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Search for "oxygen" in Full Text gives 1336 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
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
- conditions already reported in the literature for aerobic protocols. As shown in Table 1, entries 1–3, we compared xylene, toluene, and acetonitrile as solvents. According to Bhanage and Wagh [13], Cu(II) catalyses the C–H amination in xylene at 140 °C for 14 hours under oxygen. We tested the reaction in
- demonstrated good product conversion and selectivity without the need to perform the reaction under oxygen, while Cu(OAc)2 was slightly less efficient. When the catalyst loading was reduced to 15 mol %, the reaction yield decreased to approximately 75% for both copper salts. However, reducing the reaction time
- 13%, highlighting the importance of oxygen/air in the oxidative aromatisation of the benzoxazole ring. Reducing the reaction time to 1 hour or lowering the catalyst loading to 15 mol % resulted in decreased yields of 75% and 71%, respectively. The reaction was also carried out in Anton Paar equipment
Wittig reaction of cyclobisbiphenylenecarbonyl
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- nucleophilic substitution of the thus generated alkoxide to form an oxygen-containing five-membered ring. At least, density functional theory (DFT) calculations support that the nucleophilic attack of methylenetriphenylphosphorane to the exo-methylene unit is slightly favorable over reaction with the carbonyl
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
- emitters. Boron–nitrogen co-doping strategies, in particular, have facilitated the development of materials with ultra-narrowband emissions, near-unity photoluminescence quantum yields, and electroluminescence dissymmetry factors (|gEL|) exceeding 10−3. Likewise, heteroatom co-doping with oxygen, sulfur
- helicenes. Particular attention is given to multi-heteroatom systems co-doped with elements such as boron, oxygen, sulfur, and selenium, highlighting their influence on CPL performance and structure–property relationships. We classify the nitrogen-doped helicenes into only N-containing helicenes, B,N
- stimuli-responsive chiral electrochromic materials. In the same year, You’s group developed a transition-metal-catalyzed C–H/C–H-type regioselective C3-arylation of benzothiophenes using molecular oxygen as the oxidant [79]. This strategy afforded the TADF-active compound 64a, which exhibits efficient
Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds
Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105
- not allow a ground-state tautomeric process to occur. Bearing in mind the requirements for clean switching, where the tautomeric proton is transferred from the oxygen atom to the nitrogen atom of the quinolyl moiety (i.e. from E to K), a theoretical design was performed in order to see the most
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- chemistry; natural products; oxetane; reactivity; synthesis; Introduction Oxetanes are 4-membered heterocyclic compounds containing one oxygen atom whose discovery dates back to the 1870s when the first synthesis of the parent, unsubstituted oxetane was reported by Reboul [1]. Over the next 100 years, it
- in cyclobutane [3] – this difference is most likely caused by fewer gauge interactions in oxetane where one of the methylene units is replaced by oxygen. The authors also reported bond angles and lengths which are shown in Figure 1. As expected, the endocyclic angles are far from the ideal
- tetrahedral value which results in a large ring strain of 25.5 kcal/mol, comparable to oxirane (27.3 kcal/mol) and much greater than tetrahydrofuran (5.6 kcal/mol) [4]. Moreover, the strained C–O–C bond angle effectively exposes the oxygen lone pairs, making oxetane a strong hydrogen-bond acceptor and Lewis
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
- to produce amidyl radicals and oxygen anions in the presence of photocatalysts activated by visible light. Two representative cases illustrating this approach were reported in 2023. Building upon the experiments conducted by Alexanian’s group, Yan’s group extended the applicability of carborane as a
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
- radical A. This is followed by the conversion of a substrate containing C(sp3)–H bonds adjacent to an oxygen atom into an alkyl radical intermediate B. The alkyl radical intermediate then adds to the C=C bond of N-arylacrylamide, generating a second alkyl radical intermediate C, which undergoes
- then reacts with sodium trifluoromethanesulfinate (36) to form a sulfonyl hypobromite intermediate 38 (Scheme 20). This intermediate undergoes reduction at the cathode, leading to the formation of oxygen-centered and sulfonyl-centered radicals, which subsequently form a trifluoromethyl radical. This
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
- reaction times, and scope limitations. In the present work, the selective copper(II)-mediated phosphorylation of enol acetates with the formation of substituted β-ketophosphonates employing cheap copper sulfate as a catalyst and atmospheric oxygen as a terminal oxidant was carried out (Scheme 1c). Results
- radical was detected by HRMS, which supported a radical mechanism. Next, the influence of the atmosphere and the role of copper catalyst was evaluated (Scheme 4, reaction 2). Neither under argon nor under an oxygen atmosphere, the yield of 3a did not exceed 22%. However, employing 200 mol % of copper(II
- ) sulfate under an argon atmosphere afforded 3a in 33% yield. These results indicate, that copper(II) at high loading is capable of oxidizing H-phosphonate even in inert conditions [72]; however, a balanced concentration of oxygen in the reaction mixture is required for recycling of copper catalyst and
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
- resulted in more specific SMARTS patterns matching the DG. For example, Figure 3a shows the result from Tomberg et al. [9], which does not include the carbonyl oxygen in the SMARTS pattern match although the pattern marked in red in Figure 3b is part of the database. This example also highlights that in
- metal (the two oxygen atoms from the acetate moiety, the carbon atom from the reaction site, and the heteroatom from the directing group) is analysed without regard for connectivity. All four atoms have to lie within a plane after the optimization for the optimization to be considered successful. This
- is determined by calculating the angle between the normal vectors of the plane spanned by Pd, the reaction site and the heteroatom of the directing group and the plane spanned by Pd and the two oxygen atoms of the acetate moiety. This angle has to be below 5° for the atoms to be considered to be
A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones
Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92
- intermediate 7, the carbonyl oxygen interacts with AlCl₃, enhancing the electrophilicity and promoting the rearrangement to form stable oxonium ions. The removal of water from 7 is facilitated by protonation, producing reactive carbocations which undergo dehydrative aromatization to produce products 8
A versatile route towards 6-arylpipecolic acids
Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88
- . This tendency of amine bases in cross-coupling reactions aligns with the literature [44][45][46], reporting that they are either superior to or significantly outperformed by oxygen-based bases, depending on the conditions and substrates. K2CO3 was found to be the most suitable base, having similar
Supramolecular assembly of hypervalent iodine macrocycles and alkali metals
Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87
- pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen–lithium–oxygen bond angle is approximately 98.83
- °, displaying a closer arrangement of two HIMs. In contrast, the sodium complex exhibits a more open orientation of two HIMs with an oxygen–sodium–oxygen bond angle close to 167.98°. Lastly, a comparative study of association constants and binding energies for phenylalanine-based HIM with LiBArF20 and NaBArF24
- system [12]. In addition to these covalent bonding interactions, additional secondary bonding (e.g., red-dotted bonds between iodine and oxygen in phenylalanine-based hypervalent iodine macrocycle in benzene system in Figure 1A) can arise in these systems from neighboring atom lone pairs. Secondary
Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes
Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86
- enantioselectivities and high diastereoselectivities. A reasonable reaction mechanism was proposed and rationalized the experimental results. Keywords: aldehyde; annulation; aziridine; oxazolidine; ring expansion; scandium triflate; Introduction Oxazolidine derivatives are an important class of nitrogen and oxygen
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- such diradicals and we group the molecules in accordance with their type of conjugation. Kekulé-conjugated diradicals Trityl radicals and trityl-derived diradicals have been reported to be instable especially under light irradiation and in the presence of oxygen. As for the monoradicals, also
4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches
Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65
- response, respiratory, vasodilation, apoptosis, tumor growth, and cardiovascular system [1][2]. Nitric oxide (NO) is released as product of the NADPH and oxygen-dependent oxidation of ʟ-arginine to ʟ-citrulline under the catalysis of the enzyme nitric oxide synthase (NOS) [3]. There are three distinct
- a dihedral angle of 49.86(10) 86.22(11)° with the phenyl rings C6–C11 and C18–C23, respectively. The angle between both phenyl rings is 70.76(11)°. The stereochemistry around the double bond is Z, allowing an intramolecular N–H···O hydrogen bond between one of the carbonyl oxygen atoms and the amino
Synthesis and photoinduced switching properties of C7-heteroatom containing push–pull norbornadiene derivatives
Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64
- ) derivatives. Push–pull substitution on the 2 and 3 position as well as introduction of oxygen or nitrogen at position 7 of the NBD scaffold have led to the development of a new family of photoswitches. We studied the potential conversion of norbornadiene to quadricyclane (QC) isomers. As main investigation
- the corresponding boronic acid in a degassed toluene/H2O mixture (4:1, v/v) which was heated to 80 °C for 18 h (for detailed information see Supporting Information File 1). Using the described procedure, the oxygen containing derivatives O-NBD2 and nitrogen substituted N-NBD2 were successfully
- absorption maximum and onset was observed for the heterocyclic derivatives in relation to their isocyclic analogues. Basic principle of the NBD to QC conversion and vice versa. The bridge-atom at position 7 was varied to carbon, oxygen or nitrogen. The back-conversion induced via heat or a catalyst can
Recent advances in the electrochemical synthesis of organophosphorus compounds
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- synthesis of various organophosphorus compounds through the formation of phosphorus–carbon, phosphorus–nitrogen, phosphorus–oxygen, phosphorus–sulfur, and phosphorus–selenium bonds. The impact of different electrodes is also discussed in this matter. Graphite, platinum, RVC, and nickel electrodes have been
- organophosphorus compounds, in which phosphorus is attached to carbon or heteroatom centers. In this article, we describe recent advances in electrochemical green methods for the synthesis of various organophosphorus compounds through the formation of phosphorus–carbon, phosphorus–nitrogen, phosphorus–oxygen
- reaction. Some of their applications include hydrogen and oxygen production, metal electroplating, and organic compound synthesis using electrochemical methods. Depending on the reaction conditions, these cells can be divided or undivided. Divided vs undivided cells In divided cells, oxidation and
New advances in asymmetric organocatalysis II
Beilstein J. Org. Chem. 2025, 21, 766–769, doi:10.3762/bjoc.21.60
- commonly defined as a form of catalysis where a small organic molecule, an organocatalyst, accelerates a chemical reaction. Unlike previously regarded traditional catalysts involving metals or enzymes, organocatalysts are composed of nonmetal elements, such as carbon, hydrogen, nitrogen, oxygen, phosphorus
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
- set out to elucidate it by using DFT computations (Figure 2). As we have chosen as substrate in our experiments a self-prepared mixture of E- and Z-isomers (9:1) of N-acyl hydrazone 1, which allows for additional binding to oxophilic calcium via the carbonyl oxygen, we did not know a priori which of
- -tetrahedral coordination environment with cyanide, stemming from a common reagent (vide infra) and binding to the metal in a preferred side-on (π-complex) mode [54]. When the hydrazone substrate enters the catalytic cycle, it coordinates also as a bidentate ligand to calcium via oxygen and nitrogen atoms
- [1,2]H shift is orbital symmetry forbidden and has, hence, a high barrier of 39.8 kcal·mol−1, and also because a – conceivable – intermittently at carbonyl oxygen protonated species (i.e., on an iminol-type pathway) is considerably higher in energy than 10 or 11. The TMS-bound product 12, proposed in
Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives
Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58
- moderate to good yields. Subsequently, we investigated the scope of cyclobutanones and their analogues in the domino cyclization to access structurally diverse spirotetrahydroquinoline derivatives (Scheme 2). Heterocyclic analogues incorporating oxygen or sulfur atoms within the four-membered ring proved
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
- macrocycle [74][75]. 2 Ethers We now turn our attention from alkanes to what is arguably the simplest heteroatom-containing functional group: the ether. The presence of oxygen within a carbon chain offers several new opportunities for engagement by an introduced fluorine atom. First, we will consider what
- happens if fluorine is introduced onto one of the carbons that is directly attached to oxygen (Figure 6). This makes possible a hyperconjugative interaction between a lone pair on oxygen and the σ* orbital of the C–F bond (I, Figure 6) [76]. This interaction biases the rotational profile about the O–C(F
- -hybridised oxygen atom. When one fluorine is introduced into this scaffold in the form of a fluoromethyl group (43, Figure 6), the gross conformation is little changed, but notably the fluorine preferentially resides at an endo position (oriented back towards the aryl moiety) which enables nO → σ*C–F
Recent advances in allylation of chiral secondary alkylcopper species
Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51
- complex's chemical behavior (Scheme 6). Among the analyzed four-coordinate boron species, the unreactive trialkoxyborate complex A exhibited the most compact B–C bond at 1.621 Å. Following a clear trend, the B–C bond distance progressively lengthened as oxygen atoms were substituted with elements of lower
- energy compared to (S,S)-TS9. Both transition states demonstrated a lithium center's coordination involving bromide, benzoate, and ligand oxygen atoms. The (S,R)-TS8 transition state exhibited a significantly shorter Li–Br interaction distance (2.81 Å compared to 3.74 Å in (S,S)-TS9), offering
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
- tetrahydropyran-containing amino acid derivatives via anodic decarboxylation of N-acetylamino malonic acid monoesters to generate a stabilized carbocation (Hofer–Moest conditions), which were then reacted with a tethered oxygen nucleophile [4]. In this follow-up study, we demonstrate that N-protected amines are
Photocatalyzed elaboration of antibody-based bioconjugates
Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49
- oxygen [42]. Through energy transfer (EnT) from the ruthenium-based photocatalyst to triplet oxygen, singlet oxygen is produced in a targeted manner, which oxidizes histidine to an endoperoxide, significantly increasing its reactivity toward nucleophiles (Figure 4A). This strategy employs a
- functionalized ruthenium complex and a fragment crystallizable (Fc) ligand anchored to a magnetic bead, enabling the localized generation of singlet oxygen near antibodies (Figure 4B). The short lifetime and limited diffusion of singlet oxygen ensure exclusive reactions with proximal histidine residues. This
- intermediates can lead to protein denaturation or aggregation [61]. Because photoredox reactions often generate highly reactive species (such as radicals or singlet oxygen), long exposure times could cause unwanted side reactions, including the degradation of 3D structure of the protein or antibody. A short
Formaldehyde surrogates in multicomponent reactions
Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45
- (CuCl2, NaNO2, TEMPO) using molecular oxygen as a terminal oxidant have also been used [12]. Nevertheless, neither of these conditions was successful when they were applied to methanol to generate formaldehyde, because overoxidation is an important side reaction in these cases [12][13][14][15]. However
- 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
- -aza-Prins cyclization reaction of homoallylic amines with disulfides and DMSO under copper catalysis, where DMSO acts as a solvent and a formaldehyde source at the same time (Scheme 13) [48]. This protocol represents a versatile method for the construction of oxygen-containing heterocycles, in which
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