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

• extinction coefficient, Δε455(Rubpy*) = −10100 M−1 cm−1 [37][79], following excitation (Figure 4B). 0.3 mM methyl viologen (MV2+) were added to Aza-H to quantitatively quench the triplet-excited photocatalyst in an electron transfer reaction yielding Aza-H•+ and MV•+, which are clearly observed in the TA

• the reliability of our procedure. Taking the literature-known extinction coefficient of the methyl viologen radical cation Δε395(MV•+) ≈ 39000 M−1 cm−1 [82] to calculate its concentration and the initial Aza-H excited-state concentration obtained through Rubpy* actinometry allows us to determine the

• (distance 6 cm) was used as the excitation light source. D) Irradiation experiments of (E)-stilbene (blue) and (Z)-stilbene (red) with 2 mol % Aza-H employing a 427 nm LED as light source. E) Schematic energy diagram of triplet sensitized E/Z isomerization of stilbene. F) Reaction scheme of the cyclization

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• benzenoid→quinonoid excitonic transitions, respectively, which was characteristic of polyaniline existing as emeraldine free base [41][42]. The polyaniline nature was further confirmed by FTIR spectroscopy (Figure S2, Supporting Information File 1). The broad peak observed in the range of 3300–3400 cm−1 was

• due to N–H stretching of the polymer [43][44]. The peak appearing at around 3000 cm−1 corresponded to the aryl C–H stretching. The peaks observed at 1593 and 1479 cm−1 were associated with C=C and C=N stretching, respectively. The obtained result was further supported by solid-state synthesis of

• , 1282, 1073, 820, 752 cm−1. N1,N2-Diphenyloxalamide (3): Colorless solid (2.6 mg, 0.22%); mp 231–232 °C; 1H NMR (500 MHz, CDCl3, δ) 9.36 (s, 2H), 7.70 (d, J = 7.9 Hz, 4H), 7.44 (t, J = 7.8 Hz, 4H), 7.25 (t, J = 7.5 Hz, 2H); HRESIMS (m/z): [M + CH3COOH + H]+ calcd for C16H17N2O4, 301.1183; found

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• the stable CM• radical through electron paramagnetic resonance. Based on previous studies of cofactor-independent oxygenases and our results, we propose a radical-mediated catalytic mechanism for the cofactor-independent AlpJ-family oxygenases (Scheme 2). The catalytic cascade was initiated by

Synthesis of 1,4-azaphosphinine nucleosides and evaluation as inhibitors of human cytidine deaminase and APOBEC3A

• Maksim V. Kvach,
• Stefan Harjes,
• Harikrishnan M. Kurup,
• Geoffrey B. Jameson,
• Elena Harjes and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2024, 20, 1088–1098, doi:10.3762/bjoc.20.96

• anomers with a α/β ratio of 2:1, as determined by 1H and 13C NMR. Deprotected nucleosides Va and Vb but not Vc exhibited absorbance in the UV region with ε258 = 4230 L⋅mol−1⋅cm−1 and ε262 = 4730 L⋅mol−1⋅cm−1, respectively. This was most likely a result of the presence of a double bond next to the P=O unit

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

• ), solvent (either CH2Cl2 or chlorobenzene, 1.0–4.0 mL), H2O (1.5 mL), and HBr (48 wt % aqueous solution, d = 1.49 g/mL, 1.25 mL, 11 mmol, 2.2 equiv) were inserted. The mixture was kept under stirring at rt and irradiated with a LED lightbulb placed at 10 cm from the side of the reaction tube. Aqueous H2O2

• at rt, H2O (3.6 mL) and HBr (48 wt % aqueous solution, 3.00 mL, 26.5 mmol, 2.2 equiv) were inserted. The mixture was then irradiated with a LED lightbulb, placed at 10 cm from the side of the flask and aqueous H2O2 (35 wt % solution, 4.8 mL, 56 mmol, 4.7 equiv) was added over 2 h using a syringe pump

• mixture was kept under stirring at rt and irradiated with a LED lightbulb placed at 10 cm from the side of the reaction tube. Aqueous H2O2 (35 wt % solution, 3.0 mL, 23.3 mmol, 4.7 equiv) was added over 2 h using a syringe pump, through a small PTFE tube inserted through the side arm of the Schlenk. After

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• 40 μM solutions of the DCPQs and DPQDs on a Cary 100 Bio spectrophotometer using 1 cm quartz cells. All solvents were HPLC grade (purchased from Fisher) and stored over 4 Å molecular sieves. The absorption intensity at λmax was then plotted against the concentration in all cases to confirm, by

Spin and charge interactions between nanographene host and ferrocene

• Akira Suzuki,
• Yuya Miyake,
• Ryoga Shibata and
• Kazuyuki Takai

Beilstein J. Org. Chem. 2024, 20, 1011–1019, doi:10.3762/bjoc.20.89

• Evolution instruments (Horiba) with an excitation laser operated at 532 nm in the wavenumber range from 1000 to 2000 cm−1. FTIR spectra were obtained using an FT/IR-6600 (JASCO) in ATR method with a diamond prism. Magnetic susceptibility measurements were carried out by a superconducting quantum

• significant influences by nanographene domains. The Raman spectra for both ACFs and FeCp2–ACFs-150 shown in Figure 4 exhibit two broad peaks near 1350 and 1600 cm−1. The peak around 1600 cm−1 corresponds to the Raman-allowed E2g mode (G-band) in graphene. The D-band peak around 1350 cm−1 is forbidden in ideal

• graphene crystals but becomes Raman-active by an electron-scattering process due to impurities and edges in crystallites [29]. The G and D-bands were fitted with two Lorentzian curves, as shown in Figure 4. Although characteristic peaks of FeCp2 molecules around 1100 cm−1 are not obtained in the spectrum

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• appears to have the opposite effect, as 5m demonstrates. Although it was expected that this would result in a higher absorption intensity, a drastic reduction in the intensity was observed. The extinction coefficient of 5m (8766 M−1 cm−1) was rather low compared to 5d. Furthermore, the substitution of a π

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• spectra of porphyrins 2 and 3 exhibit the absorption band at 3321 cm−1 corresponded to NН stretching vibrations. Bands at 2127 cm−1 confirmed the presence of the N3 group in porphyrins 2 and 7. The IR spectra of porphyrins 5–7, 11, 12, 14, 18–20, 23, 24, and 26 exhibit absorption bands at 2605–2609 cm−1

• assigned to the BH-stretching vibration in neutral closo-carborane polyhedra and the bands at 3061–3069 cm−1 related to carborane CH groups. All prepared porphyrins 2, 3, 5–7, 11, 12, 14, 18–20, 23, 24, and 26 had the characteristic bands at ν = 1466–1499 cm−1 assigned to C–F stretching vibrations. Bands

• in the 1797–1641 cm−1 range in porphyrins 11, 12, and 14 correspond to the displacement of the C=O group. In the 1H NMR spectra eight β-protons of the porphyrin macrocycle for all compounds 2, 3, 5–7, 11, 12, 14, 18–20, 23, 24, and 26 were found between δ = 8.94–9.39 ppm and broadened singlets of the

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• , MeOH); UV (MeOH) λmax, nm (log ε): 281 (2.27), 270 (2.96), 260 (2.40); ECD (100 μg/mL; MeOH), λmax, nm (Δε): 226 (−0.31), 274 (−0.76), 282 (−0.96); IR (neat): 3443, 2965, 2925, 2896, 1646, 1457, 1086 cm−1; HRESIMS (m/z): [M + Na]+ calcd for C44H66O15Na+, 857.4294; found, 857.4294. In vitro

A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• only two sharp CO stretching frequencies were observed in the IR (Scheme 2) and so a value for Tolman’s electronic parameter (TEP) could be estimated. [33] At TEP[Ir] = 2053.1 cm−1 and 2052.8 cm−1 for 15a and 15b, respectively, the values for these AImOx ligands are towards the electron-deficient end

• seen with imidazolidines (cf. for IPr TEP[Ir] = 2050.2 cm−1) [34]. A benchmarking exercise was then performed looking at the reactivity of 13 compared against reaction of symmetrical IPrAuCl across a range of known gold-mediated transformations of alkynes featuring intermolecular attack [35

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• isolation of compound 3 (2.19 mg). Physical and spectroscopic data of compounds 1–3 Shentonin A (1): light green solid; [α]D20 +40.0 (c 0.17, CH3OH); UV (CH3OH) λmax, nm (log ε): 400 (3.45), 240 (4.24) nm; IR (KBr) νmax: 3347, 2960, 2926, 1688, 1654, 1612, 1260, 1078, 1021, 797 cm−1; for 1H NMR (CDCl3, 600

• , 981, 914, 742 cm−1; for 1H NMR (CDCl3, 600 MHz) and 13C NMR (CDCl3, 125 MHz) spectral data, see Table 1; HRESIMS (m/z): [M − H]− calcd for 311.1765; found, 311.1755. Compound 3: transparent oily liquid; [α]D20 −46.7 (c 0.18, CH3OH); IR (KBr) νmax: 3432, 2960, 2923, 1762, 1450, 1260, 1180, 1016, 800 cm

A myo-inositol dehydrogenase involved in aminocyclitol biosynthesis of hygromycin A

• Michael O. Akintubosun and
• Melanie A. Higgins

Beilstein J. Org. Chem. 2024, 20, 589–596, doi:10.3762/bjoc.20.51

• coefficient 33,460 M−1 cm−1 and 38,350 M−1 cm−1 for Hyg17 and BsIDH, respectively [29]. Protein was flash frozen in liquid nitrogen at 100 μM in 20 mM Tris pH 8, 50 mM NaCl, and 10% glycerol and stored at −80 °C for biochemical assays. Enzyme assays Generally, 100 μL reactions contained 10 mM inositol

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

• vibrations of the thiophene and amide carbonyl groups were observed at 1663–1678 and 1705–1713 cm−1, respectively. The 1H NMR spectra contained signals of methine protons (=CH–) in the region 7.92–9.02 ppm, which corresponded to the Z-configuration of the C=C bond. According to data previously obtained [14

• solutions (in a quartz cell, l = 1 cm) were irradiated with filtered light from a high-pressure Hg lamp on a Newport 66941 equipment supplied with a set of interference light filters. The light intensity was 6.4 × 1016 photons⋅s−1 for the 436 nm spectral line. (Z)-N-((3-Oxobenzo[b]thiophen-2(3H)-ylidene

• cells (l = 1 cm, V = 2 mL). Fluorescence quantum yields were determined relatively to (Z)-N-((3-oxobenzo[b]thiophen-2(3H)-ylidene)methyl)-N-phenylacetamide as a standard (φfl = 0.16 ± 0.005) [14][33]. Stock solutions of compounds 2a–c (c 1.0 × 10–4 mol⋅L−1) and metal perchlorates (c 2.0 × 10–4 mol⋅L−1

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• preparative HPLC of the crude extract, 7.9 mg of 1 was obtained (Scheme 1). Table S1 (Supporting Information File 1) shows the physicochemical properties of 1, which is a yellow oil soluble in MeOH and DMSO. The UV absorption maximum of 1 was at 286 nm (ε = 10238 M−1·cm−1). The molecular formula of 1 was

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

• Zhen Ying,
• Xiao-Ming Li,
• Sui-Qun Yang,
• Hong-Lei Li,
• Xin Li,
• Bin-Gui Wang and
• Ling-Hong Meng

Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42

• CC on silica gel eluting with a CH2Cl2/MeOH gradient (from 200:1 to 100:1) and then by preparative TLC (plate: 20 × 20 cm, developing solvents: ether/acetone 2:1) to afford compound 4 (8.6 mg). Fr. 5.4 (538 mg) was separated by CC on Si gel and Sephadex LH-20 (MeOH), after that compounds 1 (12.5 mg

• –6.10). Then, compound 2 (13.7 mg) was isolated by CC on Si gel (CH2Cl2/MeOH, 250:1 to 50:1) and preparative TLC (plate: 20 × 20 cm, developing solvent: ether/acetone 2:1) from Fr. 6.3 (578 mg). Pseudallene A (1): colorless crystals (MeOH); mp 115–117 °C; [α]D25 +20.0 (c 0.4, MeOH); 1H and 13C NMR data

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• higher-boiling heptane. In this case, the desired product was isolated by double distillation at 7 °C in 50% yield and >90% purity and was fully characterized by 1H, 19F, 13C NMR and IR spectra. The presence of a characteristic band at 2038 cm−1 in the IR spectrum confirmed the allene structure of

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

• (31), is formed between the nitro and imino groups of the N-aryl ring. The compounds 4a–h intensely absorb light in the spectral range of 400–550 nm, with maxima at 439–459 nm, ε = 20600–37100 M−1⋅cm−1 (Figure 3 and Table 1). The introduction of an amino group into the p-position of the N-phenyl

• 6a,b) and c = 2⋅10−6 M (compound 10c) in toluene solutions with a Varian Cary Eclipse fluorescence spectrophotometer. UV–vis and fluorescence spectra were recorded using standard 1 cm quartz cells at room temperature. Toluene of spectroscopic grade (Aldrich) was used to prepare the solutions. The

• , Supporting Information File 1. Thermal ellipsoids are drawn at the 50% probability level. UV–vis spectra of 6,8-di-tert-butyl-2-(arylamino)-3H-phenoxazin-3-ones 4a–h (toluene, c = 2⋅10−5 M, l = 1 cm, T = 293 K). Molecular structure of ethyl 2,4-di-tert-butyl-14H-quinoxalino[2,3-b]phenoxazine-10-carboxylate

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

• of 5 mA (3 F/mol, 57.9 C) through the CF anode (1 × 1 cm) and the Pt cathode (1 × 1 cm). The reaction mixture was concentrated in vacuo and Et2O (20 mL) was added. The resulting precipitate was removed by filtration through a short silica gel pad under reduced pressure. The filtrate was concentrated

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

• . Structures of indigo derivatives discussed in this review. Photoswitching of N,N'-diacetylindigo (9a) in CCl4 (c = 17.1 µM; cell length = 5.0 cm) irradiated with blue light (λirr = 350–510 nm): dotted line; irradiated with white light: dashed line; irradiated with yellow light (λirr > 495 nm): solid line

Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N,N-diacyl-β-amino esters

• Youlong Du,
• Haibo Mei,
• Ata Makarem,
• Ramin Javahershenas,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2024, 20, 212–219, doi:10.3762/bjoc.20.21

• . Stirring was continued at room temperature for 2.5 h and the solvent was removed in vacuum. Products 4 were purified on a TLC plate of 20 cm × 20 cm using petroleum ether/ethyl acetate 7:1 (v/v) as eluent. Mumm-type rearrangement of diazo compounds. Substrate scope study of this Cu-catalyzed reaction

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• rotation values were measured with a PU-07 automatic digital polarimeter (Russia) at 28 °C in a jacketed glass cell (10 cm length). Special precautions were made to ensure the stability of the instrument and the temperature within the measuring compartment of the instrument and the cell, which was

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

• -recombination processes were found to be located in the Marcus inverted region. The total reorganization energies and electronic coupling matrix elements estimated from the fitting of the Marcus curve were determined to be 0.66–0.79 eV and 13.9–30.9 cm−1, respectively. Using a molecular design similar to that

Electron-beam-promoted fullerene dimerization in nanotubes: insights from DFT computations

• Laura Abella,
• Gerard Novell-Leruth,
• Josep M. Ricart,
• Josep M. Poblet and
• Antonio Rodríguez-Fortea

Beilstein J. Org. Chem. 2024, 20, 92–100, doi:10.3762/bjoc.20.10

• negligible imaginary frequencies (under 10 cm−1). The projected density of states was calculated and own code estimated the bands that belong to fullerene or SWCNT. The excited states of the fullerene dimer inside the SWCNT were studied with a single-point energy calculation of a given band structure where

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

• concentration for low concentrations, which agrees with the Beer–Lambert law [33][34]. An extinction coefficient of 3.5 L g−1 cm−1 was determined by fitting the experimental data. The deviation of the absorbance from the linear relation is attributed to increased scattering at high loadings and/or long optical

• paths, where consequently the requirements for the application of the Beer–Lambert law are not fulfilled anymore. Considering the inner diameter of the loop reactor of 5 cm, a catalyst loading of 0.11 g L−1 is sufficient to absorb more than 95% of the photons. Photocatalytic hydrogen evolution Long-term

• manufactured from 2 mm thick borosilicate glass with a total height of 40 cm. Borosilicate glass was chosen as the reactor body material based on the following reasons: (1) the transmission of borosilicate glass at UV range is already over 90%, (2) borosilicate glass is easier to work with for manufacturing