Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• formation of this inclusion complex, circular dichroism spectroscopy represents a powerful tool when combined with nuclear magnetic resonance (NMR) and X-ray single-crystal analysis. This is because the induced circular dichroism (ICD) can be observed on the guest molecule of the inclusion complex derived

• ratio. Namely, the inclusion of CD prevented the aggregate formation of the conjugative polymer backbone, which usually induces a change in the absorption wavelength. Similarly, in fluorescence spectroscopy, the restriction of the nonradiative deactivation was caused by the inclusion structure

• after the de-crosslinking of the gel. In addition to the qualitative observation by the naked eye, the quantitative kinetic analysis of this decrosslinking was conducted by fluorescence spectroscopy. Such a quantitative study became possible thanks to the defined rotaxane structure, which supported the

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• configuration of the double bond was confirmed using 1H,1H-NOESY spectroscopy. As shown in Figure 2, a correlation between protons of the allyl moiety and the aryl substituent evidenced their spatial proximity in molecule 1c. The absence of a correlation between allyl and vinyl protons additionally supported

Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• S20 in Supporting Information File 1). An average binding constant for oxalate of log K = 4.39 was obtained by UV–vis spectroscopy (Figures S21–S26 in Supporting Information File 1) since the intermediate-like exchange prevents the determination directly from the 1H NMR titration. The binding constant

gem-Difluorovinyl and trifluorovinyl Michael acceptors in the synthesis of α,β-unsaturated fluorinated and nonfluorinated amides

• Monika Bilska-Markowska,
• Marcin Kaźmierczak,
• Wojciech Jankowski and
• Marcin Hoffmann

Beilstein J. Org. Chem. 2024, 20, 2946–2953, doi:10.3762/bjoc.20.247

• E-isomer of products 9 were identified. The fluorine atom signals of 9a–d were located at approximately −112 ppm (triplets, J ≈ 27 Hz, Fβ) and at −155 to −159 ppm (multiplets, Fα). The stereochemistry was determined by 19F{1H} NMR spectroscopy. The observed coupling constants J ≈ 2 Hz between

• addition–elimination reaction, affording the corresponding fluorinated 13a–d (Scheme 4) and nonfluorinated 14a–d (Scheme 5) unsaturated products. Also this time, for compounds 13a–d, the formation of only Z isomers was observed (Scheme 4). The stereochemistry was determined by 19F{1H} NMR spectroscopy

Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• product compared to the substitution of phenyl (Scheme 4, 6c). Furthermore, n-butyl isocyanide was used to increase the variety of products and the n-butyl-substituted products 6f–h were obtained with 72–78% yield . All the products were characterized by 1H NMR, 13C NMR, and infrared spectroscopy, and

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• spectroscopy, HPLC–HRESIMS) of the products of the investigated reactions unambiguously confirms the processes proceeding along routes A1 and B1 with the formation of N-aryl(alkyl)-7-oxo-5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidin-5-carboxamides 4a–i and N-aryl-2-(7-oxo-5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidin

Mechanochemical difluoromethylations of ketones

• Jinbo Ke,
• Pit van Bonn and
• Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

• standard reaction conditions with difluorocarbene precursor TMSCF2Br (2, 2.0 equiv), activator KFHF (4.0 equiv), and grinding auxiliary CsCl (4.0 equiv), difluoromethyl enol ether 3a was obtained after 90 min reaction time at 25 Hz in 74% yield, determined by quantitative 1H NMR spectroscopy (Table 1

• spectroscopy with 1,2-dichloroethane as the internal standard. After these analyses, isolating the products by column chromatography was attempted. Unfortunately, many products were highly volatile and very non-polar, rendering the purification difficult. As a result, in several cases only little or no product

• was obtained. Furthermore, most isolated products had only purities of ca. 90% still containing inseparable impurities (as revealed by NMR spectroscopy). In the first series of substrates, acetophenone derivatives with various para-substituents were applied. Similar to methyl tolyl ketone (1a), which

Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction

• Yuta Kabumoto,
• Eiichiro Yoshimoto,
• Bing Xiaohuan,
• Masato Morita,
• Motohiro Yasui,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233

• scope for the present [1,3]-proton shift reaction. aYields are determined by 19F NMR spectroscopy. Values in parentheses show isolated yields. Enantiomeric excesses are deteremined by HPLC equipped with DAICEL CHIRALPAK AD-H. bCarried our at 50 °C in the [1,3]-proton shift reaction step. Proposed

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• was studied by UV–vis and fluorescence spectroscopy. Keywords: cross-coupling; cyclization; heterocycles; palladium; Introduction Nucleobases contain the coded information and give DNA and RNA their typical structure. As a nucleobase, uracil is involved in numerous vital processes and is therefore a

• -based benzo[f]quinazoline-1,3(2H,4H)-diones C [65]. Furthermore, optical properties were analysed by UV–vis and fluorescence spectroscopy. Results and Discussion Synthesis Our strategy for the synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones is based on a four-step sequence and relies on a combination

• properties All synthesized compounds exhibit photoluminescence by excitation with UV light. Hence, we studied the photophysical properties of all obtained derivatives 5 by steady-state absorption and fluorescence spectroscopy. The influence of the substitution pattern on the photophysical properties is

Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers

• Yukiko Karuo,
• Keita Hirata,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226

• mixture of diastereomers (diastereomer ratio = 1:1) for cross-coupling, and the corresponding compounds 2 and 3 were obtained as mixtures of diastereomers in a certain ratio as estimated by proton and fluorine NMR spectroscopy. Substrate scope for cross-coupling reactions The substrate scope was

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• characterized using 1H NMR, 13C NMR, FTIR spectroscopy, and elemental analysis. Next, in a model experiment, we carried out the decarbonylation–oxidation reaction of 5-methyl-3-phenylbenzofuran-2(3H)-one (3ba) using different bases in different solvents (Table 1) under open atmospheric conditions. In the

• the 7-position does not hinder the reaction. Further, to understand the origin of the product, we monitored the progress of the reaction of 3aa using 1H NMR spectroscopy. Aliquots from the reaction mixture were taken at different time intervals (Figure 4), THF evaporated under vacuum, and the residue

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• -FF fibres (Figure 3). However, Fourier-transform infrared spectroscopy indicated that the Fmoc-S assembled on the surface of the Fmoc-FF fibres. The addition of carboxylate ions at the fibre surface allows cross-linking to occur, altering the bulk physical properties of the gel [20]. While the

• , cells that allow for the coupling of SAS with non-X-ray techniques continue to be developed; these include spectroscopy, rheology, and electrochemistry [62][63][64]. Ascribing changes in properties of interest directly to changes in the structure further elucidates the interesting properties of self

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• formation of various unidentified byproducts. The obtained tetronic acids 4 are solid crystalline compounds, whose structure was proved by 1H, 13C NMR spectroscopy and high-resolution mass spectrometry. The 1H NMR spectra of the synthesized products contain characteristic signals of protons of the methyl

Transition-metal-free synthesis of arylboronates via thermal generation of aryl radicals from triarylbismuthines in air

• Yuki Yamamoto,
• Yuki Konakazawa,
• Kohsuke Fujiwara and
• Akiya Ogawa

Beilstein J. Org. Chem. 2024, 20, 2577–2584, doi:10.3762/bjoc.20.216

• arylboronates 3 using triaylbismuthines 1 and diboron 2. Yields were determined by 1H NMR spectroscopy based on 1 as three transferable aryl groups (internal standard: 1,3,5-trioxane). Isolated yield was shown in parentheses. aCHCl3 (0.4 mL) was used as the solvent. Control experiment of the metal-free

Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

• Olivier Lessard,
• Mathilde Grosset-Magagne,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208

• ) [24]. The solution and the solid-state conformational analysis were supplemented with DFT calculations to understand key conformational drivers. This study adds more data to the field of nuclear magnetic resonance (NMR) spectroscopy of polyhalogenated molecules. It should be noted that the NMR

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• by chromatography. Examples of trifluoromethoxylated drugs. Proposed mechanism of the reaction and 19F NMR of the DDPYOCF3/PhSeBr mixture. Phenylseleno trifluoromethoxylation of various alkenes. Yields determined by 19F NMR spectroscopy with PhCF3 as internal standard (in parentheses isolated yields

• ). a24 h. b48 h. Degradation of 2a under acidic conditions. Radical deselenylation of 2. Yields determined by 19F NMR spectroscopy with PhCF3 as internal standard (in parentheses isolated yields). Reaction of 1a with PhSeX and DDPyOCF3.a Supporting Information Supporting Information File 116: Additional

Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• )AuCl was applied with a catalyst loading of 2 mol %, activated by an equal amount of the DAI salt. Due to solubility issues, the reaction had to be performed in methylene chloride instead of chloroform. The gold-catalyzed cyclization reaction (Scheme 2) was followed via 1H NMR spectroscopy (Figure 3

• ]. For all catalyst systems, decomposition of the −BArF24 anion was observed via 1H and 19F NMR spectroscopy, which is known to happen in the presence of activated gold complexes [29]. The stability of the DAI cations was checked with 1H NMR: the characteristic doublets belonging to the respective

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• proton in triphenylmethane (3, Scheme 4, bottom). Further, the yield was determined to be 67% by 1H NMR spectroscopy. These results indicated that the triphenylmethyl anion species generated by electroreductive C(sp3)–O bond cleavage acted not as nucleophile toward carbon dioxide but as base, performing

• MgSO4. Evaporation of the solvent gave a residue that was analyzed by 1H NMR spectroscopy, during which 1,4-dinitrobenzene was used as an internal standard for quantification of the substances. The products diphenylacetic acid (2a) [30][31], (4-methylphenyl)phenylacetic acid (2d) [32], (4-methoxyphenyl

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• , compounds 6–9 are products of alkylation of the nitrogen atom of the heterocycle. Thiones 6–9 were obtained in 40–79% yield (Scheme 1,b). The structures of synthesized compounds were confirmed by the spectral methods IR-, 1H NMR, 13C{1H} NMR spectroscopy (Figures S1–S18 in Supporting Information File 1

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• active catalytic species in COBI-catalysed allylations, chemical equilibria in a solution containing catalyst 72, triflic acid, and aldimine 73 were investigated by low-temperature NMR spectroscopy (Scheme 15). Protonation of oxazaborolidine 70 with triflic acid resulted in an 8.3:1 mixture of 71 and 72

Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system

• Yuri A. Sidunets,
• Valeriya G. Melekhina and
• Leonid L. Fershtat

Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200

• , indicating that the developed tandem protocol does not depend on the presence of the N-oxide moiety in the parent heterocycle. All synthesized triazinones 1 and 7 were fully characterized by IR, 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry. The structure of compounds 1b and 7h was

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• spectroscopy under ambient conditions. The CV of DAntM species showed a reversible wave at E1/2 = −0.20 V (V vs Fc/Fc+) (Figure 5a) [39]. This redox potential is close to that of TAntM radical and cation [17]. Additionally, at a scan rate of 0.1 V s−1, the current peak intensity on the anodic side (from

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• . Chemical shifts of NMR were reported in ppm relative to the residual solvent peak at 7.26 ppm for 1H NMR spectroscopy and 77.6 ppm for 13C NMR spectroscopy. Coupling constants (J) were given in Hz. The resonance multiplicity was described as s (singlet), t (triplet), and m (multiplet). FTIR spectra were

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

• Haifeng Yu,
• Wanting Zhang,
• Xuejing Cui,
• Zida Liu,
• Xifu Zhang and
• Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

• by other acids such as H2SO4 and CF3SO3H, the reaction showed poor effectiveness due to the poor solubility of 1a in water (Table 1, entries 4 and 5). Most notably, 2a was an inseparable mixture of keto and enol isomers, reaching a keto/enol ratio of 5:4 as determined by 1H NMR spectroscopy. Thus

• . Reaction conditions A: 1 (0.25 mmol), DBSA (87.9 mg, 0.25 mmol), H2O (1 mL), reflux, 5 h. Isolated yield is stated. Keto/enol ratio of 2 was determined by 1H NMR spectroscopy. Synthesis of β-keto amides 3. Reaction conditions B: 1 (0.25 mmol), NaOH (0.75 mmol, 30 mg), H2O (1 mL), reflux, 24 h. Isolated

• yield is stated. Keto/enol ratio of 3 was determined by 1H NMR spectroscopy. Gram-scale hydrolysis reactions of 1a. Proposed mechanism for formation of β-keto thioesters 2 and β-keto amides 3. Optimization of the reaction conditions. EcoScale calculations and results for the synthesis of 2a and 3a [75

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• spectroscopy to determine that the deposited metal was tin, with traces of other metals consistent with the purity of the initial tin source. The tin recovery was 99% of the theoretical. To explore recycling of this recovered tin, 1 mmol was used in a 0.5 mmol scale allylation of anisaldehyde under the

• funnel with the aid of 10 mL of deionized (DI) water followed by 20 mL of diethyl ether. The organic layer was separated, dried with anhydrous magnesium sulfate, filtered, and the solvent removed in vacuo to afford the crude product, which was first analyzed by 1H NMR spectroscopy and then purified using

• sulfate, filtered, and the solvent removed in vacuo to afford the crude product, which was first analyzed by 1H NMR spectroscopy and then purified using flash column chromatography. The graphite electrodes were not polished in between reactions, but were rinsed with DI water and then acetone. General Sn