Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• therapeutic methods [78][79][80]. Such reactions can be performed at particular locations such as DNA or tubulin, when the photocatalyst is placed via a tethered ligand (Scheme 17) [81]. In the present case, the triarylmethine dye 67 was used as sensitizer. It is in equilibrium with the lactone form 68 and

Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

• Dmitry E. Shybanov,
• Maxim E. Kukushkin,
• Eugene V. Babaev,
• Nikolai V. Zyk and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

• 9 in toluene for 7 h led to the formation of an equilibrium mixture of these compounds in a ratio of ≈2:1 (Scheme 5). We propose that the reversible transformation of 8 to 9 proceeded via the intermediate formation of zwitterion 21, in which the charges were stabilized by mesomeric effects under

Heteroannulations of cyanoacetamide-based MCR scaffolds utilizing formamide

• Marios Zingiridis,
• Danae Papachristodoulou,
• Despoina Menegaki,
• Konstantinos G. Froudas and
• Constantinos G. Neochoritis

Beilstein J. Org. Chem. 2025, 21, 217–225, doi:10.3762/bjoc.21.13

• Goals (SDGs), wherein the 7th goal focuses on ensuring access to affordable, renewable and clean energy [1]. Moreover, the European Union has committed to ambitious environmental targets as part of the European Green Deal [2]. Advancements in C1 chemistry are pivotal to achieving this equilibrium. As

Nickel-catalyzed cross-coupling of 2-fluorobenzofurans with arylboronic acids via aromatic C–F bond activation

• Takeshi Fujita,
• Haruna Yabuki,
• Ryutaro Morioka,
• Kohei Fuchibe and
• Junji Ichikawa

Beilstein J. Org. Chem. 2025, 21, 146–154, doi:10.3762/bjoc.21.8

• findings suggest that nickelacyclopropanes E and 2-fluorobenzofurans 1 are in equilibrium (see Scheme 5). Consequently, in the absence of arylboronic acids 2, the consumption of 1 was suppressed. Upon adding phenylboronic acid (2a, 1.0 equiv) to the above reaction mixture, the coupling proceeded, producing

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

• Radell Echemendía,
• Carlee A. Montgomery,
• Fabio Cuzzucoli,
• Antonio C. B. Burtoloso and
• Graham K. Murphy

Beilstein J. Org. Chem. 2024, 20, 3182–3190, doi:10.3762/bjoc.20.263

• reductive elimination (path 1) [37][38][39]. This pathway initiates by formation of a halogen bond complex between 1a and the trifuoroethyl(mesityl)iodonium ion 2a’, where adduct XB-1 is presumably in equilibrium with isomeric XB-2. Reductive elimination of the iodoarene from XB-2 would furnish B, whose

• was found at a relative energy of 10.1 kcal/mol, where the C–I–C bond angle is 178° with C–I bond lengths of 2.2 Å (I–CH2CF3) and 2.9 Å. The reaction coordinate diagram for path 1 showed a near barrierless equilibrium between halogen bond adducts XB-1 and XB-2, where XB-2 has a C–I–C bond angle of 86

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• reported the pseudorotaxane equilibrium observed by mixing α-CD and the axle molecules bearing methylpyridinium moieties on their ends, where the bigger rim of CD (the head side) was likely to include the dumbbell (Figure 8A) [71][72]. Concurrently, Komiyama and co-workers performed the kinetic analysis of

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• group, a strong blue shift occurred down to 394 nm. The only exception was a solution of 1i in acetic acid, where two peaks were observed. Apparently, the weaker acetic acid caused just a partial protonation of the amino group, and the equilibrium shown in Scheme 2 was observed. This was evidenced by

• solutions of compounds 1a–i in toluene (top) and DMSO (bottom) taken under a 365 nm UV lamp. Normalized solid-state emission spectra of compounds 1a–i (bottom) and photos of powders taken under a 365 nm UV lamp (top). Synthesis of donor–acceptor 1-pyrindane derivatives 1. Plausible equilibrium of compounds

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

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• upon binding of the enolate molecule to iodine either through a carbon–iodine or an oxygen–iodine bond. Both intermediates, I and II, are in rapid equilibrium with each other and further undergo two different types of reactions: [1,2]-ligand coupling and [2,3]-rearrangement (Scheme 2). Either of these

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• -glycosyl aniline β-22b which was formylated to give 22c in 74% yield (Scheme 16) [24]. Product 22c resides as a mixture of α- and β-anomers, because an anomeric equilibrium was activated during the acid-mediated formylation. The cyclization of 22c with oxalyl chloride, carried out under forcing conditions

• (TiCl4, chlorobenzene, 85 °C), afforded anomerically pure β-configured isatin-N-glucoside β-23a in 80% yield. The product was formed as the pure β-anomer, because the anomeric equilibrium was again active in the presence of the Lewis acid and the β-anomer is thermodynamically favored because of the

• in case of the oxoindirubins 41 seems to decrease this unfavorable dipol situation in case of the E-configured isomers. It is likely, that an E/Z isomerization takes place under acidic conditions. The barrier of this equilibrium is most likely lowered by the presence of the ring oxygen as it

Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates

• Kento Iwai,
• Akari Hikasa,
• Kotaro Yoshioka,
• Shinki Tani,
• Kazuto Umezu and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238

• hydrated product 9. The less acidic ammonium acetate was effective for the ring closure of 4a (Table 4). When a solution of 4a and ammonium acetate was heated for 15 h, a 28% yield of 5a was obtained (Table 4, entry 1). Ammonium acetate dissociates into ammonia and acetic acid in an equilibrium upon

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

• Anthony J. Burke and
• Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

• preparation of biologically active compounds [15]. The synthesis was achieved via a sulfonyl group rearrangement driven by the azide–tetrazole equilibrium in quinazolines. The researchers utilized two synthetic pathways to prepare the target compounds. The first pathway involved a nucleophilic aromatic

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

• K) suggest a kinetically controlled reaction. To further shift the chemical equilibrium toward CO2 capture, increasing steric hindrance at the epoxide was explored by introducing bulky substituents into the scaffold. This resulted in an increase in activation barriers for adduct formation. Including

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

• as final product, characterized by significant ring strain [59]. Under light irradiation, PhSSPh is in equilibrium with the corresponding thiyl radical, which is subsequently reduced to thiophenolate by PC•, originating from the reduction of *PC+. The reduction potential of PhS−/PhS• (Epred = +0.45 V

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

• ’) decreases with time in favor of the thermodynamic Markovnikov regioisomer (2e, 2i). This phenomenon cannot occur for products 2g and 2h because the kinetic and thermodynamic products are the same. This observation confirms the existence of an equilibrium between the episelenonium and the final products 2

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

• reaction) were considered, as such a coarse approximation cannot be applied after reaching the plateau due to equilibrium processes (see Supporting Information File 1 for further details). The determined TOF of tetrafluoroiodolium salt 2BArF reaches a value of 80 h−1, almost 1.7 times as high as the TOF of

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

• -((thiazol-2-ylthio)methyl)-4,6-di-tert-butylcatechol (CatH2-CH2-S-thiazolyl) (21.5 ± 1.5 µM) [54]. However, for CatH2-CH2-S-thiazolyl, the equilibrium state is reached in less than one minute which increases significantly the antiradical activity of AE compared to catechol 4. On the contrary, the presence

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• (AS-MS), co-fractionation mass spectrometry (CF-MS), or mass spectrometry integrated with equilibrium dialysis for the discovery of allostery systematically (MIDAS) [38][39][40][41][42][43][44]. The chemical proteomics approach and related activity-based protein profiling has been reviewed

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• ][5]. The transient impact of kinetic energy, channeled into the reaction, facilitates overcoming the constraints inherent in equilibrium models. Thus, employing limited substrates could potentially yield diverse products through a simple alteration of conditions, compared to solvent-based methods [6

• for unconventional reaction pathways by exploiting kinetic energy to surpass equilibrium constraints. This methodology presents several advantages over conventional solvent-based approaches, including the potential for diverse product formation with limited substrates and the development of

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

• physicochemical descriptors. A prominent early example are Hammett parameters, developed in 1937 [26][27], that relate substituent parameters to the equilibrium constant of the deprotonation of a substituted benzoic acid. The derived substituent parameters are used to gain insight into the mechanism of reactions

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• unit allows for spin localization at the 10-position of anthracene through C–C bond rotation, resulting in a tail-to-tail σ-dimer (Figure 1b). The σ-dimer exhibits an equilibrium state between the monomer radical and the σ-dimer in solution, and mechano-stimulus-induced C–C bond fission in the solid

• small about 1.18 kcal mol−1 (Supporting Information File 1, Figure S2). To investigate the activation barrier of this equilibrium, potential energy curve by changing the dihedral angle θ of one anthryl group was calculated. The transition state was calculated with the dihedral angle θ = 30.6° and the

• activation barrier is only 2.94 kcal mol−1 (Supporting Information File 1, Figure S3). Thus, these two structures are likely in equilibrium and rapidly exchange with each other in solution. The energy difference between DAntM dimer (head-to-head σ-dimer) and DAntM radical monomer was also evaluated, showing

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

• was taken into account by the polarizable continuum model using the integral equation formalism (IEFPCM) [25] for DFT calculations. The optimized molecular structures were verified by vibrational analysis; equilibrium structures did not have imaginary frequencies and transition-state structures had

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• catalyst can easily leach into the solution as it reaches equilibrium between the absorbed species on the surface and the solubilised species. To improve the stability of the supported catalyst, it is important to modify the catalyst and support to enable hydrogen bonding. This method can also bring the

Computational toolbox for the analysis of protein–glycan interactions

• Ferran Nieto-Fabregat,
• Maria Pia Lenza,
• Angela Marseglia,
• Cristina Di Carluccio,
• Antonio Molinaro,
• Alba Silipo and
• Roberta Marchetti

Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180

• ), skew (S), and half-chair (H) conformations (Figure 1). Among them, chair’ shapes typically have the lowest energy and are thus preferred, except few cases in which different conformations can exist in a dynamic equilibrium, as for the iduronic acid that can adopt three low-energy solution conformations