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Search for "radicals" in Full Text gives 344 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds
Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200
- ; NHC; organic photocatalyst; radicals; visible-light; Introduction Over the last ten years, NHC-catalyzed visible-light-promoted radical chemistry has been extensively developed for the cost-effective and practical synthesis of bioactive intermediates, pharmaceuticals, drugs, and natural products [1
- cross-coupling between the C-centered and N-centered radicals. These methods are expected to open new avenues for visible-light- and NHC/4CzIPN-catalyzed carbon–heteroatom bond-forming processes (Scheme 1) [51]. In 2021, Studer et al. developed a novel method for the 1,3-difunctionalization of
- of single-electron NHC catalysis by incorporating oxidatively generated aryloxymethyl radicals A as a key intermediate. A variety of γ-aryloxy ketones 12 were successfully prepared in the presence of NHC (15 mol %), photocatalyst (2 mol %), using 467 nm LED and a combination of alkene 11, amide 9
Catalytic enantioselective synthesis of selenium-containing atropisomers via C–Se bond formations
Beilstein J. Org. Chem. 2025, 21, 2447–2455, doi:10.3762/bjoc.21.186
- selenides, recognized as valuable synthetic intermediates and biologically active compounds, have been demonstrated to exhibit a broad spectrum of biological activities. Among them, the synthesis of β-(selenium)vinyl sulfones can be accomplished via selenosulfonylation reactions initiated by free radicals
Enantioselective radical chemistry: a bright future ahead
Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174
- . Additionally, radical chemistry offers opportunities to achieve transformations that may not proceed via two-electron processes. Radicals can be generated through several different approaches, summarized in Figure 1A. The use of organostannanes to generate carbon-centered radicals was formerly commonplace but
- has been largely supplanted by greener methods employing less-toxic reagents. Using alternative methods, radicals can be generated by hydrogen atom transfer (HAT), resulting in the homolytic cleavage of a carbon–hydrogen bond. Other approaches for radical generation in modern radical transformations
- are photoenzymatic catalysis and electrochemical oxidation or reduction. Free radicals can undergo several types of basic reactions (Figure 1B), including atom or group transfer, addition to a π-bond, and radical–radical combination. In an atom or group transfer reaction, an atom or group is
Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics
Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156
- nucleophiles [7][8][9][10][11], radicals [12][13][14][15] and electrophiles [16][17][18] to give cyclobutanes and cyclobutenes [19][20], which are building blocks in regio- and stereoselective synthesis [21][22][23][24][25][26][27] (Scheme 1a). Additionally, BCB has been used in bioconjugation due to its high
Photochemical reduction of acylimidazolium salts
Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153
- contrast to these numerous reports with carbon-based alkyl radicals, dual NHC/photoredox-mediated coupling processes between carboxylic acid derivatives and other classes of radical are lacking [22][23][24][25][26][27][28][29][30]. In particular, to the best of our knowledge, formal reduction reactions of
Transition-state aromaticity and its relationship with reactivity in pericyclic reactions
Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125
- this case, as the reactions are intramolecular, the ASM terms are referred to the initial reactants and are computed by considering the interaction between E=CH• and •CH=CH–C≡CH radicals. As shown in Figure 8, although the change in the interaction (ΔΔEint) between the fragments is stronger for the
3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles
Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123
- mechanisms of the formation of azirindine 16 under Ni(II)- and Cu(I)-catalysis. Oxidative dimerization of non-aromatic cyclic enols has been previously observed in their reactions with 3-arylazirines catalyzed by Cu(I) and Cu(II) complexes and was attributed to the recombination of intermediate free radicals
Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides
Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110
- conditions is due to a favorable formation of EWG-substituted aryl radicals from the iodonium cation, based on their reduction potentials and bond-dissociation energies calculated by Romanczyk and Kurek [45]. The reduction potential in SET reactions for iodonium salts with EWG-substituted aryls significantly
- (4-NO2C6H4) compared to (4-OMeC6H4) [45]. Therefore, despite the fact that literature data mostly suggest similar reactivity for aryl radicals with different substituents in the phenyl ring, the formation itself is more favorable for EWG-substituted radicals. To gain a deeper understanding of the
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
- two radical aza[7]helicenes, 24a and 24b, exhibiting distinct photophysical behaviors [38]. Compound 24b features a higher PLQY (0.43), while 24a demonstrates doublet-state CPL (|glum| = 5.0 × 10−4), highlighting the potential of helicene radicals for spintronic applications. Meng’s group synthesized
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- vinylsulphonium triflates 28 which combine the features of a radical acceptor (in a Giese-type addition) and a leaving group. The use of ketyl radicals for oxetane synthesis was also investigated by Schindler and co-workers and a year later the group published a methodology that utilises a similar Giese addition
- /Williamson etherification sequence (Scheme 8) [43]. In this case, however, the radicals were generated by irradiation of α-acetyloxy iodides 36, formed by treating the corresponding ketone precursors with acetyl iodide in the presence of catalytic Zn(OTf)2. The radical addition employed electron-rich alkenes
- decarboxylation was induced by a photochemical oxidation using an iridium catalyst, and the resulting benzylic radicals were coupled with activated alkenes through a Giese addition which was irreversible due to the strained nature of the starting radicals. As a result, radical dimerization was minimal and the 3,3
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
- 450002, PR China National Engineering Research Center of Low-Carbon Processing and Utilization of Forest Biomass, Nanjing Forestry University, Nanjing 210037, PR China 10.3762/bjoc.21.100 Abstract In recent years, amidyl radicals have emerged as highly efficient and versatile reagents for hydrogen atom
- transfer (HAT) in photocatalytic reactions. These radicals display exceptional selectivity and efficiency in abstracting hydrogen atoms from C–H, Si–H, B–H, and Ge–H, positioning them as invaluable tools in synthetic chemistry. This review summarizes the latest advancements in the photocatalyzed generation
- of amidyl radicals as HAT reagents, with a particular emphasis on their role in the intermolecular HAT process. We highlight key developments, mechanistic insights, and emerging strategies that harness the unique reactivity of amidyl radicals in the selective functionalization of a variety of
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
- a specific focus on strategies involving carbon-centered radicals. The reactions are systematically categorized according to their initiation modes and radical sources, including (1) transition-metal-catalyzed radical reactions, (2) peroxide-mediated thermal processes, (3) photoredox-catalyzed
- transformations, (4) electrochemical approaches, and (5) metal-free or electron donor–acceptor (EDA)-driven systems. The substrate scope, limitations, and mechanistic aspects of these radical cascade cyclization strategies are critically examined. Review N-Arylalkenes: alkyl C(sp3)–H radicals Early investigations
- to generate t-BuO and OH radicals. The t-BuO radical then abstracts a hydrogen atom from the β,γ-unsaturated ketoxime, forming the iminoxyl radical 10. This is followed by a 5-exo-trig cyclization, yielding a C-centered radical 11, which then adds to the alkene moiety of the N-arylacrylamide, forming
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
- , which generally employed stoichiometric amounts of oxidants or more expensive transition metal catalysts, the present protocol employs only cheap copper sulfate pentahydrate as a catalyst under mild reaction conditions. The achieved phosphorylation proceeds via the formation of P-centered radicals
- effective generation of phosphorous radicals. Under a pure O2 atmosphere, the interception of formed P-centered radicals by excess oxygen can presumably inhibit the target process by the formation of unreactive phosphoric acid from the corresponding H-phosphonate [73][74]. The formation of phosphoric acid
- 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
Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts
Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84
- have been considered as a promising source of aryl radicals and employed in organic synthesis [20][21][22][23][26][27][28][29][30][31][32]. This investigation aims to compare the performance of CDs prepared from several carbon precursors including citric acid, glucose, and organic waste materials via
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- Ulm, Germany 10.3762/bjoc.21.80 Abstract Organic radicals with light-emitting properties and exceptional stability offer exciting opportunities to address spin-statistical limitations in organic electronics and advance quantum technologies. These radicals, acting as small molecular magnets, exhibit
- delves into the photoluminescent properties and spin ground states of trityl-based mono-, di-, and multiradicals, examining the strategies employed to enhance their performance. Additionally, we review predictive methods for determining the luminescence and spin states of radicals, highlighting critical
- unresolved questions that must be addressed to unlock the full potential of trityl-based radicals in advanced technological applications. Keywords: Chichibabin hydrocarbon; COF; Gomberg radical; MOF; Müller hydrocarbon; Thiele hydrocarbon; Introduction Gomberg-type, triarylmethyl-centered radicals
Recent advances in controllable/divergent synthesis
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- environment around the copper center disfavors a direct interaction with nucleophilic alkyl radicals. Instead, the reaction proceeds via an outer-sphere mechanism, where the alkyl radical reacts with the copper-activated C=N unsaturated bond, enabling stereocontrolled C(sp3)–C(sp3) coupling. In contrast, with
- the anionic cyano-substituted bisoxazoline ligand L7, the glycine ester and copper catalyst form a distinct intermediate complex Int-28. The ligand’s reduced steric bulk and altered electronic properties facilitate direct interaction with alkyl radicals, forming a high-valent Cu(III) intermediate Int
- six-membered nickel ring captures radicals and undergoes reductive elimination to form β-products (kinetic control); at high temperatures, the formation of a five-membered nickel ring leads to α-products (thermodynamic control). Therefore, the formation of the more stable nickel ring drives migration
Recent advances in the electrochemical synthesis of organophosphorus compounds
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- carbonyl group. The halide salts did not lead to product formation, indicating that chloride and bromide anions cannot generate the corresponding radicals to accelerate the conversion of diphenylphosphine. The reaction yield decreased when the methyl group was placed in ortho-position. Moreover, the
- on the aromatic ring did not react in this system due to the incompatibility of the intermediate radicals. Electrochemical N–P bond formation Due to the importance of phosphoramidates in medicine and organic synthesis, Zhong et al. [64] reported an electrochemical P–N coupling of amines with dialkyl
- decomposition leads to the generation of O₂, the primary oxygen source in the reaction process. A radical process was proposed in the reaction. Diphenylphosphine oxide and carbazole radicals were formed via anodic oxidation in the presence of a base, followed by a coupling reaction to give the final P–N product
Photocatalyzed elaboration of antibody-based bioconjugates
Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49
- function. Their chemical modification has been developed using iminoxyl radicals [28]. Although numerous methods exist for the functionalization of Trp in proteins, their application in the elaboration of ADCs is limited [29]. Given the many challenges in antibody modification as outlined above, it is
- thus to have a better control of the selectivity and the DAR, leading to more homogeneous ADCs. In this specific context, photocatalysis (Figure 2) enables site-specific bioconjugation by generating reactive intermediates (such as radicals or electron-deficient species) that can selectively react under
- 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
Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions
Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33
- mechanistic scenario than that operating in solution [71], where photogenerated thiyl radicals proved crucial intermediates. Parallelly, Hernández reported a photomechanochemical approach for the borylation of aryldiazonium salts in a ball milling apparatus equipped with a transparent polymethylmethacrylate
Red light excitation: illuminating photocatalysis in a new spectrum
Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22
- the substrate, an activated ester 25, subsequently generating carbon-centered radicals without the need for sacrificial electron donors via a decarboxylation process. In reacting with electron-deficient alkenes or alkynes 26, these radicals further yield tetralin and dialin moieties 27, respectively
- detail, and the authors have proposed that the reaction proceeds through a photoinduced electron transfer mechanism (Scheme 11). Upon red-light excitation, chlorophyll generates superoxide anion radicals (O2•−) in the presence of oxygen, which act as the active oxidant to convert organoborons 31 to
- reactions with nucleophiles like malonates, cyanides, and phosphites. The study further revealed that the radicals generated from these processes can be successfully utilized in dual catalysis with copper, yielding a variety of alkynylated products (Figure 11) [65]. Compound 46 has been shown to exhibit
Cu(OTf)2-catalyzed multicomponent reactions
Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7
- to multiple C–C bonds generates extended carbon radicals capable of giving further functionalization. Regarding the ionic mechanism, the key step generally comprises the complexation with the unsaturated substrate leading to activation of the alkenyl/alkynyl moiety towards a nucleophilic attack. In
Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts
Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272
- groups (V), which proved to be useful in the transfer of imine radicals [17]. Bolm et al. contributed also to this topic by introducing a sulfoximidoyl-containing benziodoxolone (VI) [18]. Recently, our group disclosed the first HIRs bearing a primary amine moiety, the benzylamine benziodoxolone reagent
Giese-type alkylation of dehydroalanine derivatives via silane-mediated alkyl bromide activation
Beilstein J. Org. Chem. 2024, 20, 3274–3280, doi:10.3762/bjoc.20.271
- building blocks like organohalides can be converted into alkyl radicals by means of photoinduced silane-mediated halogen-atom transfer (XAT) to offer a mild and straightforward methodology of alkylation. In this research, we present a metal-free strategy for the photochemical alkylation of dehydroalanine
- , alkyl radicals have been produced from alkyl halides, using azobisisobutyronitrile (AIBN) as initiator, promoting a tin-mediated XAT (Figure 1a) [8][9]. However, tin-based compounds are highly toxic and require harsh conditions for the initiation event. Fortunately, a renaissance in the field of
- photochemistry has introduced new ways of generating radicals like photoredox catalysis and via electron donor–acceptor (EDA) complexes [10][11][12][13]. These advances, coupled with modern electrochemical methods, chemical reactor engineering and light emitting diodes (LED), have eliminated the need for thermal
Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF5- and CF3SF4-containing [2]staffanes
Beilstein J. Org. Chem. 2024, 20, 3134–3143, doi:10.3762/bjoc.20.259
- in the absence of light. Note that recent work from the laboratories of Cahard and Bizet [50] suggests that autoxidation of the ethereal solvent could serve as one possible explanation for initial formation of SF5 radicals in the absence of light to initiate a radical chain reaction. It is also well
- , the carbon-centered radicals in both INT1 and INT4 are closer to strong electron-withdrawing groups than are the radical centers in INT2 and INT5, rendering INT1 and INT4 relatively more electrophilic. Inductive effects drop off steeply with distance, and it is also established that a substituent (or
Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts
Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257
- of enol acetates with aryldiazonium salts [93]. The excitation of the porphyrin macrocycles by light irradiation initiated the catalytic cycle, generating aryl radicals from the diazonium salts, similar to findings by Gryko and co-workers. They explored both batch and continuous-flow photocatalysis
- resulted in the formation of the product in 60–89% yields and 24–81% yields for 18 and 78, respectively, confirming that even the less energetic red light is sufficient to generate aryl radicals via single-electron transfer (SET) from the excited porphyrin to aryldiazonium salt 79 (Figure 16). Further
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