Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent Cyrene^TM under one-pot conditions

• Zoltán Medgyesi and
• László T. Mika

Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117

• -dioxane) or low (DMF, NMP, DMSO) (Figure 1). While low conversion was still detected in biomass-originated 2-MeTHF, MeLev, and EtLev established better performance. When their corresponding 4-alkoxy derivatives were applied, moderate (Me-4MeOV) or slightly lower (Et-4EtOV) conversions could be observed

Azobenzene protonation as a tool for temperature sensing

• Antti Siiskonen,
• Sami Vesamäki and
• Arri Priimagi

Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115

• Due to the lone pairs on their nitrogen atoms, azobenzenes are weak bases. Their basicity can be increased by electron-donating substituents on the benzene rings. para-Alkoxy substitution effectively increases the electron density at the azo-nitrogens without introducing additional protonation sites

• . We opted for methoxy substitution on one or both benzene rings as the simplest alkoxy substituent. The protonation of azobenzene (1), 4-methoxyazobenzene (2), and 4,4'-dimethoxyazobenzene (3) is schematized in Figure 1A. In the presence of a strong acid, these compounds form an equilibrium of neutral

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• -Markovnikov selectivity catalyzed by Au(III) in the presence of dimethylaminopyridine N-oxide (DMAPO) as oxidant. The reaction proceeds via Au–allenylidene species 307 (Scheme 73) [124]. Various cinnamic esters and amides with natural product-based alkoxy groups 301–304 and sulfoximines 305 and 306, a

Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes

• Shyam Sathyamoorthi,
• Appasaheb K. Nirpal,
• Dnyaneshwar A. Gorve and
• Steven P. Kelley

Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78

• Abstract We present the first examples of alkene amino-sulfonoxylation reactions that leverage the unique reactivity of carbamate tethered N-alkoxy nitrenium ions. In almost all cases examined, the reactions deliver product with exquisite regioselectivity and diastereoselectivity. The protocols followed

• -trifluoroacetoxylation of alkenes [4]. In this protocol, an unusual N-alkoxy carbamate tether served as a precursor to a transient nitrenium ion [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], which subsequently attacked a pendant alkene to form an aziridinium intermediate. This aziridinium

• examples of alkene amino-hydroxylation reactions mediated by N-alkoxy nitreniums deliver amino-trifluoroacetate products (Scheme 1) [6]. Here, we describe the first examples of amino-sulfonoxylation reactions of alkenes, which make use of carbamate tethered N-alkoxy nitrenium ions. Results and Discussion

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• substrates 15e–l was tested. The process proceeded efficiently in all cases, yielding pyrazolodiazepines 16e–l and demonstrating tolerance for various substituents on the aniline-derived aromatic fragment, including alkyl, halogens, electron-donating alkoxy groups, as well as electron-withdrawing

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• cascade reaction for the preparation of α-alkoxy-N-alkyltriazoles 44 that was developed starting from aliphatic aldehydes, alcohols, TMSN3 as azide source and alkynes (Scheme 33) [52]. The reaction occurs under mild conditions in acetonitrile at room temperature but is inhibited when using aromatic

• ]pyrazolo[4,3-f]quinolinones 42. Synthesis of spiroindoline-3,4’-pyrano[3,2-b]pyran-4-ones 43. Synthesis of N-(α-alkoxy)alkyl-1,2,3-triazoles 44. Synthesis of 4-(α-tetrasubstituted)alkyl-1,2,3-triazoles 45. Funding This work has been supported by Università degli Studi dell’Insubria and Università degli

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• that the alkoxy groups in compound 10, which are positioned para or ortho to the reacting site, play an important role in the Scholl reaction to form compound 3. Similar substrates, where the alkoxy groups are replaced by hydrogen atoms or a 4-tert-butyl group, did not yield product 3 under similar

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• derivatives and the antiparallel stacking mode into columnar structures stabilized by arene–perfluoroarene intermolecular interactions were confirmed by the single-crystal structure of the alkoxy-free side chain analog, i.e., 1,2,4-trifluoro-3-(perfluorophenyl)triphenylene (F). UV–vis absorption and

• , C10F8 (6F-BTPn), on the other. With only four alkoxy chains, these polar “Janus” mesogens [33][44] display a columnar hexagonal mesophase over broader temperature ranges and higher mesophase stability than the archetypical 2,3,6,7,10,11-hexa(alkoxy)triphenylene counterparts [48], whereas the

• the Janus Fn derivatives exhibit a hexagonal columnar liquid crystal phase (Colhex), with clearing temperatures decreasing gradually with the elongation of the alkoxy side-chains, from nearly 200 °C for the shortest homologs down to ca. 100 °C for the dodecyloxy derivative. The larger lath-like

Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

• peroxides, oxaziridines, and their derived species are often applied as terminal oxidants [7][8]. The weakness of the O–O bond allows alkoxy radicals to form through homolysis or reduction [9]. The generated alkoxy radicals provide an accessible tool for selective radical cascades, where a variety of

• tendency to recombine with C-centered radicals and add to unsaturated bonds with the formation of new carbon–oxygen bonds. However, alkoxy radicals, which are always present in such systems, are involved not only in the formation of ROO radicals but also in hydrogen atom transfer (HAT) processes and β

• 22 (steps F, G). The third possible pathway involves the abstraction of a hydrogen atom from 4-hydroxy-2(5H)-furanone 21 by the tert-butoxy radical formed in step A to give the alkoxy radical III (step H). Intermolecular hydrogen atom transfer results in the C-centered radical IV (step I). Further

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• modification of dihydroxyviolanthrone where the effect of three alkoxy substituents on the 16,17-bis(2-ethylhexyloxy)anthra[9,1,2-cde]benzo[rst]pentaphene-5,10-dione, on aggregation and photovoltaic properties was studied [30]. It was found that derivatives with the shortest linear alkyl chain (n-hexyl

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

• structure (Figure 1a) [14][15][16]. Our extensive efforts have revealed that introducing electron-donating alkoxy and electron-withdrawing cyano groups at both ends of the diphenylacetylene scaffold slows the internal conversion to the πσ* excited state. Further incorporating four fluoro substituents in the

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

• presence of an alkoxy group at the 5-position of the 2-hydroxybenzophenones (4ga, 4ha and 4ia) did not improve the UV-protection abilities to an appreciable extent, and the SPF values decreased with increasing alkyl chain length. Conclusion In conclusion, we have developed a transition-metal-free procedure

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

• -lactams to photooxidized alkenes (Figure 2A), and our findings are presented in this study. Results and Discussion The initial phase of our investigation involved the synthesis of suitable starting compounds for the following oxidative cyclization. For this purpose, a series of 4-alkoxy-β-lactams

• 4), while reducing the amount of PhSSPh and lutidine to 20 mol % led to a lower yield (Table 1, entry 5). With the optimized reaction conditions in hand, we submitted the previously prepared 4-alkoxy-β-lactam substrates 8a–h to photoredox conditions (Scheme 1), and the salient results are reported

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

• ). Since this 1,2-shift reaction proceeds under mild conditions and in the absence of a radical initiator, it is thought to proceed by an ionic rather than a radical mechanism. Alkoxy and cyclopropyl radicals, which are more reactive than the usual alkyl radicals, are capable of abstracting hydrogen from

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

• % yield. Additional experiments were then carried out using N-methoxy-2-(prop-1-en-2-yl)benzamide with different substituents R2. Both electron-donating (methyl, alkoxy, dimethylamino) and electron-withdrawing substituents (fluoro, chloro, trifluoromethyl) were well tolerated on the phenyl ring and gave

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

• in Figure 3a. This indicates a ligand exchange of the hydroxy group resulting in a loss of electron density and the formation of the alkoxy-NHI 2'. The chemical shift is consistent with previously measured alkoxyiodanes [32]. The experiments were repeated using activated p-tolylmethanol (3a), again

• the alkyl hypochlorite IIa. The second mechanism (path b) requires a direct ligand exchange of I-OH with the alcohol and subsequent β-elimination of the alkoxy(hydroxy)iodane IIb to form the desired aldehyde 4. Conclusion In conclusion, this study has successfully introduced N-heterocycle-stabilized

• formation of a) an alkoxy-NHI which is causing a significant downfield shift of the protons in alpha-position (orange) compared to the free alcohol 2 (blue) and b) oxidation of p-tolylmethanol (3a, blue) to the aldehyde 4a (green) and carboxylic acid 4a’ (red). Reaction conditions: An equimolar mixture of

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

• Evgen V. Govor,
• Vasyl Naumchyk,
• Ihor Nestorak,
• Dmytro S. Radchenko,
• Dmytro Dudenko,
• Yurii S. Moroz,
• Olexiy D. Kachkovsky and
• Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

• (compounds 1{17–21}); for pyridazine or pyrazine derivatives, even the presence of halogen atoms was sufficient to deactivate the substrate (e.g., compounds 1{22–24}); a dialkylamino or alkoxy group at the C-6 position of pyridine derivatives also hampered the substrate’s reactivity (e.g., compounds 1{25–27

• , lowering the reactivity has been documented, other electron-withdrawing groups were reported to be generally compatible with the GBB reaction [21]. Interference of dialkylamino or alkoxy groups at the C-6 position was also mentioned previously [29]. In addition to that, it was found that electron-poor

• wide range of aminopyridines, pyrazines, and pyridazines, it worked poorly for aminoazoles, aminopyrimidines, substrates with strong electron-withdrawing groups, and substrates bearing additional dialkylamino or alkoxy substituents. The electronic nature was a major limiting factor for other two

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

• providing intermediate A. The latter, by loss of a trichloro(alkoxy)ferrate(III) anion, generates a strong electrophile such as the oxocarbenium cation intermediate B. The released trichloro(alkoxy)ferrate(III) splits into FeCl3, which enters the catalytic cycle, and a free alkoxide, which acts as a base

• catalytic cycle. Similar to what was previously observed, the elimination of the trichloro(alkoxy)ferrate(III) anion from intermediate C provides the iminium ion D, susceptible to nucleophilic attack by a water molecule present in the reaction medium, leading to the carbinolamines 6. This latter synthesis

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

• with aryl halides via dual photoredox and nickel catalysis. Deoxygenative borylation of secondary alcohol. Deoxygenative alkyl radical generation from alcohols under visible-light photoredox conditions. Deoxygenative alkylation via alkoxy radicals against hydrogenation or β-fragmentation. Direct C–O

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• , respectively. The proposed mechanism suggested that the active amido species (Mn5-a) was formed by treating Mn5 with the base. Then, the alkoxy intermediate Mn5-b is formed by reaction with the alcohol followed by release of an aldehyde and formation of the manganese hydride Mn5-c. The released aldehyde

• complex Mn9-a via the debromination of the pre-catalyst Mn9 with the help of a strong base. Then, Mn9-a treated with an alcohol provided a manganese alkoxy complex Mn9-b, which then undergoes β-hydride elimination to give the manganese hydride complex Mn9-c and the corresponding aldehyde. Further, the azo

• formed active catalyst dehydrogenates the alcohol to generate the alkoxy complex Mn-L3-II. The liberated aldehyde undergoes aldol condensation with the ketone to afford the α,β-unsaturated ketone, followed by the selective hydrogenation with Mn-L3-III to give the desired alkylated product (Scheme 27). In

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• dicyanopyrazinoquinoxaline derivatives 1a–7a. Synthesis of bis-alkoxy-substituted π-conjugated phenanthrolines 16a, 16b, 16c, and 16d. An alternative synthetic route to access 7a. Synthesis of DPQDs 1b–7b from their corresponding DCPQs 1a–7a. *THF/H2O/1,4-dioxane (4:5:1). **in situ formation. Absorbance properties of 1a–6a

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• bond migration. This is a mechanistic difference to the related 1,2-oxygen migration reactions of spiroacetals that involve alkoxy intermediates reported by Suarez and co-workers [33][34]. The presence of oxocarbenium ion 27 is inferred due to the formation of two diastereomers in Karban’s previous

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• , despite the presence of two pyridine nitrogen atoms, is extremely inert towards nucleophilic and oxidative amination reactions. Although molecule 5 does not explicitly contain deactivating electron-donating substituents such as alkoxy and dialkylamino (except for alkyl groups), the observed inertness may