Recent advances in copper-catalyzed direct hydroamination of alkenes with (hetero)aromatic amines

• Hyejeong Lee and
• Yunmi Lee

Beilstein J. Org. Chem. 2026, 22, 925–947, doi:10.3762/bjoc.22.73

• electrophilicity and lowers the barrier for nucleophilic attack (Scheme 1b). Further, copper can mediate radical-based pathways either by generating hydrogen radicals or intercepting nitrogen-centered radical intermediates in oxidative- or photoredox-assisted systems (Scheme 1c). These radical manifolds often

Site-specific labelling of native peptides and proteins: chemical and enzymatic strategies

• Antonio Angelastro,
• Jonathan Bargh,
• Subhajit Guria,
• Victor Laserna and
• Louis Luk

Beilstein J. Org. Chem. 2026, 22, 857–881, doi:10.3762/bjoc.22.67

• has led to the development of labelling techniques, wherein the C-terminal carboxylate can be functionalized via visible-light photoredox decarboxylative catalysis (Scheme 2d) [23]. Similarly, decarboxylative alkylation has been applied to complex proteomes to enable proteome-wide C-terminal profiling

• or cleavable leader peptides. C-Terminal labelling typically suffers from modest conversions (≈50% for photoredox strategies). While selectivity has been improved, few approaches are fully specific. For further discussion, see reviews [25][26]. Rebridging agents Protein sidechains frequently form

• , with applications in ADC development, radiolabelling and ROS/Ca2+ imaging (Scheme 9a) [86][87][88][89][90][91]. Methionine can also be modified via sulfonium conjugates using hypervalent iodine (23, Scheme 9b) [92] or photoredox approaches (24a/b, Scheme 9c) [93]. Histidine has been targeted using

Harnessing light energy with molecules

• Grace G. D. Han,
• Mogens Brøndsted Nielsen and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2026, 22, 680–682, doi:10.3762/bjoc.22.52

• singlet-state photoredox catalyst in the sulfonylation/arylation of styrenes and as a triplet sensitizer in energy transfer catalysis. In addition to the photoredox contribution mentioned above, this thematic issue contains two publications on photochemical reactions beyond photoisomerizations. In the

Computational prediction of C–H hydricities and their use in predicting the regioselectivity of electron-rich C–H functionalisation reactions

• Rasmus M. Borup,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2026, 22, 603–610, doi:10.3762/bjoc.22.46

• photoredox activation, followed by anion-binding-catalysed functionalisation to form β-amino esters. Here, the reacting atom is the one with the lowest hydricity and BDE. Compounds 8–10 Schmidt et al. [44] reported the visible light-catalysed bromination of compound 8, Kamon et al. [45] reported the light

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• intermediate. The in-situ amidation of the resulting acyl fluoride with ʟ-valine methyl ester produced 210 in 61% yield with 93:7 dr and 99% ee. In 2024, a metal-free photoredox catalytic method for the transamidation of PMB anilides was developed [77]. This protocol emphasizes chemoselective cleavage and

• transformation of the target amide in the presence of more reactive functional groups (Scheme 24b). Using 9-mesityl-3,6-di-tert-butyl-10-phenylacridinium tetrafluoroborate (Mes-Acr-Ph+BF4−) as the photoredox catalyst under 450 nm LED irradiation, the PMB anilide unit was chemoselectively activated and cleaved in

• ) Metal-free photoredox catalysis for cleavage of N-PMB anilide. Funding This study was supported by the Korea institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean Government (MCEE) (RS-2022-KP002707, Jeonbuk, regional Energy Cluster Training of Human resources) and

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• enriching the repertoire of arene functionalization beyond the established cross-coupling and C–H activation canon. Alternatively, merging arene activation with additional concepts, such as photoredox catalysis offers an exciting opportunity to address thermodynamic constraints and to harness light-driven

Total synthesis of natural products based on hydrogenation of aromatic rings

• Haoxiang Wu and
• Xiangbing Qi

Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4

• reduction of activated aromatic cations (e.g., pyridinium, quinolinium, or benzopyrylium salts), offering mild and chemoselective access to partially or fully saturated heterocycles. More recent advances in single-electron transfer (SET) chemistry, particularly those mediated by photoredox catalysts or

Advances in Zr-mediated radical transformations and applications to total synthesis

• Hiroshige Ogawa and
• Hugh Nakamura

Beilstein J. Org. Chem. 2026, 22, 71–87, doi:10.3762/bjoc.22.3

• for future development. Keywords: halogen atom transfer; photoredox; radical; total synthesis; zirconium; Introduction Zirconium, a transition metal in the same group as titanium, has been employed across research fields and in medical applications owing to its distinctive physical and chemical

• and accelerating the whole process. Zr-mediated catalytic radical reactions In recent years, numerous chemical transformations employing photoredox catalysts in combination with catalytic amounts of zirconium complexes have been reported. In this section, representative examples of such reactions are

• available materials, in benzene afforded the Zr(RCNN)2 complex 18. Investigation of the photoredox properties of the synthesized complex revealed trends similar to those of known photosensitizers, suggesting its potential utility as a photosensitizer [15]. Accordingly, the Zr(MeCNN)2 complex was employed as

Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review

• Daniel S. Müller

Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• ][2][3][4][5][6]. Recently developed photocatalysis affords sustainable, regioselective green methods for producing a wide range of functionalized carbonyl compounds and their related bioactive chiral intermediates under mild conditions, employing dual organic photoredox catalysis [7][8][9][10][11

• arylcyclopropanes 5 by applying NHC/ photoredox cooperative organocatalysis under visible-light irradiation. This method allows sequential C–O and C–C bond formation, leading to access to various γ-aroyloxy keto-ester derivatives 6 in good yield up to 81% and excellent functional group tolerance, including electron

• existing metal-catalyzed C–H bond functionalization methods (Scheme 3) [53]. Recently, Scheidt et al. discovered an NHC/organic photoredox-catalyzed three-component coupling reaction for the efficient and novel preparation of γ-aryloxy ketone scaffolds 12. This transformation builds on the emerging field

Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• photoredox catalysis) processes [8][9][10]. Cyclobutenone (A) is a versatile C4 synthon [11] – its [2 + 2] photocyclization yields B, featuring a strained bicyclo[2.2.0]hexane unit [12], which can fragment to form C (Figure 1a) [13][14]. However, competitive C1–C4 bond cleavage under irradiation or heating

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• , spirobenzopyran, stilbene and stiff-stilbene (Figure 2). Systems whose photoinduced behavior primarily depends on photoredox or energy-transfer mechanisms fall outside the scope of this review. Review Rotaxanes featuring photoswitches on the axle Rotaxanes that incorporate photoswitchable units into the axle are

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• Peng-Xi Luo Jin-Xuan Yang Shao-Min Fu Bo Liu College of Chemistry, Sichuan University, 29 Wangjiang Rd., Chengdu, Sichuan 610064, China 10.3762/bjoc.21.177 Abstract In recent years, the Norrish–Yang cyclization and related photoredox reactions of dicarbonyls have been extensively utilized in

• can further undergo ring-opening or rearrangement reaction to assemble complex molecular frameworks. Additionally, quinone photoredox reactions involving single-electron transfer (SET) processes provide novel strategies for the stereoselective synthesis of useful structures such as spiroketals. This

• synthesis of natural products but also establish a solid foundation for subsequent pharmaceutical investigations. Keywords: dicarbonyls; natural product; Norrish–Yang cyclization; photoredox; total synthesis; Introduction In the 1930s, Norrish documented the photodecomposition of aldehydes and ketones [1

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• describes several important catalytic asymmetric strategies applied to enantioselective radical reactions, including chiral Lewis acid catalysis, organocatalysis, photoredox catalysis, chiral transition-metal catalysis and photoenzymatic catalysis. The application of electrochemistry to asymmetric radical

• transformations is also discussed. Keywords: chiral Lewis acid; electrochemistry; enantioselective radical reaction; organocatalysis; photoenzymatic catalysis; photoredox; Introduction Asymmetric catalysis plays an integral role in the enantioselective synthesis of organic compounds. A wide variety of

• include the use of transition metals or photoredox catalysts. In photoredox catalysis, radical generation often involves single-electron transfer (SET) to or from a photoexcited state of a photoredox catalyst, usually a metal complex or organic molecule. Two other notable strategies for radical generation

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• accelerating reaction optimization. Furthermore, expanding this concept to other reaction manifolds – such as electrocyclic processes and photoredox catalysis – may uncover new avenues for molecular innovation. The pursuit of pathway-economical synthesis represents a paradigm shift toward sustainable and

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• -electron reduction delivering the same stabilized radical C. Beginning with a seminal report by di Rocco and Rovis in 2012 [21], the combination of NHC and photoredox catalysis has recently been the subject of intense research activity [22][23][24][25][26][27][28][29][30]. Employing the latter reductive

• 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

• representative substrate in two steps from benzoyl chloride, imidazole and methyl trifluoromethanesulfonate. In an initial reaction, this species was reacted under photoredox conditions in the presence of [Ir(dF(CF3)ppy)2(dtbpy)]PF6 (2 mol %, dF(CF3)ppy = 3,5-difluoro-2-[5-(trifluoromethyl)-2-pyridine, dtbpy

Asymmetric total synthesis of tricyclic prostaglandin D2 metabolite methyl ester via oxidative radical cyclization

• Miao Xiao,
• Liuyang Pu,
• Qiaoli Shang,
• Lei Zhu and
• Jun Huang

Beilstein J. Org. Chem. 2025, 21, 1964–1972, doi:10.3762/bjoc.21.152

• , C11, and C12 contiguous stereogenic centers, provided important insights that influenced the design of our second-generation total synthesis. Compared with the Snider-type radical cyclization using stoichiometric amounts of metal oxidants, visible-light-induced photoredox-catalyzed radical cyclization

• strategies have emerged as an effective synthetic route for the stereocontrolled construction of diverse, highly functionalized bioactive and pharmaceutical molecules [35][36][37]. The herein adopted synthetic strategy, employing photoredox-catalyzed radical cyclization, is illustrated in Scheme 4. Compound

• connection of C8 and C12 in compound 21 could be realized through a photoredox-catalyzed radical cyclization of unactivated alkene-substituted β-ketoester 27. This reaction was expected to involve a 5-exo-trig radical cyclization via transition state TS-3 [38], in which the diastereoselectivity could be

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• photocatalysts (Scheme 2). The combination of photoredox catalysis with imine activation enabled the reductive coupling of imines under mild reaction conditions, providing direct access to benzyl and aryl vicinal diamines with good to excellent yields. Organic electrochemistry represents an attractive and

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• enantioselectivity. Overall, with the recent rapid advancements of CPA catalysis, along with the utilization of CPA catalysts in asymmetric radical chemistry, transition metal-catalyzed reactions and photoredox chemistry, we envision that CPA catalysts will continue to play a central role in the future asymmetric

Photocatalysis and photochemistry in organic synthesis

• Timothy Noël and
• Bartholomäus Pieber

Beilstein J. Org. Chem. 2025, 21, 1645–1647, doi:10.3762/bjoc.21.128

• implement. Two decades later, photocatalysis and photochemistry remain among the most studied topics in modern organic synthesis. Nowadays, chemists can choose from a wide range of organometallic [12][13], organic [14][15], or heterogeneous photocatalysts [16][17] to trigger visible-light photoredox

• Review article discussing photocatalysts capable of harnessing low-energy red light to trigger chemical reactions [19]. In addition to photoredox catalysis, several mechanistic platforms that leverage light – such as the use of electron donor–acceptor complexes [20], proton-coupled electron transfer [21

• of alkenylboronic esters using energy transfer catalysis [26]. Gualandi and co-workers leveraged a combination of photoredox and HAT catalysis to realize the intramolecular nucleophilic amidation of alkenes with β-lactams [27]. Further, Luridiana and colleagues developed a method for the alkylation

General method for the synthesis of enaminones via photocatalysis

• Paula Pérez-Ramos,
• Raquel G. Soengas and
• Humberto Rodríguez-Solla

Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116

• intermediates in the synthesis of several derivatives with important applications in medicinal chemistry. Furthermore, many marketed drugs feature the enaminone structural moiety. In this context, we have developed a photoredox and nickel catalytic system to rapidly forge the enaminone scaffold from 3

Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides

• Nadezhda M. Metalnikova,
• Nikita S. Antonkin,
• Tuan K. Nguyen,
• Natalia S. Soldatova,
• Alexander V. Nyuchev,
• Mikhail A. Kinzhalov and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110

• diaryliodonium salts under photoredox conditions has been proposed for the first time. The suggested procedure allows preparing a broad range of benzamides using both symmetric and unsymmetric diaryliodonium salts under mild conditions. A plausible mechanism for the reaction and the selectivity of aryl transfer

• (in case of unsymmetrical iodonium salts) were studied. Keywords: arylation; benzamides; diaryliodonium salts; isonitriles; photoredox; Introduction Amides represent a crucial and ubiquitous structural motif in essential biomolecules including proteins and peptides [1], as well as in a wide array of

• benzamides from isonitriles as well as in multicomponent reactions with isonitriles in general. Only a few examples of photochemical cascade arylation–cyclizations of isonitriles with diaryliodonium salts have been published [31][32][33]. To bridge this gap, we propose a photoredox-mediated strategy for the

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• co-workers reported an unprecedented synthesis of 3-aryl-3-aminooxetanes 156 from amino acids 155 utilising a combination of photoredox and nickel cross-coupling catalysis (Scheme 39) [90]. The reaction uses low catalyst loadings, gives moderate to excellent yields and tolerates various functional

Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer

• Hao-Sen Wang,
• Lin Li,
• Xin Chen,
• Jian-Li Wu,
• Kai Sun,
• Xiao-Lan Chen,
• Ling-Bo Qu and
• Bing Yu

Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100

• -Alkylbenzamide constitutes the primary structural unit of this class of compounds. The structures of these compounds are relatively simple and readily synthesizable. In these photocatalytic systems, direct single-electron oxidation of the amide HRP occurs in the presence of a photoredox catalyst and a base via a

• across diverse bond activation challenges, particularly in C(sp³)–H, C(sp²)–H, S–H, Ge–H, and B–H bond transformations. The proposed system architecture emphasizes synergistic reagent cooperation rather than isolated component performance, representing a paradigm shift in photoredox catalysis design

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

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

• quinolinone products. Beyond electrochemical protocols, photochemical activation – particularly visible-light photoredox catalysis – has become a powerful and sustainable strategy for generating carbon radicals under mild conditions. In 2023, Fan’s group discovered a radical cyclization of N-arylacrylamides

• with α-aminoalkyl radicals generated from tertiary arylamines using photoredox catalysis (Scheme 13) [9]. In this system, Ir[dF(CF3)ppy]2(dtbbpy)PF6 was used as a photosensitizer to trigger the α-C–H activation of N,N-dimethylaniline, generating an alkyl radical under 30 W blue LED (454 nm) irradiation