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

• -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

• )-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

• acetate 3:2)); mp 187–189 °C; IR (ATR) ν̃: 1708 (s), 1654 (vs), 1574 (s), 1514 (s), 1506 (s), 1446 (s), 1423 (s), 1232 (s), 1158 (s) cm−1; 1H NMR (500 MHz, chloroform-d) δ 7.48–7.44 (m, 2H), 7.26–7.22 (m, 2H), 7.15–7.10 (m, 2H), 7.06–7.02 (m, 2H), 3.70 (s, 3H), 3.44 (s, 3H); 19F NMR (471 MHz, chloroform-d

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

• First, we optimized the conditions of the Suzuki–Miyaura cross-coupling in reference to the report by Yang et al. (Table 1) [43]. Upon the treatment of multihalogenated vinyl ether 1a with phenylboronic acid 4a (1.3 equiv) and palladium diacetate (10 mol %) as a catalyst at 40 °C, Suzuki–Miyaura cross

• -coupling proceeded to produce fluoroalkene 2a in 50% yield (Table 1, entry 1). Increasing the amount of 4a to 2.0 equiv and decreasing the amount of palladium diacetate to 5 mol % improved the reaction yield (Table 1, entry 2). When the reaction mixture was heated to 60 °C or reflux conditions, 2a could be

• mol %), cesium carbonate (1.5 equiv), palladium bis(trifluoroacetate) (5 mol %) in THF (2.0 mL) was added the respective boronic acid derivative 4 (2.0 equiv). The reaction solution was refluxed for 3.5 h. The reaction mixture was quenched by the addition of water (40 mL) at 0 °C and extracted with

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• ) irradiation (λex = 365 nm). (c) A PL color diagram defined by the Commission Internationale de l'Eclairage (CIE). (a) PL spectra of PMMA dispersion films containing 1 wt % of blue fluorophore 1a and green–yellow fluorophore 1c in various weight ratios. (b) Photographs of the PMMA dispersion films under UV

• irradiation (λex = 365 nm). (c) A CIE color diagram of the PL color of the PMMA dispersion films containing 1a and 1c in various ratios. (a) PL spectra of PMMA dispersion films containing 1 wt % of blue fluorophore 1a and yellow fluorophore 1f in various weight ratios. (b) Photographs of their PMMA dispersion

• films under UV irradiation (λex = 365 nm). (c) A CIE color diagram of the PL color of PMMA dispersion films containing 1a and 1f in various weight ratios. Photophysical data of compounds 1a–g contained in a PMMA dispersion film. Photophysical data of PMMA dispersion films containing 1 wt % of blue

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• catalyse reactions following mechanisms 2 or 3 (Figure 5B,C). For each group, an analysis was performed using two volcano plots. The first plot aids in identifying the best families, which are then exclusively considered for the second volcano plot. The second plot helps to determine the most appropriate

• the (S) epoxide with the (R) product was identified (Figure 8). Even more intriguingly, this new TS (TS_S_R in ), verified by the IRC calculation (Figure S5, Supporting Information File 1) is the most stable TS located (Figure 9). In this TS, the epoxy ring opens (Figure 9). Because of a shorter C–C

• distance between the CH3 group in the catalyst and the epoxy carbon atom (3.45 Å vs 3.75 Å in TS_S_S), a steric clash between the two methyl groups occurs (Figure 9). This results in an inversion of stereochemistry via rotation of the epoxy C–C bond, leading to the formation of the (R) product. As two TSs

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

• long time to complete. Hence, it was established that only those solvents which can produce hydroperoxides in situ were suitable for the reaction. Therefore, we chose Cs2CO3 as the base of choice, and performed the further reactions using 1.0 equiv of Cs2CO3 in THF at 50 °C in an open atmosphere

• , 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

• enolization of benzofuranone 3 in the presence of a base produced intermediate A. The latter reacted with hydroperoxide to form B with the concomitant generation of the radicals, which further reacted with intermediate B to form intermediate C. Finally, C is hydrolysed with the release of one molecule CO2 and

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

• Rattlesnake (Crotalus horridus horridus) and the Northern Copperhead (Agkistrodon contortrix mokasen), were devoid of neutral lipids. Subsequent TLC analysis of related snakes, such as the Eastern Diamondback Rattlesnake (C. adamanteus) and Florida Cottonmouth (A. piscivorus conanti), revealed the presence of

• various lipid classes including sterols, triacylglycerols, and common fatty acid methyl esters [15]. Mass spectrometric analysis of the lipid content of crotalines, mainly the Western Diamondback Rattlesnake (C. atrox), confirmed the presence of cholesterol [3][6][11][16], fatty acids [11], fatty amides

• saturated compound would provide more insight into the structure. After hydrogenation, the spectra of methylated and hydrogenated Dmh showed m/z 87 as the base peak (Supporting Information File 1, Figure S3), which is strongly characteristic of a methyl branch at C-4 [20]. The position of the second methyl

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

• (Figure 1B and C). Hydrated γ-CD Hydration and interaction with water (sequential binding of water molecules to the CD cavity) The γ-CD cavity was scanned for spots/sites with enhanced binding affinity for the incoming water molecules: γ-CD hydrates containing one to seven water molecules bound at various

• the other complexes only two options were modelled (Figure 2, n = 2–7, structures a and b). The first water molecule can bind to the narrow rim (n = 1; Figure 2, structures a–c) or the wide rim (n = 1; Figure 2, structures d and e). All attempts to position single water molecule in the cavity or near

• , structures a–c) suggest, the structures with a water molecule positioned at the narrow rim of γ-CD (n = 1; Figure 2, structures a–c) appeared to be the most stable ones. Isoenergetic structures b and c arise from initial structures with the water molecule positioned differently, in the middle of the CD

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

• determined that room temperature is inadequate for fully oxidizing substrates. The optimal oxidation temperature for uracils 1 and 4 is between 60–65 °C, whereas for pyridines 7 and 9 it is 45 °C. Heating the reaction mixture at a temperature higher than the optimum level causes the substrates to be

• )sulfate ions, thus enabling activated A or B particles to attack the substrate molecule, resulting in the intermediate σ-complex C. A like particle B [Pc–Me–Oδ−–Oδ+–SO3−] has been previously described in [33]. The formation of particle B is possible via the interaction of the catalyst PcM with the SO52

• pyrimidine ring destruction. The ideal oxidation of TMU (5) was achieved with the addition of 3.0–4.0 equiv H2O2 (Table 3). During the oxidation of pyridine (7) by the binary oxidation mixture APS/H2O2 at 45 °C, the yield of the reaction product – Py-sulfate 8 – increased gradually, reaching a maximum of 85

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

• scaffolds for bioactive molecules. Thus, it appeared interesting to explore novel molecules with extended aromatic units around this basic quinazoline core and our first choice was N-arylbenzo[h]quinazoline-2-amines with the general structure C as indicated in Figure 1. Very limited studies have been

• describe a short and efficient synthesis for this type of novel skeleton and to prepare a focused library for these targets C. Further, we will report results on their cytotoxic activities. Results and Discussion Chemical synthesis For the preparation of our targets, we selected a flexible strategy which

• Physiques de l’Ouest, Rennes (CRMPO), on a Maxis 4G. Representative synthesis: preparation of compound 4a Step 1: Synthesis of 1-fluoro-2-naphthaldehyde (2): To a stirred solution of compound 1 (3.0 g, 0.02 mol) in THF (60 mL) was added n-butyllithium (1.6 M, 12.8 mL, 0.02 mol) at −78 °C. The mixture was

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

• deprotonates to the anion B under action of DBU. Subsequent intramolecular cyclization at the double bond of pyranone fragment leads to the formation of spiro compound C. Next, opening of the dihydropyranone ring results in pyrrolidin-2-one D which further transformed to the salt of 3-acyltetronic acid E

• 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

• -ylidene)furan-2,4(3H,5H)-dione (4a). Pale yellow powder; yield 62% (0.25 g); mp 121–123 °C; 1H NMR (300 MHz, DMSO-d6) δ 7.31–7.13 (m, 5H), 4.34 (t, J = 7.5 Hz, 2H), 2.74 (t, J = 7.6 Hz, 2H), 2.56–2.48 (m, 2H in DMSO), 2.46 (s, 3H), 2.14 (t, J = 11.8 Hz, 2H), 1.64–1.54 (m, 3H), 1.41–1.09 (m, 5H); 13C NMR

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

• with halogen or triflate groups. Recently, transition-metal-catalyzed direct borylation of arenes via C–H bond activation has been reported, although the design of the substrate and ligands is somewhat complicated [16][17][18][19][20][21][22]. Since the complete removal of catalyst-derived metal

• reaction conditions were harsh, requiring heating at 260 °C for several days [50]. Thus, only two examples of the use of triarylbismuthines as aryl radical sources have been reported for the synthesis of arylboronates, which proceeds under light irradiation conditions (Scheme 1a) [47][48]. Our group has

• the subsequent trapping with E–E compounds (E = S, Se, Te, Br, and I) successfully formed new C–E bonds (Scheme 1b) [51][52][53][54][55][56][57][58]. We also demonstrated that the photoirradiation (λ > 300 nm) of the triarylbismuthines in air successfully allowed the generation of the corresponding

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

• intermolecular C–H···π interactions between the proximally located CH3 and TATA+ units, as obtained by the Hirshfeld surface analysis (Figure 4) [33][34][35][36]. The arrangement of the ion pairs depended on the counteranions, which formed different interactions. Smaller counteranions were located above the

• electron-deficient TATA+ core through the interactions of the methyl units. In fact, in 2+-Cl−, Cl− was located 3.43 Å above the TATA+ core and was interacted with the surrounding CH3 units, with C(–H)···Cl− distances of 3.74, 3.85, and 3.96 Å (Figure 3a, Figure 5a and Figure S17 in Supporting Information

• File 1). As a crystallization solvent, three CHCl3 molecules were located between the 2,6-dimethylphenyl units by forming hydrogen bonding with Cl− with C(–H)···Cl− distances of 3.36, 3.36, and 3.37 Å. A similar arrangement of the counteranions was observed for 2+-BF4− and 2+-PF6−, with the BF4− and

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• been systematically summarized, classifying them by targeted C–H bond functionalization and the newly formed bonds [4][5]. In this review, we aim to provide a comprehensive classification and overview of the currently available electrochemical and photoelectrochemical methods for the LSF of

• industrial settings. An anodic oxidation is frequently employed for C–H functionalization, which can simplify late-stage functionalization strategies. Additionally, many of these synthetic methods do not require precious metals, enhancing their appeal in terms of sustainability and cost-effectiveness

• in schemes as H2↑) in the cathodic half-reaction, which will however not be addressed in greater detail in this review. 1.1 Direct anodic oxidation of substrates 1.1.1 C–H bond functionalization. C–H bond carbofunctionalization: CF3 groups can be installed on heteroarenes at a late stage via a TM

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

• observed within 10 min (Table 1, entry 1). The Achmatowicz rearrangement product 3a was obtained in 82% yield (Table 1, entry 1) using Ru(bpy)3Cl2·6H2O as a PC under solar light at 28–34 °C, light intensity 330000–322000 lux [26] with a flow rate of 1.0 mL min−1 in 10 mL reactor (10 min duration). A light

• details in Supporting Information File 1, Table S1, entries 10–18), it was discovered that a combination of ACN/DMSO/H2O solvent, K2S2O8 oxidant, Ru(bpy)3Cl2·6H2O photocatalyst, and 28–34 °C temperature were the best-suited and optimized reaction conditions. After optimization, our efforts were put

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

• SMILES and are instead described using textual labels. A comparison of three types of reaction embedding methods: (A) descriptor-based, which use predefined features from reactants and products, (B) graph-based, which use neural networks to learn features from molecular graphs, and (C) text-based, which

HFIP as a versatile solvent in resorcin[n]arene synthesis

• Hormoz Khosravi,
• Valeria Stevens and
• Raúl Hernández Sánchez

Beilstein J. Org. Chem. 2024, 20, 2469–2475, doi:10.3762/bjoc.20.211

• . bGram-scale reaction (1.10 g of resorcinol). cReaction time increased to 24 h. dAll reactions were performed at 50 °C. Optimization of resorcin[n]arene synthesis using HFIP.a Supporting Information Supporting Information File 124: Experimental procedures for reactions, and relevant spectra of all new

• funded in part by a grant from The Welch Foundation (C-2142-20230405).

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

• ) [23][24][25]. The nucleophilic attack of the nitrogen atom on the oxidized C=C double bond results in the formation of a radical intermediate after deprotonation. This radical intermediate can proceed through various pathways (e.g., HAT, oxidation) to yield the desired final product. In the

• literature, oxacepham scaffolds, the 6-membered fused bicyclic analog of clavams, were prepared from appropriately substituted unfused precursors by intramolecular C-radical addition to alkene functionalities [44]. The utilization of radical conditions has prevented the effective nucleophilic opening of the

• the diastereoselectivity of the nucleophilic attack of the β-lactam on the radical cationic intermediate was influenced by stereoelectronic factors. Compounds unsubstituted at position C-3 of the β-lactam ring, 11d–h, showed modest stereoselectivity with a higher dr (6.7:1) for compound 11d, which has

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

• provided slight improvements in yield (Table 1, entries 2–4). The more electron-rich 2-iodo-1,3-dimethoxybenzene led to a further increase in yield to 44% (Table 1, entry 5). 1,2-Diiodobenzene has been reported to be a superior precatalyst in intermolecular C–H aminations of arenes but only provided 40

• ]. Iodoethane was also shown to be an effective reagent furnishing the product in up to 56% upon heating to 40 °C (Table 1, entries 11 and 12). It was envisaged that oxidation of iodoethane led to formation of oxidized forms of iodide by C–I-bond cleavage, therefore tetrabutylammonium iodide was utilized to see

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

• and nonbonding interactions for the halogen at C4. Finally, density functional theory (DFT) calculations corroborate the preference of talose analogues to adopt a 4C1-like conformation and a natural bonding orbital (NBO) analysis demonstrates the effects of hyperconjugation from C–F antibonding

• carbohydrates [44][45]. The C–C bond lengths within the pyran rings of halogenated analogues are between 1.50 and 1.54 Å, which is similar to native talose (18, 1.52–1.53 Å) (Table 1, entries 1–4). However, all specified bond lengths within the pyran rings are shorter for halogenated analogues compared to α-ᴅ

• analogues (Table 1, entries 7 and 8). Also, the exocyclic C1–O1 bond lengths of compounds 13–15 and 17 are in average 0.033 Å longer than native talose (18). As expected, all the C–F bond lengths are shorter than the corresponding C–OH bond lengths (Table 1, entries 10–12) [48]. The C2–F2 bond lengths are

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

• not improve the results (Table 1, entry 4). A better yield was obtained by adding first the phenylselenyl chloride and stirring the mixture for 15 min at 0 °C before adding 1a (Table 1, entry 5). During all these reactions the formation of compound 3a was observed as by-product. This compound results

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

• sequence from the corresponding chiral 4,4,4-trifluoro-3-hydroxybutyrate at low temperature [27][28][29][30], and 2) t-BuO2Li-mediated transformation of the enoates like 1g at −78 °C [31][32] and, to the best of our knowledge, no report has appeared on the convenient methods applicable to the larger scale

• equiv) at 0 °C with 6 h stirring (entry 8 in Table 1). We also tried to apply these conditions to other fluorine-containing substrates 1c–f and successfully obtained good to high yields of the desired products 2c–f, respectively (entries 10–13 in Table 1). The requirement of longer reaction time and

• 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

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• 94%, initial reactant concentration of 0.5 mol/L, reaction temperature of 40 °C, molar ratio of reactants at 4.4:1, and a residence time of 12.36 minutes. Keywords: continuous flow; kinetic modeling; nitration; reaction optimization; static mixer; Introduction The demand for high-quality

• ]. The reaction time and temperature were reduced from >2 h and 80 °C in industrial operation to 10 min and 65 °C in the microreactor with high conversion and selectivity. Since O-methylisouronium sulfate can be dissolved in high concentrations of sulfuric acid, it is expected to construct a homogeneous

• homogeneous nitration conditions, our next objective was to eliminate the influence of mass transfer. We assessed the impact of flow rate on the reaction conversion under two distinct mixing scenarios (Figure 2a and 2c). The assessments were performed with reaction temperatures at 30–40 °C to eliminate the

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

• = 10.9139(1) Å, c = 24.3668(3) Å, β = 95.601(1)°) and a density of 2.01865 g/cm3. Two units of the cationic XB donor form a dimer, which is bridged via two bromide ions (Figure 2). As usual for DAI salts, two XB axes are found on the elongations of the C–I bonds. On the one trans to the isoxazolium unit

• ), 0.1 M, 135 h at rt, 43%, (b) 1.5 equiv mCPBA, 3.0 equiv TfOH (at 0 °C), (DCM), 0.1 M, 20 h at rt, 85%, (c) 1.0 equiv NaBArF24, (acetone), 0.5 M, 2 h at 50 °C under microwave irradiation, 72%. Gold(I)-catalyzed cyclization of propargylic amide 11 as benchmark reaction for Au–Cl activation. Determined

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

• Pt cathode and a Mg anode in the presence of carbon dioxide induced reductive C(sp3)−O bond cleavage at the benzylic position in diarylmethanol compounds and subsequent fixation of carbon dioxide to produce diarylacetic acids in good yield. This protocol provides a novel and simple approach to

• diarylacetic acids from diarylmethanol species and carbon dioxide without transformation of the hydroxy group into appropriate leaving groups, such as halides and esters including carbonates. Keywords: C(sp3)–O bond cleavage; diarylacetic acid; diarylmethanol; electrochemical reduction; fixation of carbon

• dioxide; Introduction Electrochemical reduction of benzyl alcohol derivatives can induce reductive cleavage of a C(sp3)–O bond [1] at the benzylic position to generate the corresponding benzylic anion species. This protocol has been frequently applied to electrochemical carboxylation [2][3][4][5][6][7][8