Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• groups corresponding to the two methyls derived from bisalkyne 1a and the methyl in the tosyl group in the spectrum (Figure 4). These results indicate that there are three regioisomers found in a ratio of 56:29:15. Two of them result from the oxidation of α-2a, whose lack of symmetry results in two

Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• radical acceptor moieties. Therefore, we investigated the origin of this selectivity under electrochemical conditions. Results and Discussion Anodic oxidation of uridine derivative 1 was performed in a CH2Cl2/Bu4NPF6 (0.1 M) electrolyte system using a carbon felt (CF) anode and a Pt cathode in the

• -alkylation, whereas the use of AcOH provided N-alkylated product 3 (Table 1, entries 5 and 6). When acetonitrile (MeCN) was used as the solvent, cyclized dimer 4 was obtained (Table 1, entry 7). Next, 1 was subjected to cyclic voltammetry (CV) measurements under varying conditions (Figure 2). An oxidation

• wave was observed at approximately +1.4 V (Figure 2A). The oxidation current of this wave decreased significantly in the presence of a phosphate base and the subsequent addition of HFIP enhanced this phenomenon (Figure 2B, grey line). In contrast, using AcOH instead of HFIP did not affect the oxidation

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• decided to carry out its oxidation to 12 by the traditional method – the action of chloranil in boiling benzene or chloroform (in the latter, the solubility of the components is somewhat better, although the temperature of the process decreases). At the end of the synthesis, the reaction mass was treated

• with a potassium hydroxide solution, and the oxidation product was isolated by chromatography. Nitroacenaphthylene 13 can also be obtained similarly (Scheme 5). Thus, although nitro groups usually hinder the dehydrogenation of acenaphthenes, in our case, the opposite trend is observed. We believe that

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

• incorporating redox-active tetrathiafulvalene (TTF) residues (Figure 7), known for their ability to form intramolecular π-dimers upon two-electron oxidation [47]. Thus, upon irradiation of the oxidized molecule 24 with 660 nm light, the thermal half-life of the Z-isomer exhibited a significant increase

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

• exemplified by the emergence of a maximum absorption peak at 1,024 nm, indicating the one-electron reduced form of C60. Although the observation of the oxidation process of the ferrocene unit was obstructed by the more substantial absorption changes associated with fullerene reduction, the lifetimes of the

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• an electron-withdrawing functional moiety into drug molecules would increase their metabolic stability [20], by avoiding, e.g., fast oxidation by cytochrome P450 oxidases [21]. In particular, the introduction of a trifluoromethyl group (–CF3) was shown to increase the metabolic stability of molecules

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

• formation of different intermediates in the reaction sequence starting with E–Z isomerization, followed by photocyclization and subsequent oxidation. In general, the photoreaction was more efficient in polar, protic aqueous solvents (cf. Supporting Information File 1, Figures S2B–S6B) or in buffer solution

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• ) processes, and photocatalysis. Upon upscaling, both PV-E and PEC reactors exhibit pH gradients at electrodes and elevated solution electrical resistivity. These challenges arise from the substantial separation between reduction and oxidation sites, alongside mass transport restrictions in the liquid phase

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

• indenofluorene (IF) or fluorene cores and containing various dithiafulvene (DTF) donor units that gain aromaticity upon oxidation and a variety of acceptor units, such as vinylic diesters, enediynes, and cross-conjugated radiaannulenes (RAs) that gain aromaticity upon reduction. In some cases, the DTF units are

• change significantly when comparing IF-DTFs 10 and 11, indicating that the extent to which the absorption changes upon oxidation from a dihydropyrrole to a pyrrole unit depends on the substituent on the N of the dihydropyrrole/pyrrole ring. Introducing the diester electron-acceptor in compound 15 does

• stronger electron withdrawing vinylic diester renders the first oxidation more difficult (by 40 mV). An anodic shift of 40 mV was also observed for the second oxidation. Oppositely, compound 15 underwent a significantly easier first reduction than 11 (−1.00 V vs −1.35 V), and it also underwent a second

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• reaction [11][12]. Recently, our working group has investigated electron-rich triarylphosphines [13][14][15] as viable alternatives to alkylphosphines, which often suffer from their pronounced susceptibility to oxidation. In this regard, we wanted to explore hydroxy-substituted arylphosphines as potential

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• -heterocyclic carbenes (NHCs), extensively studied as organocatalysts as well as ligands for transition-metal-promoted synthetic methodologies [97][98][99]. Under anodic oxidation, the electrogeneration of boron trifluoride (BF3) from tetrafluoroborate ILs occurs [100][101]. Moreover, we have recently

• the 19F NMR analysis of BMIm-BF4 after anodic oxidation in a divided cell, which shows a peak at −147.3 ppm (besides the peak at −150.6 due to BF4−) (see Supporting Information File 1, Figure S1e), which is replaced by a peak at −144.0 ppm (referred to −150.6 ppm for BF4−) when the electrolysis is

• was set at −150.6 ppm in 19F NMR spectrum [112]. We thus carried out the anodic oxidation of pure BMIm-BF4 (divided cell, galvanostatic conditions) and stopped the electrolysis after 60 C (corresponding to 0.6 mmol of electrons). At the end of the electrolysis, 0.6 mmol of DIPEA were added to the

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• competitive. In the case of (Cyc-DMBI)2, the second-order rate constant, kET, is estimated as 6.0 × 10−3 M−1 s−1, whereas for (N-DMBI)2, kcl = 4.7 × 10−5 s−1 and kET = 1.0 × 10−2 M−1s−1. The difference in kET values is qualitatively consistent with the peak oxidation potentials, Epa(D2•+/D2), of the two

• depopulations of the bibenzoimidazole-based HOMO, which, as well as π-character also has significant C–σ-bonding character associated with the inter-monomer bond, suggesting that excitation should weaken the bond (in a similar way to oxidation associated with removal of an electron from the same orbital). To

• between D2 and D• oxidation potentials). Debromination of benzyl bromide (1a). Dehalogenation of various benzyl, alkyl, and aryl halides using (N-DMBI)2 (or, in parentheses Cyc-DMBI)2.a Supporting Information Supporting Information File 18: Synthetic and other experimental procedures, additional data

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• acenes exhibit increased reactivity, readily undergoing processes of oxidation and dimerization, consequently disrupting the molecular conjugation [4]. This instability poses a significant obstacle in their widespread application across various devices [4]. The decline in stability seen in larger acenes

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• monomer 22 much less significantly. With less electron-deficient NDIs carrying two sulfide donors in the core, the catalytic activity of 45 dropped below that of fullerene monomer 22. Oxidation of the sulfide donors into sulfoxide acceptors increased the catalytic activity much less than expected, resting

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• using ferrocene (Fc) as inner standard. The CV curves are shown in Figure 6 and the data are collected in Table 1. The reduction onset potentials (Ered,onset) of compounds 6–9 fall in the range from −1.63 to −1.47 V, while the onset values of the first oxidation wave range from 1.02 to 1.09 V. The

• values of Ered,onset are comparable with those of recently published compounds containing a dicyanopyridyl moiety as a central electron-accepting core [7]. In case of oxidation potentials (0.96 to 1.04 V) there is only a slight effect of the extended conjugation between the dicyanopyridyl moieties. The

• under a nitrogen atmosphere. TGA allows us to observe the weight changes of the samples as a function of temperature, providing valuable insights into processes such as decomposition, volatilization, and oxidation. In the case of DSC measurements, the samples were heated at a rate of 10 °C/min in a

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• structure is described as La3+C823−. We previously investigated the reaction of M@C2v-C82 ions (M = Y, La, Ce) with disilirane, which possesses high reactivity toward electron acceptors [16][17]. Interestingly, the reactivity of M@C2v-C82 toward disilirane was increased by the one-electron oxidation of M

• @C2v-C82. Moreover, the reaction was suppressed by the one-electron reduction of M@C2v-C82. These results suggest that oxidation and reduction reactions are useful for tuning the reactivity of metallofullerenes. Recently, remarkable reactivity of [M3N@Ih-C80]2− (M = Lu, Sc) toward benzal bromide was

Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• intermediates II or III, at rt form hexaphyrinogen and the subsequent oxidation gives A4B2-hexaphyrin. Similarly, [3 + 1] reactions of intermediates I and II or I and III provide the formation of porphyrinogen and their oxidation gives A3B-porphyrin as indicated in route II. The presence of starting material 1

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

• hydrogenation or hydrogen transfer [40], electrocatalysis coupled with water oxidation [41], and sustained visible-light-induced photocatalysis [42]. Among the different strategies available, the use of a mild photocatalytic process involving hole-driven hydrogen transfer with hydrogen donors or hole scavengers

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

• ), while a reductive quenching by BIH could be possible since the oxidation potential of BIH is 0.27 V (ΔG < −0.25 V). We performed Stern–Volmer analyses to verify our hypothesis. As expected, the lifetime of the PS* (τ0 = 14 ns in aerated DMA/TEA 7:1), is reduced upon the addition of the sacrificial

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• oxidation/cyclization with NXS or Cu(OAc)2. Notably, some of the resultant CF3-substituted 1,6-dihydropyridazines exhibited aggregation-induced emission [102][103] (Scheme 16). The hydrocyanation of acylhydrazones is an important method for the preparation of α-hyrazino acids. Hu et al. reported a Lewis

• . [3 + 2] Cycloadditions of difluoromethylated hydrazonoyl halides. Preparation and early applications of trifluoromethylated acylhydrazones. 1,2-Nucleophilic addition reactions of trifluoromethylated acylhydrazones. Cascade oxidation/cyclization reactions of trifluoromethylated homoallylic

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• first to establish the suitability of N-acylhydrazones as novel metallophores able to affect protein aggregation and/or oxidation enhanced by physiological metal–protein anomalous interactions related to Alzheimer's (AD) and Parkinson's (PD), as well as to prion diseases [27][28][29][30][31][32][33][34

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• -phenylindoloquinoxaline (PhIQ) derivatives, shown in Figure 6 as Qx50 series, by chemically modifying the PhIQ groups. In particular, substituents at the 2- and 3-positions of PhIQs were introduced, allowing regulation of the reduction–oxidation potentials of the compounds. The PhIQs exhibited fluorescent solvatochromism

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• optoelectronic devices. The electrochemical behavior of TPECNz was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2 containing 0.1 M n-Bu4NPF6 as a supporting electrolyte. As illustrated in Figure 5b, the molecule shows multiple quasi-reversible oxidation and reduction

• behavior in the potential window from −1.5 eV to 2.0 eV. The reduction wave appeared at a half-wave potential (E1/2) of −1.26 eV assigned to the reduction of an electron-deficient Nz core as observed in the calculated LUMO orbital [39]. The first oxidation wave occurred at E1/2 of 1.05 eV and was ascribed

• to the oxidation of the π-conjugated backbone along the Nz core and end-capped carbazole moieties as seen in the computed HOMO orbital, while the second oxidation wave at E1/2 of 1.47 eV was attributed to the oxidation of the π-conjugated TPE–carbazole fragment as depicted in the calculated HOMO−1

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• condenses with the aldehyde but where the subsequent second condensation and oxidation does not take place, i.e., structures of type IV (Scheme 1), which are known to be converted to benzimidazoles by various oxidants and/or catalysts [30][31][32]. The benzimidazoles were then doubly methylated with

• electrochemical section; however, the observed rate constants for 1bH and 1iH suggest that 5-dimethylamino-2-thienyl affords less net charge stabilization than 4-dimethylaminophenyl. Two reaction pathways have been established for the oxidation of organometallic and organic dimers. A “cleavage-first” mechanism

• dimeric dopants (the Y = metallocenyl DMBI dimers 1c2 and 1d2 as well as various organometallic dimers) with VII [14][46][61], as well as in the oxidation of bis(3,5,5-trimethyl-2-morpholinon-3-yl), 52 (Figure 2), by isatin derivatives [62]. In the alternative “ET-first” mechanism the first step is an

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• precursor for coordination compounds. The following transmetallation with cobalt(II) produced an intriguing Pacman-like coordination compound 16-Co(II) (Scheme 6) [66]. The spontaneous oxidation of cobalt(II) to cobalt(III) resulted in modifying the cobalt cation coordination sphere from a distorted-square

• ligands. Compound 19-Co (structure not shown) retained the cobalt(II) oxidation state with a water molecule within the cleft. The XRD analysis of the structures of 19-Co and 18b-Co exhibited Pacman conformation. The X-ray molecular structure of 19-Co provided further insights, showing a square-planar

• notable distinction as they could readily undergo oxidation to yield the corresponding crownphyrins 28–33, incorporating a dipyrrin unit. The synthetic pathway towards crownphyrins is straightforward and relies on a one-pot reaction between diformyldipyrromethane 20a/b and a diamine which introduces the