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Search for "oxidation" in Full Text gives 1426 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Photochemical reduction of acylimidazolium salts
Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153
- suitably electrophilic substrate at the carboxylic acid oxidation level provides an acylazolium species B, which typically reacts directly with nucleophiles or may first be transformed into the corresponding enolate derivative. Regardless of the individual pathway, NHC-catalyzed reactions of this type
- acid derivative substrates [16]. Over the last few years, a wide range of valuable NHC-catalyzed transformations have also been developed that incorporate redox steps. As an enamine species, single-electron oxidation of a Breslow intermediate is comparatively favored with the resulting open shell
- synthesis with complete reduction to the alcohol followed by partial re-oxidation often being conducted. Conclusion In conclusion, we have developed novel light-driven methodologies for the reduction of acylazolium salts using benzoylimidazolium triflate as a model substrate. In the presence of a
Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis
Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151
- sequence including oxidation and subsequent hydrogenation. The Huang group reported their synthesis of (+)-brazilin and its racemic form in 2022 (Scheme 5) [34]. They first evaluated the feasibility of the Prins/Friedel–Crafts tandem reaction in the construction of the 6/6/5/6 tetracyclic skeleton
- 139, epoxide 136 was first prepared from (R)-130 in two steps. Parikh–Doering oxidation of 136 followed by addition with Et2Zn in the presence of ligand 137 afforded alcohol 138, which was subsequently converted into amine 139 via a seven-step sequence. With the fragments 135 and 139 in hand
- ) and the following acid-mediated cyclization formed another tetrahydrofuran ring. The resulting compound was then converted into lactone 174 via 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-mediated oxidation. Lactone 174 was then converted into aldehyde 175 in three steps, which underwent Horner
Synthesis, biological and electrochemical evaluation of glycidyl esters of phosphorus acids as potential anticancer drugs
Beilstein J. Org. Chem. 2025, 21, 1909–1916, doi:10.3762/bjoc.21.148
- alkylating agents 1–3. The motivation behind these experiments was to explore whether these compounds, which individually exhibit no appreciable redox activity in the potential window applied, can chemically modify (alkylate) serum albumin and thus suppress its characteristic oxidation peaks. Human serum
- albumin was chosen as a model protein because of its well‐characterized structure and the presence of reactive sites that are known to be susceptible to alkylation. In standard aqueous media, the electrochemical oxidation of HSA can be observed via LSV as a broad wave, which is often attributed to the
- oxidation of amide and other amino acid side‐chain fragments. By tracking changes in this oxidation signal upon addition of an alkylating agent, we can infer whether the agent has effectively reacted with (and thus structurally altered) the protein. As illustrated by the black trace in the LSV plot, pure
Photoswitches beyond azobenzene: a beginner’s guide
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
- the photoswitch. Examples of photogenerated side reactions can be oxidation or irreversible rearrangements. In the following sections, seven classes of photoswitches beyond the classic azobenzene are introduced and discussed (Scheme 1). Each of them shows unique photophysical behaviour and has
- be synthesised through oxidation of aminoheteroarenes 12 (Scheme 4A) or reduction of nitroheteroarenes 13 (B). Bayer–Mills coupling (Scheme 4C) is suitable for both symmetric and asymmetric targets, usually in acidic conditions. Basic conditions [14] are more effective with very electron-poor
- , the synthesis can be directed towards the desired target with the use of protecting groups [41]. For the synthesis of azothiazoles 25, the addition of phenylhydrazine (22) to ammonium thiocyanate followed by ring closure and oxidation was recently proposed (Scheme 6A) [42]. Heteroarylazo-1,2,3
[3 + 2] Cycloaddition of thioformylium methylide with various arylidene-azolones in the synthesis of 7-thia-3-azaspiro[4.4]nonan-4-ones
Beilstein J. Org. Chem. 2025, 21, 1791–1798, doi:10.3762/bjoc.21.141
- (Supporting Information File 1, part 4). In contrast, compounds 8 and 6 quickly transformed into the single product (by TLC analysis) under the action of alkali, but this product was unstable in its individual form after evaporation from the solution (Supporting Information File 1, part 4). Oxidation, however
- , proved to be a more promising derivatization approach (Scheme 4). Thus, the short-term action of hydrogen peroxide successfully converted compounds 7e, 7c, and 9e to their corresponding sulfoxides 11e, 11c, and 13e. However, prolonged oxidation led not only to sulfone formation but also to deeper
- transformations. For example, compound 7e underwent both sulfone formation and S/O atoms exchange in the heterocyclic core. For derivatives 6 and 8, any oxidation conditions resulted in even more complex product mixtures (presumably due to the additional sulfur atom in the second ring), whose structures could not
Research progress on calixarene/pillararene-based controlled drug release systems
Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139
- destruction of aromatic macrocycles and their components. The external triggers include: pH [93], oxidation–reduction states [94], enzymatic actions [95], and light [96]. Specifically, within host–guest frameworks, the capability to meticulously regulate the assembly of complexes and synchronize them with
Preparation of a furfural-derived enantioenriched vinyloxazoline building block and exploring its reactivity
Beilstein J. Org. Chem. 2025, 21, 1737–1741, doi:10.3762/bjoc.21.136
- oxidation in methanol in batch electrolysis conditions, providing unsaturated esters S-3d and R-3d, respectively (Scheme 2). The previously used one-reactor two-step conditions were found to be productive for the electrosynthesis of S-3d, requiring the addition of acetic acid for the intermediate spiroketal
- 4d oxidation (Table 1, entry 1). We found that substrate S-2d can be transformed to ester S-3d in a single step with a reduced amount of HFIP as the only additive (Table 1, entries 2 and 3). Given the high cost of HFIP, we examined if it could be replaced with other proton donors for the cathode
- acetic acid or HFIP the electrochemical oxidation also provided the desired product 3d, although in reduced yield (Table 1, entry 7). An increased amount of acetic acid (1 mL or ≈ 18 equiv) also reduced the yield (Table 1, entry 8). The attempt to use LiOAc as electrolyte instead of LiClO4 was not
Approaches to stereoselective 1,1'-glycosylation
Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133
- traceless hydrolysis of β-GlcN-derived allyl glycosides with retention of the anomeric configuration [102]. Anomeric deallylation was achieved through an initial double-bond isomerization to the propenyl moiety, followed by oxidation of the glycosidic prop-1-enyl group to a formyl group, as in 111, with
Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade
Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132
- -flow configurations demonstrate superior safety and efficiency. While the synthetic significance of nitration is underscored by the broad utility of nitro derivatives, persistent technical challenges including regioselectivity control, over-nitration phenomena, and substrate oxidation side reactions
- the material [70]. Oxygen balance (OB), a critical parameter quantifying how well an explosive provides its own oxidant, reveals potential safety risks when OB values exceed the threshold of −200. Since the energy release predominantly originates from oxidation reactions, the available oxygen content
Influence of the cation in hypophosphite-mediated catalyst-free reductive amination
Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130
- pH 0) [19], and usage of an additional amount of base leads to stronger reductive properties. Moreover, the role of the cation could be critical for the thermal stability against disproportionation or aerobic oxidation of hypophosphite [38]; salts with larger cations are also more soluble in organic
Chemical synthesis of glycan motifs from the antitumor agent PI-88 through an orthogonal one-pot glycosylation strategy
Beilstein J. Org. Chem. 2025, 21, 1587–1594, doi:10.3762/bjoc.21.122
- over the following steps: 1) deprotection of the TBDPS group, 2) phosphitylation of the free alcohol with phosphoramidite 11 in the presence of 1H-tetrazole and 4 Å MS, and 3) oxidation of the phosphite by mCPBA. Hydrogenolysis of Bn and Cbz groups in 14 with Pd(OH)2/C and subsequent saponification of
Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer
Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119
- macrocycle whose structure has been confirmed by X-ray diffraction analysis. Next, oxidation of 4 was attempted using [bis(trifluoroacetoxy)iodo]benzene (PIFA) in CH2Cl2 at −78 °C (Scheme 2). These reaction conditions had previously proven effective for the oxidation of 3 and other o-phenylene-bridged
- common organic solvents. Conclusion A novel o-phenylene-pyrrole-thiophene hybrid macrocycle (icosamer 4) was synthesized via Suzuki–Miyaura cross-coupling and isolated in 6% yield. Oxidation of 4 with PIFA produced a partially fused aza[5]helicene-containing macrocycle 5 in 58% yield, which was also
Heterologous biosynthesis of cotylenol and concise synthesis of fusicoccane diterpenoids
Beilstein J. Org. Chem. 2025, 21, 1489–1495, doi:10.3762/bjoc.21.111
- biosynthesis; P450 oxidation; synthesis; Introduction Fusicoccanes are a family of 5-8-5 tricyclic diterpenoid natural products that are produced by bacteria, fungi, algae, and plants (Figure 1a) [1][2][3][4][5][6][7]. Fusicoccanes possess a broad range of biological activities, including anticancer, anti
- biosynthetic pathway for brassicicenes, which share the same carbon skeleton and similar oxidation and unsaturation states as cotylenol and cotylenin A [36]. In a previous study, Oikawa and co-workers reported the identification of brassicicene BGC in Pseudocercospora fijiensis [37]. By heterologous expression
- cotylenin A and cotylenol (Figure 3a). Oxidation of brassicicene I with Dess–Martin reagent afforded intermediate 9 in 92% yield. The tertiary hydroxy group of compound 9 was further protected with a TMS group to provide compound 10 in 90% yield, a key intermediate in the synthesis of cotylenol and
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
- synthesis of various benzoxazole derivatives, demonstrating its versatility and practical applicability. Keywords: aerobic oxidation; copper; grafted silica; heterogeneous catalysis; microwave; Introduction 2-Aminoazoles are nitrogenous heterocyclic compounds of high relevance due to their biological and
- developed for the amination of oxazoles, with many of them utilizing aerobic oxidation to improve the sustainability of the process. Indeed, in 2011, Guo et al. [45] developed a protocol for the direct C–H amination of benzoxazoles and oxadiazoles, under an O2 atmosphere using 20 mol % of a Cu(II) catalyst
- open derivative, and the subsequent ring oxidation upon closure (as shown in the mechanism in Scheme S1 (Supporting Information File 1), the reaction mixture may contain the desired 2-substituted benzoxazole 2a together with its open-form precursor 2a-o. The latter can be hydrolysed to give N
Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications
Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106
- with Ru(II) to form NIR-emissive complexes that exhibit redox-responsive chiroptical switching, notably with complex 8 showing reversible electronic circular dichroism (ECD) upon oxidation [21]. Liao and co-workers introduced a narrowband CP-TADF emitter 9, characterized by a narrow emission bandwidth
- BCPL value of 13.2 M−1 cm−1. Notably, compound 21c undergoes reversible redox interconversion to its radical cation 21c•+ and dicationic 21c2+ states via chemical oxidation, enabling controllable switching between antiaromatic and aromatic configurations. These results provide a compelling strategy for
- ), exceptionally high BCPL as 100.2 M−1 cm−1, and marked chiroptical activity (|gabs| = 2.50 × 10−3 at 435 nm; |glum| = 5.00 × 10−3 at 460 nm) (Table 6). Upon mild oxidation, neutral 22 undergoes stepwise conversion into highly charged, multispin open-shell species 222+2• and 224+4•, preserving strong chiroptical
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- from esters of functionalised arylacetic acid 5 or 6 and involves two separate protocols: first, a metallacarbene, which undergoes the insertion, is generated from the corresponding diazo precursor formed either in flow via hydrazone oxidation (PS-TsNIK packed column), or in batch mode via diazo
- /RPC mechanism starts with a single-electron oxidation of the cobalt catalyst followed by a reaction with the siloxane to generate a cobalt–hydride complex. Subsequent hydride transfer to the alkene produces radical pair 23 which collapses to alkylcobalt intermediate 24. Another single-electron
- oxidation of the metal centre turns the cobalt into an excellent leaving group, allowing for an intramolecular displacement reaction that affords the oxetane ring and regenerates the Co(II) catalyst. In 2023, Silvi et al. described a versatile and practical methodology that couples Williamson etherification
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
- amidyl radicals from HRP: (a) direct single-electron oxidation of amide HRP in the presence of photocatalyst and a base via a proton-coupled electron transfer (PCET) process by the cleavage of the N–H bond; (b) single-electron reduction of HRP catalyzed by photocatalyst via a single-electron transfer
- -Alkylbenzamide constitutes the primary structural unit of this class of compounds. The structures of these compounds are relatively simple and readily synthesizable. In these photocatalytic systems, direct single-electron oxidation of the amide HRP occurs in the presence of a photoredox catalyst and a base via a
- PCET process, involving the oxidation of excited 4CzIPN* and deprotonation by a base. The resulting amidyl radical 20 smoothly abstracted a hydrogen atom from the substrate via a HAT process, generating a radical 4. This C-centered radical subsequently underwent Giese addition with activated alkenes
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
- red solid in only 4% yield. A similar strategy was used by Osborn for the synthesis of isomeric compound 6 (Scheme 1) [32]. In this case, compound 3 was dehydrogenated giving compound 4 which was then reduced to the direct precursor 5. Subsequent oxidation using chloranil yielded cyclohepta[klm]benz[e
- construction of the azulene moiety in the final step by creation of new C–C bond(s) or oxidation of a partially saturated precursor (Figure 3a); 2) The use of precursors that already contain the azulene moiety or moieties, which are then annulated into fully fused PAHs in the final step (Figure 3b). Obviously
- , the synthesis of more complex molecules may require elements of both strategies. Construction of the azulene moiety in the final step Oxidation of partially saturated precursors: With modern cross-coupling reactions providing access to larger precursors, a synthetic strategy involving the
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
- . Based on these results and previous studies, a detailed reaction mechanism was proposed as shown in Scheme 12. The process begins with the oxidation of Cp2Fe at the anode to form Cp2Fe+, which then facilitates the deprotonation of the α-C–H bond of the 1,3-dicarbonyl compound by methoxide, generated at
- , affording the products 29e and 29f in quantitative yields. A plausible mechanism for the electrochemically induced radical cyclization is proposed in Scheme 16. Due to its lower oxidation potential, Cp2Fe(II) is first oxidized to Cp2Fe(III), which then oxidizes the carbanion intermediate 30 generated from
Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates
Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96
- produced by the oxidation of PH-reagents by copper(II)-containing species. Employing anhydrous CuSO4 instead of the pentahydrate led to a dramatic phosphorylation yield drop from 70 to <5%. It seems that the ligand environment of copper is very important for the effective reaction: other Cu(II) and Cu(I
- radicals and product 3 can be described by several pathways. The direct oxidation of 2 by Cu(II) A leads to the formation of P-centered radical E and Cu(I) B. Under air atmosphere, the formed Cu(I) species B can react with molecular oxygen resulting in the formation of peroxycopper intermediate C [75][76
- hydroperoxide transfer from copper complex D with the formation of intermediate H and, therefore, regenerating Cu(I) B. Alternatively, the latter can be formed by oxidation of benzylic radical G with the formation of carbocation I. However, given that in the absence of oxygen the β-ketophosphonate was formed
Synthetic approach to borrelidin fragments: focus on key intermediates
Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91
- to afford the corresponding sulfone 41. However, Uguen found that a more efficient route involved treating alcohol 40 with tosyl chloride in pyridine and DMAP, followed by nucleophilic displacement with sodium thiophenol and oxidation of the resulting sulfide with m-CPBA, yielding sulfone 41 in 85
- 94% yield. Like 40, iodination of ent-40 gave crystalline product ent-42, and its structure was confirmed by XRD crystallography. The intermediate ent-40 was then subjected to the same tosylation/thiolation/oxidation sequence used for the 40 to 41 conversion, yielding ent-41 in comparable yield (82
- , followed by oxidation with m-CPBA to provide sulfone 33, which readily was reacted with another epoxide 46b. The sequential treatments used for the condensation of ent-27 and 46a to 48a were applied to 33 and 46b, yielding the desired product 49a (77%) along with a small amount of isomeric 49b (8%). The
Gold extraction at the molecular level using α- and β-cyclodextrins
Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89
- and/or audio, bringing the benefit of enhanced signal transmission (because of its high conductivity), reliability and durability (a direct result of its high resistance to oxidation) [7][8]. In medicine, gold is used as an inert and non-allergenic alternative metal in devices such as pacemakers [9
- , heat, oxidation, and hydrolysis. Owing to their properties, cyclodextrins are frequently applied in pharmaceutical formulations with low-soluble or unstable drugs [28][29][30], in cosmetic formulations [31][32], and in the food industry [33][34]. The vast majority of guests in these applications are
Recent advances in synthetic approaches for bioactive cinnamic acid derivatives
Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85
- situ formation of an active enol ester 26. The phenol was formed in situ during the second step from phenylboronic acid oxidation utilizing H2O2 (30%) as green oxidant (Scheme 8B) [40]. Sureshbabu and co-workers (2023) activated the carboxyl group of 4-hydroxycinnamic acid (1) by selectively reacting
- CuBr promoted hydrogen atom abstraction from the amide 94 resulting in the benzylic radical species 95, followed by oxidation to give acyliminium species 96. Luque and co-workers (2020) developed a biogenic carbonate of CuO–CaCO3 to catalyze solvent- and additive-free amidation reactions in air
- reaction (143) to activate the isothiocyanate as the coupling partner (Scheme 44) [83]. On the other hand, nucleophile activation could also be achieved via a catalytic oxidation reaction. For instance, Ablajan and co-workers (2024) reported the preparation of phenyl cinnamate (24) starting from the acid
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
- the terminal alkene and the conformational strain of forming a bridge[3.2.1]bicycle might be responsible for a selective 6-exo-trig cyclization. From tricyclic compound 4, anti-Markovnikov oxidation catalyzed by palladium led to the formation of aldehyde 5. When treated with p-TsOH, the intramolecular
- on this strategy, the authors also accomplished the total synthesis of (−)-lycospidine A in only 10 steps [20], another Lycopodium alkaloid with a truncated tetracyclic skeleton and distinct oxidation levels, further highlighting the versatility and efficiency of the enamide aza-Prins approach
- a regioselective manner. From tetracyclic compound 11, a one-pot facial and regioselective hydroboration/amide reduction followed by oxidation produced (+)-lycoposerramine Q, which was then converted to (+)-fawcettidine by Ley oxidation. Alternatively, hydroboration of 11 in mild conditions without
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- radical unit. Now, the chlorine substituents screen the hemispheres above and below this plane, protecting the unpaired electron in the p-orbital from oxidation or other detrimental degradation. The weak emission of PTM with ϕ of 0.7% peaks at 609 nm (in tetrachloromethane (CCl4)) [40]. The racemic
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