Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• the borylation reaction (see above). Photochromism of naphthylnorbornadiene 6b The photoisomerization reaction of substrate 5b was monitored by absorption spectroscopy (Figure 1) and by 1H NMR-spectroscopic analysis (see Supporting Information File 1, Figure S51). In MeCN solution, norbornadiene 5b

• exhibits the lowest-energy maximum at 305 nm, which is comparable to the reported absorption spectra of known naphthyl-substituted norbornadiene derivatives [36][37]. Irradiation of 5b at 315 nm leads to a decrease of the absorption band with simultaneous formation of a blue-shifted maximum at 292 nm

• overlap of its absorption with the one of the norbornadiene. However, upon heating to 60 °C in MeCN solution the norbornadiene was regained after 25 h, as shown by photometric monitoring of the reaction (Scheme 3 and Figure 1, inset). These photochemical properties are comparable to the ones of literature

Glycosylated coumarins, flavonoids, lignans and phenylpropanoids from Wikstroemia nutans and their biological activities

• Meifang Wu,
• Xiangdong Su,
• Yichuang Wu,
• Yuanjing Luo,
• Ying Guo and
• Yongbo Xue

Beilstein J. Org. Chem. 2022, 18, 200–207, doi:10.3762/bjoc.18.23

• absorption bands at 325 and 293 nm indicated the presence of a coumarin-type chromophore. The IR spectrum of 1 demonstrated absorption bands characteristic for an hydroxy group (3266 cm−1), α,β-unsaturated carbonyl group (1739 and 1701 cm−1), and an aromatic ring (1624 and 1457 cm−1). The 1H NMR spectrum of

Multi-faceted reactivity of N-fluorobenzenesulfonimide (NFSI) under mechanochemical conditions: fluorination, fluorodemethylation, sulfonylation, and amidation reactions

• José G. Hernández,
• Karen J. Ardila-Fierro,
• Dajana Barišić and
• Hervé Geneste

Beilstein J. Org. Chem. 2022, 18, 182–189, doi:10.3762/bjoc.18.20

• reaction gave a mixture of 2c'', 2c', and 2c in a ratio of 79:16:5 vs a ratio of 80:12:7 in the absence of SiO2 (Scheme 2a). Moreover, the presence of SiO2 improved the absorption of reactants and rendered a reaction mixture physically more appropriate for the milling process, which in turn enabled a

Tenacibactins K–M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum

• Yasuhiro Igarashi,
• Yiwei Ge,
• Tao Zhou,
• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku and
• Agus Trianto

Beilstein J. Org. Chem. 2022, 18, 110–119, doi:10.3762/bjoc.18.12

• three different seawater-based media, and butanolic extracts of the fermented cultures were subjected to HPLC/DAD analysis, which detected several unknown metabolites not present in our in-house UV database, showing UV end-absorption in the culture extract of A11M seawater medium. Purification of these

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• structural assignment of regiospecific compound 4a was readily deduced via detailed spectral data analysis. The IR spectrum of 4a contained characteristic absorption bands such as 1723 (C=O, ester), and 1687 (C=O, Boc) cm−1. The 1H NMR spectrum of compound 4a revealed a characteristic resonance for the Boc

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• , analysis of the structural diversity of the two isomers of P5 indicates that P5 cis (P5.1) is more disordered (see Supporting Information File 1, Table S3), which also correlates with a blue-shifted absorption minimum compared to P5 trans (P5.2). In the partially helical structures of aAxWt (i.e., second

Unsaturated fatty acids and a prenylated tryptophan derivative from a rare actinomycete of the genus Couchioplanes

• Shun Saito,
• Kanji Indo,
• Naoya Oku,
• Hisayuki Komaki,
• Masashi Kawasaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2939–2949, doi:10.3762/bjoc.17.203

• determined to be C10H16O2 on the basis of its NMR and HR–ESI–TOFMS data (m/z 191.1044 [M + Na]+, Δ + 0.1 mmu). Three degrees of unsaturation, calculated from the molecular formula, a UV absorption maximum at 264 nm, and IR absorption bands at 1679 and 2800–3200 cm−1, suggested dienone and hydroxy

• molecular formula was determined to be C18H22N2O3 based on its NMR and HR–ESI–TOFMS data (m/z 313.1556 [M – H]–, Δ – 0.2 mmu), corresponding to nine degrees of unsaturation. The UV spectrum, exhibiting the absorption maxima at 229 and 282 nm, was typical of an indole functionality. The IR absorption bands

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

• coefficients of absorption and high ΦPL [15][16][17][18]. This led to OLEDs employing dual or multi emitter-designed compounds to show much improved EQEmax compared to devices with their single-emitter counterparts (Figure 1), albeit with a red-shifted emission [16][17][18][19]. The advantages of the dual

• stabilized compared to that predicted from DFT (EHOMO: −5.03 eV); however, the less positive oxidation potentials in DICzTRZ versus ICzTRZ does align with the predictions obtained by DFT. The UV–vis absorption spectrum of DICzTRZ, while slightly red-shifted and with higher molar absorptivity (as was the case

• similar to those associated with ICzTRZ. The two absorption bands located between 330 and 350 nm are ascribed to the LE transitions within the diindolocarbazole donor. The two lower energy and lower absorptivity bands at 390 nm and 410 nm are both assigned to CT-type transitions (Figure 4b

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• ] and CPE was investigated using UV–vis spectroscopy utilizing the molar ratio and Job's method under neutral conditions (Figure 3). Figure 3A shows that CPE has a strong absorption peak at λ = 278 nm and the absorption intensity gradually decreases after the continuous addition of Q[8]. When n(Q[8])/n

• (CPE) = 1:1, the absorbance exhibits an obvious turning point and further increasing the concentration of Q[8] does not change the absorption of the system. The spectrogram determined using Job's method is shown in Figure 3B. When n(Q[8])/[n(Q[8]) + n(CPE)] = 0.5, the maximum value of ΔA appears

• variation of the UV absorption intensity of CPE and CPE@Q[8] over time in simulated gastric juice (pH 1.2). Figure 7B shows the relationship between the UV absorption intensity of CPE and its inclusion complex in artificial intestinal fluid (pH 6.8) with time. The results show that CPE itself has high

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• the series of compounds 3aa–fa and 3bb–be was carried out using chloroform (CHCl3), methanol (MeOH) or dimethyl sulfoxide (DMSO) solutions. As comparison, the UV–vis absorption spectra of compounds 3ea and 3be, which contain the nitro group in two different ring positions of the molecules recorded in

• the three solvents are depicted in Figure 3. The values of maximum molar absorption coefficients (in log ε) and wavelengths (nm) of all compounds are listed in Table 1. The absorption spectra of the studied Schiff base series presented electronic transitions in the 250–500 nm UV–vis region. In the

• the imine portion of the molecule. In comparison to the absorption spectra of aminoquinolines published by Kappenberg and co-workers [14], the Schiff bases studied here show similar absorption behavior, making it clear that these transitions originate mainly from the substituents (NH2, CF3, and R

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• Finnigan LTQ FT Ultra Fourier Transform Ion Cyclotron Resonance device at 250 °C for ESI. IR spectra were recorded on a Perkin Elmer FT-IR Paragon 1000 instrument as neat materials. Absorption bands were reported in wave numbers (cm−1), obtained on a ATR PRO450-S accessory (Jasco). Melting points were

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

• by blood and has high absorption speed and uptake values, this would mean the cryogel works well for blood clotting purposes. Overall, it was tested against gelatin sponges and traditional gauze which it outperformed. Figure 9 shows the results of Zhao et al. in vivo experimentation. The

• promotion of cell proliferation [117]. The tannic acid and ferric ions provide photothermal properties whereby under near infrared (NIR) radiation the temperature increased to enhance the antimicrobial properties, while also showing good hemostasis properties such as blood absorption and clotting, and cell

• proliferation. Chitosan has also been used by Meena et al. for producing cryogels for haemostatic applications, with locust bean gum (LBG) incorporated to enhance mechanical properties and water absorption [32]. This chitosan/LBG semi-interpenetrating network cryogel was investigated for its swelling

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

• ; however, they suffer from relatively poor photostability [14][15][16]. Transition-metal-photoredox catalysts, such as ruthenium and iridium polypyridyl complexes, exhibit high redox potentials, long excited state lifetimes, and strong absorption [17][18][19][20]. However, high cost and their scarcity

• homolysis to produce CuI species and radical intermediates. These intermediates can initiate productive organic transformations [39]. 2.1 Visible-light-mediated Cu(I) catalytic cycle Upon the absorption of a photon (Scheme 4), CuILn forms a singlet MLCT state, which subsequently yields the excited triplet

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• catalytic efficiency due to their low absorption characteristics and require complicated synthetic procedures. In this respect, it is worth to mention that elemental 2D materials with a proper bandgap and charge mobilities have been shown to act as photocatalysts in several reactions [34][35]. Exfoliated

• absorption, and novel electronic band structure, fills the gap between graphene and wide bandgap semiconductors [35][38]. Furthermore, BP shows a layer thickness tunable bandgap ranging between 0.3 and 2.1 eV. Therefore, BPNs can efficiently be applied as a photoredox catalyst with broadband solar absorption

• [40]. BPNs were tested as NIR photoinitiator for the CuAAC reactions of low molar mass compounds and polymers possessing antagonist azide and alkyne functionalities (Figure 1). The optical absorption spectra of BPNs, copper(I) chloride (CuICl, 0.05 mmol) and copper(II) chloride (CuIICl2, 0.05 mmol

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• /bjoc.17.162 Abstract A facile synthesis of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridine derivatives is reported which is based on POCl3-mediated cyclodehydration followed by double Suzuki–Miyaura cross-coupling. The absorption and fluorescence properties of the obtained products were investigated and

• trifluoromethoxy group (OCF3), a longer reaction time of 6 hours was required to obtain the product 4c in decreased yield (57%). Photophysical properties. We studied the steady-state absorption and emission of selected tetrahydroacridines 4a–d to gain insights into their photophysical properties. The UV–vis

• absorption spectra were measured in diluted dichloromethane solutions (c = 1 × 10−5 M) at room temperature. Table 2 summarizes the obtained spectral data, fluorescence quantum yields, stokes shifts, and optical band gap energies. As shown in Figure 2, most of the compounds show a broad band at around 320–360

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• through oxidative quenching of the excited substrate. While an excited state of 1 could react in a similar fashion, the absorption maximum of 1 is centered around 280 nm, which is outside the emission spectrum of green LEDs. A recent study by Hashmi et al. [44], however, shed a completely different light

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• non-specific protein absorption. Su et al. [40] investigated the effects of a protein corona on active and passive targeting using 20 different types of PEGylated gold nanoparticles, which were decorated with cyclic RGD (arginylglycylaspartic acid) peptides. As a result, the active targeting

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

• Luiz Claudio Ferreira Pimentel,
• Lucas Villas Boas Hoelz,
• Henayle Fernandes Canzian,
• Frederico Silva Castelo Branco,
• Andressa Paula de Oliveira,
• Vinicius Rangel Campos,
• Floriano Paes Silva Júnior,
• Rafael Ferreira Dantas,
• Jackson Antônio Lamounier Camargos Resende,
• Anna Claudia Cunha,
• Nubia Boechat and
• Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

• spectra, which are present in intermediates 5 and 9, respectively, and compounds 2a–j showed carbonyl absorption at 1671–1660 cm−1 (amide). 1H NMR spectrum analysis showed the appearance of a single signal at 8.52 ppm and between 8.61–7.79 ppm referring to the hydrogen of the 1,2,3-triazole (C-5) for

• radiation (λ = 0.71073 Å) at 298 K. Data collection, cell refinement, and data reduction were performed with Bruker Instrument Service v4.2.2, APEX2 [40] and SAINT [41], respectively. Absorption correction using equivalent reflections was performed with the SADABS program [35]. The structure solutions and

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

• , cyclopentanes, and n-pentane. The proposed catalytic cycle is initiated by the absorption of light by xanthone PC 21-I to get excited (Figure 21) [136]. The excited ketone PC undergoes a HAT process with the benzylic C–H substrate to generate a pair of ketyl radical 21-IV and benzylic radical 21-III. At the

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• similar to those for the tetronic acid bearing an exo-methylene substituent in known natural products [16][17][18]. Secondly, the UV spectrum of 3, showing absorption maxima at 243 and 302 nm, was matched well with that for ecteinamycin, which possesses the exo-methylene-substituted tetronic acid moiety

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

• of polymerization of ≈7) leaving speculation about a higher degree of polymerization for the THF-insoluble component of PAZ-Br2. The UV–vis spectrum of the chloroform-soluble fraction of PAZ-Br2 displayed absorption bands in the 190–330 nm region like the azulene monomer, and a long tail with a broad

• the azulene units in 1,3-polyazulene 5. The robustness of the 1,3-polyazulene backbone was evidenced by TG analysis where it retained over 60% of its mass even after heating to 1000 °C. The absorption spectrum recorded in chloroform revealed a considerable red shift in the absorption band of 1,3

• -polyazulene 5 (417 nm) compared to azulene (1, 341 nm) supporting the presence of extended conjugation prevailing in the polymer. The absorption and EPR spectral patterns of 1,3-polyazulene 5 recorded in TFA and H2SO4 were contrasting to each other inferring the varied degree of protonation caused by these

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• be obtained with a reaction yield ranging from 85% to 95% (see Scheme 5). It has to be noticed that this strategy has previously been reported in the literature [17][18]. Light absorption properties of the different NIR dyes The light absorption properties of the different proposed dyes are depicted

• in Figure 1. They are characterized by a sharp and intense absorption band in the NIR range. Remarkably, absorption of most of the dyes is excellent in the 700–850 nm spectral range, ensuring fairly good overlap with the emission spectrum of the laser diode used in this work (i.e., LD@785 nm

• ). Interestingly, no effect of the counter anion was observed (some of the dyes with two different counter ions were prepared and compared). In each case, we observed that the maximum absorption wavelength depends on the structure of the dye and not of the counter anion: i) λmax = 798 nm for CBPh1 and CI1; ii

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• enhance the pharmacokinetic properties of lead candidates in drug research through the improvement in lipophilicity, absorption, distribution, hydrophobicity and metabolism. Considering the high importance of organofluorine chemistry and that of fluoroalkyl groups in pharmaceutical chemistry, a wide range

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• electron-rich benzylic position, rationalizing the involvement of electrophilic metallonitrene intermediate 18A. Manganese-catalyzed late-stage C–H methylation The incorporation of methyl groups has the potential to manipulate absorption, distribution, metabolism, and excretion (ADME), solubility, and