Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• example, as a photosensitizer in photodynamic therapy. Keywords: biomaterial; fullerene; peptide; water-soluble; Introduction Since the seminal discovery in 1985 by Kroto, Smalley, Curl, and co-workers [1], fullerenes, specifically buckminsterfullerene C60, have intrigued the scientific community. The

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• photosensitizer in an energy-transfer (EnT) mechanism. This proposal was supported by fluorescence quenching measurements, as well as the direct excitation of 44 by UV irradiation, resulting in the formation of 45 in a 45% yield. According to this hypothesis, NHPI ester 44 would adopt a favorable conformation (46

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• ]. Results and Discussion To test the feasibility of this reaction sequence, the aromatic substrate 1 readily accessible by the prenylation of commercial diethyl benzylmalonate [21] was first used. The photooxygenation of 1 was performed in CH2Cl2 in the presence of methylene blue (MB) as a photosensitizer

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• ; heterocycles; photocyclization; photosensitizer; styrylpyridines; Introduction DNA intercalators – most often represented by small planar heteroaromatic compounds – play an important role as chemotherapeutic agents [1][2][3][4]. Specifically, upon intercalation into the DNA double helix such ligands can cause

• cancer [39], and bacterial, fungal, parasitic and viral infections [40][41]. In general, PDT operates on the basis of a photosensitizer, which generates reactive intermediates upon irradiation [42][43][44][45]. Hence, in the type-I mechanism the photosensitizer induces the formation of reactive oxygen

• species (ROS), such peroxyl, alkoxy and hydroxyl radicals, or carbon-centered radicals, which subsequently induce DNA strand cleavage. In the type-II mechanism, a triplet-excited photosensitizer reacts with molecular oxygen to give highly reactive singlet oxygen, 1O2, as reactive intermediate, which in

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• Supporting Information File 1). We speculate that this degradation is due to the reaction with singlet oxygen generated by the compound as a photosensitizer; indeed, we have recently shown [31] that IF-TTF compounds are reactive towards singlet oxygen at the central fulvene bond but, in contrast, IF-TTFs

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• adapted with permission of Institution of Chemical Engineers (IChemE) and The Royal Society of Chemistry from [38] (“Cationic and radical polymerization using a boron–thienothiophene–triphenylamine based D-π-A type photosensitizer under white LED irradiation”) by A. Suerkan et al., Mol. Syst. Des. Eng

Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• purpose, three main components are needed: a photosensitizer (PS), which acts like a light-antennae harvesting system in natural photosynthesis, a catalyst (Cat.), reacting directly with CO2 after being reduced, and a sacrificial electron donor (SeD). When the involved (photo)catalysts are homogeneous

• developing the major components of a photocatalytic system for CO2 reduction, such as the photosensitizer (PS), the catalyst, and the sacrificial electron donor (SeD). Nevertheless, the solvent and eventual additives play an important role too [6], as they can influence the (photo)redox properties of the

• complex [Cu(dmp)DPEPhos](BF4), well-investigated and used in several photocatalytic reactions [20][21][41], acting as a cost-effective benchmark photosensitizer. Herein, we present a study for the selectivity control of the novel Co(II) catalyst 1, aiming at maximizing the catalytic efficiency, and

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• couple the reduction to water oxidation or other reactions. Furthermore, the performance of the molecular photosensitizer and catalyst combinations developed are often very dependent on the properties of the sacrificial donors. This review has two aims: 1. Highlight work being done to recycle sacrificial

• in systems for carbon dioxide reduction (see Figure 1). Reductive quenching of the photosensitizer occurs when the sacrificial donor reduces the photoexcited photosensitizer (reductive quenching pathway). Regeneration of photooxidized photosensitizers occurs when the excited dye is first oxidatively

• low absorption in the visible region to prevent side reactions and allow the photosensitizer to absorb as much light as possible. The oxidation potential of the sacrificial electron donor must be less positive than the reduction potential of the excited or oxidized photosensitizer for quenching or

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• different flexibility. The crown ether derivative acts as a chassis in order to fix the thread. A ferrocenyl group attached at one of the ends of the linear component serves as a photosensitizer allowing the absorption of visible light. The different substitution induced different types of deformations

• different materials [11]. Towards biocompatible applications [71], the use of visible light irradiation as input which leads to the desired function is a necessary requirement. In this scenario, the incorporation of photosensitizer motifs is a suitable strategy to allow such a performance. Towards this

• direction, one potential strategy is the approach followed by Feringa and co-workers [72], in which palladium-porphyrin photosensitizer-based struts were employed within a metal-organic material, allowing the use of green light as irradiation source because of the effective energy transfer between these

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• , Gutierrez and Molander reported the coupling 4-alkyl-1,4-dihydropyridines 31 with heterobicyclic alkenes 30 under photoredox/Ni dual catalysis (Scheme 6) [39]. In contrast to other photoredox-mediated transformations, the authors utilized the inexpensive organic photosensitizer 4-CzIPN (Scheme 6 and Scheme

• photoexcitation of the photosensitizer 43 to form 44 which can oxidize aniline 36a to give radical cation 46 (Scheme 7). Deprotonation by DBU produces the radical 40. The radical anion photosensitizer 45 can reduce Ni(I) to Ni(0), closing the first catalytic cycle. The Ni(0) complex can undergo oxidative addition

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• . Interestingly, irradiation at 365 nm even in the presence of photosensitizer and O2 failed to furnish (+)-jungermatrobrunin A (89), and 90 was obtained as the sole product, albeit in low yield (14%). Attempts to optimize the yield always afforded recovered 88, hinting at a potential equilibrium between 88 and

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• . Notably, the reaction did not proceed in the dark or in the absence of the photosensitizer at 30 °C; further, the reaction generated the desired product in lower yield at 120 °C. The scope was broad and tolerated a wide array of 1,3-keto esters and 1,3-diketones, as well as both benzylic and aliphatic C

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

• product Nu–R can be obtained through an inner-sphere pathway between [LnCuIINu]X and the radical R• [41][42] (Scheme 5A). Alternatively, a photosensitizer generated a radical via reduction or oxidation, and is not engaged in the key bond construction. [LCuI] is photoexcited to generate LnCuI*, which

• form the desired product 13 (Scheme 9). In 2019, the same group [56] applied this protocol to the asymmetric cyanofluoroalkylation of alkenes. Under visible-light irradiation, the Cu-based catalyst plays a dual role as both the photosensitizer for the SET and the catalyst for asymmetric control (Scheme

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• -catalyzed C–H alkylation strategy to use the readily available inexpensive organo-photocatalyst benzaldehyde as the HAT photocatalyst under UVA irradiation [68][86]. Thus, the combination of NiBr2·glyme/dtbbpy, benzaldehyde as both the photosensitizer and hydrogen abstractor, and K2HPO4 as a base under

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• ][9]. NIR dyes, and more especially cyanine dyes, have been studied in NIR photosensitive systems [5][6][7][9][10][11][12][13][14][15]. The cyanine acts as a photosensitizer: it absorbs the light emitted in the NIR range and then acts with a combination of additives (oxidant agents and reducing agents

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• explained as follows: the zinc(II)–cyclen complex can absorb light and facilitate the intramolecular electron transfer from benzyl alcohol to the excited flavin, and thus the benzaldehyde and the photoreduced flavin were produced. The study indicates the significance of connecting a photosensitizer and a

• ], the [Co(dmgH)2(4-ppy)2]NO3 (27, dmgH2 = dimethylglyoxime, 4-ppy = 4-phenylpyridine) guest, and the EY photosensitizer, respectively (Figure 16) [49]. When mixed with the sacrificial electron donor TEOA in an anaerobic H2O/CH3CN 1:1 solution, this supramolecular system 27@CB[7]/EY could realize an

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• complementing the series, but did not yet describe synthetic details [7]. Xue et al. published a donor–acceptor photosensitizer for dye-sensitized solar cells, in which the N-phenylated SN4 unit serves as bridge between donor and acceptor moieties [34]. Further replacement of sulfur by nitrogen can lead to

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• with a length of 11.5 m and an inner diameter of 0.8 mm were wrapped around two Pyrex® glass columns. UV lamps were placed inside the glass columns. A representative setup is given in Figure 3a. The addition of isopropanol to 2(5H)-furanone in the presence of the photosensitizer 4,4’-dimethoxy

• this paper. This was because the large reactor volume (10 × 5 mL) was illuminated effectively by two low-power lamps (2 × 18 W). In addition, several photosensitizer and reactant concentrations were screened before the reaction was scaled up. With the selected photosensitizer concentration (10 mM), the

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• absorption of radiation by another molecular entity called a photosensitizer. In mechanistic photochemistry, the term is limited to cases in which the photosensitizer is not consumed in the reaction” [89]. One can appreciate the close connection of this definition to that of photocatalysis, defined by the

• principle, the photosensitizer is regenerated and therefore functions in a very similar way to a catalyst and can be deemed a photocatalyst. A common example of this concept is triplet photosensitization. The excited photocatalyst has a relatively high triplet-state energy and a long lifetime, such that it

• deemed to proceed via SET. 2 Principles of photosensitization; selection of the photosensitizer and fluorinating reagent in C–H fluorinations 2.1 Photosensitization and appropriate photosensitizer The general mechanism of photosensitization is described in Figure 3 [86]. Initially, the PS absorbs visible

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• reaction media in order to transfer electrons from the low-valent metal complex formed in situ after reductive elimination of the product (Figure 4, right). In this way, the metalacyclic intermediate is reoxidized while the photosensitizer is reduced, thus completing the C–H activation catalytic cycle. By

• described the combination of rhodium and photoredox catalysis for the direct C–H ortho-olefination of arylamides (Figure 7) [74]. The procedure was performed under air at 80 °C and turned out to be efficient using a low loading of a Ru-based photosensitizer. A broad range of DGs could be installed on the

• of the photocatalyst in the absence of oxygen, suggesting that a direct electron transfer from the photosensitizer allowed the reoxidation of the active catalyst. However, the participation of molecular oxygen cannot be excluded. Rueping further demonstrated the capacity of the dual catalytic systems

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• ] (Scheme 33). 2.7. Photocatalyzed benzylic fluorination of N-phthalimido phenylalanine The photocatalyzed benzylic fluorination of phthalimide-protected phenylalanine methyl ester 145, using the photosensitizer 1,2,4,5-tetracyanobenzene (TCB), and Selectfluor in acetonitrile was carried out using a pen

• lamp (λmax = 302 nm). By this route, the β-fluoro derivative 146 was obtained in 62% yield as racemic mixture [71] (Scheme 34). Recently, Egami and coworker also synthesized compound 146 in 43% yield (dr = 1:1) via the fluorination of 145, however without TCB as photosensitizer, but instead using an

• using photosensitizer TCB. Synthesis of β-fluorophenylalanine derivatives using Selectflour and dibenzosuberenone. Synthesis of protected β-fluorophenylalanine via aziridinium intermediate 150. Synthesis of β-fluorophenylalanine derivatives via fluorination of α-hydroxy-β-aminophenylalanine derivatives