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Search for "photoactivation" in Full Text gives 18 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments
Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30
- hydride resulted in the formation of the oxepine ring by a double substitution reaction, to yield the desired dinaphthooxepine 33. The non-planar character of dinaphthooxepine bisimides was confirmed by X-ray crystal structure, and stability towards thermal or photoactivation was also established. Cyclic
- product thiarubrine A [70]. Examples of S-extrusion from annelated 1,2-dithiins under photoactivation (top) or thermal activation (bottom) [71][72]. Synthesis of dibenzo[1,4]dithiapentalene upon photoextrusion of SO2 [78]. Extrusion of SO in naphthotrithiin-2-oxides for the synthesis of 2,5
Recent advancements in iodide/phosphine-mediated photoredox radical reactions
Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131
- amount of ammonium iodide under irradiation in the absence of triphenylphosphine (Scheme 12). The generation of alkyl radicals was attributed to the photoactivation of a transient electron donor–acceptor complex formed between iodide and N-(acyloxy)phthalimide, in line with earlier findings. These
Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series
Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23
A photochemical C=C cleavage process: toward access to backbone N-formyl peptides
Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202
- give amide 12 with a half-life (t1/2) of 6.4 h. The observation of N-formyl products can be rationalized with a bifurcating mechanism (Figure 5). Following photoactivation, H-atom abstraction and nucleophilic addition of water would produce the key intermediate B. Such hemi-aminal compounds would be
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
- the variety of possibilities in combining transition metal C–H activation and visible-light photoactivation to reach sustainable synthesis. The particular focus is put on the mechanisms of such complex catalytic systems, highlighting the unique reactivity that arises from the original combination of
- azoles. His research group discovered that the abundant and inexpensive CuI catalyst allowed the direct arylation of benzoxazoles under UV-photoactivation (Figure 46) [106]. Remarkably, this totally site-selective photoinduced C–H arylation took place at room temperature and the use of amino acid ligands
Photocontrolled DNA minor groove interactions of imidazole/pyrrole polyamides
Beilstein J. Org. Chem. 2020, 16, 60–70, doi:10.3762/bjoc.16.8
- been used to exert genomic effects on mRNA expression [56]. Therefore, the photoactivation of such interaction may be a future application. The incorporation of the photoswitchable 3-((3-(aminomethyl)phenyl)diazenyl)phenylacetic acid linker upon replacement of the γ-aminobutyric acid linker is a
Light-controllable dithienylethene-modified cyclic peptides: photoswitching the in vivo toxicity in zebrafish embryos
Beilstein J. Org. Chem. 2020, 16, 39–49, doi:10.3762/bjoc.16.6
- ) was recorded, and then in situ illumination (“photoactivation”) was applied to switch into the ring-open photoform and obtain the respective LD50(opened) values (see Figure 2 for the study design and the killing curves). Each time, 12–15 or 18–20 zebrafish embryos at 3 dpf were treated by applying the
- 2.4 ± 0.2 µg/mL GS 1 and 2.1 ± 0.3 µg/mL ring-open 2. With increasing incubation time, lower concentrations were expected to achieve comparable mortality; however, the difference between 1 h and 24 h incubation was low for both peptides (Table 2). The photoactivation assay, in which two photoisomers
- displayed an about 16-fold decrease in the LD50 value after in situ photoactivation. This difference indicates that the ring-open isomer of 2 indeed possesses a higher toxicity than the ring-closed isomer, and it demonstrates in vivo photoswitching of the whole-body toxicity. Since the determined LD50
N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes
Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5
- ion. This was one of the features to use N-phenylphenothiazine for the photoactivation of SF6 for the pentafluorosulfanylation of styrenes [2]. This two photon concept can further be extended to the photoredox catalytically generation of hydrated electrons as very powerful reductants (E = −2.8 V (vs
Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH
Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163
- these requirements particularly well. The diazirine photophore is small and its photoactivation is possible at wavelengths around 350 nm and thus does not perturb protein structures. According to the literature, irradiation of a diazirine-functionalized ligand leads to a reactive carbene which can
Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing
Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32
The reductive decyanation reaction: an overview and recent developments
Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30
- ) iodide/THF/HMPA at respectively 0 °C and room temperature [123]. Metallic samarium can also promote the decyanation [124]. Doni and Murphy have reported the reductive decyanation of malononitriles and α-cyanoesters by using the neutral organic electron donor 78 (Scheme 25) under photoactivation (method A
A self-assembled cyclodextrin nanocarrier for photoreactive squaraine
Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248
- the importance of introducing a platform for the immobilization of the squaraines as to provide steric separation and suppress aggregation. In the next step, we investigated the photoactivation under irradiation. To this end, a solution of AdSq was irradiated with light of a wavelength higher than 630
Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis
Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173
- a reaction partner because on photoactivation it supplies electrons and holes while also donating protons from surface hydroxy groups. An interesting adjunct to these results was our finding that aryloxy-, arylthio- and anilino-acetic acids, carrying electron donor substituents (2-, 3- or 4-MeO, t
- generation of acyl radicals. Radical polymerizations are hugely important industrially and it seems certain SCPC has a role to play in this area too. Production and utilization of h+ and e– by photoactivation of a semiconductor. Photoredox activity of TiO2 with moist air. TiO2 promoted oxidation of
One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates
Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316
- -polar solvents, yet low photocatalyst solubility in these solvents precluded photoactivation of 4a. Thus, a solvent switch was used to capitalise on the beneficial properties of both solvents. At this stage, we employed an MeCN/H2O (4:1) solvent system and Ru(bpy)3Cl2 in photoactivations which
- in a 1:4:4 ratio by LC–MS, respectively (Figure 2). First, we sought to rule out the possibility of Ru(bpy)3Cl2 promoting these undesired pathways. Although Ru(bpy)3Cl2 could not be separated from 5a after photoactivation due to their similar polarities, we successfully separated the less polar
- used, allylindium reagents generated and indium trihalide salt byproducts are non-toxic [43]. Our conditions benefit from the absence of amide side-products typically effected by peroxide intermediates in aerobic photoactivation of THIQs [16][22] and so our methodology serves to complement existing
[3 + 2]-Cycloadditions of nitrile ylides after photoactivation of vinyl azides under flow conditions
Beilstein J. Org. Chem. 2013, 9, 1745–1750, doi:10.3762/bjoc.9.201
A chemist and biologist talk to each other about caged neurotransmitters
Beilstein J. Org. Chem. 2013, 9, 64–73, doi:10.3762/bjoc.9.8
- rapid photoactivation of a particular enzyme, the Na,K-ATPase. It was the latter group that dubbed such photochemical probes “caged compounds”. This simple term has been adopted by biologists since that time [3][4][5][6][7][8][9], perhaps because the photolabile ATP compound was the one that was used in
Fine-tuning alkyne cycloadditions: Insights into photochemistry responsible for the double-strand DNA cleavage via structural perturbations in diaryl alkyne conjugates
Beilstein J. Org. Chem. 2011, 7, 813–823, doi:10.3762/bjoc.7.93
- acetamides. The significant protecting effect of the hydroxyl radical and singlet oxygen scavengers to DNA cleavage was shown only with m-lysine conjugate. All three isomeric lysine conjugates inhibited human melanoma cell growth under photoactivation: The p-conjugate had the lowest CC50 (50% cell
- photochemistry is vital for unraveling the mechanistic scenarios that account for DNA cleavage by these compounds (Figure 3) [25]. As illustrated in Figure 3, multiple reaction pathways are potentially unlocked by the photoactivation of alkyne conjugates. In the past, we observed dramatic differences in
- The ability of compounds 1, 6, and 7 to inhibit cell proliferation in human melanoma cell lines was tested in the dark and under photoactivation (Figure 9). According to the control experiments with all three conjugates in the dark, these compounds do not inhibit cell proliferation at concentrations
Light-induced olefin metathesis
Beilstein J. Org. Chem. 2010, 6, 1106–1119, doi:10.3762/bjoc.6.127
- metathesis stands out as both academically motivating and practically useful. Starting from early tungsten heterogeneous photoinitiated metathesis, up to modern ruthenium methods based on complex photoisomerisation or indirect photoactivation, this survey of the relevant literature summarises past and
- present developments in the use of light to expedite olefin ring-closing, ring-opening polymerisation and cross-metathesis reactions. Keywords: catalysis; light activation; olefin metathesis; photoactivation; photoinitiation; photoisomerisation; RCM; ROMP; ruthenium; tungsten; Introduction The metal
- reactions was not explained, even though it is slightly counterintuitive. In order to improve the understanding of the photoactivation mechanism, complex 16g was irradiated by visible light both in the presence and absence of cyclooctene. NMR and UV spectra confirmed the release of p-cymene from the complex
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