Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• catalytic amount of I2 under an aerated condition. After the photolysis, the acetal moiety was partly cleaved to produce a mixture of acetal 9 and aldehyde 10. The obtained reaction mixture was treated with TsOH in acetone to afford desired fluorinated phenanthrenecarbaldehyde 10 in moderate yield (46% from

• compounds, F8PIC and F8FUL, were obtained through the Wittig-reaction and Mallory-photoreaction sequence (Scheme 2). Thus, reactions between phosphonium salt 5 and specific aldehydes, 10 and 13, followed by photolysis in the presence of I2 and O2, respectively, afforded F8PIC (57%) and F8FUL (52%). F87PHEN

Giese-type alkylation of dehydroalanine derivatives via silane-mediated alkyl bromide activation

• Perry van der Heide,
• Michele Retini,
• Fabiola Fanini,
• Giovanni Piersanti,
• Francesco Secci,
• Daniele Mazzarella,
• Timothy Noël and
• Alberto Luridiana

Beilstein J. Org. Chem. 2024, 20, 3274–3280, doi:10.3762/bjoc.20.271

• photocatalyst (Figure 1d) [25]. Noël et al. [26] have further extended this approach to include alkyl bromides (Figure 1e) [26]. Despite the effectiveness of the photolysis, benzophenone derivatives have also been shown to enhance the productivity of silane-mediated conjugate additions, using alkyl halides [27

• (N); state-of-the-art: (c) silane-mediated alkylation initiated by a photocatalyst, (d) silane-mediated alkylation initiated by photolysis of alkyl iodides, (e) silane-mediated alkylation initiated by photolysis of alkyl bromides in flow; this work: silane-mediated alkylation of Dha derivatives

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• particular, this system shows a high energy storage capacity of up to 1 MJ/kg, and the energy can be conveniently released in form of heat by controlled photolysis, thermolysis, or catalysis [8][14]. However, the parent norbornadiene (1a) only absorbs ultraviolet light, which is of limited availability in

Visible-light-mediated flow protocol for Achmatowicz rearrangement

• Joachyutharayalu Oja,
• Sanjeev Kumar and
• Srihari Pabbaraja

Beilstein J. Org. Chem. 2024, 20, 2493–2499, doi:10.3762/bjoc.20.213

• developed by Guan-Ben Du et al. [14]. Very often, the photolysis reactions performed in batch process encounter issues that include ineffective illumination, improper mixing, prolonged reaction durations, low quantum efficiency and mass transfer, a limited surface-to-volume ratio, along with an inadequate

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• -phase photolysis at −80 °C from 1,2-difluoroethylene and diazomethane (Scheme 19). Unfortunately, the product yield was not reported. Diels–Alder reaction of (E)- and (Z)-1,2-difluoroethylenes with hexachlorocyclopentadiene was studied by Ihrid and Smith [99]. It was shown that (Z)-1,2-difluoroethylene

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• thorough photochemical characterization is essential for efficient light-driven applications. In this article, the mode of action of a polyazahelicene catalyst (Aza-H) was investigated using laser flash photolysis (LFP). The study revealed that the chromophore can function as a singlet-state photoredox

• mechanism of the recently reported sulfonylation/arylation [45][46] reaction using laser flash photolysis (LFP). LFP is a powerful spectroscopic tool in photocatalysis that allows us not only to distinguish between energy and electron transfer but also to detect transient triplet states and radicals

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• solution of Dip2Si(SiMe3) as a silylene precursor and C60 in toluene was irradiated by a 125-W low-pressure mercury lamp in a quartz tube for 2 h (Scheme 1). During reaction, the color of the solution turned to dark brown. After the photolysis, the bis-silylene adduct 3 was isolated in 36% yield

• period of 200 ms, and a scan rate of 50 mV/s. Synthesis of 3. A degassed solution of Dip2Si(SiMe3) (30 mg) and C60 (4.6 mg) in toluene (20 mL) in a quartz tube was irradiated by a 125-W low-pressure mercury lamp for 2 h [15]. After the photolysis, 2 (22% yield) and 3 (36% yield) were isolated by flash

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• positions (Equation 3). In the context of the radical process, it is noteworthy that a standard household LED lamp can serve as an efficient initiator, capable of triggering bromine photolysis (Equation 3, top) [45]. Hence, no oxidant-derived residues apart from water are formed and, at the end of the

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• “overall quantum yield” is used in Table 1 [29]. The formation of the short-lived E-isomer was earlier observed only in vitrified solvents at 77 K or under flash photolysis conditions [14]. As such, the parameters of the thermal acyl migration under steady-state irradiation conditions were not determined

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• precursor, recovery of the target π-CPC is possible via a cheletropic decarbonylation step upon photolysis or thermolysis (Scheme 1, bottom right). This dual activation mode has led to the solid-state formation, on a preparative scale, of higher acenes up to nonacene [28][29][30][31][32][33] and

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• the flash photolysis by a ruby laser (λ = 694 nm) in combination with photostationary methods [41]. The data on the absorption maxima, decay times, and extinction coefficients for Z-11a and Z-12 obtained in these measurements significantly differed from those reported by Pummerer and Marondel [40]. In

• photolysis in combination with steady-state measurements [59]. It was found that the E–Z photoisomerization of 9a, 9d, 9g, 9h occurred through a singlet mechanism upon direct excitation. However, the triplet state could be achieved by a sensitized reaction. At room temperature, a transient species that could

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• the plausible energy transfer from the local charge-separated (CS) state of the push–pull chromophore (namely N,N-diethylanilino (DEA)•+–TCBD•−) to the singlet excited state of C60 (1C60*). In transient absorption spectral measurements conducted via the femtosecond laser-flash photolysis of compound

• measuring the charge-separation and charge-recombination lifetimes of these molecules by laser-flash photolysis (excitation wavelength = 420 nm) and the resulting electron-transfer rates were plotted. In the measurements in toluene, the lifetimes of the CS states and charge-recombination events differed

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• . PPh3-catalyzed alkylative iododecarboxylation with LiI. Visible-light-triggered iodination facilitated by N-heterocyclic carbenes. Visible-light-induced photolysis of phosphonium iodide salts for monofluoromethylation. Funding This work was financially supported by the Central University Basic

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• achieved (Scheme 1), showing that photolysis of stoichiometric Cu(II) chloride in the presence of unactivated alkenes allows for direct formation of vicinal dichloride products. The mechanistic study implicated initial formation of a chlorine radical through homolysis of a Cu–Cl bond via ligand-to-metal

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• intrinsic decay rate of *PC1. Since no quenching by 1d or B2pin2 could be observed, the formation of PC1•− can be attributed exclusively to the thermodynamically favored reductive quenching of *PC1 by DBU. Nanosecond laser flash photolysis techniques were employed to directly monitor the back electron

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• photolysis spectrometer (Edinburgh Instruments, Ltd., U.K.). The data (kinetic decay traces and the transient difference absorption spectra) were analyzed with the L900 software. All samples were deaerated with N2 for ca. 15 min before measurement and excited with a nanosecond pulsed laser (OPO nanosecond

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• or by photolysis of pyrazolines bearing difluoromethylphosphonate moieties (Scheme 1C) [35][36][37][38]. Notably, among the various CF2-containing functionalities, difluoromethylphosphonates represent a distinct class of compounds whose potential as nonhydrolyzable phosphate mimics is unquestionable

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• recorded on a LP920 laser flash photolysis spectrometer (Edinburgh Instruments, Ltd., U.K.). The data (kinetic decay traces and the transient difference absorption spectra) were analyzed with the L900 software. All samples were deaerated with N2 for ca. 15 min in collinear configuration of the pump and

High-speed C–H chlorination of ethylene carbonate using a new photoflow setup

• Takayoshi Kasakado,
• Takahide Fukuyama,
• Tomohiro Nakagawa,
• Shinji Taguchi and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2022, 18, 152–158, doi:10.3762/bjoc.18.16

• quite low (0.12 mL/min of toluene), the residence time was less than 14 seconds. More recent studies on flow C–H chlorination reactions focused on the use of Cl2 gas in situ generated by photolysis of sulfuryl chloride [10] or by acid treatment of NaOCl [11][12]. We thought that if rationally designed

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• addition experiment with methyl acrylate (Supporting Information File 1, Table S5), along with the strong dependence of aryl bromide electronics on the yield indicate the protagonism of the nickel-aryl bromide system. We hypothesized a HAT step by the bromine radical, generated by nickel complex photolysis

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

• photolysis of DTBP producing an alkyl radical, which reacted with nitrogen-containing compounds to give the target products 63. The catalytic cycle involves a photoinduced copperII peroxide system with an in situ-generated CuII–N complex as the key catalytic species. In 2020, Anandhan’s group [98] developed

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

• oxidation of 4-V by the photoexcited iridium(III) photocatalyst 4-II results in the nickel(III) species 4-VI. Photolysis of 4-VI generates a chloride radical, which rapidly abstracts the α-oxy C(sp3)−H of the ether to provide the alkyl radical species. The alkyl radical rebound to 4-VIII produces the nickel

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• •−. Photolysis of the CeIV–OBn complex (II), leads to the formation of the corresponding benzyloxy radical (III) and regenerates the CeIII species. A further abstraction of a benzylic hydrogen atom by the peroxide radical then generates the final product 2 [48]. However, at this moment we cannot exclude the

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

• alcohols with HBr, PBr3, or other brominating reagents [7][8][9][10][11][12][13]. Direct C–H halogenation is one of the most efficient methods used for the synthesis of halogenated organic molecules. This direct method involves the reaction of an alkane with Br2, CBr4, or H2O2–HBr under photolysis or at

[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

• chromatography (HPLC) (methanol/toluene as the eluent) to isolate a reddish-brown powder of methanofullerene 3 in 21% yield (Scheme 4). Similar to photolysis, the thermal rearrangement of kinetic products gives [6,6]-closed isomers that are thermodynamically more stable. After some time, the team of scientists

• % yield [100]. Photolysis of derivatives of para-substituted 3-fluoromethyl-3-phenyldiazirones in the presence of C60 gave phenylmethanofullerenes 53–56 in acceptable yields (Scheme 17) [101]. The electrochemical properties of the products were characterized by cyclic voltammetry and differential pulse

• fullerene based on diazo compounds allows us to state the following: An alternative to the synthesis of methanofullerenes by the Bingel methodology is provided by the thermal [2 + 1] cycloaddition of diazo compounds to the fullerene. Then follows the photolysis or thermolysis of pyrazoline intermediates by