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

• : 3a (1 mmol), CDI (0.49 g, 3 mmol), DBU (0.17 g, 1.1 mmol), MeCN (7 mL). Proposed reaction mechanism for the formation of products 4. Synthesis of derivatization products 7 and 9. Optimization of the reaction conditionsa. Supporting Information Supporting Information File 141: General information

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

• , due to the protonation of triticonazole, the participation of the protonated form in the overall reaction mechanism is also considered in pathway B (Scheme 21). Benzo[c][1,2]oxazines are useful scaffolds for the synthesis of natural products. In 2021, the Han group developed the electrochemical [4 + 2

• leelamine, racemorphan, and analogs of sertraline and celecoxib was achieved with yields ranging from 40% to 92%. The reaction mechanism begins with the photoexcitation of the intermediate [TAC2+•]*, which oxidizes the arene substrate to form a cation radical. This radical is deprotonated and then further

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

• mapping (AAM) is a process that establishes the correspondence between atoms before and after a reaction, reflecting the reaction mechanism. AAM-exempted methods [145][146][147][148][149][150] apply graph convolutions to each reactant and product molecule separately, and then use a pooling function or

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

• translated to the formation of other macrocycles as long as they share a similar reaction mechanism. (a) Control experiment testing deiodination of 2-iodoresorcinol. (b) Molecular crystal structure of chlorinated resorcin[4]arenes 1h and 1i, and carboxylic acid-containing 1s at 100 K. Thermal ellipsoids are

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

• cyclization occurred by producing trans-15 in 35% yield as the single diastereoisomer. For the reaction mechanism, we propose a mechanistic hypothesis according to the study by Nicewicz and Nguyen (Figure 3) [23]. The incorporation of electron-donating groups into the acridinium core, as in catalyst IV

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

• additionally confirmed by X-ray diffraction (see Supporting Information File 1 for details) (Figure 2). To confirm the reaction mechanism, we performed diazotization followed by azo coupling of amide 2a using labeled Na15NO2 as the nitrosating reagent (Scheme 4). As a result, 15N-labeled triazinone 8 was

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

• give rise to epoxidation products. Epoxides are not on-path to the observed aziridines. f) Proposed reaction mechanism. Optimization of HFIP-promoted aziridination of cyclohexene (1a). Conditions: 0.20 mmol 1a, 0.40 mmol PhINTs 2a, 1.0 mL HFIP, N2 atmosphere, 20 °C, 16 h. Yield was determined via 1H

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• the ML model by being considered as a nucleophile or electrophile, depending on the reaction mechanism. Descriptors allowed for the inclusion of a variety of co-catalysts, ranging from Fe-piano stool complexes to copper complexes. The consideration of co-catalysis into model development further

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

• electricity was passed to the solution. A plausible reaction mechanism for the current reactions is described in Scheme 3. The reaction of carbon–carbon triple bonds and H+ species, which are derived from the Brønsted acid (in method A) or EGA (in method B), gives the vinylic carbocation intermediate A, which

• for 2a. Plausible reaction mechanism. Optimization of the gem-difluorination of hex-5-yn-1-ylbenzene (1a) to form difluorinated compound 2a (method A). Scope and limitations. Supporting Information Supporting Information File 84: Experimental procedure, characterization data of compounds and copies

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

• substituents has a lower Ea than DBA with electron-donating substituents. DFT calculations The reaction mechanism was investigated by computational calculations. The reaction mechanism between 5 and benzyl azide was supported by the ωB97X-D/6-31G(d,p) calculations with the CH2Cl2 polarizable continuum model

• . (a) Strain-promoted azide–alkyne cycloaddition between DBA 5 and benzyl azide and (b) 1H NMR spectral change at 30 °C in CDCl3. Arrhenius plots of the rate constants for the reaction between 5 and benzyl azide in CDCl3. Proposed reaction mechanism for the formation of compound 6a. Free energy

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

• reported in due course. Biologically active derivatives of cyclohexanones. X-ray structure of 4a (CCDC 2351387). Origin of stereoselectivity in the double Michael addition. The Michael donor–acceptor reactivity of curcumin: previous vs present work. A plausible reaction mechanism. Scale-up reaction

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

• access to diazo compounds as either synthetic intermediates or products. A special attention is paid to the reaction mechanism with the aim to encourage further development in this field. Keywords: C–H functionalization; diazo compound; electrosynthesis; hydrazone; nitrogen-containing heterocycle

Radical reactivity of antiaromatic Ni(II) norcorroles with azo radical initiators

• Siham Asyiqin Shafie,
• Ryo Nozawa,
• Hideaki Takano and
• Hiroshi Shinokubo

Beilstein J. Org. Chem. 2024, 20, 1967–1972, doi:10.3762/bjoc.20.172

• CH2Cl2. Cyclic voltammogram of 2a in CH2Cl2. Supporting electrolyte: 0.1 M Bu4NPF6; working electrode: glassy carbon; counter electrode: Pt; reference electrode: Ag/AgNO3; scan rate: 50 mV⋅s−1. Reaction of norcorrole 1 with AIBN. Reaction of norcorrole 1 with V-40. Plausible reaction mechanism

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• - or 4-substituted isoquinolinone derivatives with excellent chemoselectivity. These interesting findings led us to investigate the reaction mechanism. To gain insight into the mechanism and chemoselectivity of the reactions above, we performed a control experiment. With acetonitrile as the solvent, a

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

• Ivana Weisheitelová,
• Radek Cibulka,
• Marek Sikorski and
• Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

• source in this reaction, a deuterium labelling experiment was conducted (Scheme 2C). Indeed, the deazaalloxazine derivative 6-d with quantitative incorporation of deuterium in C(5) position, was isolated and confirmed by 1H NMR analysis and mass spectrometry (for more details on possible reaction

• mechanism, see Supporting Information File 1). Such results with previous reports on DMSO acting as a methine source in the synthesis of heterocyclic compounds [35][36] are opening a new avenue for the green synthesis of non-substituted 5-deazaalloxazines in a pseudo MCR fashion. Conclusion In summary, we

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• yields (82–85%) (Scheme 28). The authors proposed a free radical mechanism facilitated by hydrogen peroxide, generating a primary radical at the terminal nitrogen atom -CO-HN• which then adds to the carbon atom of the imino group. The reaction mechanism was substantiated by theoretical calculations

• –water–NaOAc mixture. Spiro heterocycle 99 was obtained in 52% overall yield as a single product (Scheme 29). The reaction mechanism was elucidated based on the hard and soft acid and base theory. Spiro-1,3,4-thiadiazoline steroids In 2006, Mazoir et al. [56] reported the synthesis of 4α,14α-dimethyl-5α

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• decomposition for thiophenylmethanol 3y. Regarding the reaction mechanism, two plausible pathways can be discussed based on literature examples (Scheme 1, path a [17] and path b [33]). In either path, initial ligand exchange to the hydroxy(chloro)iodane I-OH is proposed. For getting an indication of a chloride

Divergent role of PIDA and PIFA in the AlX₃ (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study

• Kevin A. Juárez-Ornelas,
• Manuel Solís-Hernández,
• Pedro Navarro-Santos,
• J. Oscar C. Jiménez-Halla and
• César R. Solorio-Alvarado

Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141

• Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Avenida Francisco J. Múgica S/N 58030, Morelia, Michoacán, México 10.3762/bjoc.20.141 Abstract The reaction mechanism for the chlorination and bromination of 2-naphthol with PIDA or PIFA and AlX3 (X = Cl, Br), previously

• : MeCN) ω-B97XD/(6-311G(d,p),LANL08d)//ω-B97XD/6-31G(d), LANL08d. Chlorination mechanism The reaction mechanism for the chlorination of 2-naphthol using one equivalent of PIFA and two equivalents of aluminum chloride is outlined in Scheme 4. The chlorination mechanism starts when PIFA coordinates the

• . As a consequence of the previous analysis, the chlorination process is energetically favored in the presence of PIFA/AlCl3, 1:2 through the formation of PhICl–TFAO–AlCl3 in equilibrium with [PhICl][TFAO–AlCl3] as chlorinating species. Bromination mechanism The reaction mechanism for the bromination

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• measured by HPLC analysis using a stationary phase chiral column. Synthesis of 3aa on preparative scale. Proposed reaction mechanism. Optimization of reaction conditions.a Supporting Information Supporting Information File 2: Additional optimization studies, characterization data of compounds 3aa–na and

Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement

• Ziya Dağalan,
• Muhammed Hanifi Çelikoğlu,
• Saffet Çelik,
• Ramazan Koçak and
• Bilal Nişancı

Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129

• compounds 4a–j were also obtained in very good yields (60–98%, Scheme 2). Since the reaction mechanism proceeding with a Wagner–Meerwein rearrangement does not cause racemization or a diastereomeric mixture and preserves the initial enantiomeric excess in the camphene's fluoroalkoxy derivatives (Scheme 4

Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl₂ and NH₄SCN/KSeCN

• Jialiang Wu,
• Haofeng Shi,
• Xuemin Li,
• Jiaxin He,
• Chen Zhang,
• Fengxia Sun and
• Yunfei Du

Beilstein J. Org. Chem. 2024, 20, 1453–1461, doi:10.3762/bjoc.20.128

• 3a and their derivatization. Plausible reaction mechanism. Optimization of oxidative thiocyanation of pyrazole.a Supporting Information Supporting Information File 28: Synthetic details and compound characterization data. Funding We acknowledge the National Key Research and Development Program of

Rapid construction of tricyclic tetrahydrocyclopenta[4,5]pyrrolo[2,3-b]pyridine via isocyanide-based multicomponent reaction

• Xiu-Yu Chen,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2024, 20, 1436–1443, doi:10.3762/bjoc.20.126

• -position of the o-methoxyphenyl group. Therefore, compound 6g has the same relative configuration to that of the above mentioned product 3a, which also indicated that this reaction has same steric controlling effect. A plausible reaction mechanism is proposed in Scheme 1 to explain the formation of the

• . Molecular structure of compound 4a. Molecular structure of compound 6g. Proposed reaction mechanism. Optimizing reaction conditionsa. The synthesis of the tricyclic compounds 4a–ta. The synthesis of the tricyclic compounds 6a–ka. Supporting Information The crystallographic data of the compounds 4a (CCDC

Synthesis of cyclic β-1,6-oligosaccharides from glucosamine monomers by electrochemical polyglycosylation

• Md Azadur Rahman,
• Hirofumi Endo,
• Takashi Yamamoto,
• Shoma Okushiba,
• Norihiko Sasaki and
• Toshiki Nokami

Beilstein J. Org. Chem. 2024, 20, 1421–1427, doi:10.3762/bjoc.20.124

• rate: 7.5 mL/min, recycle numbers: 3) to obtain pure cyclic oligosaccharide 16 (0.125 mmol, 79.7 mg, 62%). Preparation of cyclic oligoglucosamines a) via intramolecular glycosylation and b) via polyglycosylation and intramolecular glycosylation. Proposed reaction mechanism of the formation of 1,6

• -anhydrosugar 7. Electrochemical polyglycosylation of monomer 14 with a 2,3-oxazolidinone protecting group. Proposed reaction mechanism of the formation of cyclic trisaccharide 19a. Influence of the functional group in position C-2 on the formation of the cyclic product. Electrochemical polyglycosylation of

Challenge N- versus O-six-membered annulation: FeCl₃-catalyzed synthesis of heterocyclic N,O-aminals

• Giacomo Mari,
• Lucia De Crescentini,
• Gianfranco Favi,
• Fabio Mantellini,
• Diego Olivieri and
• Stefania Santeusanio

Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123

• content of the reaction environment during the time. Then, to explain the related formation of 5 and 6, we hypothesized a plausible reaction mechanism in which iron is involved in two concomitant catalytic cycles (Scheme 4). Initially, FeCl3 forms an acid–base complex with one of the alkoxy groups of 4

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• conventional metal hydrides, such as tin or silicon hydrides. The reaction mechanism is interesting since first, a Lewis acid–base adduct is generated by interaction of Et3N with a boron atom of bis(catecholato)diboron (B2cat2, 19). As a result, one of the catecholate ligands experiences an increase in