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

• cyclic voltammogram of 1. (B) Cyclic voltammograms of 1 in the presence of additives (AcOH or HFIP). (C) Comparison of oxidation potentials of 1 using Bu4NOAc or Bu4NCl. (D) Cyclic voltammograms for the cathodic side. All cyclic voltammograms were recorded in CH2Cl2/Bu4NPF6 (0.1 M). Sample concentration

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

• and straightforward as it is usually considered. Keywords: concentration; glycosylation; protecting groups; reactivity; sialic acids; stereoselectivity; Introduction Glycoconjugates containing sialic acid occur on the surface of all cell types in a variety of organisms. They participate in a broad

• ]. As in other glycosylation reactions [22][23][24][25][26][27][28][29], the result of sialylation is affected by a variety of variables [30][31][32][33][34][35][36][37][38][39] including the nature of protective groups on either partner [26][38][40][41][42][43][44][45] and concentration of reagents [31

• affect the outcome of glycosylation [31][33][34][37][39][43][44][46][56][57], one must choose a concentration at which to perform the test glycosylation. This can be done either by analogy with similar reactions or by utilizing some rationalization, the second approach is more attractive. For the

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• large excess of HF·Py (40 equiv) proved to be necessary to remove the bulky silyl group. After concentration, the crude product was acetylated (Ac2O/Py, 1:2, v/v), furnishing per-acetylated compound 8 in a 53% yield over the 3 steps. Deacetylation of 8 with freshly prepared 1 M NaOMe/MeOH in MeOH at pH

• cell. Samples were prepared at the concentration (g/100 mL) in the solvent indicated. Deprotected glycans were lyophilised using a freeze-dryer Alpha 1-2 LDplus (Christ Ltd): pressure: 0.055 mbar; ice-condenser temperature: −55 °C. 2-[2-(2-Azidoethoxy)ethoxy]ethyl 3-O-acetyl-2-deoxy-4,6-O-di-tert

• hours. Filtration followed by concentration and lyophilisation of the filtrate yielded 2 as a pale-yellow foam (972 mg, 66%). Rf = 0.3 (EtOAc/MeOH, 3:2); [α]D +76 (c 1.0, H2O); 1H NMR (500 MHz, D2O) δ 4.95 (d, J = 3.8 Hz, 1H, H-1GalNAc), 4.62 (d, J = 7.9 Hz, 1H, H-1Gal), 4.41–4.31 (m, 4H, H-2GalNAc, H

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

• results in the formation of a 6,6-dicyano-heteropentafulvene derivative 37 as an additional byproduct along with the typical TCBD adduct 4 (Scheme 14) [117]. The yields and formation ratios of 4 and 37 depend on the type and concentration of the surfactant employed. For instance, when the nonionic

• surfactant, Brij 30, was used as the reaction solvent at a concentration of 20 mM, exceeding the critical micelle concentration, 4 and 37 were obtained in a ratio of 53:47, with 64% yield. Notably, 37 exhibits instability in silica gel and polar solvents. In particular, when 37 is kept in ethyl acetate or

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

• comparison with control experiments without photosensitizer. In general, a photoinduced DNA damage by the quinolizinium 3f was observed, whose extent increased with increasing irradiation time and with increasing concentration of 3f. Thus, after 2 min of irradiation with fixed concentration (c = 2.5 × 10−5 M

• ) 38% of the supercoiled DNA were transformed to the open-circular form, whereas after 5 min, 73% of the DNA were damaged by strand cleavage (Table 2A). At the same time, experiments with varying ligand concentration revealed 81% of damaged DNA after 2 min of irradiation with c = 5.0 × 10−5 M, which

• -electrophoretic analysis of photoinduced DNA-strand cleavage in the presence of 3f depending on the irradiation time (A), on the concentration (B), and in the presence of 3c,e–g (C). Lanes 1, 10 and 11 (A) and lane 11 (B): control experiment without 3f. Lanes 1 and 2 (B): control experiment without 3f, irradiated

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

• coefficient, c is the concentration of a light-absorbing solute, and d is the optical path length. Figure 8 shows the measured absorbance as function of the photocatalyst loadings in the methanol/water solution using different optical path lengths. The absorbance depends linearly on the photocatalyst

• 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

• photon flux density, c0 is the photocatalyst concentration, and kr is the recombination rate. The linear correlation between reaction rate and photon flux visible in Figure 12b indicates that the system is still in regime 1 and the hydrogen generation rate is limited by the available photon flux, even

Preparing a liquid crystalline dispersion of carbon nanotubes with high aspect ratio

• Keiko Kojima,
• Nodoka Kosugi,
• Hirokuni Jintoku,
• Kazufumi Kobashi and
• Toshiya Okazaki

Beilstein J. Org. Chem. 2024, 20, 52–58, doi:10.3762/bjoc.20.7

• dispersion is likely composed mostly of isolated DWCNTs. To investigate the liquid crystal behavior, the DWCNT dispersion was concentrated by ultra-filtration (Figure 2a). As the concentration of DWCNTs increased, the isotropic phases (Figure 2d, the DWCNT concentration = 0.078 vol %) changed to the nematic

• phase (Figure 2b, the DWCNT concentration = 0.41 vol %). At intermediate concentrations, biphasic states appeared where the nematic droplets, tactoid, coexisted in the isotropic phase (Figure 2c, the DWCNT concentration = 0.16 vol %) [15][17][22][23][29][30]. The nematic phase shows disturbed textures

• obtained values for the SWCNT-SC dispersions (L/D = 1088 and = 665, black symbols) [22][23]. The Onsager theory predicts that the phase transition concentration for rod-like particles with aspect ratio L/D is ϕiso~bip = 3.34 D/L and ϕbip~nem = 4.49 D/L [24]. The L/D dependence of each phase transition

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

• study was performed by monitoring the appearance of the zwitterion absorption by means of UV–vis spectroscopy in chloroform or in methanol as the solvent. The concentration of the respective Michael acceptor was varied ([Michael acceptor] = 2.5 mmol/L to 10 mmol/L) and was at least ten-fold higher than

• the concentration of the phosphine 1 ([1] = 0.25 mmol/L) to obtain pseudo first-order kinetics. Figure 4 shows typical time vs conversion plots for an initial Michael acceptor concentration of 7.5 mmol/L. Time conversion plots were then evaluated using COPASI [47]. To obtain second-order rate

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• tighter and more adaptable aromatic–aromatic stacking interactions. The aliphatic amphiphile sodium dodecyl sulfate (SDS) showed a 10-times lower efficiency compared to PA-Im under the same conditions (Figure S38 in Supporting Information File 1). The concentration of C60 in the solution of (PA-Im)n·(C60

• showed broad, featureless absorption bands, with a characteristic small peak at ≈580 nm for the E22 transition only in the case of the s-CNT host–guest composite (Figure 4f,g) [24]. The concentration of GN in the aqueous solution of (PA-OCH3)n·(GN)m was estimated to be ≈0.03 mg mL−1. Amphiphile PA-OCH3

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• cells within the concentration range. This indicates the low cytotoxicity of these compounds. Meanwhile, compounds 3m,l are characterized by a borderline inhibition of cell culture viability. Attention is drawn to the increased toxic effect of 3m on cells of tumor origin, in comparison with normal human

Identification of the p-coumaric acid biosynthetic gene cluster in Kutzneria albida: insights into the diazotization-dependent deamination pathway

• Seiji Kawai,
• Akito Yamada,
• Yohei Katsuyama and
• Yasuo Ohnishi

Beilstein J. Org. Chem. 2024, 20, 1–11, doi:10.3762/bjoc.20.1

• OD600 reached 0.8. After the culture was cooled on ice for 30 min, isopropyl β-ᴅ-thiogalactopyranoside (IPTG) was added to the culture (for CmaA1 and CmaA3 expression, final concentration was 100 µM; for CmaA6 expression, IPTG was not added) and incubated with shaking (150 rpm) at 15 °C for 20 h. Cells

• µL of 4.0 µM AvaA7 (final concentration: 0.2 µM) and 5.0 µM of different concentrations of NADPH or NADH (final concentration: 25–800 µM) were added to the reaction mixture (final reaction volume: 100 µL). The initial velocity of the reaction catalyzed by AvaA7 was estimated by monitoring the

• decrease in absorbance at 435 nm for 3-DAA using a SpectraMax M2 microplate reader (Molecular Devices, San Jose, CA, USA). The kinetic parameters (Vmax, kcat, and Km) were calculated by fitting the substrate concentration [S]–initial velocity (v) plot using the equation v = Vmax × [S] / (Km + [S]). To

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

• many radicals [28][29][30][31]. The reaction is substantially accelerated by UV excitation at 365 nm; quantitative conversion of benzyl bromide at low initial concentration (3 mM) can be achieved within 1 h using both (N-DMBI)2 or (Cyc-DMBI)2 and UV (Table 1, entries 3 and 6), while even at higher

• -normalized initial reaction rate (d([RX]/dt)0/[D2]0) as a function of the initial benzyl bromide concentration ([RX]0) obtained from several experiments of the type shown in part (a) for different [D2] and [RX] for both D2 = (Cyc-DMBI)2 and (N-DMBI)2. For these slow reactions, the “initial” rates were

• estimated from the change of substrate concentration over the first 30 min reaction time. Top: UV–vis absorption spectra for the two dimeric reductants in THF emphasizing (a) the different positions of the relatively strong absorption peaks and (b) the presence of a low-energy shoulder in the spectrum of (N

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

• . By using these solvents, we aimed to investigate and visualize the charge transfer nature of the organic compounds under study through their spectra. To prepare the films, we used a spin-coating method by using a high-concentration THF solution (2 mg/mL). To study the phosphorescence spectra of Me

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

• @C2v-C82 anion with 1a. 110 °C, 2 h. (b) La@C2v-C82 with 1a. 110 °C, 2 h. (c) La@C2v-C82 anion with 1a. hv > 350 nm, 1 h. (d) La@C2v-C82 with 1a. hv > 350 nm, 1 h. Black line is the HPLC profiles of La@C2V-C82 at the same concentration as the reaction. Reaction mixtures with La@C2v-C82 anions were

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• -quinolone-3-carboxamides 5a–i and some of their N-hydroxy derivatives 4a–e. Compounds of this type with C-2 substitution other than methyl [71] have not been previously described. All of the obtained products were screened for antimicrobial activity at a concentration of 1 mg/mL against S. aureus and E

• . coli, using the hole-plate method in Mueller–Hinton agar, with 100 µg loading of each compound in 100 µL DMSO (Table 6). Interestingly, at this concentration most of the compounds showed weak to moderate activity against E. coli, while S. aureus was inhibited only by C5 and C7-substituted analogs

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

• concentration of this greenhouse gas by upcycling. Selectivity towards CO2-reduction products is highly desirable, although it can be challenging to achieve since the metal-hydrides formation is sometimes favored and leads to H2 evolution. In this work, we designed a cobalt-based catalyst, and we present herein

• Supporting Information File 1). The redox properties of 1 were investigated using cyclic voltammetry in a DMA solution with 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte (Table 1). The concentration of the analyte was 5 mM. Only the cathodic scan resulted in a rich

• possible. In some cases, this metal hydride favors the production of formate [51]. However, it may induce the concomitant formation of H2. This might have been the case of the photo-driven catalysis by complex 1 in DMA/TEOA (Table 2, entries 2–4), where upon decreasing the concentration of TEOA down to

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• Dolzhenko’s conditions (4 equivalents of N2H4·H2O, concentration of 4 = 0.5 mmol/mL, reflux, 2 h) [40]. The resulting precipitate was isolated by filtration and washed with EtOH. In contrast to the reported data, the yield of the obtained product was significantly lower and did not exceed 38%. Moreover

• varying promoter, its amount, solvent, substrate concentration, and reaction time (Table 1). First, we studied the dimerization of 8 promoted by hydrazine hydrate in EtOH under reflux (Table 1, entries 1–3). We found that the starting material was completely consumed in the presence of 3 equivalents of

• (25 mL) and petroleum ether (50 mL), and 1 time with a mixture of ether (10 mL) and petroleum ether (20 mL) at room temperature. The extraction was considered as completed when the brown oil solidified. The product precipitated upon concentration of the combined extracts under reduced pressure. The

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

• dichloromethane at 1 mg mL−1 concentration. Molecular absorption spectroscopy Molecular absorption spectra were recorded on Agilent Cary 100 conc UV–visible spectrophotometer between the range of 200 and 800 nm in quartz cuvettes. Stock solutions of the compounds were prepared in spectroscopic grade DMSO at 5

• were used to calculate the percentage decrease in concentration of the compound with respect to the first reading and data were processed using the OriginPro 21 software. X-ray diffraction Single crystals of hdz-CH3 and hdz-NO2 suitable for X-ray diffraction were obtained from the slow evaporation of

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

• , whereby the dimer is in equilibrium with a small concentration of the corresponding odd-electron monomer, which can then rapidly react with an acceptor such as an organic semiconductor (SC) through an exergonic electron transfer (ET), has been observed for the reactions of several relatively weakly bonded

• . Furthermore, the ordering of ET-first rates (1h2 > 1g2 > 1b2 > 1e2, that for 1e2 being estimated by extrapolating previously reported parameters to the present conditions of temperature and concentration) reflecting the trend expected based on the E(12•+/12) values of Table 1. It is worth noting that

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• cast from a solution at a concentration of 1 mg/mL in ethyl acetate, where a concentration of 1 mg/mL was used due to CN-PDIN-FB exhibiting a maximum solubility of 1.2 mg/mL (see below). The PDIN-B film has the highest absorbance of 0.037 at its λmax of 535 nm for the 0 → 0 transition and an onset of

• filter. The absorbance of each saturated solution was measured with a UV–visible spectrophotometer to determine the concentration using the Beer–Lambert law and the previously determined molar extinction coefficients. PDIN-FB reached a saturated solution at a concentration at 8.4 mg/mL, PDIN-B a

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• revealed that compound 7 was cytotoxic to RAW 264.7 cells at concentrations above 25 μM (Figure 6d). Furthermore, 7 suppressed the LPS-induced increases in IL-1β and IL-6 transcriptional levels in a concentration-dependent manner from 1 or 2.5 μM (Figure 6e). Thus, while cytotoxicity was likely involved in

• -stimulated increase in IL-1β and IL-6 production was suppressed by compound 7 at a concentration of 10 μM (Figure 6f and 6g). Thus, compound 7 inhibited LPS-stimulated IL-1β and IL-6 mRNA and protein expression in RAW 264.7 cells. Although confirmed only at the mRNA level, 1, 2, and 6 likely exhibit similar

• appropriate concentrations by dissolving in DMSO and diluting 1000-fold in medium. RAW 264.7 cells were preincubated with fresh medium containing test samples or vehicle (DMSO) for 24 h. After preincubation, LPS was added at a final concentration of 50 ng/mL. qRT-PCR analysis Total RNA was extracted using

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• consists of a bundle of disc-tipped acellular thread called byssus, which connect the mussel to the surfaces of substrates [10]. A family of proteins called mussel foot proteins (mfp’s) distribute throughout the whole length of byssus while there is an extremely high concentration of mfp’s at the plaque

• assumption of a steady state with respect to the concentration of chain carriers (radicals) [17]. Radical polymerization is a complex mechanism. The basic reactions have been known for quite some time now. They can be simply described by 8 equations (Equations 1–8) as follows. In the equations, I2 represents

• radical concentration in the latex is greatly higher than in a typical bulk polymerization. Meanwhile, the polymerization rate is higher in emulsion polymerization compared to bulk or suspension polymerization. Radicals are divided in different particles also allows for longer lifetimes, which results in

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• monitored following the release of SRB with time. The results demonstrated that the CDs effect on the membrane depends on the CD type, CD concentration, and membrane CHOL content. The investigated CDs exhibited an instantaneous permeabilizing effect promoting vesicle leakage of SRB from the various

• membranes; this effect increased with CDs concentration. Among the studied CDs, α-CD, β-CD, and RAMEB were the most permeabilizing CDs on the different membranes. Similar modifications of SRB release from the various liposomal formulations were obtained with HP-β-CD, CRYSMEB, and SBE-β-CD. γ-CD was the less

• the effect of the CD concentration on the SRB release for a specific membrane composition, while the horizontal reading of the tables highlights the impact of CHOL content on the permeability of membranes at various intervals of time. The SRB release kinetics for blank liposomes (untreated with CDs

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• the amount of LiHMDS used versus the yields of the product formed. Other bases, such as Cs2CO3 or K3PO4, resulted in slightly lower yields (Table 1, entries 17–19). Without any base or catalyst, the reaction yield was much lower (20%, Table 1, entry 21). A further screen of the concentration of the

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• concentration. HMF was then directly used in the Knoevenagel condensation with rhodanine in Pro/Gly yielding product 3j in 72% yield. The overall yield for this two-step process was 36%. As some of the products have already been described in the literature, we compared our results with the reported conditions

• same protocol as described by Molnar et al. [43] where DPPH and the synthesized compounds were tested in a solution at 0.2 mM concentration in DMSO as solvent. Because phenolic compounds can be easily oxidized to quinones, it is well known that most hydroxylated compounds have antioxidant properties

• solution of the corresponding synthesized compound (1.5 mL, 0.2 mM) was added to a DMSO solution of DPPH radicals (1.5 mL, 0.2 mM), so that the final concentration of DPPH radical and the synthesized compound in a solution was 0.1 mM. The mixture was shaken and allowed to stand at room temperature. After