32c). A 1,2-hydride shift, followed by a 1,2-methyl shift towards that same carbon and an elimination, forms the tetrasubstituted double bond in 33, the precursor for sodorifen (32

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• in the maleimide: in most cases the endo-isomer is the main (or only) product, but for some N-arylmaleimides the exo-product is predominant. The proposed mechanism is discussed, and the products were characterized by detailed spectral analysis. The configuration of the stereocenters was determined by

• azabicyclo[3.1.0]hexane and cyclopropa[a]pyrrolizine moieties can be synthesized via 1,3-dipolar cycloaddition between cyclopropene derivatives and azomethine ylides generated in situ from alloxan and α-amino acids [43]. In [43], a mechanism was proposed for the formation of azomethine ylides from alloxan

• unable to isolate individual products either by chromatography or by recrystallization. The proposed reaction mechanism is shown in Scheme 5, where it can be seen that the intermediate azomethine ylide, acting as a 1,3-dipole, undergoes a [3 + 2] cycloaddition with N-substituted maleimides 3a–p. The

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

• , display remarkable substitution inertness, even toward strong π-acids and good σ-donors. The substitution rate being relatively independent of the incoming ligand is consistent with a dissociative substitution mechanism. Typically, coordination occurs at positions that minimally disrupt the arene π-system

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

• yields (Scheme 5). The proposed mechanism of the four-component reaction is illustrated in Scheme 6. ʟ-Proline, via its amino group, nucleophilically attacks the carbonyl of the aromatic aldehyde, forming an iminium zwitterion intermediate A. Concurrently, ʟ-proline promotes the generation of the

• consistently confirmed the trend: greater electrophilicity is observed for the carbonyl carbon in pyranoquinoline, corroborating the experimental observations. Based on these results, the proposed mechanism of the multicomponent reaction involves initial lactone formation, followed by ring opening

• using various approaches. Four-component synthesis of 3-(6-halo-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-3-(3,4-dimethoxyphenyl)propanoic acid esters 9 and 10. The proposed mechanism of the four-component reaction. Synthesis of isopropyl (12a–c) and cyclohexyl (13а–с) esters of 3-(4-hydroxy-2-oxo-1,2

Synthesis of diaryl phosphates using phytic acid as a phosphorus source

• Kazuya Asao,
• Seika Matsumoto,
• Haruka Mori,
• Riku Yoshimura,
• Takeshi Sasaki,
• Naoya Hirata,
• Yasuyuki Hayakawa and
• Shin-ichi Kawaguchi

Beilstein J. Org. Chem. 2026, 22, 213–223, doi:10.3762/bjoc.22.15

• the other mechanism is based on an E2 reaction, which involves the elimination of phosphoric acid accompanied by alkene formation. The phosphoric acid ester of a secondary alcohol releases phosphoric acid and alkenes through thermal degradation, which has been previously observed using isosorbide

Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

• ). Therefore, the reaction is most likely not proceeding via a free radical mechanism. To clarify the influence of the amide group on the developed transformations, dihydrothiophene 4g bearing a sulfonylimine group instead of an amide was treated with sodium methoxide in methanol or with sodium ethoxide in

• elemental sulfur S6. Probably, the reaction is accompanied by the desulfurization of the oxidized intermediate, which causes the yellow color of the reaction solutions. The proposed mechanism for the developed transformations is depicted in Scheme 6. The reaction of dihydrothiophene 1a with sodium ethoxide

• (0.13–0.22 mmol, 1.0 equiv), sodium (0.66–1.11 mmol, 5 equiv), dry EtOH (2.5–3.0 mL). Control experiments. Proposed mechanism. Optimization of the transformation of dihydrothiophene 1a.a Optimization of the transformation of dihydrothiophene 4a.a Supporting Information Supporting Information File 17

Circumventing Mukaiyama oxidation: selective S–O bond formation via sulfenamide–alcohol coupling

• Guoling Huang,
• Huarui Zhu,
• Shuting Zhou,
• Wanlin Zheng,
• Fangpeng Liang,
• Zhibo Zhao,
• Yifei Chen and
• Xunbo Lu

Beilstein J. Org. Chem. 2026, 22, 158–166, doi:10.3762/bjoc.22.9

• reactivities of the two diastereomers. Although these findings strongly support the occurrence of a partial kinetic resolution, further kinetic measurements would be required for definitive confirmation. A plausible mechanism is outlined as follows. First, the sulfenamide 1 is oxidatively brominated by N

Asymmetric Mannich reaction of aromatic imines with malonates in the presence of multifunctional catalysts

• Kadri Kriis,
• Harry Martõnov,
• Annette Miller,
• Mia Peterson,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2026, 22, 151–157, doi:10.3762/bjoc.22.8

• . Although the activation mechanism was not proved unambiguously, it is assumed that steric effects of the chiral fragment together with a network of noncovalent interactions, including halogen and hydrogen bonds, are responsible for the high enantioselectivity of the reaction. Further developments of the

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

• theory (DFT) methods. The dyes also exhibit chemosensor properties, showing selectivity for cyanide via a Michael addition mechanism that causes the disappearance of the ICT band, and a significant color change was observed in both organic and aqueous media. In addition, the interaction mechanism between

• under ambient light. In addition, interaction mechanisms of dyes with cyanide were studied using the 1H NMR titration method, and it was determined that they interacted through an addition mechanism. Photophysical properties and interaction mechanisms of the compounds were also supported through density

• groups is disrupted. These results strongly suggest the addition of cyanide to the vinyl bridge. Furthermore, the color of dyes 2a–c, blue, green, and pink, respectively, under ambient light changed to yellow when interacting with cyanide. The interaction mechanism was determined by 1H NMR, and the

Highly electrophilic, gem- and spiro-activated trichloromethylnitrocyclopropanes: synthesis and structure

• Ilia A. Pilipenko,
• Mikhail V. Grigoriev,
• Olga Yu. Ozerova,
• Igor A. Litvinov,
• Darya V. Spiridonova,
• Aleksander V. Vasilyev and
• Sergey V. Makarenko

Beilstein J. Org. Chem. 2026, 22, 123–130, doi:10.3762/bjoc.22.5

• –C2H protons of the cyclopropane ring (3JH(1)H(2) = 5.7–7.5 Hz) indicate their transoid arrangement [38][39][45]. This makes it possible to assign 1SR,2RS configurations to the stereocenters. The proposed mechanism for this transformation is depicted in Scheme 6. Michael addition of the CH-acid anion I

• -fused trichloromethylnitrocyclopropane 6. Synthesis of spiro-fused trichloromethylnitrocyclopropanes 7–9. i: 1.5 AcOK, MeOH, rt, 3 h. Main NOE correlations in 9a, 9b. Proposed mechanism of the formation of trichloromethylnitrocyclopropanes. Reaction of compound 1 with malononitrile leading to

Advances in Zr-mediated radical transformations and applications to total synthesis

• Hiroshige Ogawa and
• Hugh Nakamura

Beilstein J. Org. Chem. 2026, 22, 71–87, doi:10.3762/bjoc.22.3

• intramolecular addition to the olefin, affording the cyclized acetal product 4. The reaction proceeded efficiently across a range of substrates bearing various substituents at R¹–R⁴, delivering the desired cyclized products 4a–f in good yields. The proposed mechanism is illustrated in Scheme 1C. Initially

• , demonstrating excellent functional group tolerance. The proposed mechanism is shown in Scheme 2C. Zirconocene dichloride is first reduced by zinc dust to generate ZrII. The resulting low-valent zirconium species reacts with the alkyl iodide to form a metal-centered radical intermediate. This species undergoes

• molecules such as allose (23i) and cholesterol (23k), delivering the desired alcohols in good yields with excellent regioselectivity. The proposed mechanism is shown in Scheme 5C. Homolytic cleavage of the C–O bond in the epoxide generates a strong Zr–O bond, while the resulting alkyl radical abstracts a

Reactivity umpolung of the cycloheptatriene core in hexa(methoxycarbonyl)cycloheptatriene

• Dmitry N. Platonov,
• Alexander Yu. Belyy,
• Rinat F. Salikov,
• Kirill S. Erokhin and
• Yury V. Tomilov

Beilstein J. Org. Chem. 2026, 22, 64–70, doi:10.3762/bjoc.22.2

• chlorine is associated with an increase in energy of the lowest unoccupied molecular orbital of halogen molecules and a decrease in their electrophilicity. Therefore, if an electrophilic mechanism takes place, iodine apparently reacts with the main conformer faster than a transition to conformer 2' may

• possibility of i-halogenation via a chain radical mechanism (Scheme 3). The initiation stage includes an oxidation of anion 2 into the corresponding radical 13 which in turn reacts with halogens to form products 4a,b and a halogen atom which can also oxidize the anion. Quantum chemical calculations revealed

• negative free energy changes for all the stages of this reaction. A chlorination experiment with 2,2,6,6-tetramethylpiperidinyloxyl revealed a trace amount of a trap product detected by high-resolution mass spectrometry to support the radical mechanism. However, this does not exclude the possibility of a

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

• synthesis lies beyond the scope of the present discussion. Regarding the use of color in graphical representations, structural highlighting was applied selectively, only when judged necessary in the clear identification of the transformation or mechanism depicted. Chapter 2 highlights key applications of

• unable to efficiently separate 61 from side product 94, which was likely formed via addition of acetyl chloride to 61 followed by conversion of the ketone to the alkenyl chloride. Regarding the mechanism (Scheme 18B), acid-catalyzed enolization of the ketone is proposed (enol I), followed by acetylation

• compound loss or degradation at the purification step. 1.2 Exchange reactions This chapter deals with exchange reactions, meaning that a given substituent on the alkene is formally exchanged for chlorine. The reactions are very different from each other in terms of mechanism and for a full discussion the

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

• nucleophilic substitution of –ONO2 groups. To clarify the reaction mechanism, cyclic voltammetry (CV) studies were conducted. CV curves of cyclohexanone oxime (S1), 1-bromo-1-nitrosocyclohexane (S2), 1-chloro-1-nitrosocyclohexane (S3), 1-nitrosocyclohexyl acetate (S4), 1-nitro-1-nitrosocyclohexane (1c), 1

• product nitro-NNO-azoxy propane 2a exhibits an oxidation peak at +1.68 V (Figure 2, pink curve). Despite the lower oxidation potential of 2a, we speculate that an excess of ADN suppresses competitive oxidation of the reaction product. To gain insight into the reaction mechanism, control experiments were

• studied reaction was also carried out under controlled potential conditions (Scheme 4, reaction 2) at E ≈ 1.8 V for 2.0 F per mol 1a. In this case, the formation of 2a was observed in a 68% yield. To gain insight into the reaction mechanism of the discovered nitro-NNO-azoxylation process quantum chemical

Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones

• Svetlana O. Kushch,
• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess,
• Pavel A. Slepukhin,
• Alexandrina S. Volobueva,
• Vladimir V. Zarubaev and
• Victor I. Saloutin

Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209

• minor when heated in 1,4-dioxane (Scheme 3, Table 3). Previously, we proposed and experimentally confirmed an aldol mechanism underlying the three-component cyclization of polyfluoroalkyl-3-oxo esters with α-methylene ketones and amines in piperidone derivatives. According to this mechanism, the key

• , AcOH, Et3N, 60 °C. The proposed mechanism of three-component cyclization of 3-oxo ester 1, methyl ketones 2a–d and 1,3-diaminopropan-2-ol (3). Optimization of the reaction conditions for ethyl trifluoroacetoacetate (1), acetone (2a) and 1,3-diaminopropan-2-ol (3). The conversion and the preparative

Mechanistic insights into hydroxy(tosyloxy)iodobenzene-mediated ditosyloxylation of chalcones: a DFT study

• Jai Parkash,
• Sangeeta Saini,
• Vaishali Saini,
• Omkar Bains and
• Raj Kamal

Beilstein J. Org. Chem. 2025, 21, 2703–2715, doi:10.3762/bjoc.21.208

• Jai Parkash Sangeeta Saini Vaishali Saini Omkar Bains Raj Kamal Department of Chemistry, Kurukshetra University, Kurukshetra, Haryana 136119, India School of Basic and Applied Sciences, Raffles University, Neemrana, Rajasthan 301705, India 10.3762/bjoc.21.208 Abstract In this paper, the mechanism

• nature of para-substituents on the reaction mechanism. The substituents considered in the study include -OCH3, -SCH3, -Cl and -NO2 groups. For these chalcones, different possible pathways at various steps during the reaction are investigated leading to formation of α,β-ditosyloxy ketones and β,β

• -ditosyloxy ketones. It is found that the mechanism for the formation of α,β-ditosyloxy ketone involves only electrophilic addition of HTIB, and the mechanism is the same for all studied chalcones, irrespective of whether an electron-donating or electron-withdrawing substituent is present on the aryl ring

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

• (c, d) reaction mixtures in MeCN. Examples of hydrothiocyanation/cyclization of alkynes. Plausible reaction mechanism. Oxidation of isothiazolium thiocyanate 2a. Screening of reaction conditions. Scope of iminopropargyl alcohols 1. Supporting Information Supporting Information File 10: Full

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

• compounds 3n and 4n was carried out using torsion angle analysis and 13C NMR chemical shift calculations to evaluate the absence of expected signals in the NMR spectra of these compounds. Their photophysical properties were also assessed, confirming a preference for a fluorescence mechanism via an ICT

• . Photophysical studies indicated a fluorescence mechanism via intramolecular charge transfer (ICT). Results and Discussion Synthesis of 5-arylidene derivatives under microwave heating To find the ideal reaction conditions for the synthesis of 5-arylidene derivatives, benzaldehyde (1a) and rhodanine (2a) were

• decrease in yields (Table 1, entries 19–21). To confirm the critical role of ethylenediamine in the reaction mechanism, an experiment without its presence was conducted, resulting in only 2% of the desired product (Table 1, entry 22). With the optimized reaction conditions established, this methodology was

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

• Lewis acid-mediated traditional Friedel–Crafts acylation of 2-methoxynaphthalene typically proceeds at the ortho positions relative to the methoxy group due to the electron-rich nature of these sites, while the meta position remains deactivated under the ionic mechanism. Notably, the present work

Total syntheses of highly oxidative Ryania diterpenoids facilitated by innovations in synthetic strategies

• Zhi-Qi Cao,
• Jin-Bao Qiao and
• Yu-Ming Zhao

Beilstein J. Org. Chem. 2025, 21, 2553–2570, doi:10.3762/bjoc.21.198

• . While its mechanism remains incompletely understood, this additive’s unique efficacy in such transformations is unprecedented. Subsequent steps involved hydroxylation of the double bond and the protection of the vicinal diol as a dimethyl ketal giving ester 100. Oxidative dehydrogenation, benzyl

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

• measurably bioactive, including those serving as controls for the five bioactive derivatives, highlighting the additional importance of structural rigidity on bioactivity within this series. Elucidation of the mechanism of action for these bioactive pentacyclic compounds will be the focus of future

• similarity showed significant antimicrobial potency towards Gram-positive bacteria and yeast relative to their non-annulated control analogs as well as to the other annulated pentacycles in this study, warranting a future investigation into their possible mechanism of action. Studies focusing on the