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Search for "radical" in Full Text gives 835 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Recent advances in synthetic approaches for bioactive cinnamic acid derivatives
Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85
- O atom of the carboxylate group. For instance, Coote and co-workers (2019) reported electrochemical methylation of cinnamic acid 7 using the TEMPO-Me reagent via reactive radical cation 59 to give the corresponding methyl ester 44 in moderate yield (Scheme 21A) [53]. Wang and co-workers (2019
- 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
- proceeding via C–N-bond cleavage of the oxidized tertiary amine 116 (Scheme 35) [70]. Cinnamic acid (7) was activated by forming the acyl radical 118 after −OPyf group cleavage from 117. Recently, Li and co-workers (2024) studied visible-light-mediated FeCl3-catalyzed reductive transamidation of nitro
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
- , with particular attention to the 1,2-difunctionalization of olefins by alkyl halides via atom transfer radical addition processes in the presence of amorphous nitrogen-doped carbon dots (Scheme 1a) [20]. In the framework of this research topic, we decided to investigate the use of carbon dots as
- from direct photoreactivity [24][25], sulfonium salts can be easily reduced under photoredox-catalyzed conditions [20][21][22], and the resulting radical undergoes homolytic cleavage of one of the C–S bonds, releasing an aryl radical Ar• and a diaryl sulfide Ar2S. Subsequently, triarylsulfonium ions
- material was observed, thus pointing out the key role of CDs in the process. Some additional irradiation was carried out to identify the aryl radical released during the irradiation. Unfortunately, when the reaction was conducted in the presence of both furan and allyl phenyl sulfone [27] no arylation
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
- have attracted considerable attention due to their promise in the total synthesis of alkaloids [16]. Notably, these valuable compounds can be employed as efficient synthons in enamide–alkyne cycloisomerization, [n + m] cycloadditions, pericyclic reactions, and radical cyclizations. A comprehensive
- bridge cycle [36][37]. The excellent diastereoselectivity in this radical cyclization was further rationalized by DFT calculations, which suggests an energy discrepancy of the hydrogen atom transfer process from different faces of the resulting α-hydroxyl radical. Final reduction of the ketone and amide
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- 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
- ][14]. While first examples of radical emitters in light-emitting diodes (LEDs) only delivered around 12% internal quantum efficiency [7], representing no improvement compared to conventional emitters, optimization of the donor-functionalized TTM radical and of the device geometry quickly allowed
- demonstration of LEDs with 100% internal quantum efficiency [8][12]. Modern approaches also incorporate light-emitting TTM radical derivatives into LEDs based on thermally activated delayed fluorescence to moderate excited triplet, doublet, and singlet states in an attempt to improve the overall device and
Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts
Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76
- computational study to design new PCs to be employed in atom transfer radical polymerization (O-ATRP) [17]. Notably, the sulfur-based structure 2 showed excellent performance for this transformation. One year later, the same research group reported its use in a reversible addition-fragmentation chain-transfer
- surprisingly, 5e showed only traces of 8, even with an E*ox of −1.85 V (Table 2, entry 5). Under the oxidative quenching study, we also evaluated the photocatalytic potential of the new family of D–A compounds in the atom transfer radical addition (ATRA) reaction involving styrene and tosyl chloride (TsCl), as
- facilitated by reduced photocatalyst (PC) and the interaction of 15 with the radical cation of DIPEA. The best result, again, was attributed to molecule 5a with 60% isolated yield (Table 5, entry 1). In contrast, molecule 5b showed the worst performance with 41% NMR yield (Table 5, entry 2). For compounds 5c
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
- L9, and reagents, delivering enantioenriched 2-/3-alkyl-substituted pyrrolidines with excellent regio- and enantioselectivity (up to 97% enantiomeric excess). Radical-clock experiments and deuterium-labeled silane studies revealed that cobalt catalysis proceeded via irreversible Co–H migratory
- ) and (3 + 2) cyclization strategies. Two distinct pathways were established: (1) The titanium-catalyzed ring opening of bicyclobutane (BCB) 32 generates a γ-carbonyl radical intermediate Int-42, which undergoes trapping by vinylazide 33. Subsequent dinitrogen extrusion produces an iminyl radical
Recent advances in the electrochemical synthesis of organophosphorus compounds
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- that when the reaction was carried out in the presence of TEMPO as a radical scavenger, a side product, TEMPO-P(O)R2, was formed (it was confirmed using high-resolution mass spectrometry). The results revealed that the reaction proceeded in a radical pathway (Scheme 1). Based on the cyclic voltammetry
- nickel as the cathode in the presence of tetrabutylammonium bromide (TBAB) at the constant current of 6 mA. The electrodes used in the reaction are all in plate form. The presence of TBAB causes the resulting bromide anion to oxidize to bromine radical and react with R2P(O)–H to produce a radical
- performed in the presence of TEMPO, the product of TEMPO-P(O)R2 was formed, which showed that the process proceeded through a radical path. In addition, the reaction was carried out in an electrochemical environment with an undivided cell, using graphite and platinum plate electrodes as the anode and
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
- addressed. Initially, we hypothesized that 11a may form by a single-electron oxidation/decarboxylation (Kolbe reaction) of 9a to generate carbon-centered radical, followed by hydrogen abstraction from solvent. To verify the hypothesis, an electrolysis of acid 9d was performed under optimized conditions
- observed by LC–MS when the electrolysis was performed in 5:1 MeCN/D2O (Scheme 2, reaction 2). The considerably higher O–H bond dissociation energy (119 kcal/mol) [12] as compared to that of the C–H bond in MeCN (86 kcal/mol) [13] renders the hydrogen atom abstraction from water by a carbon-centered radical
Formaldehyde surrogates in multicomponent reactions
Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45
- this case, the mechanism appears to proceed through the formation of free radical species, where APS plays the role of oxidant and radical activator of DMSO, generating reactive radical species of DMSO or dimethyl sulfone that react with the nitrogen of saccharine compound 19 without the need for a
- catalyst. Another recent example for the use of DMSO as C1 synthon was reported by Bhattacharjee et al. They used DMSO in a 3CR to install a methylene unit between an indazole 24 and a carboxylic acid 25 (Scheme 18) [52]. Under radical conditions using K2S2O8, they obtained a series of carboxylic acid
- salts and TEMPO as the radical initiator/oxidant couple that promoted the intramolecular radical cyclization of suitable 1,3-dicarbonyl Ugi adducts 54 and 55 (Scheme 45) [108][109]. The stabilization of the enol in the 1,3-dicarbonyl Ugi adduct allows single-electron transfer (SET) with the anion
Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene
Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39
- higher selectivity with milder reaction temperatures. The weaker C(sp2)–Br bond is easier to cleave than a C(sp2)–H bond, resulting in a higher likelihood of radical substitution at those positions. To the best of our knowledge, there are no previous examples of perfluorobenzyl substitution of any PAH(Br
Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions
Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33
- benefits of the photomechanochemical approach in the field of synthesis [77]. Specifically, they developed photomechanochemical conditions for the atom-transfer-radical addition (ATRA) of sulfonyl chlorides to alkenes, pinacol coupling of carbonyl compounds, decarboxylative acylation, and photocatalyzed [2
- reactions: A) atom-transfer-radical addition, B) pinacol coupling, C) decarboxylative alkylation, D) [2 + 2] cycloaddition. The photo in Scheme 11 was reproduced from [77] (© 2024 F. Millward et al., published by Wiley-VCH GmbH, distributed under the terms of the Creative Commons Attribution 4.0
Electrochemical synthesis of cyclic biaryl λ3-bromanes from 2,2’-dibromobiphenyls
Beilstein J. Org. Chem. 2025, 21, 451–457, doi:10.3762/bjoc.21.32
- starts with a single-electron oxidation of 4a on the electrode surface to form cation radical A, in which Br(II) is chelation-stabilized by the carboxyl group [21] and the neighbouring Br substituent [24]. Intermediate A rapidly undergoes irreversible chemical reaction by HFIP coordination to transient
- Br(II) followed by subsequent deprotonation to generate radical B. A following disproportionation of radical B would lead to the formation of Br(III) species C (anodic oxidation cannot be fully excluded), which undergoes intramolecular SNAr-type substitution to form cyclic λ3-bromane 1a and
Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides
Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25
- to inhibit p38α MAPK and 0.5 µM for TNF-α [10]. Pyrazolobenzothiazines containing a triazole moiety have also been studied as potential antibacterial drugs [7]. Other applications of N-substituted benzyl/phenyl acetamide pyrazolobenzothiazines include superoxide anion and DPPH radical scavenging
Red light excitation: illuminating photocatalysis in a new spectrum
Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22
- catalysis in recent years not only with heavy metals such as ruthenium and iridium [1][2][3][4][5], but also with lighter elements [6][7][8]. This field of light-mediated organic transformations relies on the use of a photocatalyst to promote radical reactions through electron transfer between this former
- 9,10-dicyanoanthracene radical anion (DCA•−) [29]. This system effectively drives photoredox-mediated reduction and C–C cross-coupling reactions under mild red-light conditions with various aryl halides, an aliphatic iodide, and O- and N-tosylated substrates (Scheme 4a). The authors discuss two
- plausible mechanisms: a photoinduced electron transfer (PET) between the 3MLCT state of the copper complex and DCA or a triplet–triplet energy transfer (TTET) between the 3MLCT state of the copper complex and DCA. In both of these mechanisms, the involvement of a doublet excited-state of the radical anion
Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity
Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20
- radical cations and dications of linear and angular [3]naphthylenes, consisting of fused aromatic naphthalenoid and antiaromatic cyclobutadienoid moieties and containing different degrees of paratropicity. Electronic absorption and vibrational Raman spectroscopies were used to describe the more relevant
- report that compounds 1 and 2 can both be easily oxidized to form relatively stable radical cations (1•+, 2•+) and dications (12+, 22+). Interestingly, oxidation reverses local antiaromaticity to aromaticity, a transition that is particularly noticeable in 1 → 1•+ → 12+, where stabilization of the
- dication is associated to the appearance of a global diatropic ring current which stabilizes the whole molecule. On the contrary, 22+ can be better viewed as two segregated radical cations with slight, but high enough, local diatropic character in each. Here, we use electronic UV–vis–NIR absorption and
Synthesis of disulfides and 3-sulfenylchromones from sodium sulfinates catalyzed by TBAI
Beilstein J. Org. Chem. 2025, 21, 253–261, doi:10.3762/bjoc.21.17
- (sp2)–H radical sulfenylation of enaminones or chromones has emerged as a popular strategy using various sulfenyl precursors such as thiophenols [38][39][40], sulfonyl hydrazides [41][42], disulfides [43], KSCN [44], S8 [45], methylsulfinyl derivatives [46], sodium sulfinates [47], and thiosulfonates
- whether the reaction proceeded through a free radical mechanism, different free radical inhibitors were added to the reaction (reaction 7, Scheme 5). The addition of TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl) resulted in complete inhibition of the reaction, while BHT (2,6-di-tert-butyl-4-methylphenol
- ) exhibited a lesser effect. Considering that TEMPO, as an oxidizing agent, affected the reaction, it could be concluded that the reaction did not proceed through a free radical mechanism. Based on the results of the control experiments and the related literature [26][30][41][52], a possible mechanism for the
Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles
Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15
- , Palestine 10.3762/bjoc.21.15 Abstract An efficient and eco-friendly approach for synthesizing difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles was established via a visible-light-promoted radical cyclization reaction. This method employed the readily accessible and inexpensive
- target products in good to excellent yields. Mechanistic studies revealed that the reaction proceeds via a radical pathway. Keywords: cyclization; difluoromethylation; hypervalent iodine; polycyclic imidazole; visible light; Introduction Organofluorine compounds continue to play important roles in
- both difluoromethylated and aryldifluoromethylated benzimidazoles. Inspired by previous work in radical chemistry, we turned our attention to difluoroacetic acid (CF2HCOOH) and α,α-difluorobenzeneacetic acid (PhCF2COOH), both of which are inexpensive and readily available industrial raw materials. In
Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations
Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12
- nitrenoid intermediate was characterized by the same group [75]. Further radical rebound from INT-4 induces the enantioselective C–N bond formation. Finally, the desired product 2 is released from INT-4, regenerating the active chiral copper species to participate in the catalytic cycle. 1.2 C(sp2)–H
- Synthesis of primary amides via the generation of copper–imidate radical intermediates In a subsequent study, the research group of Son developed a method for the reduction of dioxazolones to synthesize primary amides under mild reducing conditions in copper catalysis (Scheme 10) [103]. The reaction was
- was proposed for the copper-catalyzed synthesis of primary amides. Dioxazolone first binds to the copper catalyst, forming the dioxazolone-copper complex (INT-34). The silane reductant then reduces INT-34, forming the copper imidate radical species INT-35, furnishing the formation of primary amides 28
Recent advances in electrochemical copper catalysis for modern organic synthesis
Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9
- electrochemistry and copper catalysis for various organic transformations. Keywords: copper; electrochemistry; radical chemistry; single-electron transfer; sustainable catalysis; Introduction Transition-metal-catalyzed cross-coupling has emerged as an effective method for forming carbon–carbon (C–C) and carbon
- remains a significant challenge owing to the high energy barrier required for oxidative addition and facile β-hydride elimination [12]. The development of radical approaches facilitated by transition-metal catalysis has provided a promising solution to overcome the limitations of conventional coupling
- reactions, particularly in controlling the high reactivity and selectivity of radical intermediates [13][14]. Early studies on copper-mediated radical reactions, such as Julia’s work on radical cyclization reaction [15], along with advancements in dimerization [16][17], oxidative cleavage [18][19], and
Cu(OTf)2-catalyzed multicomponent reactions
Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7
- or radical (Figure 1). The latter is typically operative when the reaction is carried out under oxidative conditions, usually in the presence of O2 and TEMPO, involving the formation of radical species through single-electron transfer (SET) from a copper catalyst to a precursor. Subsequent addition
- reaction proceeds through an initial single-electron transfer from NFBS assisted by the active copper species, followed by intermolecular hydrogen-atom transfer from the carbazate. The nitrogen radical intermediate I thus formed is decomposed into the acyl or alkyl radical intermediates II and III
- , respectively. The latter interacts with the alkene generating an alkyl radical IV that converts to the cationic intermediate V by single-electron oxidation by the Cu(II) species. Finally, the attack of the nucleophile leads to the desired products 6. Starting from aryl carbazates, intermediate II, adds
Recent advances in organocatalytic atroposelective reactions
Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6
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
- . A plausible mechanism is proposed, suggesting a possible radical pathway. Keywords: electrophilic amination; hypervalent iodine reagents; sulfinamide; sulfonamide; Introduction Iodine(III) compounds, known as λ3-iodanes, have been extensively applied in organic synthesis. Although initially used
- a high decrease in the isolated amount of 3a, compared to the same experiment carried out in the presence of light, from 20% to 2% yield). Considering the potential occurrence of a radical pathway, additional experiments were conducted in the presence of galvinoxyl and TEMPO, powerful radical
- scavengers capable of abstracting the radical species that could emerge in the reaction media. The use of galvinoxyl proved to be insufficient to conclude since a control experiment showed that HIRs 2 decompose in the presence of galvinoxyl. When using TEMPO (Scheme 5), sulfinamide 6aa was not detected, but
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
- derivatives. Upon abstraction of a hydride from tris(trimethylsilyl)silane (TTMS) by an excited benzophenone derivative, the formed silane radical can undergo a XAT with an alkyl bromide to generate an alkyl radical. Consequently, the alkyl radical undergoes a Giese-type reaction with the Dha derivative
- ; Introduction The construction of C(sp3)–C(sp3) bonds is a highly important target in synthetic organic chemistry. Historically, polar conjugate additions have been a benchmark method for constructing these bonds by functionalizing an electron-deficient olefin [1][2][3]. Recently, however, radical-based
- approaches have also gained widespread attention for their unique advantages in these transformations [4]. Radical chemistry often exhibits complementary reactivity to two-electron pathways and can be performed with high selectivity, atom economy, and functional group tolerance [5]. A well-known radical
Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives
Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264
- derivatives, were synthesized using two reaction sequences (Table 1). The first sequence involved the chloroformylation of isoxazolones 3 to 5-chloroisoxazole-4-carbaldehydes 4 by POCl3/DMF [20][21][22][23], followed by radical chlorination of 4 with SO2Cl2/AIBN [24]. The alternative route to acid chlorides 1
- included oxidation of aldehydes 4 with Oxone to acids 5 and the conversion of the latter into acid chlorides with thionyl chloride. The first reaction sequence was suitable for obtaining compounds 1a–c,e,f with substituents tolerant to radical reaction conditions. A significant advantage of the method is
Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies
Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261
- antioxidant properties were determined by oxygen radical absorbance capacity assay (ORAC-FL), expressed as Trolox equivalents (TE) and using fluorescein as probe. Additionally, the study investigated the ability of the compounds to activate the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway in
- regulates kinases involved in the hyperphosphorylation of tau, contributing to neurofibrillary tangles. Meanwhile, melatonin is known for its neuroprotective properties, countering oxidative stress by scavenging radical oxygenated species and exhibiting potent antioxidant capacity [44][45]. The calcium
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