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

• reported the first [3]rotaxane with three azobenzene units in the axle and two α-cyclodextrins as the macrocycle. The rotaxane was obtained as a single stereoisomer, where the two narrow rings of the cyclodextrin point to each other. Although no photoswitching studies were conducted, 1H NMR results showed

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• but insoluble in CHCl3, CH2Cl2, methanol, acetone, acetonitrile, and hexane; G2W4: soluble in CHCl3, CH2Cl2, acetonitrile, DMSO, and TFA but insoluble in methanol, acetone, and hexane). The new hosts G2W1–G2W4 were fully characterized spectroscopically (1H and 13C NMR, IR, MS) and the data is in

• accord with the depicted C2v-symmetric structures. Figure 3 shows the 1H NMR spectra recorded for G2W1–G2W4 in DMSO-d6 at 400 MHz. As expected, all four hosts display two singlets for the equatorial CH3 groups (a, b), two pairs of doublets for the diastereotopic CH2 groups (c,c’ and d,d’) in the expected

• deshielding effect of the lone pairs on the adjacent OCH3 group and the neighboring aromatic ring. Similarly, the number of resonances in the 13C NMR recorded for G2W1 (19 observed, 19 expected), G2W2 (17 observed, 17 expected), G2W3 (13 observed, 13 expected), G2W4 (11 observed, 11 expected) are also

Halogenated butyrolactones from the biomass-derived synthon levoglucosenone

• Johannes Puschnig,
• Martyn Jevric and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2025, 21, 2297–2301, doi:10.3762/bjoc.21.175

• fluorination attempts. Maintaining some residual solvent allowed for the characterization of compound 13 by NMR spectroscopy. Stereochemical assignment in 13 was based on a large trans-axial coupling constant JH2exo-H3 = 10.6 Hz in the 1H NMR spectrum and interactions between H3endo and H7endo on the

• oxymethylene bridge in the 2D NOESY NMR spectrum. Given the instability of fluoro-ketone 13, a one-pot procedure was developed in which the reaction mixture containing 13 was subjected to the Baeyer–Villiger oxidation with H2O2 giving the fluorinated and stable lactone 14, which is the expected kinetic product

Research towards selective inhibition of the CLK3 kinase

• Vinay Kumar Singh,
• Frédéric Justaud,
• Dabbugoddu Brahmaiah,
• Nangunoori Sampath Kumar,
• Blandine Baratte,
• Thomas Robert,
• Stéphane Bach,
• Chada Raji Reddy,
• Nicolas Levoin and
• René L. Grée

Beilstein J. Org. Chem. 2025, 21, 2250–2259, doi:10.3762/bjoc.21.172

• Supporting Information Supporting Information File 26: Detailed experimental procedures and spectral data, kinase inhibition studies, molecular modelling studies, analysis of dose-dependent effect of VS-77 on the kinase activity of Mm_CLKs and copies of the 1H and 13C NMR spectra. Acknowledgements We thank

A chiral LC–MS strategy for stereochemical assignment of natural products sharing a 3-methylpent-4-en-2-ol moiety in their terminal structures

• Rei Suo,
• Raku Irie,
• Hinako Nakayama,
• Yuta Ishimaru,
• Yuya Akama,
• Masato Oikawa and
• Shiro Itoi

Beilstein J. Org. Chem. 2025, 21, 2243–2249, doi:10.3762/bjoc.21.171

• A terminal 3-methylpent-4-en-2-ol (MPO) moiety is a common structural feature in various polyketide natural products. Stereochemical assignments of this moiety have mainly relied on computational analyses of NMR, ECD, and specific rotation data. However, none of these approaches can be applied to

• research areas, including the development of synthetic methodologies, the investigation of modes of action, and the evaluation of pharmacological potential, among others. Advancements in spectroscopic techniques, such as nuclear magnetic resonance (NMR) and mass spectrometry (MS), have enabled the

• typically determined using NMR-based techniques, such as coupling constant analysis and NOE experiments, sometimes with the aid of computational chemistry [3][4][5][6][7]. In contrast, absolute configuration remains more challenging to determine, as it frequently requires chemical degradation or

Pd-catalyzed dehydrogenative arylation of arylhydrazines to access non-symmetric azobenzenes, including tetra-ortho derivatives

• Loris Geminiani,
• Kathrin Junge,
• Matthias Beller and
• Jean-François Soulé

Beilstein J. Org. Chem. 2025, 21, 2234–2242, doi:10.3762/bjoc.21.170

• from phenylhydrazine and aryl bromides. The gray box provides a detailed list of all identified side-products. Supporting Information Supporting Information File 20: Details of optimization experiments, full characterization data, and NMR spectra (1H, 13C, 19F) for all products. Funding L.G

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• variety of new tri-, tetra- and pentacyclic ring systems. The structural characterization of (E)- and (Z)-hydrazones was supported by 2D NMR techniques, while that of the target compounds by single-crystal X-ray measurements. The hydrazone intermediates and the new title compounds were subjected to a

• spatial proximities obtained from either NOESY or ROESY NMR measurements. The NH moiety is close to N=CH in the (E) isomer, while NH is close to CH2 in the (Z) isomer. As an example, in case of hydrazone 7h, a selective 1D NOESY spectrum was recorded with the excitation of NH (Figure 2 and Figure 3). In

• both Figures, beside the selective 1D NOESY spectrum (upper part in Figure 2 and Figure 3), the 1H NMR spectrum (lower part) is also presented. The spatial proximity of NH with N=CH (marked with a red arrow in Figure 2) or with CH2 (red arrow in Figure 3) proves the (E) or (Z) configuration of the N=C

A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• , empirical approaches based on 1H NMR anisotropy method have gained attention as alternative strategies for stereochemical assignment of chiral molecules. Among these, the modified Mosher method, which utilizes the ring current effects of aryl substituents, has been extensively applied to chiral alcohols [2

• used without further purification. Melting points were obtained with a Mel-Temp capillary apparatus and were not corrected. IR spectra were obtained as KBr disks on a JASCO FT/IR-410 spectrophotometer. The FAB mass spectra were recorded using a JEOL 600H mass spectrometer. 1H and 13C{1H} NMR spectra

• were recorded on a Jeol ECP400 spectrometer (400 MHz) and a Bruker AVANCE II spectrometer (400 MHz). All NMR spectroscopic data of CDCl3 solutions are reported in ppm (δ) downfield from TMS. UV and CD spectra were recorded on JASCO V-650 and JASCO J-820 spectrometers, respectively. X-ray single-crystal

Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions

• Xiaoming Ma,
• Zijie Gao,
• Jiawei Niu,
• Wentao Shao,
• Shenghu Yan,
• Sai Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167

• 1H NMR spectra are different (Figure 2). The most evident differences are the disappearance of the signal for the alkyne H at 2.36 ppm in the spectrum of 6a and the appearance of a peak at 8.14 ppm for the proton on the triazole ring of 8a. The aromatic protons in 8a show two distinct doublets and

• 7a–k in 36–90% yields, 8a–g in 77–92% yields. Note: When 2-yn-1-amine hydrochlorides 2b–e were employed in this one-pot reaction, Et3N (0.3 mol, 1.5 equiv) was added into the vessel at the initial stage. Some bioactive molecules bearing triazole, tetrazole, and 1,4-benzodiazepin rings. 1H NMR spectra

Further elaboration of the stereodivergent approach to chaetominine-type alkaloids: synthesis of the reported structures of aspera chaetominines A and B and revised structure of aspera chaetominine B

• Jin-Fang Lü,
• Jiang-Feng Wu,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2025, 21, 2072–2081, doi:10.3762/bjoc.21.162

• intermediate 17 [65] yielded the thermodynamically stable C2/C11-trans and C3/C14-trans diastereomers 19 and 20 (dr = ca. 1:1) in a combined yield of 75% (Scheme 2). The 1H NMR spectrum of this diastereomeric mixture shows only one set of resonance signals, but two sets of resonance signals were observed on

• the 13C NMR spectrum. We have succeeded in preparing a single crystal from the oxidation products. Interestingly, the X-ray diffraction analysis [66] showed that the single crystal contained two diastereomers (19/20) with the structures displayed in Scheme 2. Similarly, the DMDO oxidation of

• cytopathogenicity in MDCK cells with IC50 values of 15.5 and 24.5 μM, respectively. Attracted by both their structure and bioactivities, we anticipated their synthesis. The author determined the structure by means of spectroscopic (1H, 13C NMR, HSQC, HMBC, and 1H-1H COSY), and MS analysis, and claimed that “their

Discovery of cytotoxic indolo[1,2-c]quinazoline derivatives through scaffold-based design

• Daniil V. Khabarov,
• Valeria A. Litvinova,
• Lyubov G. Dezhenkova,
• Dmitry N. Kaluzhny,
• Alexander S. Tikhomirov and
• Andrey E. Shchekotikhin

Beilstein J. Org. Chem. 2025, 21, 2062–2071, doi:10.3762/bjoc.21.161

• a series of 6-aminomethyl-substituted indoloquinazoline derivatives 14а–d (Scheme 5). The structures of all compounds were analyzed and confirmed by NMR and HRMS methods. Samples of all indolo[1,2-c]quinazoline derivatives with good analytical purity (HPLC, ≥95%) were further subjected to biological

Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• products capillosanol and chabranol, respectively [18]. Chabranol was identified to contain a new bridged skeleton through extensive NMR experiments. However, no single-crystal X-ray diffraction analysis was conducted, making the structural determinations not that solid. It showed moderate cytotoxicity

• subsp. brachystachys, and discovered a series of complex natural products named sargalmides A–E [43] (Scheme 7a). To clearly elucidate the complex structures, Yue and co-workers used multiple methods including extensive spectroscopic analysis (NMR, IR and MS), X-ray crystallography, quantum-chemical

Switchable pathways of multicomponent heterocyclizations of 5-amino-1,2,4-triazoles with salicylaldehydes and pyruvic acid

• Yana I. Sakhno,
• Oleksander V. Buravov,
• Kostyantyn Yu. Yurkov,
• Anastasia Yu. Andryushchenko,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2030–2035, doi:10.3762/bjoc.21.158

• control of the reaction, while oxygen-bridged heterocycles 4 are formed under thermodynamic control. The purity and structure of compounds 4 and 5 were established by elemental analysis, mass spectrometry, 1H and 13C NMR spectroscopy, and X-ray diffraction study (Figure 1). For example, the 1H NMR spectra

• characterized by the following signals in the 1H NMR spectra: a proton singlet of the pyrimidine NH group at 8.30–8.31 ppm, a multiplet of aromatic protons in the region of 6.95–7.51 ppm, a proton multiplet of the CH group at 4.65–4.68 ppm and singlet for protons for the triazole CH3O group at 3.7 ppm. The 1H

• NMR spectra of heterocyclic acids 5a–c exhibited a broad singlet of proton of the carboxyl group at 11.88–14.02 ppm, a singlet of proton of the hydroxy group at 9.41–9.86 ppm, a singlet of proton of the pyrimidine NH group at 7.72–7.91 ppm, a singlet of proton of the triazolylamine NH group at 7.44

α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• and 13C NMR spectroscopy, and by X-ray diffraction study (see Experimental part). The 1H NMR spectra of compounds 5 are characterized by the following signals: a broad carboxyl group proton singlet at 12.10–12.17 ppm, an NH group proton singlet at 7.74–8.02 ppm, an aromatic protons multiplet at 6.52

• –8.15 ppm, a CH group singlet at 5.93–6.12 ppm, triplets for two CH2 groups in the range of 2.04–2.89 ppm, a tert-butyl group singlet at 1.23–1.25 ppm, and signals for protons of the functional group. It should be noted that a doubling of the 1H NMR signals is observed for the azide derivatives 8

• compared to compounds 5, which can be clearly seen in the spectrum of compound 8h with both substituted ortho-positions of the amine moiety. In our opinion, this indicates the presence of rotamerism [59][60] caused by the restricted rotation of the sterically hindered amide group. The 1H NMR spectra of

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

• by the diene/indene 10a/11a molar ratio (determined by NMR). Among the tested diaryl-λ3-iodanes, only those containing a triflate anion showed reactivity. PhMesIOTf (I-1) and Ph2IOTf (I-2) showed comparable results in terms of diene yield, however, the symmetrical iodane I-2 displayed better

• ) catalytic cycle [28]. However, in the case of Cu(OTf)2, the active catalytic species must be generated in situ. The highest diene 10a NMR yields (63–66%) were achieved by using 20 mol % of CuCl, 3.0 equiv of Ph2IOTf (I-2) and 1.2 equiv of 2,6-di-tert-butylpyridine (B1) in EtOAc at 70 °C (Table 1, entries 16

• NMR spectra. Interestingly, the internal alkyne 7c (R = Ph, Si = TIPS) was completely unreactive under both standard arylation conditions (70 °C in EtOAc) and higher reaction temperatures (110 °C in BuOAc). In these cases, the starting material was recovered with no signs of degradation. This

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• = 4,4′-di-tert-butyl-2,2′-dipyridine) as a photocatalyst and the simple tertiary amine diisopropylethylamine (DIPEA, 5 equiv) in MeCN (0.05 M). After 24 h under irradiation with light from blue LEDs (λmax = 440 nm), the crude mixture was concentrated under reduced pressure and analyzed by 1H NMR

• spectroscopy. As shown in Figure 2, complete consumption of 1 was observed under these conditions with concomitant formation of a major new species with a characteristic 1H NMR signal at δ = 4.42 ppm (in CDCl3, Table 1, entry 1). Comparison of the spectrum with that of an authentic sample (see Supporting

• two reduction steps with an initial reaction with the acylazolium starting material being followed by a presumably more challenging second reduction of a less-activated intermediate species. Using CH2Br2 as an internal reference, a 1H NMR yield of 39% was calculated with further analysis of the crude

Asymmetric total synthesis of tricyclic prostaglandin D2 metabolite methyl ester via oxidative radical cyclization

• Miao Xiao,
• Liuyang Pu,
• Qiaoli Shang,
• Lei Zhu and
• Jun Huang

Beilstein J. Org. Chem. 2025, 21, 1964–1972, doi:10.3762/bjoc.21.152

• an inseparable mixture of diastereomers at C-15 in a ratio of 1.0/1.1 (1H NMR analysis). Having established a route to the bicyclic hemiketal 21, we investigated the stereoselective introduction of an allyl moiety at C8 for the synthesis of compound 25 according to the strategy in Scheme 3. Treatment

• ester 4. Optimization of conditions to convert diketone 15 into cyclopentanone 14.a Supporting Information Supporting Information File 42: Experimental procedures, characterization data and copies of 1H and 13C NMR spectra. Acknowledgements We thank Prof. Zhen Yang (Peking University) for helpful

Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis

• Lihua Wei,
• Rui Yang,
• Zhifeng Shi and
• Zhiqiang Ma

Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151

• confirmed by X-ray crystallographic analysis. Comparative analysis of the 1H NMR data with authentic samples of the natural heliannuol G and heliannuol H enabled structural revision of these compounds, correcting prior misassignments in the literature [31][32]. Through enzyme-catalyzed asymmetric

Rhodium-catalysed connective synthesis of diverse reactive probes bearing S(VI) electrophilic warheads

• Scott Rice,
• Julian Chesti,
• William R. T. Mosedale,
• Megan H. Wright,
• Stephen P. Marsden,
• Terry K. Smith and
• Adam Nelson

Beilstein J. Org. Chem. 2025, 21, 1924–1931, doi:10.3762/bjoc.21.150

• isolated and structurally characterised (using, where appropriate, HMBC, COSY and nOe NMR methods; see Figure 3). In general, the yields of these products were rather low, which may stem from poor (co-)substrate solubility in some cases; and/or competitive O–H insertion into adventitious water. On the

• ). Outcomes of reactions between α-diazoamide substrates and co-substrates. Supporting Information Supporting Information File 40: Experimental part and NMR spectra of synthesised compounds. Acknowledgements We thank Dan Cox, Samuel Liver, Chris Arter, Jeanine Williams, Mark Howard, Alex Heyam, Lawrence

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• introduced. In contrast, when bulky 3,5-bis(trifluoromethyl)phenyl groups were introduced, only inherent chiral macrocyclic products (MC3) were obtained in high yield. Their molecular structures are unambiguously characterized by NMR, mass spectra and X-ray crystallographic characterization. In addition

• characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Single crystals suitable for X-ray diffraction measurements of compounds 3a, MC2, and MC3 were successfully obtained to reveal their molecular structures. In the crystal structure of 3a (Figure 2a), the two pyrene units are nearly

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

• as thick liquids with good yields (44–67%) and purity. The structures of glycidyl esters of phosphorus acids 1–3 were confirmed by 31P, 1H NMR, IR spectroscopy, and elemental analysis (see Experimental part for additional information). The 31P{1H} NMR spectrum of diglycidyl methylphosphonate (1

• ) shows a singlet at +32 ppm; for diglycidyl methylphosphate (2) and triglycidyl phosphate (3) also a singlet in the region 0–1 ppm is observed, despite the presence of a chiral carbon atom in the oxirane fragment. In the 1H NMR spectra of esters 1–3 the characteristic signals of the oxirane fragment at

• 2.41–3.24 ppm and the POCH2- fragment at 3.66–4.36 ppm can be observed. The NMR data for the glycidyl esters of phosphorus acids 1–3 are comparable to those of related compounds. Biological activity of glycidyl esters of phosphorus acids To evaluate the biological activity of diastereomeric mixtures of

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• extracted three times with CH2Cl2. The combined organic layers were dried over Na2SO4, filtered and concentrated under vacuum. Yields were calculated on the reaction crude by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as internal standard. In the case of the large-scale reaction the crude was

• /cm2), total charge 2.2 F/mol, dry DMF (0.125 M). Yields reported are isolated yields. Reactions were performed on a 0.5 mmol scale. Continuous flow synthesis of piperazine 2a. The yield was determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as internal standard. Reactions were performed

• procedures and physical data for the new compounds, copies of 1H and 13C NMR spectra of the prepared compounds. Acknowledgements The authors thank Prof. A. Puglisi (Università degli Studi di Milano) for valuable discussions. For the single-crystal X-ray diffraction analysis the Unitech COSPECT (Università

Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition

• Beth L. Ritchie,
• Alexandra Longcake and
• Iain Coldham

Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146

• leaving group and activated, electron-poor dipolarophiles has been reported [31][32]. Treatment of aldehyde 4 with hydroxylamine in toluene at 60 °C for 1–3 h resulted in loss of the aldehyde as judged by 1H NMR spectroscopy of the crude mixture. When this was carried out in the presence of N

• -methylmaleimide with the mixture being heated under reflux for 3–4 h, we were pleased to obtain the spirooxindole product 5, which was formed as a mixture of stereoisomers (Scheme 3). The ratio of isomers was determined by 1H NMR spectroscopy and the major isomer could be isolated after careful column

• fumarate was also successful and gave a mixture of the stereoisomeric cycloadducts 7 (Scheme 5). The yield was high and three inseparable stereoisomers could be detected by 1H NMR spectroscopy. In each case we assume that the methyl ester groups are trans to one another due to the expected concerted nature

Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• respective isocyanate in acetonitrile at 80 °C; KSU-1 reacted with isopropyl, tert-butyl, n-hexyl, and tetradecyl isocyanate to generate KSU-1iPr and KSU-1t-Bu, KSU-1n-Hex, and KSU-1C14, respectively. Successful post synthetic reaction was observed by proton nuclear magnetic resonance (1H NMR) spectroscopy

• at the hydroxy. To prevent excessive reaction at the amine, both reactions were stopped at 2 hours. Aside from 1H NMR, the independent functionalization of KSU-1 with isocyanates was also confirmed by conducting electrospray ionization mass spectrometry (ESI–MS) on samples of the MOF products

• , diluted in CDCl3 and conversions were determined by analyzing the 1H NMR specta of the samples (Figure 3). The results showed a general increase in catalytic efficiency as we increased the lipophilicity of the MOF pores. However, the observed differences in conversion between the lipophilicized catalysts

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

• presence of H-bond acceptors [102][104][107]. The presence and the nature of the H-bond can be identified by 1H NMR spectroscopy since the N–H proton has a characteristic chemical shift depending on the H-bond acceptor [101]. Arylhydrazones based on pyridine have been intensively studied since the H-bond