Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• visible light. How to design a bioinspired approach may be most attractive to synthetic chemists. Recently, Tang [16] and Jia [17] independently reviewed their remarkable bioinspired total syntheses as accounts. Tang documented their longtime carrier of learning from nature aiming to achieve better

• invented. Moreover, bioinspired total synthesis involving visible light and enzymes are new significant trends in this field, and these techniques have demonstrated great power in achieving unprecedented selectivity and reactivity. Since nature still prevails in rapid generating molecular complexity and

Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

• Jie Yan,
• Shaodong Sun,
• Minghao Wang and
• Si Wu

Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159

• visible light under sunlight irradiation [59], achieving a solar efficiency of 0.4% and a solid-state isomerization efficiency of 72.7% (Figure 5b). Feng and co-workers reported the synthesis of three azopyridine polymers (ortho-, meta-, and para-) [60], with the m-azopyridine polymer exhibiting a

• azobenzene small molecules into polymer fibers [65], enabling solvent-free charging and discharging under visible light (Figure 6a). This material exhibited good capacity for releasing high-temperature heat (80–95 °C) at room temperature and in cold environments, along with an energy storage lifetime

• persist. First, a major limitation is that most azobenzene-based solar thermal fuels can only store UV or visible light, which represent a minor portion of the solar spectrum. In contrast, approximately 50% of the solar irradiance is in the form of near-infrared (NIR) radiation, highlighting the urgent

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

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• Azoheteroarenes are azoswitches of which at least one aromatic ring is a heteroarene (Figure 3). The variety of heterocycles and substitution patterns that can be used gives rise to a considerable number of variants covering all the UV and visible spectrum and with thermal Z-isomer lifetimes that span from

• pocket in its (metastable) trans-isomer, inhibiting RNA translation (Scheme 16). In contrast, the azo-puromicin did not show significant change in activity between the two isomers [60]. Indigoids Indigoid photoswitches are characterised by switching in both directions with visible light (Figure 11). The

• already known as dye [89] have only been studied very recently. Exchanging the C=C bond for a C=N bond gives a new subclass of extremely short-lived T-type photoswitches with visible light activation, thermal half-lives in the µs range, and very large spectral separation. The study of iminothioindoxyl

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• employed as an external trigger for supramolecular systems. Azobenzene can regulate geometry, shape, and interfacial curvature under ultraviolet or visible light irradiation. It undergoes cis–trans isomerization, which can trigger alterations in bioactivity or assembly configurations. Methods for creating

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

• ; photochemistry; Soon after its first reported synthesis in 1936 [1], [Ru(bpy)3]Cl2 (bpy = 2,2'-bipyridine) and its derivatives attracted significant attention due to their photophysical properties [2][3][4]. These complexes can efficiently absorb visible light through a metal-to-ligand charge transfer (MLCT

• in the presence of electron donors and acceptors. Furthermore, [Ru(bpy)3]Cl2 can engage in Förster and Dexter energy transfer processes, enabling the transfer of excited-state energy to molecules that do not themselves absorb visible light. This versatility is arguably the reason for the tremendous

• impact of [Ru(bpy)3]Cl2 on several research areas, including solar energy conversion [5], optosensing [6], photodynamic therapy [7][8] and bioimaging [9]. Scattered examples of [Ru(bpy)3]Cl2 being used as a photocatalyst for visible-light-driven organic synthesis appeared in the scientific literature as

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• simple SiO2 column chromatography. In addition, they were purified using a recyclable high-performance liquid chromatography (HPLC) to remove unidentified impurities to obtain (Sp)-6 and (Sp)-7 in 16% and 3% isolated yields, respectively. The ultraviolet–visible (UV–vis) absorption spectra and normalized

Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads

• Issei Fukunaga,
• Shunsuke Kobashi,
• Yuki Nagai,
• Hiroki Horita,
• Hiromitsu Maeda and
• Yoichi Kobayashi

Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121

• featuring high photostability and strong visible absorption. Perylene–phenothiazine (Pe–PTZ) derivatives have been previously investigated for their excited-state dynamics [15]. Incorporating additional electron-donating groups such as triphenylamine (TPA) onto the PTZ core is expected not only to enhance

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

• ]. Thus, the use of visible light as an energy source provides more efficient chemical transformations and minimize the use of harmful reagents, the generation of waste and the consumption of energy, fulfilling several principles of Green Chemistry and promoting greener opportunities for organic synthesis

• [37][38]. In this context, the reactivity of enaminones under visible-light-mediated reaction conditions has attracted significant attention [39]. However, it is rather surprising that a photocatalytic approach for the synthesis of enaminones has yet to be explored. Herein, we report the first light

• while 3-iodochromone failed to provide the desired enaminone 9a (Table S7, Supporting Information File 1). Control experiments including the reaction in the absence of visible-light or photocatalyst, showed no product formation (Table 1, entries 16 and 17). Interestingly, the yield of 9a dropped to 30

Azobenzene protonation as a tool for temperature sensing

• Antti Siiskonen,
• Sami Vesamäki and
• Arri Priimagi

Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115

• calculations revealed that a second acid molecule significantly enhances protonation, prompting further investigation into the reaction stoichiometry. Upon protonation of 3, the n → π* transition disappears and the π → π* transition red-shifts from 358 nm to 502 nm (Figure 1B), resulting in a visible color

Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions

• Himani Malik,
• Sudha Devi,
• Debapriya Gupta,
• Ankit Kumar Gaur,
• Sugumar Venkataramani and
• Thiruvancheril G. Gopakumar

Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112

• -resolution images, and an example is shown in Figure 2d. The resonances in the 2D-FFT are originated from the moiré pattern of the super-lattice. Two distinct orientations are visible in the 2D-FFT. The 3-fold orientation of islands suggests that the molecular lattices are oriented with respect to the

• visible in large-area STM images as well. A super-periodic pattern is visible at low resolution, and the periodicity (≈6.1 nm) matches with the AFM measurements. Additional STM images of the ultra-thin film of FNAAP at different resolutions are provided in Supporting Information File 1, section 5. Next

• calculations assume a commensurate hexagonal lattice. The graphite lattice directions are marked by the 3-black arrows. The unit cell parameters of optimized geometry (a = 1.968 nm, b = 1.968 nm and γ = 120°) match well with the experiments. The microscopic arrangement of the molecules is clearly visible. It

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

• . Control experiments, Figure S20). Conclusion In conclusion, a novel synthetic methodology for the preparation of benzamides from isonitriles and diaryliodonium salts has been proposed utilizing visible-light photoredox ruthenium-based catalysis. Both symmetrical and unsymmetrical diaryliodonium salts were

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• , or selenium enables spectral tuning across the visible to near-infrared range, improved photostability, and dual-state emissive behavior. In parallel, significant progress in synthetic methodologies – including enantioselective catalysis, electrochemical cyclizations, and multicomponent reaction

• chiroptical retention upon nitrogen incorporation. Qian’s group developed a series of azahelicenes 15a–d through Bischler–Napieralski cyclization [28]. Notably, compound 15b displayed a high interconversion barrier of 36.0 kcal mol−1, enabling enantiomeric resolution. All compounds exhibited visible-range

• %, representing the highest reported values for thermally activated delayed fluorescence (TADF) emitters operating above 650 nm. Shortly thereafter, Wang’s group reported a related series of B,N-containing compounds 38a–c, which displayed pronounced chiroptical activity in the visible region [53]. These compounds

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

• performing the reaction under visible light irradiation, or coupling the reaction to other light-induced processes to produce new classes of products. In 2018, Aitken and co-workers reported a synthesis of previously unknown tricyclic 4:4:4 oxetanes 73 through a photochemical triple cascade reaction starting

• , γ-H transfer and Paternò–Büchi reaction. In 2020, two highly similar methodologies based on a visible-light-mediated Paternò–Büchi reaction between simple alkenes 77 and α-ketoesters 78 were reported independently and shortly after one another (Scheme 21) [61][62]. They both use blue light for

• promoted by visible light at room temperature, requires no protecting atmosphere or additives, and the resulting polysubstituted oxetanes are obtained in moderate to good yields. Additional advantages include scalability and high chemoselectivity as various functional groups were tolerated, including

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

• modified. In recent years, photocatalysis has been widely adopted due to its green and efficient nature [45][46][47][48][49][50][51]. The generation of amidyl radical is implemented by HRP. Six different methods (Figure 2c), which have been developed for visible-light mediated reactions, could generate

• (SET) process by the cleavage of the N–O bond; (c) direct homolytic cleavage of weak N–S or N–X bonds in HRP initiated in the presence of visible light; (d) the intersystem crossing (ISC) of S1 to T1 state directly from the amide anion. This review is organized by bond cleavage type, offering a deep

• demonstrated the homolytic cleavage of the N–O bond using N-(tert-butyl)-O-(1-phenylvinyl)-phenylhydroxyamide as a HAT reagent [78][79]. This compound was capable of initiating the formation of amidyl radicals through visible light activation. Although their controlled experiments showed that this method was

Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

• Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

• | values of helicenes in the visible range. Miscellaneous reactions: The scope of reactions that can be used as the final fusion step when azulene-containing precursors are employed is not limited to those described above. A synthetic strategy involving condensation followed by the reaction of the

• planar π-structures and exhibit weak azulene-like S0→S1 transition absorptions in the visible regions. Single-crystal ribbons of 176 exhibit p-type semiconducting behaviour with hole mobilities of up to 0.29 m2 V−1s−1. Typical Cadogan products can be obtained when the NO2 group is localized in the

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

• 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

• radical then reacts with acrylamide to yield the desired product 37. As shown in Scheme 21, a visible light-induced trifluoromethylation/arylation using Umemoto’s reagent for the synthesis of trifluoromethylated oxindole derivatives was reported by Huang and Zhang’s group in 2021 [13]. This method is

• ), the process involves the homolytic cleavage of Umemoto's reagent 39 under visible light irradiation, releasing a trifluoromethyl radical 42. The radical then adds to the double bond of N-arylacrylamide, forming intermediate radical 43. Subsequently, this intermediate undergoes intramolecular

Gold extraction at the molecular level using α- and β-cyclodextrins

• Susana Santos Braga

Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89

• expected tridimensional CD-MOF in the presence of KAuBr4 in aqueous solution. Instead, they self-assembled into unidimensional threads that aggregated into superstructures and formed, in less than one minute, needle-shaped crystals visible to the naked eye. In these crystals, the molecules of α-CD stacked

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• (2022) investigated the visible-light-mediated amidation of cinnamic acid (7) by using ethyl 2-diazoacetate and acetonitrile to give its corresponding amide 103 in excellent yield (Scheme 32) [29]. The reactive free carbene 104 was released upon light exposure of the diazo ester leading to the nitrilium

• 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

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

• ); triarylsulfonium salts; visible light; Introduction Carbon dots (CDs) are a class of zero-dimensional carbon-based semiconducting nanoparticles bearing on the surface a wide range of functional groups, such as carboxylic acids, alcohols, and amines, that garnered significant attention in the last decade among the

• their size, surface defects, and functional groups, which can be engineered to tune their optical properties. Accordingly, their emission spans a broad range of wavelengths, from ultraviolet to the visible region, allowing for the potential application in an impressive range of applications, such as

• biocompatibility. The electrochemical properties of such materials have been then evaluated by cyclic voltammetry (CV). For all the properties mentioned above, CDs emerged as low-cost and sustainable photocatalysts. Indeed, upon visible-light irradiation, the generated excited state CD* can operate as either

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• , there is a lack of understanding of why the absorption and photoluminescence of D3 symmetrical triphenylmethyl radicals are so weak in the visible spectrum. While it is understood that the functionalization with donor moieties breaks the D3 symmetry, the ϕ varies greatly among different donors and also

• Gomberg (see TTM and PTM in Figure 1a) [31]. Gomberg’s radical emits light in the green region of the visible spectrum, which is shifted bathochromically by substituting the ortho- and para-positions of the trityl phenyl rings with halogens. However, all symmetrical halo-trityl radicals exhibit low ϕ

• bromine substitution decreases the spin–lattice relaxation time T1 of the radical electron. This is due to increased spin–orbit coupling in the brominated species. By contrast, the phase memory time Tm becomes longer for successively brominated radicals, visible from the concurrent spectral broadening in

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• absorption profile in the visible region, ii) a long lifetime of the excited states, and iii) balanced redox potentials in both the ground and excited states [7]. In 2018, Zeitler and her collaborators conducted an innovative and in-depth study on modulating the photochemical properties of a family of donor

• 6a, we observed a blue-shifted absorption profile due to the break of the conjugation in sulfur-based acceptors. Compounds 4a and 6a presented a similar absorption profile, while molecule 5a showed a red-shifted spectrum tailing up to the visible region (Figure 2a). The lack of a significant charge

• Supporting Information File 1, Table S3). As we expected, due to the blue-shifted absorption presented in molecules 4a and 6a, it was impossible to excite them under visible light (400 nm). Gratifyingly, PC 5a delivered product 8 with a promising 63% NMR yield. Next, we compare the photocatalytic behavior of

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• enantiocontrol. Conversely, the bulky tert-butyl-decorated (R)-spirophosphoramidite L5 imposed a confined cavity, steering selectivity toward Si–C(sp2)-bond activation and predominantly afforded the regioisomeric (S)-2-silacyclohexenylarenes 18. In 2025, Gong and co-workers reported a visible-light-mediated

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• reported to either bathochromically shift the UV–vis absorption spectrum or lead to a better separation of the n→π* bands of the two photoisomers and allow for visible-light-responsive switches [23][24][25][26]. In recent years, heteroaryl azobenzene derivatives have revealed superior properties to

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• ) that can form covalent bonds when exposed to UV or visible light. These photoaffinity tags or crosslinkers are designed to bind to specific biomolecules, such as proteins, nucleic acids, or lipids, in a highly selective manner. The light irradiation triggers a chemical reaction, such as a bond

• the agency of low-energy visible light with specific functional groups on biomolecules. This allows precise control over the conjugation process, enabling targeted modifications without affecting non-reactive sites. Although previous reviews have discussed the more traditional synthetic methods

• emerged as a transformative approach in the modification of proteins, enabling researchers to achieve selective and efficient conjugation under mild conditions [37]. By utilizing visible light and transition-metal catalysts, this technique allows the generation of reactive intermediates that can