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

• suppress side reactions. The cross-dehydrogenative coupling reactions, under near-infrared irradiation, was found to proceed via an energy-transfer mechanism involving singlet oxygen generation rather than the typical electron-transfer pathway observed in the presented visible-light-mediated reactions in

• this review hitherto. This singlet oxygen is generated by the energy transfer from the excited state of the phthalocyanin zinc complexes to molecular oxygen, allowing the oxidation of the N-phenyltetrahydroisoquinoline 21 into a reactive iminium intermediate that subsequently couples with nucleophiles

• light (λ = 750 nm), followed by triplet energy transfer to molecular oxygen, generating singlet oxygen as the active species. Similarly as in the case of the Furuyama et al. study, the singlet oxygen subsequently oxidizes the amine substrate to an iminium ion, which reacts with a cyanide nucleophile to

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• pentacenes, are relatively stable molecules under ambient conditions, longer acenes undergo spontaneous dimerization and react with oxygen [5][6], owing to the rising diradical character. This behavior was also observed in the oxidized species of shorter acenes [7]. Surprisingly, Bettinger and Einholz [5

Synthesis of disulfides and 3-sulfenylchromones from sodium sulfinates catalyzed by TBAI

• Zhenlei Zhang,
• Ying Wang,
• Xingxing Pan,
• Manqi Zhang,
• Wei Zhao,
• Meng Li and
• Hao Zhang

Beilstein J. Org. Chem. 2025, 21, 253–261, doi:10.3762/bjoc.21.17

• catalysts in conjunction with oxygen [17][18][19][20][21][22], electrochemical oxidation [23][24], and photochemical oxidation techniques [25] have emerged as alternative methods. However, these approaches have a significant limitation: the substrates must be thiols, which have unpleasant odors. This has

• produce oxygen and HI. Conclusion In summary, we have developed a new TBAI-catalyzed method for the synthesis of symmetrical disulfides using sodium sulfinates as starting materials. The method requires no additional redox reagents and is broadly applicable to both sodium arylsulfinates and sodium

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• region of the DNA double helix, leading to the formation of a reversible covalent bond [9][10][11][12]. In this process, the oxygen functional groups at the C8 and C18 positions of the core scaffold interact with the DNA bases through multipoint hydrogen bonds (HBs), allowing recognition of approximately

• avenues for the development of fluorescent probes based on the bis-THIQ alkaloidal scaffold. Further efforts to develop a concise and modular synthetic process for saframycins are currently underway. Representative bis-tetrahydroisoquinoline (THIQ) alkaloids and their analogues. Oxygen atoms on both the A

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• oxygen, nitrogen, or sulfur, and a positively charged hydrogen atom, which interacts with a lone pair on the acceptor. Apart from these common heteroatom-containing hydrogen bond donors, certain carbon–hydrogen moieties can also act in this way, although in a substantially weaker capacity [5][6][7][8][9

• oxygen lone pairs (LPs) of Me3PO with the H–CF2Ar antibonding orbital (σ*). Such hyperconjugative interactions indicate the magnitudes of the charge transfer from the LPs to the σ* orbitals and are considered the major contributors to hydrogen bonding [57]. Using this analysis, strong linear correlations

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• amide macrocycle with six aromatic residues (hereafter called cyclo[6]aramide for brevity, Scheme 1a) could mediate dimerization as a host. That is because such a 2D macrocycle has six carbonyl oxygen atoms pointing inwards as binding sites, demonstrating excellent affinity for cationic organic guests

• -ray structure of the complex H2 ⊃ G1. a) Dimeric structure formed by cyclo[6]aramide H2 and cationic guest G1, with each guest molecule threading one molecule of H2 at its end. b) A portion of the dimeric structure showing an array of hydrogen bonding interactions between the amide oxygen atoms of H2

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• . THIQ (13) was rapidly oxidized to an iminium intermediate under the action of electricity and oxygen. However, when the iminium intermediate was converted to the desired product 19, electrolysis had no effect, and this step proceeded more gradually than the initial oxidation step. Therefore, the

• is reoxidized to Cu(I) 121 at the new anode. The Cu(I) species 121 is either oxidized to the Cu(II) complex by oxygen or plated again on the cathode. The Cu(II) catalyst reacts with aniline to produce a Cu(II) intermediate 122, which then generates a Cu(III) complex 124 through transmetalation of

Nickel-catalyzed cross-coupling of 2-fluorobenzofurans with arylboronic acids via aromatic C–F bond activation

• Takeshi Fujita,
• Haruna Yabuki,
• Ryutaro Morioka,
• Kohei Fuchibe and
• Junji Ichikawa

Beilstein J. Org. Chem. 2025, 21, 146–154, doi:10.3762/bjoc.21.8

• -deficient carbon atom owing to the nearby fluorine and oxygen atoms. We expected that 2-fluorobenzofurans 1 could form nickelacyclopropanes E upon treatment with zero-valent nickel species. Subsequent β-fluorine elimination from these intermediates E would facilitate the activation of aromatic C–F bonds

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• involves a Friedel–Crafts alkylation of the arene followed by hydroamination (Scheme 6) [5]. The mechanism plausibly starts with the in situ formation of triflic acid from Cu(OTf)2 which leads to protonation of the oxygen atom of the alcohol with generation of the activated allyl alcohol. This latter gives

• of an ortho-quinone methide intermediate XXXVII formed through nucleophilic attack of the 2-naphthol to the aldehyde followed by reaction with 1,3-dicarbonyl compound coordinated by the copper. The subsequent intramolecular nucleophilic attack of the oxygen to the enol and water elimination resulted

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• product (75%), but at a significantly slower rate than the catalyzed one. Methylation of the oxygen in azaborinephenol 232 led to no product being formed. On the other hand, methylation of nitrogen in azaborinephenol 232 still provided the product in decent yield and enantioselectivity (79%, 89% ee

• between the ketomalonate and organocatalyst Int-68 were shown as the pivotal interaction that formed the chiral pocket for the induction of chirality. Nucleophilic addition followed by rearomatization of the pyrrole ring and protonation of the oxygen forms the axially chiral arylpyrrole 237. The

Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• convenient methodology for global optimization, eliminating the necessity of a theoretical model. A reconfigurable automated flow platform integrating online HPLC monitoring was used for the cobalt-catalyzed aerobic oxidative dimerization of desmethoxycarpacine (6) to carpanone (7) in the presence of oxygen

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• clarification). Structure of (M,P,M)-3 in the crystal of 3·CH2Cl2 (carbon and oxygen atoms are shown as grey and red ellipsoid at the level of 50% probability, and hexyl groups and hydrogen atoms are removed for clarity). UV–vis absorption spectrum (black line) and emission spectrum (blue line, excited at 400

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• oxidation of sulfinamide 6aa by dissolved oxygen molecules in the media. Therefore, an additional experiment was conducted using sodium benzenesulfinate to simulate the potential in situ oxidation of the sulfenate anion before the addition of BBX 2a, but only trace amounts of sulfonamide 5ea were observed

• Supporting Information File 1). We propose a mechanism pathway involving the retro-Michael addition of 4, releasing acrylate and hydrogen (H2). The charge of the sulfenate anion may shift between sulfur and oxygen atoms, possibly leading to an O-Michael addition (pathway B) [35]. The intermediate of these

• reactions could undergo disproportionation, a radical process resulting in the homolytic cleavage of the S–O bond [35]. The formation of disulfide 7 isolated in the experiments can be explained by combining two radical sulfur species. Furthermore, the oxygen species generated in this radical reaction may

Giese-type alkylation of dehydroalanine derivatives via silane-mediated alkyl bromide activation

• Perry van der Heide,
• Michele Retini,
• Fabiola Fanini,
• Giovanni Piersanti,
• Francesco Secci,
• Daniele Mazzarella,
• Timothy Noël and
• Alberto Luridiana

Beilstein J. Org. Chem. 2024, 20, 3274–3280, doi:10.3762/bjoc.20.271

• obtained for compound 13 with a longer chain length than for 12. Similarly, the secondary cyclic alkyl substrates used in compound 18 (60%) and 3 (56%) worked well for this reaction. Besides, oxygen-containing compounds 14 and 15 were obtained in yields of 51% and 67% and medicinally interesting groups

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• carbamate group by interaction with the oxygen atom of the phosphoryl group. Although recently Rana and co-workers published a review article covering catalytic asymmetric transformations of azadienes [16], there is still room for this review which only focuses on non-covalent organocatalyzed cyclizations

• concerted mechanism which could be explained by the transition state depicted in Scheme 16: the chiral phosphoric acid could act as a bifunctional catalyst; the OH group acts as a Brønsted acid activating the 1-azadiene, while the phosphoryl oxygen atom activates the enecarbamates as a Lewis base. In order

Ceratinadin G, a new psammaplysin derivative possessing a cyano group from a sponge of the genus Pseudoceratina

• Shin-ichiro Kurimoto,
• Kouta Inoue,
• Taito Ohno and
• Takaaki Kubota

Beilstein J. Org. Chem. 2024, 20, 3215–3220, doi:10.3762/bjoc.20.267

• inductive effect is attached to the carbon bearing the cyano group, the intensity of the absorption derived from the cyano group in the IR spectrum decreases significantly. This phenomenon has been reported, particularly in compounds where halogen or oxygen atoms are bonded to the carbon bearing the cyano

Discovery of ianthelliformisamines D–G from the sponge Suberea ianthelliformis and the total synthesis of ianthelliformisamine D

• Sasha Hayes,
• Yaoying Lu,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2024, 20, 3205–3214, doi:10.3762/bjoc.20.266

• pyrrolidone moiety. A 1,3,4,5-tetrasubstituted aromatic ring was assigned based on 3JCH correlations from the isolated aromatic signal (δH 7.89) to its symmetrically placed carbon (δC 131.6) and to an oxygen-bearing carbon (δC 153.9) along with 2JCH correlations to a brominated (δC 118.0) and sp2 phenyl

Germanyl triazoles as a platform for CuAAC diversification and chemoselective orthogonal cross-coupling

• John M. Halford-McGuff,
• Thomas M. Richardson,
• Aidan P. McKay,
• Frederik Peschke,
• Glenn A. Burley and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2024, 20, 3198–3204, doi:10.3762/bjoc.20.265

• extensive scope across a range of benign solvent conditions [7][8][9][10]. In addition, the CuAAC reaction uses inexpensive Cu catalysts [11], is insensitive towards oxygen and water [12][13], and consistently delivers high yields and (where relevant) enantioselectivities [8][9][10][14][15][16][17][18][19

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• biomolecules like DNA and lipids. Lipid peroxidation and membrane disruption can cause random cross-linking, resulting in cell death and the fragmentation of proteins and enzymes. Elevated concentrations of reactive oxygen species (ROS) from various molecular processes contribute to the oxidation of proteins

• 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

• oxazepane scaffold 11 (Scheme 11). Replacing the nitrogen in the bioactive lactam 11 (γ-secretase inhibitor in AD therapy) with an oxygen should reduce the hydrogen bond donating (HBD) ability of the compounds. The method employs readily available starting materials, resulting in the desired compounds in a

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• compounds tend to deprotonate to form highly stable anions. The air stability of TBF conforms to that model. In contrast, although the dianion of BFC can be generated with tert-butoxide under inert atmosphere, in the presence of water it quenches and exposed to oxygen it oxidizes to form the diketone

• titrations the moisture and oxygen contents in argon were always under 10 ppm during measurements. Triflic acid (Aldrich, 99+%) and phosphazene base P2-Et (165535-45-5, Aldrich, ≥98%) were used to prepare the acidic and basic titrant solutions, respectively. Acetonitrile (Romil 190 SpS far UV/gradient

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• , the intramolecular HVI-mediated halocyclisation of alkenes using carbon, oxygen, nitrogen or sulfur nucleophiles. Herein, we describe the examples reported in the literature, which are organised by the different halogens involved and the internal nucleophiles. Keywords: cyclisation; halogenation

• reductive ligand coupling (RLC) pathway would be suppressed due to reduced fluxionality of the carboxylate ligand on I(III). These important findings are expected to enhance the use of aryl iodane(III)-dicarboxylates for constructing fluorinated azaheterocycles with improved selectivity and control. Oxygen

• internal oxygen nucleophile and fluoride then sequentially attack the activated alkene, to either form 5- or 6-membered furan or pyran heterocycles depending on the chain length in the substrate. The pyran ring is only formed from the alcohol starting material, presumably because the oxygen is reactive

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• electrophilic CO2, leading to the formation of 18-IV. The negatively charged oxygen in 18-IV is then responsible for removing the chloride atom leading to the major isomer as a final product. The results of this study suggest that nonplanarity or distortion of the tetrapyrrolic macrocyclic core is not a

• photochemistry, porphyrins are mainly used for the generation of singlet oxygen (1O2) or other reactive oxygen species. Porphyrins in the triplet excited state can relax to the ground state by transferring energy to molecular oxygen (triplet state) forming 1O2 (Figure 13b) [67]. Photosensitized singlet oxygen

• frameworks (COF), have been extensively studied as photosensitizers of singlet oxygen and photoredox catalysts [87][88][89][90]. However, using metal-free porphyrins as photoredox catalysts for C–C or C–heteroatom bond formation is an area which has recently started to be explored. In 2016, Gryko and co

Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

• development of efficient synthetic approaches to implement organic peroxide functionality in various substrates is a timely task. From the synthetic point of view, organic peroxides are one of the best sources of oxygen atoms for a variety of oxygenation reactions [6]. Hydroperoxides (especially TBHP), acyl

• tendency to recombine with C-centered radicals and add to unsaturated bonds with the formation of new carbon–oxygen bonds. However, alkoxy radicals, which are always present in such systems, are involved not only in the formation of ROO radicals but also in hydrogen atom transfer (HAT) processes and β

• in Kwon’s review [34]. Cu-catalyzed oxygen atom transfer with TBHP were discussed in the review [35]. The review by Xiao considered visible light-driven C–C bond cleavage enabled with organic peroxides [36]. This comprehensive review summarizes all ever published studies on radical peroxidation with

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• ; perfluorinated aliphatic carboxylic acids; porphyrin synthesis; Introduction Metal porphyrins are prosthetic groups in a number of essential biomolecules, including hemoglobin, chlorophyll, and cytochromes, supporting processes such as oxygen transport, photosynthesis, and electron transfer [1][2][3][4][5

• phenyl group of the porphyrin and the perfluoroalkyl chain. The oxygen atom, especially in the 2-position, should even improve the electronic properties of the porphyrin. Results and Discussion Our synthesis started with the readily available fluorinated symmetric diols HO–CH2–(CF2)n–CH2–OH (n = 2,4,6

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• upon binding of the enolate molecule to iodine either through a carbon–iodine or an oxygen–iodine bond. Both intermediates, I and II, are in rapid equilibrium with each other and further undergo two different types of reactions: [1,2]-ligand coupling and [2,3]-rearrangement (Scheme 2). Either of these

• copper catalyst afforded nearly better results for the arylated products. In 2022, Linde et al., demonstrated a conventional approach for achieving arylations of nitrogen- and oxygen nucleophiles via SNAr reaction, using o-fluorinated diaryliodonium salts 40, which enabled access to a greater range of

• strong C–N bond. The ring opening incorporated nitrogen, oxygen, sulfur, carbon, and halogen-containing nucleophiles and their derivatives. The substrate scope was examined with numerous aryl groups on iodonium salts 40 and the progress of aryl migration happens fruitfully by considering electronic