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

• demonstrate that these simple D–A structures exhibit promising photocatalytic properties, comparable to those of more complex D–A–D systems. Keywords: donor–acceptor system; photocatalyst design; photoredox catalysis; organic photocatalyst; Introduction In recent years, photocatalysis has emerged as a

Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters

• Lewis McGhie,
• Hannah M. Kortman,
• Jenna Rumpf,
• Peter H. Seeberger and
• John J. Molloy

Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69

• the alkene leading to the generation of an 89:11 (E/Z) mixture of geometrical isomers (Table 1, entry 3). The use of xanthone (74 kcal/mol), a highly powerful organic photocatalyst, enabled enhanced reactivity producing a photostationary state of 73:27 after 16 hours (Table 1, entry 4). Varying

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

• previously observed results, Gianetti et al. have speculated that N,N′-di-n-propyl-1,13-dimethoxyquinacridinium (55, DMQA) tetrafluoroborate could serve as a versatile NIR organic photocatalyst [69]. Redox potentials of this photocatalyst engaged in both oxidative quenching and reductive quenching cycles

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

• in artificial photosynthesis [3][29][48]. Glusac and co-workers published studies on the photochemical recycling of BIH analogues [49]. They used an organic photocatalyst to reduce the oxidized benzimidazole 1,3-dimethyl-2-(2,4,6-trimethoxyphenyl)-2H-benzimidazole (BIM) twice in the presence of

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

• lutidine base, 7 mol % organic photocatalyst 4CzIPN, 30 mol % NiBr2, and 30 mol % bpy provided 57% of 9. Intramolecular Friedel–Crafts reaction by Et2AlCl and HFIP complex led to 123, possessing the correct connectivity for the divergent synthesis of the family. Choreographically executed sequential

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

• proposed to proceed via a similar mechanism to the one shown in Figure 2. In 2018, Huang and Rueping devised reaction conditions for the photochemical nickel-catalyzed arylation of allylic C(sp3)‒H bonds with aryl bromides 3 in the presence of the organic photocatalyst 9-mesityl-10-methylacridinium

• transformation, the combination of NiBr2·diglyme/bipyridine in the presence of the iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 under blue light irradiation was found to be appropriate to give optimal results (Scheme 26) [72]. The König group recently disclosed that the organic photocatalyst 1,2,3,5

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

• and B) [145]. The authors successfully applied a manganese salt in catalytic amounts, allied with the use of an electrical current in combination with blue LED lights and an organic photocatalyst (DDQ), affording azidated alkyl moieties in excellent yields and chemoselectivity through alkyl C–H bonds

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• ) [121]. Notably, the organic photocatalyst eosin Y was employed, and the cyclizations proceeded with excellent diastereoselectivity, usually higher than 19:1. When 1,3-ketocarbonyl substrates 100 were employed, the use of a weak Lewis acid (LiBr) was required to accomplish the cyclizations, and no

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

• as sole oxidant and implementing two photoredox cycles is presented in Figure 16. After a ligand exchange, Co(II) undergoes a single-electron transfer (SET) oxidation to Co(III) with a concomitant formation of the reduced organic photocatalyst. The thus generated highly reactive Co(III) complex

• combining palladium-catalyzed C–H activation and photoredox catalysis (Figure 27) [89]. Interestingly, the transformation occurred smoothly in the presence of eosin Y, an inexpensive (in comparison with Ir- or Ru-based photoredox catalysts), and easily accessible organic photocatalyst. The reaction, carried

• catalytic system. The strategy used the Fukuzumi acridinium salt organic photocatalyst and Pd(TFA)2 to promote the C–H activation step. In this case, the transformation was only compatible with aromatic α-ketoacids. Nevertheless, the reaction was performed at room temperature and tolerated a wide spectrum

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

• use of the strong oxidant Mes-Acr-Ph+ (OD3, E(PC+*/PC) ≈ 2 V) as organic photocatalyst leads to the oxidation/decarboxylation of the in situ-generated carboxylates (Eox ≈ 1.3 V). An organic disulfide cocatalyst, (PhS)2, activated by the reduced photocatalyst, was found to act as a co-base (PhS−) and a

• similar strategy for radical generations was applied by Glorius and co-workers. They exploited a combination of organophotoredox and copper catalysis to achieve the conversion of carboxylic acids into alkenes using N,N-diaryldihydrophenazine as an organic photocatalyst [46]. Rose bengal (OD15) was also

• exploited as an organic photocatalyst to trigger the reductive fragmentation of phthalimide-based redox-active esters [47]. Other oxidative fragmentations In addition to the decarboxylation reactions, organic photoredox catalysis can be exploited to access C(sp3) radicals via the oxidative fragmentation of

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

• Kaj M. van Vliet,
• Nicole S. van Leeuwen,
• Albert M. Brouwer and
• Bas de Bruin

Beilstein J. Org. Chem. 2020, 16, 398–408, doi:10.3762/bjoc.16.38

• organic photocatalyst, showing hyperfine interactions with two equivalent nitrogen nuclei (giso = 2.0032; ANiso = 18.6 MHz). The HRMS of this species showed the mass of the catalyst, thus confirming that the oxidized catalyst precipitates as a salt from solution when using benzene as a solvent. Based on

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

• metal-free method for the synthesis of benzothiophenes via a photocatalyzed tandem addition/cyclization reaction (Scheme 11) [41]. Aryl thiols were coupled with dimethyl acetylenedicarboxylate, applying 9-mesityl-10-methylacridinium perchlorate (Acr+-Mes ClO4−) as organic photocatalyst and benzoic acid

• -workers and the working groups of Fraile and Aleman independently reported of visible-light photocatalyzed procedures for the preparation of sulfoxides from the respective sulfides and alkenes by radical thiol–ene reactions (Scheme 15) [45][46]. Wei and Wang applied Rose Bengal as organic photocatalyst

• 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

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• the presence of the organic photocatalyst N-methyl-9-mesitylacridinium (17), CF3SO2Na was converted into CF3• upon visible-light irradiation. The CF3• radical reacted with the vinyl azide to give the iminyl radical 18 that was reduced by Mes-Acr• (Mes-Acr: 9-mesityl-10-methylacridinium) into the

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• spectroscopy revealed just the presence of both reactants, both in the presence or absence of the organic photocatalyst eosin Y (5.0 mol %). Ruling out a sole mechanochemical activation pathway (Table 1, entries 1 and 2). Repeating the reaction in the presence of the PC in the transparent PPMA milling jar

• reaction mixture reached 6:94 (entry 12 in Table 1). Alternatively, longer reaction times allowed reducing the amount of the organic photocatalyst to 1.0 mol % and 0.5 mol % (entry 13 in Table 1; for more details, see Table S1 in Supporting Information File 1). Then, using the green LEDs an experiment in

• milling conditions (vide supra) could have been indeed the result of a photoredox transformation where the organic photocatalyst eosin Y played a key role in triggering the SET process. Conclusion In summary, simultaneous activation of an organic system by light and ball milling techniques has been

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• solvent-free photocatalysis is the application of heterogeneous, semiconducting photocatalysts, often based on titanium dioxide and other metal oxides [6][7][8]. However, to the best of our knowledge, no solvent-free visible-light driven transformation of a solid substrate applying an organic

• photocatalyst has been reported yet. In this work, we present a novel milling apparatus, which we developed especially for the conversion of solid substrates. Applying this apparatus, the solvent-free oxidation of various benzylic alcohols to their corresponding carbonyl compounds using riboflavin tetraacetate