Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• the radical cation iPr2NEt•+ (iPr2NEt/iPr2NEt•+ = +0.72 V vs SCE) and the reduction of O2 by the reduced photocatalyst, forming the superoxide radical anion O2•− (O2/O2•− = −0.57 V vs SCE). This latter can then react with arylboronic acids 59 to give, after hydrolysis, phenol derivatives 60. Other

Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions

• Hayato Takagi,
• Çetin Çelik,
• Ryosuke Fukuda,
• Qi Guo,
• Tomohiro Higashino,
• Hiroshi Imahori,
• Yoko Yamakoshi and
• Tatsuya Murakami

Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231

• safer control of Vm. Keywords: liposome; π–π interaction; reactive oxygen species; superoxide radical anion; Introduction The [60]fullerene (C60) is known as an excellent electron acceptor [1][2] and is commonly used in organic solar cell applications [3]. Taking advantage of the fact that C60 can be

• generation of ROS by catC60 in the absence or presence of PyBA. As spin trapping reagents for the singlet oxygen (1O2), hydroxyl radical (•OH) and superoxide radical anion (O2•–); 2,2,6,6,-tetramethyl-4-piperidone (4-oxo-TEMP), 3,4-dihydro-2,3-dimethyl-2H-pyrrole 1-oxide (DMPO), and 5-(diethoxyphosphoryl)-5

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• antioxidant properties were determined using the reaction with synthetic radicals, the cupric reducing antioxidant capacity assay, the inhibition process of superoxide radical anion formation by xanthine oxidase, and the process of lipid peroxidation of rat liver (Wistar) homogenates in vitro. Keywords

• in the reaction with a diphenylpicrylhydrazyl (DPPH) radical, ABTS·+ radical cation, CUPRAC test, and inhibition process of superoxide radical anion formation by xanthine oxidase (NBT assay). The presence of a catechol fragment and thioether or thione groups determines the ability to neutralize

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• photoexcitation the CuI acetylide A undergoes a SET process to form the CuII phenylacetylide species B and a superoxide radical anion. In parallel, under irradiation the homolytic S–S-bond cleavage in 2-aminothiophenol dimer 38 forms thiol radicals 40. The nucleophilic addition of the amino group in radical 40 to

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• ][67][68][69]. Under aerobic conditions the catalytic CeIII(OBn)Ln species I (in situ derived by the reaction of CeCl3 (CeIIILn) with the substrate benzyl alcohol, BnOH) could be oxidized to LnCeIV–OBn complex II [67][68][69]. During this process O2 is converted into a superoxide radical anion O2

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• superoxide radical anion by a reductive quenching and the rearrangement of the hydroperoxide intermediate [41]. The heterogeneous protocol using MOF porphyrins was significantly faster than the corresponding homogeneous photocatalysis, which was attributed to higher photostability of the porphyrins as MOF

• application in the synthesis of quinazolin-4-(3H)-ones by the one-pot reaction between alcohols and 2-aminobenzamide under an oxidative quenching, visible light irradiation using air or oxygen as oxidant (60–81% yields). The authors propose the generation of the superoxide radical anion with the MOF. The

• superoxide radical anion oxidizes the alcohol to aldehyde, which is then converted to an imine after coupling with the amine. The products are obtained after cyclization and oxidation of the cyclic intermediates (Scheme 21) [46]. Similarly, Jiang and co-workers reported the selective photooxidation of

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• mechanism suggested by the authors was in agreement with the literature [46]: The excited copper catalyst oxidizes the tetrahydroisoquinoline and forms an N-centered radical cation. The copper catalyst is regenerated upon oxidation with O2. The resulting superoxide radical anion allowed the formation of the

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• finally oxidized by an in situ generated superoxide radical anion to form the respective sulfoxide. In contrast, Fraile, Aleman and co-workers use the organic photocatalyst Eosin Y and propose a different mechanism for their method (Scheme 15b). Based on several quenching experiments, they suggest that

• after the radical thiol–ene cross-coupling of the thiol with the alkene, the respective sulfide-adduct is oxidized by in situ generated singlet oxygen instead of the superoxide radical anion. Their method was compatible with a similar scope of thiols and alkenes like the one of Wei and Wang. A very

•  28) [63]. The reaction mechanism is different from the previous examples. The photoexcited state of Eosin Y can be quenched reductively by tertiary amines to form an Eosin Y radical anion and an amine radical cation. Molecular oxygen regenerates Eosin Y and is reduced to its superoxide radical anion

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• confirmed the presence of H2O2 [43] resulting from the superoxide radical anion (O2·−) generated during reaction under oxygen atmosphere. It is also possible that the superoxide radical anion oxidizes the alkyl selenide anion (11) to the corresponding alkyl selenide radical and the formed O22− affords H2O2

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• rate of α-linolenic acid (an omega-3 FA) is 2500 times higher in comparison with saturated stearic acid [15]. Light (photo-oxidation) and the presence of heavy metal ions, heme and hemin proteins or superoxide radical anion-generating enzymes are involved in the initiation of auto-oxidation. The main

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• oxidation, with the production of a superoxide radical anion O2•−. Deprotonation of 4 generates α-aminoalkyl radical 5. Then 5 reacts with 2 to generate radical 6, and the latter then undergoes cyclization to form intermediate 7. Proton and electron transfer from 7 to O2•− yields the final product 3 and HOO

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• electrochemically generated superoxide radical anion (O2·−) in acetonitrile was described in 1997 [37]. It was established that in dry solution, with water content below 4%, no products were observed. However, cholesterol was oxidized to 7-oxocholesterol (9), 7α-hydroxycholesterol (7), and 7β-hydroxycholesterol (8

• ) when hydrogen peroxide was combined with superoxide solution in water matrix. The authors suggested that under these conditions the rate of the disproportionation reaction of superoxide radical anion is increased, and the formation of more reactive oxygen species such as hydroxyl radical or singlet