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

• reaction mechanism. Investigation of the reaction conditions. Supporting Information Supporting Information File 3: Full experimental details, 1H, 13C, 19F NMR spectra of 16a–g and 23a–g, and HPLC charts of racemic as well as chiral compounds 23a–g. Supporting Information File 4: Crystallographic

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• laboratory, and the results will be reported in due course. Experimental General methods 1H, 13C and 19F NMR spectra were recorded on a JEOL 400 spectrometer (at 400 MHz, 101 MHz and 376 MHz, respectively). Unless otherwise stated, NMR spectra were recorded using residual solvent as the internal standard; 1H

• NMR: TMS = 0.00; (CD3)2SO = 2.50; and 13C NMR: CDCl3 = 77.16; (CD3)2SO = 39.52. Data for 1H NMR spectra are reported as follows: chemical shift (δ ppm), multiplicity, coupling constants (Hz) and integration. Data for 13C NMR spectra are reported in terms of chemical shift (δ ppm). Interpretation of

• spectra has been made also with the aid of gCOSY, gHSQC and gHMBC experiments. The following abbreviations are used to indicate the multiplicity in NMR spectra: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet. For some compounds the extra peaks are due to residual of the starting material (<5

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

• , bathochromically shifted absorption and emission spectra with elevated extinction coefficients and quantum yields up to 71%. Further studies will be directed to the synthesis to polycyclic, π-conjugated uracil derivatives. Experimental General information Nuclear magnetic resonance spectra (1H/13C/19F NMR) were

• )-dione (4g). Compound 4g was obtained as a brown solid in 58% yield (58.3 mg, 184 µmol, Rf 0.19 (heptane/ethyl acetate 3:2)); mp 152–154 °C; IR (ATR) ν̃: 1695 (s), 1642 (vs), 1582 (s), 1493 (s), 1440 (s), 1421 (s), 1176 (m), 1079 (m), 756 (s) cm−1; 1H NMR (500 MHz, chloroform-d) δ 7.51–7.48 (m, 2H), 7.45

• –7.41 (m, 2H), 7.41–7.36 (m, 2H), 7.34–7.29 (m, 2H), 7.24–7.21 (m, 2H), 3.71 (s, 3H), 3.45 (s, 3H); 13C {1H} NMR (126 MHz, chloroform-d) δ 162.1, 151.6, 134.3, 133.2, 131.9, 130.9, 130.5, 128.7, 128.3, 128.0, 120.7, 119.0, 104.2, 81.0, 34.6, 28.7; EIMS (70 eV) m/z (%): 315 (100, M+), 258 (26), 230 (67

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

• and 3 as new fluorine-containing building blocks. Experimental General information 1H NMR, 19F NMR, and 13C NMR spectra were recorded on JEOL ECZ 400S spectrometers. Chemical shifts of 1H NMR are reported in ppm from tetramethylsilane (TMS) as an internal standard. Chemical shifts of 13C NMR are

• reported in ppm from the center line of the triplet at 77.16 ppm for deuteriochloroform. Chemical shifts of 19F NMR are reported in ppm from CFCl3 as an internal standard. All data are reported as follows: chemical shifts, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, sep = septet, br

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

• developed. NMR studies confirmed the role of in-situ-generated hydroperoxide in the conversion. The protocol was applied to a diverse range of substrates to access the target products in good to excellent yields. A structure–activity study for the 5-substituted-2-hydroxybenzophenones towards UV-protection

• 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

• , all the structures corroborated with the expected structure, as shown in Figure 3. To confirm the formation of hydroperoxide in THF via autooxidation, freshly distilled THF was heated under open atmosphere at 50 °C for 4 h, and was concentrated under vacuum to obtain the hydroperoxide residue. 1H NMR

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

• Jonas Holste,
• Paul Weldon,
• Donald Boyer and
• Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

• ) were observed with similar mass spectra. The amount of secretion available and the complex mixture did not allow for the isolation of enough material for NMR analysis. Therefore, for the structure elucidation of these unknown compounds, we used different analytical methods, including GC–MS, GC–IR, and

• diastereomers were then subjected to silver nitrate column chromatography to separate the geometric isomers. This separation was only partially achieved (Supporting Information File 1, Figure S10), but one diastereomer was enriched and the sample was subjected to NOESY NMR experiments. Coupling was observed

• ) and C-6-methyl (1.56 ppm) and was assigned as the E-diastereomer. This assignment is further supported by the 13C NMR spectra. The major diastereomer shows C-7 at 39.7 ppm, a typical value for (E)-configured aliphatic chains with allylmethyl groups [29], while the (Z)-isomers show values around 30 ppm

Deciphering the mechanism of γ-cyclodextrin’s hydrophobic cavity hydration: an integrated experimental and theoretical study

• Stiliyana Pereva,
• Stefan Dobrev,
• Tsveta Sarafska,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2024, 20, 2635–2643, doi:10.3762/bjoc.20.221

• molecule (O2/O3 side of the truncated cone). These hydrogen bonds have been detected experimentally by NMR: it was supposed that the OH-3 group of one glucose monomer is interacting with the OH-2 group of the neighboring glucose unit [21][22]. Experimental evidence for the involvement of primary hydroxy

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

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

• Alfiya R. Gimadieva,
• Yuliya Z. Khazimullina,
• Aigiza A. Gilimkhanova and
• Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

• classes. Experimental 1H and 13C NMR spectra were recorded on a Bruker Avance III 500 MHz spectrometer at 500.13 MHz (1H) and 125.73 MHz (13C) with 5 mm QNP sensors at a constant sample temperature of 298 K. The solvents were DMSO-d6, D2O, CDCl3 and the internal standard was SiMe4. Chemical shifts in the

• 13C and 1H NMR spectra are given in parts per million (ppm). Elemental analyses were performed on a CHNS Euro-EA 3000 automatic analyzer. Melting points were determined on combinated Boetius tables. IR spectra were obtained on an IR Prestige-21 Shimadzu spectrophotometer in KBr pellets. Freshly

• brown color. After recrystallization from ethanol, 1.11 g (90%) of pyridine 9 were obtained as a light yellow powder. Mp 108–110 °С; 1H NMR (CDCl3) δ 6.16 (dd, 1H, С5H), 6.38 (d, 1H, С3H), 7.38 (d, 1H, С6H), 7.40 (dd, 1H, С4H), 11.5 (s, 1H, C1-OH); 13С NMR (CDCl3) δ 104.8 (С4), 119.7 (С3), 135.2 (С6

Synthesis and cytotoxicity studies of novel N-arylbenzo[h]quinazolin-2-amines

• Battini Veeraiah,
• Kishore Ramineni,
• Dabbugoddu Brahmaiah,
• Nangunoori Sampath Kumar,
• Hélène Solhi,
• Rémy Le Guevel,
• Chada Raji Reddy,
• Frédéric Justaud and
• René Grée

Beilstein J. Org. Chem. 2024, 20, 2592–2598, doi:10.3762/bjoc.20.218

• bromides and other reagents were used as they were received from commercial suppliers, unless otherwise noted. THF and Et2O were dried over sodium-benzophenone and distilled prior to use. 1H NMR spectra were recorded at 300 and 400 MHz, and 13C NMR spectra at 75 and 100 MHz, in CDCl3 or DMSO-d6 using TMS

• better accuracy on small coupling constants, resolution in 1H NMR was enhanced using Traficante. All compounds were purified by flash column chromatography on silca gel unless otherwise noted. Melting points were obtained using an Electrothermal IA9200 series digital apparatus with thin-wall glass tube

• reduced pressure to afford crude compound 2 as pale-yellow solid (65% yield). Its NMR data are in agreement with literature [5]. 1H NMR (400 MHz, DMSO-d6, δ ppm) 10.49 (s, 1H), 8.26 (d, J = 8.4 Hz, 1H), 8.10 (d, J = 8.0 Hz, 1H), 7.90 (d, J = 8.8 Hz, 1H), 7.84–7.74 (m, 3H). Step 2: Synthesis of benzo[h

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

• Unless otherwise stated, all starting chemicals were commercially available and were used as received. The starting compounds 1 were prepared by a procedure described in the literature [33][34]. NMR spectra were recorded with Bruker AM 300 (300 MHz) in DMSO-d6. Chemical shifts (ppm) are given relative to

• solvent signals (DMSO-d6: 2.50 ppm (1H NMR) and 39.52 ppm (13C NMR)). High-resolution mass spectra (HRMS) were obtained on a Bruker micrOTOF II instrument using electrospray ionization (ESI). The melting points were determined on a Kofler hot stage apparatus. A magnetic stirrer IKA C-MAG HS 7 was used for

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

• confirmed and characterized by the 1H NMR measurement of the crude reaction mixture (Scheme 4b) [48]. These results clearly showed that the thermal generation of aryl radicals from triarylbismuthines is one of the key factors for the transition-metal-free synthesis of arylboronates, and oxygen (air) would

•  1) was analyzed by 11B NMR measurement. It was noteworthy that diboron 2 was reactive with air under the reaction conditions, and the decomposition of 2 to form pinB–O–Bpin and pinB–OH was confirmed. The decomposition was also occurred by heating the solution of diboron 2 in BTF in air; however, in

• without further purification. All solvents were used without distillation. Triarylbismuthines 1 were synthesized according to the previously reported procedures [62]. 1H, 13C{1H}, and 11B NMR spectra were recorded in CDCl3 using a Bruker AVANCE III HD 500 spectrometer at 500, 126, and 160 MHz

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• assemblies, 2+-BF4− was further treated with NaPF6, LiB(C6F5)4, and NaPCCp for the ion-pair metathesis to afford ion pairs 2+-X− (X− = PF6−, B(C6F5)4−, and PCCp−) in 44–68% yields. The obtained ion pairs were characterized using 1H, 13C, and 19F nuclear magnetic resonance (NMR) and matrix-assisted laser

• further purification unless otherwise stated. According to the previous procedure [30], 4,8,12-tris(2,6-dimethylphenyl)-4,8,12-triazatriangulenium as a Cl− ion pair, 2+-Cl−, was prepared. NMR spectra used in the characterization of products were recorded on a JEOL ECA-600 600 MHz spectrometer. All NMR

• , 0.209 mmol, 19%) as a red solid. Rf 0.33 (MeOH/EtOAc/CH2Cl2 1:2:8); 1H NMR (600 MHz, CDCl3, 20 °C) δ (ppm) 7.68 (t, J = 8.4 Hz, 3H, TATA-H), 7.51 (t, J = 7.8 Hz, 3H, Ar-H), 7.44 (d, J = 7.8 Hz, 6H, Ar-H), 6.37 (d, J = 8.4 Hz, 6H, TATA-H), 2.10 (s, 18H, CH3); 13C NMR (151 MHz, CDCl3, 20 °C) δ (ppm

Visible-light-mediated flow protocol for Achmatowicz rearrangement

• Joachyutharayalu Oja,
• Sanjeev Kumar and
• Srihari Pabbaraja

Beilstein J. Org. Chem. 2024, 20, 2493–2499, doi:10.3762/bjoc.20.213

• corresponding products (3o, 3p) in good yields. All the products obtained were characterized by 1H NMR, 13C NMR and mass spectrometry techniques. A plausible catalytic cycle has been postulated based on a literature study [13], and is shown in Figure 2. With the exposure of photocatalyst to sunlight/LED light

• mechanism for the photochemically induced Achmatowicz rearrangement. Strategies for Achmatowicz rearrangement. Optimization of continuous flow Achmatowicz reactiona. Supporting Information Supporting Information File 133: Experimental section and NMR spectra. Supporting Information File 134: Video of the

Machine learning-guided strategies for reaction conditions design and optimization

• Lung-Yi Chen and
• Yi-Pei Li

Beilstein J. Org. Chem. 2024, 20, 2476–2492, doi:10.3762/bjoc.20.212

• . [47]. Literature-extracted yields can be derived from different methods, such as crude yield, isolated yield, quantitative NMR, and liquid chromatography area percentage, and they can also vary in precision due to human bias or equipment quality. HTE data for specific reactions, however, are usually

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• , entry 1). Assignment of the relative configurations as cis or trans was achieved by 1H NMR analysis, considering the chemical shifts of the proton in the α-position of the β-lactam nitrogen atom and the geminal protons in the benzylic position (see Supporting Information File 1). The difference in the

• stereocenter in the five-membered ring was attributed by 1H NMR analysis for 11c. Moreover, the configuration was also confirmed by NOE studies on the two isolated diastereoisomers, which confirmed the preferred trans-isomer formation (see Supporting Information File 1). Analysis of the dr values revealed that

• intramolecular photoredox reaction. Photoredox-catalyzed intramolecular N-alkylation reactions of various β-lactams. The trans/cis dr was determined by 1H NMR analysis of the crude reaction mixture. Synthesis of the model substrate 14 and its photoredox-catalyzed intramolecular N-alkylation reaction. The trans

Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols

• Smaher E. Butt,
• Konrad Kepski,
• Jean-Marc Sotiropoulos and
• Wesley J. Moran

Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209

• benzoyl group on the nitrogen atom preventing equilibration to the thermodynamic piperidine product [21]. Basic workup hydrolyzes the trifluoroacetoxy ester in 14 to alcohol 7a. Consideration of the literature NMR data for the three possible isomeric products (i.e., pyrrolidine, piperidine, and

• Information File 120: Experimental procedures, compound characterization data, copies of NMR spectra, cartesian coordinates and energies of calculated structures. Acknowledgements We thank Professor Mark Heron for his useful discussions and Dr Neil McLay for his NMR expertise. We also acknowledge Joshua

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

• order to decipher the key physical properties of complex pyran inter-halides, we performed 19F NMR analysis of halogenated talose analogues 12–15 (Figure 2). First, all analogues adopt standard 4C1-like conformations. Comparison of the vicinal and geminal coupling constants for each organohalogen

• −200.55 ppm for 15. Talopyranose analogues 12–15 incorporate a 2,3-cis, 3,4-cis relationship for the halogens. We previously prepared a small set of trihalogenated allopyranose analogues that also included the 2,3-cis, 3,4-cis relationship for the halogens (Figure 1a) [23]. 19F NMR analysis of halogenated

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

• , entry 7). Finally, the reaction time was reduced from 24 h to 2.5 h without affecting the yield (Table 1, entry 8). In order to better understand the mechanism of the reaction, an NMR study of the premixing of DDPyOCF3 with PhSeBr was performed. The disappearance of the broad signal of CF3O− and the

• of the oxidative conditions used (mCPBA [75], H2O2 [75], selectfluor®/H2O [76], SO2Cl2/NaHCO3 (aq) [77][78]), in most cases a complex mixture was observed and no corresponding vinylic compound was detected by NMR. The phenylselenyl moiety could also undergo radical reduction to produce

• stirred at room temperature for 2.5 h (unless otherwise stated). Note that a yellowish precipitate is formed during the reaction for high yielding substrates. The reaction is monitored by 19F NMR (PhCF3 as internal standard). At the end of the reaction, the content of the vial is transferred to a

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• during the lactone-forming process. Their close structural resemblance led to a significant peak overlap both in the 1H and 19F NMR spectra which made it difficult to obtain their exact ratio and thus, the combined 19F NMR yields were shown in Table 4. Separation of these two compounds was eventually

• the complex mixture after mixing 2b with t-BuOK and nitroacetate in DMSO at 80 °C, the unexpected compound 2,3-dihydroxybutyrate anti-10a was isolated as a single isomer. Its production was also detected by 19F NMR from the reaction mixture when nitromethane (16%) and ethyl (diethylphosphono)acetate

• of the reductive elimination very slow, the intermediary Cu(III) species safely existed until the addition of D2O. Because the significant overlap of NMR peaks was observed due to the quite similar structure of 11a and 11a-D, quantitative analysis of the deuterium content of 11a-D was not possible

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

• , several control experiments were also performed, even though the benchmark reaction has already been established in halogen-bonding activation. In the presence of 2 mol % of either the unactivated gold complex (PPh3)AuCl or the XB donors 1BArF–4BArF + 7BArF, 1H NMR showed no conversion within 18 h

• , indicating that the activated gold complex is the catalytically active species. Furthermore, stability measurements (1H and 19F NMR) of 1:1 mixtures of the gold complex and the XB donors were performed in order to investigate the stability of the cationic iodonium structures towards the gold complex [28

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

• in less than 10% yield, determined through 1H NMR analysis, except for Table 1, entries 3 (13%) and 5 (25%). It should also be noted that electrolysis was carried out at room temperature, but the temperature of the reaction mixture increased to 40–50 °C at the end of the electrolysis in every case

• of dechlorinated diphenylmethanol (1a) in the recovered starting material were confirmed by 1H NMR analysis. These results suggested that 2a was produced from 1a, which was generated in situ by electroreductive dechlorination of 1b. In other words, electroreductive dechlorination of 1b, producing 1a

• , took place preferentially over electroreductive C(sp3)–O bond cleavage of 1b. It should also be noted that no aromatic carboxylic acids were detected by 1H NMR analysis. In contrast, the electrochemical carboxylation of 1c, containing a fluorine atom, gave a mixture of fluorine-containing carboxylic

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

• oxidation peak of the catechol fragment to the cathode region (Figure 7). This is due to the less acceptor nature of the thiazole ring compared to the more electron-deficient oxadiazole cycle, which contains three heteroatoms. In addition, according to NMR spectral data, one proton of the hydroxy group of

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

• two enantiotopic faces of acylimine 2, exposing only one face to the attack by the allyl group. The replacement of one isopropoxy (iPrO) group between allylboronate 1 with BINOL was confirmed by ESI-MS and NMR analysis of the reaction mixture. Interestingly, both (E)- and (Z)-crotyl boronates 6 and 8

• 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

• , in the COBI–imine complex 74 it appears at 8.41 ppm, while in the imine TfOH salt 75 it shows at 9.24 ppm. This detailed NMR investigation sparked further interest in the structure of the transition state of this reaction. An analysis of the potential energy profiles of the two hypothetical pathways

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

• obtained. Thus, we have demonstrated that the terminal nitrogen atom in the diazonium fragment of intermediate 9 becomes the N5 atom of compound 8 (corresponding 15N NMR spectra are provided in Supporting Information File 1). To explore the potential application of the obtained compounds 1 and 7, we

• . Supporting Information Supporting Information File 96: Experimental procedures, characterization data of all products, copies of 1H, 13C NMR, 15N spectra of new compounds, DSC curves,X-ray crystallographic data and copies of IR spectra. Acknowledgements The crystal structure determination was performed at