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Search for "activation" in Full Text gives 1181 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides
Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110
- . Finally, control experiments without irradiation gave only traces of the benzamide 2aa showing no activation by the Ru complex at room temperature (Table 1, entry 24). An experiment conducted under an air atmosphere yielded only 9% of 2aa (Table 1, entry 25) indicating that the presence of atmospheric
Microwave-enhanced additive-free C–H amination of benzoxazoles catalysed by supported copper
Beilstein J. Org. Chem. 2025, 21, 1462–1476, doi:10.3762/bjoc.21.108
- ][44] and sulfamoyl chlorides [32] can perform the coupling under basic conditions, the need for the activation of the amine as an electrophilic agent generates additional waste. This reduces atom economy and indicates lower reaction efficiency. Acid-catalysed protocols have also been specifically
- temperatures were generally required for the heterogeneous catalytic reactions due to them having higher activation barriers than the homogeneous procedures. As reported in Table 3 (entry 3), excellent results were observed with the silica-supported catalyst when the reaction was performed at 80 °C for 6 hours
Wittig reaction of cyclobisbiphenylenecarbonyl
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- slightly preferred at room temperature with approximately a 3:2 ratio of figure-eight and bathtub conformations. We have also estimated the activation barriers of the interconversion of 3 and 5 between the figure-eight and bathtub conformations by measuring VT 1H NMR spectra in toluene-d8 because the
- signals due to the exo-methylene groups overlapped with the solvent signal in CD2Cl2. The thus obtained activation barriers of 3 and 5 were 11 and 12 kcal mol–1 at 263 and 253 K, respectively (Figure S27 in Supporting Information File 1). Previous DFT calculations at the B3LYP/6-31G(d) level of theory
- conformation (Sa,Sa)-A is feasible with a small activation barrier of 9.9 kcal mol−1. The figure-eight conformer (M,M)-B untwists to adopt an achiral conformation C with the exo-alkene units rotated inwards in opposite directions. These conformational changes are almost identical to those of CBBC 1. However
High-pressure activation for the solvent- and catalyst-free syntheses of heterocycles, pharmaceuticals and esters
Beilstein J. Org. Chem. 2025, 21, 1374–1387, doi:10.3762/bjoc.21.102
- hydrostatic pressure (HHP) was found to be an efficient activation method in several catalyst- and solvent-free reactions and has found application for the syntheses of heterocycles and the preparation of active pharmaceutical ingredients (APIs) via acylation and acid- and solvent-free esterification. The
- -products. A computational study accompanies the experimental data to interpret the outcome of the reactions. Keywords: acetaminophen; acetylsalicylic acid; benzimidazoles; catalyst-free synthesis; cyclization; esters; high hydrostatic pressure; pyrazoles; Introduction Non-traditional activation methods
- are one of the major driving forces in green synthesis [1][2]. High hydrostatic pressure (HHP) activation, one of such methods, is based on mechanical compression force. The typical pressure range is 2–20 kbar that is orders of magnitude greater than the conditions traditionally employed in chemistry
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- (176, X = NHBoc or NHCbz) is allowed to cyclise into a lactam. 3 Reactions of oxetanes 3.1 Ring-opening reactions The inherent ring strain of oxetanes and its polarised C–O bonds allow for relatively facile ring-opening reactions, typically upon a Lewis-acid activation. This type of reactivity has been
Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer
Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100
- activation energy modulation during transition state formation. Specifically, donor/acceptor electronic configurations in the substrate could either stabilize or destabilize the transient hybrid state, thereby thermodynamically governing the energy barrier for intermolecular HAT progression. When the partial
- demonstrated the homolytic cleavage of the N–O bond using N-(tert-butyl)-O-(1-phenylvinyl)-phenylhydroxyamide as a HAT reagent [78][79]. This compound was capable of initiating the formation of amidyl radicals through visible light activation. Although their controlled experiments showed that this method was
- across diverse bond activation challenges, particularly in C(sp³)–H, C(sp²)–H, S–H, Ge–H, and B–H bond transformations. The proposed system architecture emphasizes synergistic reagent cooperation rather than isolated component performance, representing a paradigm shift in photoredox catalysis design
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- ]. Interestingly, initial attempts to convert 65 into 66 using various procedures for the palladium-catalysed C–H activation were unsuccessful, even when conducted at elevated temperatures. However, treatment of 65 with KOH in refluxing quinoline successfully yielded the desired PAH 66, albeit in a modest 15
Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents
Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98
- -coupling, using Cp2Fe-catalyzed electrochemical oxidation. This method leveraged the selective activation of the acidic α-C–H bond within the 1,3-dicarbonyl moiety to generate a carbon-centered radical, which was crucial for the subsequent cyclization. The reaction was carried out under reflux conditions
- quinolinone products. Beyond electrochemical protocols, photochemical activation – particularly visible-light photoredox catalysis – has become a powerful and sustainable strategy for generating carbon radicals under mild conditions. In 2023, Fan’s group discovered a radical cyclization of N-arylacrylamides
- with α-aminoalkyl radicals generated from tertiary arylamines using photoredox catalysis (Scheme 13) [9]. In this system, Ir[dF(CF3)ppy]2(dtbbpy)PF6 was used as a photosensitizer to trigger the α-C–H activation of N,N-dimethylaniline, generating an alkyl radical under 30 W blue LED (454 nm) irradiation
Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups
Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94
- molecular architectures in pharmaceuticals, polymers, and agrochemicals. Despite advancements in directing group (DG) methodologies and computational approaches, predicting accurate regioselectivity in C–H activation poses significant difficulties due to the diversity and complexity of organic compounds
- . This study introduces a novel quantum mechanics-based computational workflow tailored for the regioselective prediction of C–H activation in the presence of DGs. Utilizing (semi-empirical) quantum calculations hierarchically, the workflow efficiently predicts outcomes by considering concerted
- metallation deprotonation mechanisms mediated by common catalysts like Pd(OAc)2. Our methodology not only identifies potential activation sites but also addresses the limitations of existing models by including a broader range of directing groups and reaction conditions while maintaining moderate
Recent advances in synthetic approaches for bioactive cinnamic acid derivatives
Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85
- ) reported a carboxyl group activation of cinnamic acid (7) by applying pivalic anhydride in a single step to afford the corresponding amide 8 in excellent yield (Scheme 3B) [35]. Moreover, pivalic anhydride is easier to handle than its chloride counterpart. Wang and co-workers (2022) utilized 5-nitro-4,6
- could be recycled by adding POCl3 and KSCN, thus promoting the reagent’s sustainability by reducing waste. Carboxyl group activation can also be achieved by using triazine-based reagents. For example, Saberi and Salimiyan (2019) applied 2,4,6-trichloro-1,3,5-triazine (TCT) to perform amidation of
- cinnamic acid (7) and N,N’-dimethylformamide (DMF)-mediated by POCl3 via acid chloride 36 formation (Scheme 20) [52]. On top of the carboxyl activation approaches demonstrated above, O/N-acylation could also be achieved by employing an electrophilic alkylating agent by exploiting the nucleophilicity of the
Pd-Catalyzed asymmetric allylic amination with isatin using a P,olefin-type chiral ligand with C–N bond axial chirality
Beilstein J. Org. Chem. 2025, 21, 1018–1023, doi:10.3762/bjoc.21.83
- Education, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan Soft Molecular Activation Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan Institute for
Recent total synthesis of natural products leveraging a strategy of enamide cyclization
Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81
- first report by Stork in the 1950s [1][2][3]. Compared with enols, enamines benefit from the lone pair of electrons on the nitrogen atom, which enhances the nucleophilicity of the alkene, enabling it to react with a broad range of electrophiles. This activation mode of carbonyl compounds has been so
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- , hinting at the type of non-radiative decay pathways in these molecules [63]. For medium strong donors the Gibbs energy of activation ΔGCT‡ for crossing over into the CT state is low, and emission can occur from here with high ϕ (see point 2 in Figure 9). For strong donors, ΔGCT‡ is close to 0 allowing
Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines
Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74
- ) [46]. In 2019, Li, Yang, Van der Eycken and co-workers reported a modification of this strategy relying on thermal activation instead of cationic gold catalysis [47]. The approach worked particularly well with substrates featuring terminal alkynes. Inspired by these developments and taking into
- heteroannulation leading to the pyrazolo[1,5-a][1,4]diazepine scaffold. Our initial choice was to investigate the use of silver(I) triflate (AgOTf) as a catalyst in toluene, given its previously demonstrated efficiency in various transformations involving the activation of triple bonds towards nucleophilic attack
- . The first step, the Ugi-4CR, introduces molecular diversity, while the second step, an efficient silver(I)-catalyzed heteroannulation, facilitates the formation of the pyrazolodiazepine core via alkyne activation towards the nucleophilic attack by the pyrazole nitrogen. This strategy expands the array
Recent advances in controllable/divergent synthesis
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- pathway bifurcated based on the steric demands of Si–C-bond activation. The methyl-substituted ligand (S)-8H-binaphthyl phosphoramidite L4, featuring a spacious cavity, favored sterically encumbered Si–C(sp3)-bond activation, selectively delivering axially chiral (S)-1-silacyclohexenyl arenes 17 with high
- enantiocontrol. Conversely, the bulky tert-butyl-decorated (R)-spirophosphoramidite L5 imposed a confined cavity, steering selectivity toward Si–C(sp2)-bond activation and predominantly afforded the regioisomeric (S)-2-silacyclohexenylarenes 18. In 2025, Gong and co-workers reported a visible-light-mediated
- species Int-44. This reactive intermediate then engages with a Ti(IV)-enolate complex through radical recombination, ultimately delivering 2-aza-bicyclo[3.1.1]heptene (BCHepe) while regenerating the Ti(III) catalyst to complete the catalytic cycle. (2) Scandium-catalyzed pathway: Activation of the donor
Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters
Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69
- facilitated landmark organic transformations, such as the venerable Paternò–Büchi [6][7][8], Norrish–Yang [9][10][11], and enone–alkene cycloadditions [12][13][14], that proceed via the generation of a singlet or triplet diradical through the activation of an unsaturated bond [2][14]. While these seminal
- contributions have enabled the efficient activation of carbonyl and alkene moieties, the inability of most organic molecules to efficiently absorb photons at longer wavelengths often preclude their use in direct excitation strategies, requiring unique experimental set ups and light sources that are
- activation of polyboronated alkenes [51] and β-borylstyrenes [43][48], was ineffective and no reactivity was observed. Implementing a higher energy iridium sensitizer (≈60 kcal/mol) was also unsuccessful (Table 1, entry 2), however, employing thioxanthone (65 kcal/mol) demonstrated efficient activation of
Substituent effects in N-acetylated phenylazopyrazole photoswitches
Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66
- triplet state [48], appear to play a role. Specifically, the rotation mechanism does not explain the low activation entropy observed in azobenzene systems [49] sparking new discussions on the possibility of alternative isomerization pathways [34]. Recently, Reimann et al. computationally showed that the
- involvement of a triplet state mechanism, which crosses the transition state for the Z→E relaxation, could explain the low values of the activation entropy. The same authors also showed experimental evidence for this proposal by an external heavy atom effect on Z→E isomerization. To understand the thermal Z→E
- activation enthalpy ΔH‡ and ΔS‡. In particular, NAc-PAP-CN showed a negative ΔS‡ = −30.0 ± 2.0 J/(mol·K), while NAc-PAP-OMe showed a relatively similar value (−39.0 ± 4.0 J/(mol·K)), hinting towards the same mechanism of relaxation operating for both compounds. Comparing these values to the calculations for
Recent advances in the electrochemical synthesis of organophosphorus compounds
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- or ketones. They used nickel foam as both anode and cathode electrodes in an undivided cell under air at room temperature. The reaction was carried out in the presence of KI as an electrolyte, a key additive, and acetone as a solvent. HI increases the reaction yield due to the activation of the
New advances in asymmetric organocatalysis II
Beilstein J. Org. Chem. 2025, 21, 766–769, doi:10.3762/bjoc.21.60
- Radovan Sebesta Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia 10.3762/bjoc.21.60 Keywords: asymmetric organocatalysis; covalent activation; noncovalent activation; Organocatalysis is
- ]. Kowalczyk and co-workers showed how asymmetric organocatalysis can benefit from mechanochemical activation. They established that Michael additions of thiomalonates to enones, catalyzed by cinchona-derived primary amines, is efficient and enantioselective under ball-milling conditions [24]. Kondratyev and
- organocatalytic cycloaddition reactions of unsaturated imines. A broad variety of activation modes, as well as catalyst structures, was covered and found to be useful in affording a diverse array of chiral N-heterocycles [27]. In my group, we recently became interested in atroposelective catalytic syntheses
Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones
Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59
- and TMSCN (8). Model complex 4 initially reacts with TMSCN to give MeOTMS and HCN. Even under methanol-free conditions, an excess of TMSCN is therefore needed to achieve complete conversion (Table 1), which hints at a mechanism of catalyst activation through reaction of the metal complex with the
- the R-product from E-hydrazone is slightly lower in energy (Table 3). However, the activation barrier for the rate-limiting step is 0.4 kcal·mol−1 lower for the pathway shown in Figure 2 and that yields the S-product from the Z-hydrazone. As the activation barrier to thermal E/Z-isomerization is more
Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion
Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57
- 3αMan 5, first order reactions were assumed with the rate constants k5, k7, and k6 (Figure 2C). In order to determine the half-lifes τ1/2 and activation energies Ea of the photoswitching units comprised in the homobivalent glycocluster 6αMan3αMan 2, the decay of the metastable ZZ isomer to the
- k7 obtained with a first-order exponential decay fit (Table 2 and Supporting Information File 1, Figures S7, S9, and S11). The half-lifes τ1/2 and the activation energies Ea of thermal relaxation were calculated based on the determined rate constants. The kinetics show that thermal relaxation of the
- ), resulting half-lifes (τ1/2) and activation energies (Ea) for the thermal ZZ to EE isomerization of glycoclusters 1 [24] and 2 and thermal Z to E isomerization of the glycoantennas 3, 4, and 5 at 37 °C. The top-ranked results of the molecular modeling study of the various isomers of the ligands 6βGlc3αMan 1
Origami with small molecules: exploiting the C–F bond as a conformational tool
Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54
- -fluoroamide gauche effect has frequently been exploited is N-acylpyrrolidines, a structural motif found within many bioactive molecules (e.g., the fibroblast activation protein (FAP) inhibitors 111 and 112, Figure 12) [188][189][190][191][192]. When fluorinated analogues of N-acylpyrrolidines are prepared
Recent advances in allylation of chiral secondary alkylcopper species
Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51
- configurationally stable organoboron compounds was recently developed by Morken and co-workers, which employs only catalytic amounts of copper [47][48]. Their strategy uses chiral secondary organoboron compounds 20 as precursors to generate chiral alkylcopper species through a carefully controlled activation and
- transmetalation sequence (Scheme 6). For secondary boronic esters, Morken and co-workers conducted a systematic investigation to develop an efficient activation strategy [47]. Computational studies using DFT revealed an important relationship between the length of the boron–carbon bonds and the corresponding
- electronegativity, reaching 1.648 Å in the reactive alkoxytrialkyl complex D and 1.659 Å in the tetraalkyl "ate" complex E. The B–C bond lengths in amido- and alkyl-substituted boronic ester complexes B and C fell between these extremes, suggesting an intermediate level of activation. These findings prompted
Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters
Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50
- -disubstituted piperidine-containing amino acid subunits. Likewise, a cyano-substituted cyclic aminal is a core structural unit of the fibroblast activation protein inhibitor 5 [3] (Figure 1). The widespread use of non-proteinogenic cyclic amino acids in drug discovery justifies both the design of new analogs
Formaldehyde surrogates in multicomponent reactions
Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45
- products (products 2 to 5, Scheme 4). In other cases, under acidic and thermal conditions, DMSO can undergo a Pummerer-type process in which, upon activation of the sulfoxide oxygen, a reactive methyl(methylene)sulfonium ion (MMS) is formed (Scheme 5) that acts as an active electrophile. Depending on the
- ). Additionally, the Tiwari group developed a metal-free protocol using only K2S2O8 as an oxidant for the activation of DMSO to MMS (Scheme 8, path II) [38]. Under these conditions, an alternative mechanism arises in which the imine intermediate B, formed as previously stated through reaction between the aniline
- , methyl aryl ketones, and DMSO under iron(III) catalysis and using K2S2O8 for its activation [39]. The proposed mechanism is very close to those described above, with the methyl aryl ketone taking part of the reaction in place of the styrene component in the Povarov cyclization. In this case, the imine
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