Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• each addition. In situ preparation of the [Tb.1·3Cu]3+ sensor. Solutions of 5 μM [Tb.1·3Cu]3+ were prepared by combining a DMSO stock solution of Tb.1 (100 μM) with 1 mM Cu(NO3)2·5H2O(aq). Solutions were then diluted with the appropriate amount of buffer (final concentration 10 mM Tris–HCl or 10 mM

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

• Jinbo Ke Pit van Bonn Carsten Bolm Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany 10.3762/bjoc.20.235 Abstract We present a mechanochemical synthesis of difluoromethyl enol ethers. Utilizing an in situ generation of difluorocarbenes, ketones are

• isolating the low-boiling non-polar products. Mechanistic studies suggested that in situ-generated difluorocarbene reacts with the ketone oxygen, followed by intermolecular protonation/deprotonation. Although the process has still synthetic limitations, also acyclic ketones can now be converted into

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

• , our plan provides: the oxidation of N-aryltetrahydroisoquinolines (N-Ar-THIQs) generating in situ the iminium ions 1, the 3C Ugi-type reaction of an electron-rich aniline, an isocyanide and 1; the subsequent oxidation of the Ugi-type product 2; and the final cyclization to give the spiro[indole-THIQs

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

• protocol using a hydroperoxide (Figure 2d) gave us an idea that the use of an in-situ-generated hydroperoxide may trigger the reaction, and may avoid the use of transition metal in the reaction. Many solvents, e.g., tetrahydrofuran (THF), dioxanes etc. are known for producing hydroperoxides in situ on long

• , after getting the best yield of the product using Cs2CO3, we changed the solvent to dichloromethane, 1,4-dioxane, and acetonitrile. Except for 1,4-dioxane (Table 1, entries 18–20), where hydroperoxide is known to be produced in situ, the yields were very low. However, the reaction in 1,4-dioxane took a

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

• pinhole to select focal planes, allows fluorescence at various depths to be focused and imaged. The resulting 2D focal plane images can be stacked to yield a 3D fluorescence image of high resolution, allowing complex morphologies to be visualised (Figure 2) [11]. While CLSM provides in situ 3D imaging

• is the possibility of using different probes in a multicomponent network. Onogi et al. reported one of the first examples of direct imaging, in situ, of self-sorted supramolecular nanofibres [17]. TEM was able to show that the mixture of gelators gave rise to nanofibres with a morphology similar to

• entangle each other. By obtaining images in three dimensions, the orthogonal assembly could be directly visualised throughout the materials microstructure (Figure 2) [17]. This in situ method of CLSM also allows the kinetics of self-assembly to be elucidated, as demonstrated by Wang et al. [23]. By using

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

• diborons can capture the in situ-generated carbon-centered radicals [28][29][30][31][32][33][34][35][36]. Among the aryl sources in organic synthesis, triarylbismuthines are shelf-stable and easy-to-handle reagents with appropriate reactivities in transition-metal-catalyzed reactions and radical reactions

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

• that dimerize to form iodine (I2). Subsequent anodic oxidation of in-situ formed Et3N produced an α-amino radical. The iodine then reacts with the alkene to form an iodonium intermediate, which undergoes intramolecular cyclization with losing an electron, and a second water attack to yield the desired

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

• algorithm for the shell growth of core-shell semiconductor nanoparticles. This involves various unit operations such as phase separation, washing, and continuous in-situ spectral monitoring. Although the process conditions for this reaction system do not have as extensive a literature base for training data

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

• . If the in situ conversion of anti,syn-7a to anti,syn-7b follows the above ester alcohol exchange mechanism, employment of dibenzyl malonate should afford a single compound. This is actually the case and the expected dihydrofuran anti,syn-7c was obtained in 53% yield as a 98:2 diastereomer mixture

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

• is produced in situ from the imidoyl chloride 9 [21]. The one-pot oxidation and ring-closure reaction [22][23] to iodoloisoxazolium(III) salt 7OTf and the salt metathesis with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBArF24) were then realized with 85% and 72% yield, respectively

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

• 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

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

• , prenylboronic acid (R = H) was synthesised in only 31% yield. Given the 1.5 equiv loading of the boronic acids in the allylation protocol, the overall atom economy is not ideal. Asymmetric allylation of in situ-formed imines catalysed by chiral BINOLs received further development in the work of Schaus [26]. The

• -substituted aldimines. This was later addressed by the same researchers [15], who developed an organocatalytic kinetic resolution of secondary boronates to furnish bench-stable homochiral (S)-35. The latter were then employed in the asymmetric allylation of in situ-formed primary aldimines 37, leading

• organocatalytic enantioselective Hosomi–Sakurai reaction of imines using allyltrimethylsilane was reported by List and co-worker [32]. In this approach, the direct synthesis of Fmoc-protected homoallylic amines 47 was achieved by a three-component coupling of allyltrimethylsilane (46) with the in situ-formed N

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

• , whether isolated or generated in situ, may undergo various controlled transformations [42]. However, previously, we failed to introduce amino-1,2,5-oxadiazoles bearing an amide functionality into the diazotization protocol, arguably due to an increased electron-withdrawing effect and elevated instability

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• (Table 1, entry 9). Attempts to generate 2a in situ using 1 equivalent of TsNH2 (4) in combination with 1 or 2 equivalents of PhIO (5) resulted in aziridination yields of 19% and 27%, respectively (Table 1, entries 10 and 11). Finally, exclusion of ambient light had no impact of the aziridination of 1a

• challenging iminoiodinanes). In situ preparation of the iminoiodinane intermediates is possible, and for those reagents that undergo facile decomposition, aziridination is more efficient using these conditions (yields for in situ-generated iminoiodinanes are in parentheses in Scheme 3, with N-o-methyl (6g

• ), 0.40 mmol iminoiodinane 2, 1.0 mL HFIP, N2 atmosphere. Conditions using in situ-generated iminoiodinane: 0.20 mmol cyclopentene (1b), 0.20 mmol sulfonamide, 0.40 mmol iodosylbenzene (PhIO), 1.0 mL HFIP, N2 atmosphere. a) 20 °C for 16 h, b) 40 °C for 16 h. a) The broadening of the hydroxide proton

gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• Brønsted acid, such as Tf2NH and TfOH, with Bu4NBF4 might be effective to promote the gem-difluorination of alkynes because of the in situ generation of HF equivalents (Figure 1, reaction 6, chemical method). In addition, the electrogenerated acid (EGA) [43][44][45][46][47][48][49][50][51][52] from a

• also needs only electricity and solid Bu4NBF4, which realizes in situ formation of “HBF4” equivalents. Conclusion In summary, we have carried out the gem-difluorination of carbon–carbon triple bonds using Tf2NH/Bu4NBF4 or EGA from Bu4NBF4/CH2Cl2. The feature superiority of these methods is that they do

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

• reducing the waste generated in these allylations. While non-sacrificial graphite electrodes had failed to result in any reaction, it seemed possible that the use of a catalytic amount of tin metal or a tin salt with graphite electrodes would result in a superior reaction due to in situ reduction and/or

Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation

• Andrey R. Galeev,
• Maksim V. Dmitriev,
• Alexander S. Novikov and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188

• interrupted Kröhnke reaction (Scheme 1B) [51][52]. The main step of this process is an intermolecular cyclization of the formed 1,5-diketone followed by aromatization. Previously we have shown that 1,3-diketones bearing an electron-withdrawing group (EWG) adjacent to one of the carbonyls readily react with in

• situ-generated acetone imines in a (3 + 3) manner to afford meta-substituted anilines (Scheme 1C) [53][54]. Various EWGs (ester, carbamoyl, ketone, trifluoromethyl) have been successfully employed which motivated us to evaluate other possible EWGs. Results and Discussion Based on the fact, that many

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• pointed out, though for the first time truxene was reported in 1894 by Kipping [9], whereby 3‐phenylpropionic acid in situ cyclized under acidic conditions to indan‐1‐one which under the same conditions offered a mixture of both isomers, that is truxene as well as isotruxene. However, the practical

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• to imidoyl units generated in situ by radical addition to isocyanides, innovative molecules with a variety of functions can be obtained. In other words, if functional groups can be prepared simultaneously with the formation of an imidoyl group, it would be an extremely useful method for the synthesis

• lack of geometrical isomerization of the C–N double bond of the dithiolation products [32]. The thioselenation product 6’, an imine derivative, can be converted to a β-lactam derivative by [2 + 2] cycloaddition with ketene generated in situ. For example, thioselenation of RNC (R = (EtO)2P(O)–CH2) gave

• can add to isocyanides to form the imidoyl radicals. In this reaction, telluro radicals (ArTe•) also forms in situ, but the relative reactivity of them toward isocyanides might be very low. In addition, dimerization of ArTe• to (ArTe)2 is very fast, and therefore, the ArTe-substituted imidoyl radical

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• efficiency of these reactions. In particular, traditional multistep syntheses of pyrazoles have considerably been extended by MCR. Progress has been made in the cyclocondensation of 1,3-dielectrophiles that are generated in situ. Limitations in the regioselectivity of cyclocondensation with 1,3-dicarbonyls

• of the carbonyl groups and their derivatives. 1,3-Dicarbonyl compounds as key intermediates The most common and classic synthesis of ring-forming pyrazoles is the cyclocondensation of 1,3-dicarbonyl compounds with hydrazines (Knorr synthesis) [42][43]. Therefore, the in situ generation of 1,3

• -dicarbonyl compounds and their one-pot transformation pave the way for MCR syntheses of pyrazoles. 1,3-Dicarbonyl compounds can, for example, be generated in situ from enolates and carboxylic acid chlorides. They can be converted to the corresponding pyrazoles 1 in a consecutive multicomponent reaction with

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

• Deepa Nair,
• Abhishek Tiwari,
• Banamali Laha and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2024, 20, 2016–2023, doi:10.3762/bjoc.20.177

• synthesize functionalized pyrimidobenzothiazoles [37]. An in situ generated conjugated α-cyanoester/malononitrile has been successfully employed as substrate in the double Michael reaction with curcumins by Lalitha et al. [38]. An organocatalytic cascade double Michael reaction between curcumins and 2

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• mechanisms of structural changes using in-situ light irradiation with rapid, time-resolved data collection. However, X-ray irradiation has been shown previously to induce Z-to-E isomerisation of Azo-PS, which can lead to inaccuracies in the measured photostationary state. Here, we investigate the effect of

• light and X-ray irradiation on micelles formed from two different PS, containing either an Azo or AAP photoswitch using SAXS with in-situ light irradiation. The effect of X-ray irradiation on the Z isomer is shown to depend on the photoswitch, solvent, concentration and morphology. We use this to create

• brilliance of synchrotron X-ray sources enables the mechanisms of structural changes in PS to be studied, using in-situ light irradiation with time-resolved data collection. For example, Tribet and co-workers used this approach to explore the kinetics of micellisation and dissolution of cationic Azo-PS, both

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• one, which is consistent with the finding of ketone side-product. In 2018, the group of Zhang established an intramolecular C(sp2)–H functionalization of aldehyde-derived N-(2-pyridinyl)hydrazones 15 to produce 1,2,4-triazolo[4,3-a]pyridines 16 (Scheme 4) [39]. Interestingly, the hydrazone was in situ

• point of view, the authors proposed the formation of N-pyridyl radical 18 through the anodic oxidation of in situ-generated anion 17. Subsequent radical cyclization, second anodic cyclization and deprotonation yielded the fused heterocycle 16. Similarly, Youssef and Alajimi disclosed the electrochemical

• undergo deprotonation delivering the oxadiazole 24a. Alternatively, from 23b (R2 ≠ H), nucleophilic addition of methanol to oxycarbenium 26b yielded the oxadiazoline 24b (Scheme 6) [41][42]. In 2020, Lei, Zhang and Gao et al. described the electrooxidative cyclization of in situ-generated α-keto acid

Development of a flow photochemical process for a π-Lewis acidic metal-catalyzed cyclization/radical addition sequence: in situ-generated 2-benzopyrylium as photoredox catalyst and reactive intermediate

• Masahiro Terada,
• Zen Iwasaki,
• Ryohei Yazaki,
• Shigenobu Umemiya and
• Jun Kikuchi

Beilstein J. Org. Chem. 2024, 20, 1973–1980, doi:10.3762/bjoc.20.173

• Abstract A flow photochemical reaction system for a π-Lewis acidic metal-catalyzed cyclization/radical addition sequence was developed, which utilizes in situ-generated 2-benzopyrylium intermediates as the photoredox catalyst and electrophilic substrates. The key 2-benzopyrylium intermediates were

• catalytic cycles). In catalytic cycle I, the key cationic components, 2-benzopyrylium intermediates A, are generated in situ by the activation of the alkyne moiety of ortho-carbonyl alkynylbenzene derivatives 1 in the presence of the π-Lewis acidic metal catalyst [M]X [AgNTf2 or Cu(NTf2)2] and subsequent

• feature of this sequential transformation is that the in situ-generated 2-benzopyrylium intermediates A are used not only as an electrophile but also as a photoredox catalyst. However, as this reaction is carried out under relatively harsh conditions (i.e., light irradiation, use of an excess amount of

Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles

• Ivan Lyutin,
• Vasilisa Krivovicheva,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 1894–1899, doi:10.3762/bjoc.20.164

• -methoxyethylamine. Attempts to obtain directly 2-oxoazetidine carboxylic acid (or its decarboxylation product) or its trifluoroethyl ester by running the synthesis with water or trifluoroethanol were also unsuccessful. Acylation of the π-excessive double bonds of N-alkylindole and dihydropyran by the in situ