Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• lines, 1H NMR spectroscopy is a very useful method to follow the photoreaction, ideally upon direct irradiation in the NMR probehead (in situ NMR), because it potentially enables accurate structure elucidation. But even though this method may enable the accurate monitoring of a stepwise photochromic

• compared with the ones of the parent compound 1b [22]. The [2 + 2] photocycloaddition reaction of 1f was initiated by direct irradiation with 315 nm. The photoreaction was significantly slower (4 h to achieve photostationary state) compared with the one of the parent compound 1b (0.5 h) [22]. Monitoring

• , 3J = 1.4 Hz, 1H), 2.21 (dt, 3J = 4.5 Hz, 3J = 2.2 Hz, 1H), 2.24 (dt, 2J = 11.1 Hz, 3J = 1.4 Hz, 1H). Structures and MOST parameters of representative bis- and trisnorbornadienes 1b–d; t1/2 = half-life determined at 25 °C; n.d. = not determined. Photometric monitoring of the photoreaction of 1f in

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• and HRMS monitoring indicated that the reaction reached completion within one day. While some studies have reported the formation of hydroxamic acids from esters at neutral pH [54], in our study the conversion leading to PCP HA (Figure 1) was observed exclusively under alkaline conditions (pH ≥ 10

Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene

• Yukiho Hashimoto,
• Yuuya Kawasaki,
• Kazunobu Igawa and
• Katsuhiko Tomooka

Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30

• showed similar sense of CD signals, in which the first eluates were detected as a positive signal, and the second eluates detected as a negative signal using the monitoring wavelength at 254 nm (Figure 7). Moreover, the direct CD spectra measurements in a flow cell showed characteristic Cotton effects

• compounds 1ab and 1ad using an OJ-H column at 25 °C (OJ-H column, 4.6 mm × 250 mm, eluent: hexane/iPrOH 95:5, flow rate: 0.5 mL/min, monitoring wavelength: 220 nm). Chromatograms of HPLC analysis of 1ac (IE column, 4.6 mm × 250 mm, eluent: hexane/iPrOH 95:5, flow rate: 1.0 mL/min, monitoring wavelength: 254

• nm). Plausible phenyl-substituent effect on the stereochemical stability of 1ac. Kinetic measurements for the racemization of 1ab and 1ad. HPLC analysis of 1ab and 1ad using a CD detector at 5 °C (OJ-H column, 4.6 mm × 250 mm, eluent: hexane/iPrOH 95:5, flow rate: 0.5 mL/min, monitoring wavelength

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

• interaction mechanism is determined as mono-cyanide addition to the vinyl group via Michael reaction. These results show that symmetrical indanone-based D–π–A–π–D dyes can be used in future optoelectronic devices and environmental monitoring. Design of the functional dyes. Normalized absorption spectra of

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

• direct anodic oxidation of dinitramide anion with the formation of N-centered radical A. Monitoring of the reaction potential during electrolysis under standard conditions using a reference electrode revealed that the measured potential ranged from 2.2 V (at the start of the reaction) to 2.4 V (at the

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

• formation and ratio of the products in contrast to the substituents in the imine fragment. NMR monitoring of reactions (1a/NaSCN/AcOH or 1g/NaSCN/AcOH in MeCN) did not allow to detect any intermediates even when the temperature was lowered to 0 °C. In the 1H and 19F NMR spectra the signals of products 2a

• imino group in the E-isomer of adduct A leads to 4-thiocyano-2,5-dihydrofuran 3. Taking into account the NMR monitoring data, it can be assumed that the yield and ratio of products are influenced by the stereoselectivity of the reaction and the stability of salts 2 under reaction conditions. We also

• stirring. The reaction mixture was heated in a glycerol bath at 80 °C for 10 h. The solvent was evaporated and the residue was purified by column chromatography (eluting with hexane/acetone 1:1) to obtain the mixture of products 4 and 5. 1H and 19F NMR monitoring of 1a/NaSCN/AcOH (a, b) and 1g/NaSCN/AcOH

Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions

• Udyogi N. K. Conthagamage,
• Lilia Lopez,
• Zuliah A. Abdulsalam and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192

• permeabilization was assessed by monitoring the release of encapsulated sulforhodamine B dye, serving as a reporter for membrane perturbation. Specifically, we examined LUVs in the liquid-disordered (Ld), liquid-ordered (Lo), and gel (Lβ) phases. As control molecules, we also investigated the membrane perturbation

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• obtained from the FTIR monitoring of the cycloaddition reaction between C,N-diphenylnitrone (1a) and N-phenylmaleimide (2a) carried out as a model reaction are given in Figure 13. As illustrated in Figure 13a, the superimposed spectra of C,N-diphenylnitrone and N-phenylmaleimide are presented. Figure 13b

• molecular database). Signals of protons used in the calculation of the diastereomeric ratios (cis/trans) of cycloaddition products 3a–u. Results of studies on the recovery of solvents used in the reaction. Simplified scheme describing the reaction monitoring and solvent recovery. a) The superimposed spectra

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• efficient iodide recognition and suggests possible applications in environmental monitoring, particularly for detecting radioactive iodine species in nuclear waste streams. Additionally, the cavity size of the macrocycle can be precisely modulated by varying the number of bridging benzene substituents

Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

• Jie Yan,
• Shaodong Sun,
• Minghao Wang and
• Si Wu

Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159

• understanding of azobenzene-based solar thermal fuels has significantly advanced, driving continuous innovation in this field. The application scope of these materials has expanded beyond initial temperature monitoring [58][92][93] to practical energy utilization scenarios. For instance, Li et al. utilized

Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics

• Leticia A. Gomes and
• Steven A. Lopez

Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156

• with CASSCF (8,9)/ANO-S-VDZP, monitoring C–C-bond formation, H–C–C–C dihedral angle, and relative energy for 1 (b), 3 (c), and 5 (d). The energy is relative to the lowest total energy of each trajectory. The red trajectories return to reactant, the green trajectories form retained housane, the blue

Synthesis, biological and electrochemical evaluation of glycidyl esters of phosphorus acids as potential anticancer drugs

• Almaz A. Zagidullin,
• Emil R. Bulatov,
• Mikhail N. Khrizanforov,
• Damir R. Davletshin,
• Elvina M. Gilyazova,
• Ivan A. Strelkov and
• Vasily A. Miluykov

Beilstein J. Org. Chem. 2025, 21, 1909–1916, doi:10.3762/bjoc.21.148

• (LSV) to investigate the alkylating properties of the synthesized compounds. Unlike traditional biochemical assays, this electrochemical approach enabled real-time monitoring of protein modifications. The significant suppression of human serum albumin (HSA) oxidation peaks following exposure to

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

• of the metastable isomer [5][6][7], thus they are also important factors to consider when choosing the solvent and the concentration of the solution. The half-life can be extrapolated by monitoring the photoswitch in the metastable form over time by various spectroscopic methods (UV–vis, NMR) in the

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

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• analytical monitoring, and auxiliary functional components to achieve higher levels of system integration. Development of continuous-flow nitration processes The successful application of the flow-chemistry technology to nitration reactions necessitates a systematic approach, beginning with the judicious

• nominal operating parameters (e.g., elevated temperatures approaching the decomposition threshold of nitro compounds, prolonged residence times that may promote polynitration, or extreme reagent stoichiometries that could generate unstable intermediates) while monitoring key performance indicators such as

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

• low racemization barrier as with structurally similar methylenedioxy-substituted DBC derivative [22]. Racemization dynamics The racemization barriers of CBBC 1, mono-olefin 3, and bis-olefin 5 were evaluated by monitoring the decrease of circular dichroism (CD) signals in 1,2-dichlorobenzene at 170 °C

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• synthesized (Scheme 1, bottom). In contrast to the previously synthesized large library carbon-based NBDs [40], only a few heterocyclic derivatives were successfully isolated. During the monitoring of additional reactions attempting to reproduce the literature scope, in most cases traces of new NBD species

• -containing push–pull derivative that could be synthesized in rather high quantity and purity. Monitoring first the switching process from O-NBD2 to O-QC2 by UV–vis spectroscopy showed complete formation of O-QC2 was achieved after 5 seconds, indicated by the major decrease of the NBD signal at λmax = 392 nm

• observed π–π* absorption from λπ–π* = 294 nm to 298 nm was found. Prolonged irradiation up to 660 s led to a complete change in the overall absorption properties with maxima at λ = 348 nm and 297 nm and an absorption shoulder at λ = 228 nm suggesting photodecomposition. Next, NMR monitoring of the

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• fluorescent protein (GFP), has revolutionized genetics by providing highly accurate real-time detection of fusion proteins in vitro and in vivo [1]. Pioneering work on GFP-tagged proteins for real-time monitoring of gene expression was first reported by Chalfie and co-workers in 1994 [2]. For a long time

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• (C8F17)2 [36]. These results make it clear that monitoring photoirradiated solutions by UV–vis spectroscopy must be accompanied by complementary analyses to enable accurate interpretation of the changes in the UV–vis spectra and identification of the photoproducts. The next comparative photostability

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• was then taken at time intervals of 15–30 minutes for a total of 3 h. The UV–vis monitoring revealed that the absorbance decreases as irradiation continues, indicating photodegradation; however, no evidence of a [2 + 2] cycloaddition product was seen in the spectra (Supporting Information File 1

Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• all synthesized compounds. Thermal half-lives (t1/2) were determined by monitoring the thermal relaxation of the synthesized diazocines at 25 °C in a UV spectrometer (see Supporting Information File 1, section III). The dihalogenated N-acetyl diazocine 4 shows a significantly reduced half-life

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• . Solvent screening for the kinetic resolution of rac-1. Screening of catalyst and co-catalyst for kinetic resolution. Monitoring the kinetic resolution of 1 over time. Study of the concentration's effect on kinetic resolution. Substrate the scope of kinetic resolution reactions. Study of the kinetic

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• technique for high-throughput experimentation [83]. A further area of development would be the possibility of integrating options for the in-situ monitoring of reactions, such as X-ray and Raman techniques [47][48][84][85][86][87]. In conclusion, in recognizing that both photochemistry and mechanochemistry

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• significantly spurred the scientific curiosity of researchers over the past few decades [1]. Intensive studies revealed that this subtle code of cell surface glycans is extensively responsible for monitoring a plethora of diverse biological phenomena like post-translational modification of proteins [2][3

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• assigning specific contributions of each to the observed binding affinities. Even so, 1H NMR titration experiments with phosphine oxides still allow us to partially resolve these two forces by monitoring the proton of the CF2H group. Such issues are particularly salient when quantification methods that rely