SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• ]. On the other hand, the nature of the alkene might be limited as it would strongly influence the oxidation potential of the carbon radical and the stability of the resulting carbocation. Recently, we reported the first successful application of an RPC strategy for the azido-alkynylation of styrenes

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• in the closed state splits the second oxidation of the porphyrins from a two-electron process to two single-electron processes. This is due to the electrostatic repulsion between the two positively charged complexes that shift the second oxidation potential. The absorption bands of the closed state

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• , Supporting Information File 1), 2-(arylamino)-3H-phenoxazin-3-ones 4a–h manifest two reduction waves at Е1/2RED1 = −1.36 ± 1.69 V and Е1/2RED2 = −1.85 ± 2.12 V. Oxidation of 4a–f,h occurs as an irreversible process at Е1/2OX = 0.81–1.07 V. For 4g bearing an amino group, the oxidation potential is shifted to

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

• (Figure 2B, blue line). However, in the presence of AcOH, the N-alkylation yield was low (Table 1, entry 6) owing to the competitive Kolbe oxidation of the cathodically generated acetate anion. In fact, the oxidation potential of Bu4NOAc is lower than that of 1 (Figure 2C, orange line). A decrease in the

• affect the oxidation current. In cathodic events, the reduction of CH2Cl2 primally occurred under standard conditions because the reduction wave of the blank solution appeared at approximately −1.0 V (Figure 2D, blue line). The resulting cathodically generated chloride ion (Cl−) has a lower oxidation

• potential than 1 (Figure 2C, grey line); thus, it was subsequently oxidized on the anode to afford the halonium ion (Cl+), which can react with 1 to form unstable N−Cl species (B) in situ (Figure 4). Although we cannot detect the chlorinated intermediate of 1, electrolysis of N-propylcarbamate derivative

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

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• benzoguanidine moieties. This explains the ca. 0.2 eV more stabilized LUMO energy level for compound 4BGIPN compared with 4CzIPN. Both 4CzIPN and 4BGIPN exhibit an irreversible oxidation wave observed at +1.25 V for 4BGIPN in THF and +0.94 V for 4CzIPN in MeCN [15]. A higher oxidation potential (Ep) for 4BGIPN

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

• considered: solubility in the chosen solvent, absorption spectrum, oxidation potential, and the reversibility of the sacrificial donor oxidation. As the sacrificial donor is a reactant in the photoreduction reaction of carbon dioxide, it needs to be highly soluble in the solvent used. It also needs to have a

• low absorption in the visible region to prevent side reactions and allow the photosensitizer to absorb as much light as possible. The oxidation potential of the sacrificial electron donor must be less positive than the reduction potential of the excited or oxidized photosensitizer for quenching or

• photochemical carbon dioxide reduction research, this technique is used to measure the reduction potential of the oxidized photosensitizer and the oxidation potential of the electron donor. However, the reduction potential of the photoexcited photosensitizer is usually estimated using the Rehm–Weller equation

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

• -light photons [77]. In their previous work, the Polyzos group discovered the capability of [Ir1]+ to reduce diarylimines via SET in presence of Et3N albeit the large difference in the oxidation potential of [Ir1]0 (E1/2 = −1.47 V vs SCE) and the reduction potentials of imines (e.g., Epred = −2.18 V vs

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• shows the most positive oxidation potential and rate of the first oxidation as well as the lowest rate of reduction. However, the relatively small differences may simply be due to the different local solvation of the CF3 substituent. Conclusion Glaser–Hay homocoupling of 2-ethynyl-7-(arylethynyl)-1,8

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• chemical transformations. The oxidation potential value of the deprotonated glycine complex correlates with the reactivity of the α-carbanionic species towards electrophiles [37]. Therefore, the electrochemical approach is very convenient and informative for the estimation of the relative reactivity of the

• complexes derived from various chiral ligands. The oxidation potential can be determined from the voltammetry curve measured for the quantitatively deprotonated complex. The electrochemical deprotonation using an electro-generated base is the most convenient approach [37][44]. Comparison with the Eox values

• the original Belokon complexes) is prevented, thus opening a route to the targeted electrochemically induced oxidative modification of the amino acids side chain. Second, as follows from the comparison of the oxidation potential values, the reactivity of the deprotonated glycine complex towards

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

• protected tryptamine starting materials. The utilization of a chiral phosphate base is essential for the formation of a hydrogen bond between phosphate and tryptamines, allowing the decrease of the oxidation potential. This concept was used for the synthesis of pyrroloindoline natural products (Scheme 17

Comparison of crystal structure and DFT calculations of triferrocenyl trithiophosphite’s conformance

• Ruslan P. Shekurov,
• Mikhail N. Khrizanforov,
• Ilya A. Bezkishko,
• Tatiana P. Gerasimova,
• Almaz A. Zagidullin,
• Daut R. Islamov and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1499–1504, doi:10.3762/bjoc.18.157

• ferrocene moieties. It should be noted that the first oxidation potential is almost identical to free ferrocene [6]. Herein we report the crystal structure of triferrocenyl trithiophosphite. For triferrocenyl trithiophosphite a trans-gauche-gauche configuration with torsion angles of −34°, −40°, and 173

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• the HOMO energy of 1,2-diphosphaferrocenes 8. The number of phosphorus atoms in cyclopentadiene had a much greater effect on the shifts of the FeII/FeIII oxidation potential. As shown earlier, an increase in the number of phosphorus atoms led to the irreversible oxidation of phosphaferrocenes

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• . DiKTa possesses an oxidation potential of 1.66 V and an associated HOMO energy level of −5.93 eV. The reduction potentials, Ered, are −1.67 V and −1.61 V, respectively, for DiKTa-OBuIm and DiKTa-DPA-OBuIm. The corresponding LUMO levels are −3.13 eV and −3.18 eV for DiKTa-OBuIm and DiKTa-DPA-OBuIm

Synthesis of protected precursors of chitin oligosaccharides by electrochemical polyglycosylation of thioglycosides

• Md Azadur Rahman,
• Kana Kuroda,
• Hirofumi Endo,
• Norihiko Sasaki,
• Tomoaki Hamada,
• Hiraku Sakai and
• Toshiki Nokami

Beilstein J. Org. Chem. 2022, 18, 1133–1139, doi:10.3762/bjoc.18.117

• electrochemical polyglycosylation is also discussed, based on the oxidation potential of the monomer and oligosaccharides. Keywords: electrochemical glycosylation; glucosamine; oligosaccharide; oxidation potential; polyglycosylation; Introduction Chitin oligosaccharides are partial structures of chitin, which

• . Contrary, thioglycoside 1c (Ar = 4-MeC6H4, Eox = 1.47 V vs SCE), which had the lowest oxidation potential, showed the lowest conversion (51%) and the lowest yield of tetrasaccharide 4c (2%) [8]. This being the case, lower conversion of the building block 1c and lower yield of oligosaccharides 2c–4c

• indicated that thus-generated oligosaccharides 2c–4c, with a lower oxidation potential, also consumed electricity and converted to the corresponding hydroxy-substituted sugars, as observed by MS analysis. Thioglycoside 1d (Ar = 2,4-F2C6H3, Eox = 1.73 V vs SCE), which had the highest oxidation potential

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

• Yi-Lun Li,
• Zhaojiang Shi,
• Tao Shen and
• Ke-Yin Ye

Beilstein J. Org. Chem. 2022, 18, 1026–1031, doi:10.3762/bjoc.18.103

• oxidation of the isopropylbenzene moiety [31][36], which was consistent with its relative low oxidation potential (Eonset = 1.68 V vs Fc+/0). Other electron-donating substituents, such as the OMe (10–12), OPh (13), and OAc (14) were also well tolerated. However, halogenated substrates, including fluoro (15

Electrochemical and spectroscopic properties of twisted dibenzo[g,p]chrysene derivatives

• Tomoya Imai,
• Ryuhei Akasaka,
• Naruhiro Yoshida,
• Toru Amaya and
• Tetsuo Iwasawa

Beilstein J. Org. Chem. 2022, 18, 963–971, doi:10.3762/bjoc.18.96

• DBCs with MeO groups located at X and/or Y (MeO-DBC-1, MeO-DBC-2, and MeO-DBC-3, Figure 1b) [43]. The first oxidation potential (Eox1) of MeO-DBC-1 was reported to be 0.40 V (based on Fc/Fc+), which is 0.48 V lower than that of DBC. In contrast, when a MeO group is introduced at the X position (MeO-DBC

• -2), the Eox1 is lower by only 0.15 V than that of DBC. It has also been reported that the oxidation potential of MeO-DBC-3, in which the MeO groups are attached at both X and Y, is 0.06 V higher than that for MeO-DBC-1. These remarkable substituent effects are an interesting and important finding

• groups are introduced in place of the isopropyl groups, which has a 0.06 V higher oxidation potential than that of MeO-DBC-1. This indicates that alkyl substituents in the X position are effective in stabilizing the radical cation, thus making it more susceptible to oxidation. Unlike DBC-H, an

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• as the electrolyte and Fc/Fc+ as the internal reference, data are reported versus a saturated calomel electrode (SCE). In both DICzTRZ and ICzTRZ [14] we observed a reversible oxidation wave with respective oxidation potential (Eox) at 0.87 V and 0.96 V vs SCE (Figure 4a). Both compounds also present

• a second oxidation wave that is more prominent and cathodically shifted for DICzTRZ at 1.05 V, compared to 1.14 V for ICzTRZ. No reduction wave is observed for DICzTRZ. The HOMO value calculated from the oxidation potential obtained from differential pulse voltammetry (DPV), is −5.21 eV, which is

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• forms of monomer 24, dimer 29, and polyazulene 31 were further red-shifted and their respective energy gaps were also reduced compared to their neutral forms. The oxidation potential for the neutral (−0.23 V) and protonated forms of polyaminoazulene 31 (0.70 V) was significantly different unlike the

• and larger cathodic shift of the oxidation potential in these polymers compared to their metal-free counterparts. In 2012, Hawker and co-workers [22], along with 17–20, also synthesized a polymer 45 which had azulene and thiophene units connected via the 4,7-positions of azulene. The reaction of 4,7

• –144 containing azulene-carbazole-benzothiadiazole, with varying composition of N-alkyl carbazole and benzothiadiazole units by a Suzuki protocol (Scheme 24). These polymers exhibited Mn in the range 4200–7200 Da with PDI 1.14–1.38. The oxidation potential of the benzothiadiazole-containing polymers

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• formation of the corresponding phosphine oxide derivative as the only decomposition product was observed. The results, shown in Figure 3, reveal that the oxidation stability is decreasing in the order TPP > MMTPP > TMTPP, which is in line with electrochemical studies showing a decrease of the oxidation

• potential from 1.400 V (TPP) to 1.050 V (TMTPP) [35]. Furthermore, the share of phosphine oxide is dependent on the oxygen solubility in the solvent, as indicated by the experiments in chloroform and 1-hexanol exhibiting the higher oxygen solubility [36]. To obtain further insight, the SOMO energies of the

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• Information File 1. Parent compound 2 and borane complex 6 showed reversible reduction peaks (Ered = −1.25 and −1.26 V, respectively). Due to the increased electron–acceptor character of the phosphorus center, P-modification compounds 4 and 5 show a more positive oxidation potential than parent 2 [26

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

• ]helicene 12 was equal to 2.92 eV [42]. The Egopt values for its π-extended analogs were 2.45 eV (10a), 2.76 eV (10b) and 2.85 eV (10c), suggesting a higher HOMO and lower oxidation potential, which are typically desired characteristics when designing organic materials. Unfortunately, for all azine-fused [6

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• replacement of sulfur by nitrogen atoms in the tetra- and hexacyclic systems leads to a red-shift in absorption, a decrease in oxidation potential and energy gap. On the other hand, the replacement of a thiophene ring by benzene leads to the opposite effects. Keywords: Buchwald–Hartwig amination; Cadogan

• TTA, SN4 9, and SN4'' 33 irreversible oxidation waves were obtained due to follow-up reactions of the formed radical cations and peak potentials gradually decrease from 0.81 V for TTA to 0.07 V for SN4'' 33 (Figure 2, right). As expected, the oxidation potential is substantially influenced by the

• increasing number of electron-rich pyrrole rings and drops continuously. As expected, if an electron-rich fused thiophene ring in H-SN4 13 is replaced by a phenyl ring in 19, the oxidation potential is increased by 190 mV. The value for hexacyclic 22 (Epox1 = 0.33 V) is in the same regime than for H-SN4 13

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• TTFC7, respectively, in a DCE/CH3CN 1:1 solution has no significant effect on E1/2ox1 and E1/2ox2 (see Supporting Information File 1). However, an increase in the oxidation potential (ΔE1/2ox1 = +0.04 V) was observed for the A2·PF6@TTFC7 complex in pure DCE, which can be attributed to the increased

Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K₂S₂O₈

• Qiang Liu,
• Weibang Lu,
• Guanqun Xie and
• Xiaoxia Wang

Beilstein J. Org. Chem. 2020, 16, 1974–1982, doi:10.3762/bjoc.16.164

• obtained. Dimethylphosphine oxide (2k) did not participate in the reaction, likely due to its high oxidation potential and poor ability to undergo tautomerization [36]. To demonstrate the practicability of this methodology, a gram-scale experiment was next performed, employing 1b and 2a as substrates under