A study of the photochemical behavior of terarylenes containing allomaltol and pyrazole fragments

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2022, 18, 588–596, doi:10.3762/bjoc.18.61

• -induced processes are of considerable interest in the context of green chemistry [8][9]. At the same time in some cases UV irradiation of organic compounds leads to the formation of highly reactive intermediates. Such objects may, possessing a specific reactivity, which define their further application in

• of photoreactions can occur under UV irradiation: the classical photocyclization of the 1,3,5-hexatriene system and excited state intramolecular proton transfer (ESIPT) – promoted photoprocesses typical for a 3-hydroxypyran-4-one core. For the ESIPT-induced reactions the general direction is the

• processes can be complicated if additional photosensitive fragments are presented in the structure. For example, we previously studied the photochemical behavior of oxazolone terarylenes 9 containing the allomaltol fragment (Scheme 1C) [26]. It has been shown that UV irradiation of such systems leads to a

Anomeric 1,2,3-triazole-linked sialic acid derivatives show selective inhibition towards a bacterial neuraminidase over a trypanosome trans-sialidase

• Peterson de Andrade,
• Sanaz Ahmadipour and
• Robert A. Field

Beilstein J. Org. Chem. 2022, 18, 208–216, doi:10.3762/bjoc.18.24

• ) and compounds were visualised by UV irradiation (λ = 254 nm) and/or dipping in ethanol/sulfuric acid (95:5 v/v) followed by heating. A Biotage SP4 flash chromatography system was used for purification of the protected sugars with normal phase silica (pre-packed SNAP Ultra cartridges). Deprotected

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

• Luke O. Jones,
• Leah Williams,
• Tasmin Boam,
• Martin Kalmet,
• Chidubem Oguike and
• Fiona L. Hatton

Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• synthesis of trisphaeridine to afford the product in four linear steps in an overall yield of 6.5% from 1-bromo-2,4,5-trimethoxybenzene. Keywords: aromatic compounds; cyclization; iminyl radical; phenanthridines; radical cation; synthesis; UV irradiation; Introduction Phenanthridine derivatives have

• reported by Rodrıguez and Walton we envisaged that under these photochemcial conditions, intermediate 8 would be formed. Contrary to the expected results, in our labs exposure of oxime 7 to UV irradiation yielded phenanthridine 9 as the main product alongside the nitrile 10 in lower yields [13]. We

• hydrochloride and then acetyl chloride afforded oxime 22. Next was the key photochemical step. Exposure of 22 to UV irradiation resulted in the formation of the desired phenanthridine 23 in a disappointing yield of 41%, together with the benzonitrile 24. Phenanthridine 23 was then treated with CAN followed by

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• the products that absorbed UV light were detected by UV irradiation. The melting points were measured using a Yanaco MP-S3 apparatus and are uncorrected. IR spectra were recorded on a Perkin–Elmer Frontier FTIR in the ATR mode. NMR spectra were recorded in CDCl3 solutions using a JEOL JNM-LA 300, JEOL

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• radical C(sp3)−H halogenation at the benzylic and allylic position using N-halosuccinimide with azobisisobutyronitrile or benzoyl peroxide as a radical initiator is known as the Wohl–Ziegler bromination reaction, which requires heating, acidic/basic conditions, and/or UV irradiation (Scheme 1a) [17][18

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• ethereal solution of diazomethane in toluene at 0 °C resulted in pyrazoline derivative C [81]. The adduct isolated chromatographically was exposed to ultraviolet (UV) irradiation for 25 min at 25 °C in a quartz tube. The resulting isomers 3 and 4 were separated by reversed-phase high-performance liquid

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• crystallinity, reduced chain mobility and hydrophobicity of polymers [114][115], which makes biodegradation often ineffective and time-consuming, particularly for polyolefins, such as polyethylene, polyvinyl chloride (PVC), polystyrene or PET [116][117]. Thus, abiotic pretreatments may be required, including UV

• irradiation [118], oxidation [119] or acidic degradation [120]. It is worth mentioning that organocatalytic depolymerisation methods have also been reported [121][122]. Despite these systems represent promising “greener” options, they still are in an early development stage. Uses are mainly limited to

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• ]helicenes 10 only weak fluorescence in the solution under UV irradiation was observed (Table 7, see also Supporting Information File 1, Figures S42–S45). Helicenes 10b and 10c exhibited blue emission with emission peaks at 481 and 440 nm, respectively. Quinoxaline-fused helicene 10a demonstrated a yellow

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• solvents with different polarity [39][40][41][42][43][44][45]. The emission spectra of the dyes 3 and 8 and the color changes observed upon UV irradiation of both dyes in various solvents are shown in Figure 3. Both series of the dyes showed fluorosolvatochromic behavior in all solvents used except for

• = 10 μM. Emission spectra of dyes 3 (a, left) and 8 (b, right). Inset: Color of dyes 3 and 8 in the indicated solvents of different polarities under UV irradiation (λex = 365 nm, c = 1 μM). Red shift phenomena with changing substituents in absorption (a, left) and emission (b, right) spectra of dyes 3

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

Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Valerii V. Tkachev,
• Andrey N. Utenyshev,
• Olga Yu. Karlutova,
• Alexander D. Dubonosov,
• Vladimir A. Bren,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149

• -Benzo[b]thienyl fulgides and fulgimides containing bulky diphenylmethylene substituents were synthesized in the form of their ring-opened E- or Z-isomers. In contrast to the majority of known fulgides/fulgimides, that form colored ring-closed structures under UV irradiation, the obtained compounds

• photochromic properties of 2-benzo[b]thienylfulgides [22]. UV irradiation of acetonitrile solutions of these compounds results in the electrocyclic hexatriene–cyclohexadiene rearrangement of the ring-opened isomers O into the colored ring-closed ones C (Scheme 1) which exhibit enhanced spectral characteristics

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• found to split water to oxygen and hydrogen gas under strong UV irradiation. This gained significant attention in the wider scientific community for the potential generation of solar fuels [27][75] and formed the foundation of modern heterogeneous photocatalysis. With this brief historical perspective

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• of a [3 + 2] cycloaddition reactions under UV irradiation with azobis(isobutyronitrile) (AIBN) as the free radical initiator and phenyl disulfide as the catalyst, in which the three-membered rings containing double bonds and substituted olefins were transformed into five-membered-ring structures with

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• both (R) and (S)-isomers, and 1,1-diphenylethene (216c) under UV irradiation. As the products spirothietane-pyrrolidinones 320 were obtained in 65–89% yield. The diastereoselectivity was controlled by the steric effect of the ortho-substituents on the phenyl ring [88] (Scheme 59). The intermolecular

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• [46], Pb(OAc)4 [44][46][47][48][49][50][51], PbO2 [52], Mn(OAc)3 [46], KMnO4 [46], Ag2O [53], AgO [54], Horseradish peroxidase/H2O2 [55], metal-free oxidants PhI(OAc)2 [46], t-BuOOt-Bu [53] or quinones [56] under UV irradiation. Anodic oxidation was also reported [57]. The establishing of the self

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

• radicals Thiyl (sulfenyl) radicals Thiyl radicals are common, versatile, strong nucleophilic radicals. They are efficient at performing atom abstractions, in particular with H-atoms, adding to π-systems and electrophiles, such as carbonyl compounds [166]. They can be generated from the UV irradiation of

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• that acetone (4) could efficiently initiate photografting under UV irradiation when mixed with water [41] and performed a theoretical study on the matter a few years later [42]. The same research group later studied other aliphatic ketones for their efficiency in initiating photografting [43][44

• of the benzophenone 172 to the triplet state 173 by UV irradiation, followed by HAT from the aldehyde 170 to 173 and the formation of the acyl radical 175. At the same time, the nickel(0) complex 176 performs an oxidative addition reaction to the aryl bromide 171, and the nickel(II) complex 177

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• addition of P–H to unsaturated organic compounds (hydrophosphination) presents an atom economical, efficient and green strategy for the preparation of phosphines. The process can be initiated thermally, chemically or by UV irradiation. Radicals can also be used in hydrophosphination reactions. For example

• , azobisisobutyronitrile (AIBN) can initiate the addition of secondary phosphines to N-vinylpyrroles under heating or UV irradiation resulting in regio- and chemospecific adducts. Using the same approach Trofimov et al. [96] reported on the selective synthesis of tertiary diorganyl pyrrolylphosphines 105 and 106 in high

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• presence of DNA. Based on our interest in the chemistry and biology of the oxime functionality [54][55][56][57], as well as in their DNA photolytic interaction upon UV irradiation [9][10][11][43] we have decided to investigate the behaviour of carefully designed O-carbamoyl derivatives of p-pyridine

• and subjected to UV irradiation in the presence of plasmid DNA. Not all derivatives were active, nevertheless all amidoxime, ethanone oxime and aldoxime derivatives showed similar effects, indicating the cause of action to be considered on the carbamate moiety rather than the oxime. The affinity of

• , respectively. Photo (A): wells 3–8: DNA + carbamoyl amidoximes (8 or 9, or 10, or 11, or 12, or 13, respectively) + UV irradiation; Photo (B): Mechanistic studies involved by derivative 26 under UV irradiation: well 3: DNA + 26; well 4: DNA + 26 + argon; well 5: DNA + 26 + DMSO (20%); well 6: DNA + 26 + NaN3

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• derivatives using the cumene process or single-step oxygenation suffers from poor yields, high reaction temperatures, and high-energy UV irradiation conditions [155][156]. To overcome this, in 2012, Fukuzumi and co-workers used 3-cyano-1-methylquinolinium perchlorate (8) as a photoredox catalyst for the

Photocontrolled DNA minor groove interactions of imidazole/pyrrole polyamides

• Sabrina Müller,
• Jannik Paulus,
• Jochen Mattay,
• Heiko Ihmels,
• Veronica I. Dodero and
• Norbert Sewald

Beilstein J. Org. Chem. 2020, 16, 60–70, doi:10.3762/bjoc.16.8

• and Figure 1C). However, the Z-isomer content could not be increased further by UV irradiation. The Z-isomer could subsequently be switched back to the E-isomer (19% Z-configuration after 30 min) by irradiation at 420 nm (Figure 1D). The thermal conversion to the E-isomer in the dark was slow at room

Light-controllable dithienylethene-modified cyclic peptides: photoswitching the in vivo toxicity in zebrafish embryos

• Sergii Afonin,
• Oleg Babii,
• Aline Reuter,
• Volker Middel,
• Masanari Takamiya,
• Uwe Strähle,
• Igor V. Komarov and
• Anne S. Ulrich

Beilstein J. Org. Chem. 2020, 16, 39–49, doi:10.3762/bjoc.16.6

• initially handled as ring-open photoforms under ambient (visual, vis) light conditions. Each of the ring-open photoforms was converted into the ring-closed photoforms by UV irradiation in a solution of denaturing agents, reproducing previously documented results [29][30][52]. All studied compounds were

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• . Photoisomerization UV irradiation was performed by placing a 365 nm LED (897-LZ440U610; LED Engin) operating at 68 mW/cm2 above the sample tube for 1 minute. For blue light irradiation, a 440 nm LED (Luxeon III Star LED Royal Blue Lambertian; Luxeon Star LEDs) operating at 40 mW/cm2 at 700 mA was used in the