One-pot multicomponent green Hantzsch synthesis of 1,2-dihydropyridine derivatives with antiproliferative activity

• Giovanna Bosica,
• Kaylie Demanuele,
• José M. Padrón and
• Adrián Puerta

Beilstein J. Org. Chem. 2020, 16, 2862–2869, doi:10.3762/bjoc.16.235

• particularly positive effect. Since the presence of water was shown to be detrimental, the ammonium acetate (3) used was left to dry in a desiccator before use. Reaction monitoring was mostly done using thin-layer chromatography (TLC) and at times also GC. These techniques showed the occurrence of at least

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• innovative catch–release system with multiple functions combined the ON/OFF-adjustment of silver(I) catalysis and fluorescence monitoring [59]. Actually, the ratiometric luminescence response allowed the exact monitoring of the catalytic activity. In the initial incomplete self-sorting (state SelfSORT-I

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• presence of positive surface charges on the multivalent aggregates led to ATP binding which was accompanied by a significant increase in the excimeric emission intensity. This provided a convenient way of monitoring ATP binding in a “turn-on” mode and an efficient detection of ATP was achieved in aqueous

Activation of pentafluoropropane isomers at a nanoscopic aluminum chlorofluoride: hydrodefluorination versus dehydrofluorination

• Maëva-Charlotte Kervarec,
• Thomas Braun,
• Mike Ahrens and
• Erhard Kemnitz

Beilstein J. Org. Chem. 2020, 16, 2623–2635, doi:10.3762/bjoc.16.213

• =CHCH2C6D5 (9) and CF3CH=CHC6D5 (8, Scheme 11, middle). In neat silane, 5 and 6 were detected in a ratio of 1:4 (Scheme 11, bottom). Notably, for all conversions (C6D6 and silane, C6D12 and silane, or in neat silane), monitoring of the reaction by 19F NMR spectroscopy led to the observation of the early

Anion exchange resins in phosphate form as versatile carriers for the reactions catalyzed by nucleoside phosphorylases

• Julia N. Artsemyeva,
• Ekaterina A. Remeeva,
• Tatiana N. Buravskaya,
• Irina D. Konstantinova,
• Roman S. Esipov,
• Anatoly I. Miroshnikov,
• Natalia M. Litvinko and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2020, 16, 2607–2622, doi:10.3762/bjoc.16.212

• gently stirred at 47 °C for 48 h, with monitoring the product formation by HPLC. After 48 h, the conversion of the base into nucleoside reached equilibrium at 85% of the latter. The turbid (not reacted starting base according to TLC and barium phosphate) reaction mixture was filtered, the filtrate

• ; 1.2 mequiv/mL) in 15 mL of distilled water; pH 7.0), Ara-U (170 mg, 0.7 mmol) and MgCl2·6H2O (71 mg, 0.5 mmol of MgCl2 per 1 mmol of Ara-U), followed by UP (105 IU; 150 units per 1 mmol of substrate) were added, and the reaction mixture was gently stirred at 40 °C with monitoring the Ara-U

• reaction mixture was gently stirred at 47 °C for 48 h with monitoring the product formation by HPLC (HPLC system A, 5% H2O/MeCN), λ = 260 nm, 1 mL/min; tR 4.5 and 5.1 min for the base and nucleoside, respectively). After 48 h, the conversion of the base into nucleoside reached 85%. The turbid (not reacted

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• while titrating the other binding partner. However, for larger supramolecular hosts that encapsulate a large part of their (usually smaller) guest, it is advantageous to monitor the guest’s resonances. Monitoring binding with this simple spectrum requires at least one signal that does not overlap with

• supramolecular tweezers that bind to lysine or arginine, tweezers have been titrated to the free amino acids or short peptides, monitoring the Lys and Arg resonances [5][80]. While all resonances of the guest amino acid shift upon tweezer binding, the effect is most severe for the H atoms at the end of the side

• experiment, monitoring 15N,2H-labeled 14-3-3ΔC protein in 1H,15N-TROSY-HSQC experiments [103], was used to investigate the stabilizing effect of several compounds on the interaction of 14-3-3 with different unlabeled peptide epitopes derived from 14-3-3 cargo proteins [104][105][106]. E.g., a semi-synthetic

Tools for generating and analyzing glycan microarray data

• Akul Y. Mehta,
• Jamie Heimburg-Molinaro and
• Richard D. Cummings

Beilstein J. Org. Chem. 2020, 16, 2260–2271, doi:10.3762/bjoc.16.187

• monitoring for accurate printing. Between the printing of each probe (glycan), there is usually a wash step which is performed to prevent any carryover for the next ligand, and this would need to be determined empirically depending on the glycoconjugates used. After the entire print run, the slides are left

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• molecules were dyes used for the DNA/RNA labelling or even monitoring or influencing DNA/RNA function [3][4]. However, due to the complexity of DNA-coded or RNA-coded processes, also including epigenetics, there is permanent need for novel dyes, differing in selectivity, colour, or method of monitoring [5

• monitoring, fluorescence is still the most popular method [8][9][10][11]. However, many new techniques or established ones with increased sensitivity are constantly improved or developed to report complementary to fluorescence. For instance, circular dichroism (CD) spectropolarimetry, highly sensitive to

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• °C, 19F NMR monitoring of the reaction’s progress indicated the appearance of a second product beside the 1,4-cyclohexadien-1-iminium salt 4-Ch. Further investigations revealed that the new product was the dihydrofluorene 7, resulting from 4-Ch by an intramolecular electrophilic aromatic substitution

Three new O-isocrotonyl-3-hydroxybutyric acid congeners produced by a sea anemone-derived marine bacterium of the genus Vibrio

• Dandan Li,
• Enjuro Harunari,
• Tao Zhou,
• Naoya Oku and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1869–1874, doi:10.3762/bjoc.16.154

• (10 × 250 mm), eluted by a gradient method (MeCN/0.1% HCOOH) at 4 mL/min, with monitoring at 254 nm, to give the (S)-PGME amide 4a (2.9 mg, 93%) as colorless oil. The PGME amides 1a/b–3a/b and 4b were prepared by the same procedure but replacing the starting material and the chiral reagent accordingly

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• with radioactively labeled substrates, the use of fluorescently labeled probes offers several advantages, including the continuous monitoring of the transport and a better time resolution. For reasons of comparison, the α-configured ᴅ-mannose probe MPC-3 was synthesized in parallel. The

Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner–Wadsworth–Emmons-based approach

• Rhys A. Lippa,
• John A. Murphy and
• Tim N. Barrett

Beilstein J. Org. Chem. 2020, 16, 1617–1626, doi:10.3762/bjoc.16.134

• to account for the deprotonation of the more acidic phosphonate product 7 versus the starting material 13, and potential lithium sequestration by chelation between an oxygen atom of the phosphonate and the nitrogen atom of the unsaturated ring. Monitoring of the deprotonation followed by quenching

Synthesis of new dihydroberberine and tetrahydroberberine analogues and evaluation of their antiproliferative activity on NCI-H1975 cells

• Giacomo Mari,
• Lucia De Crescentini,
• Serena Benedetti,
• Francesco Palma,
• Stefania Santeusanio and
• Fabio Mantellini

Beilstein J. Org. Chem. 2020, 16, 1606–1616, doi:10.3762/bjoc.16.133

• detectable only in traces (Table 1, entries 1–5). The monitoring by TLC of the reaction conducted in acetonitrile reveals the formation of derivative 2a, which, however, does not precipitate in the reaction medium (Table 1, entry 6). The spontaneous precipitation is particularly relevant to prevent any

• in dichloromethane (3.0 mL) of α-bromohydrazones 1a–n [71] (1.0 mmol) was added the unsubstitued dihydroberberine [66][67] (1.0 mmol). The reaction was allowed to stand at room temperature under magnetic stirring until the complete disappearance of the starting materials (TLC monitoring) and the

• magnetic stirring until the complete disappearance of the starting hydrazono-DHBERs 2a–n (2.0–3.0 h, TLC monitoring). The reaction solvent was then evaporated under reduced pressure. The crude mixture was then purified by column chromatography on silica gel (elution with cyclohexane/ethyl acetate mixtures

Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers

• Vyacheslav I. Supranovich,
• Vitalij V. Levin and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 1550–1553, doi:10.3762/bjoc.16.126

• starting enol ether. Moreover, a further increase in reaction time was accompanied by a decrease in the product yield. Finally, GC monitoring suggested complete consumption of the silyl enol ether within 6 hours. It should also be pointed out that the addition of basic additives, which are frequently

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• monitored with in-line and on-line spectroscopies, such as UV–vis, FTIR, mass spectrometry, and NMR [63][64][65][66][67][68]. These systems can be automated to ensure consistency and to remove the need for laborious manual sampling. In-line and on-line monitoring is well aligned with automated synthesis and

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• susceptibility of 2-chloro-N-phenethylacetamide (13), towards halogen exchange mediated by BTMS (Scheme 6). The reaction progress was monitored by 1H NMR spectroscopy monitoring the signals of the methylene groups C(O)CH2Cl in 13 vs C(O)CH2Br in the product 22 (see Figure S16 in Supporting Information File 1

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• and the difficulties associated with the interpretation of the obtained data [53]. During EPR monitoring of the generation and decomposition of iminoxyl radicals, the formation of several free-radical products of a non-iminoxyl type, probably of the general formula R1R2NO•, was observed. It was

Anthelmintic drug discovery: target identification, screening methods and the role of open science

• Frederick A. Partridge,
• Ruth Forman,
• Carole J. R. Bataille,
• Graham M. Wynne,
• Marina Nick,
• Angela J. Russell,
• Kathryn J. Else and
• David B. Sattelle

Beilstein J. Org. Chem. 2020, 16, 1203–1224, doi:10.3762/bjoc.16.105

• available, enabling utilisation and modification by other groups. Stress-Chip is a chip that allows the isolation of a hundred worms in single-worm arenas and monitoring as chemicals flow over the worms [153]. The CAD file for producing the microfluidic device has been made available on Figshare under the

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• , such as monitoring of specific biological activities and as antimalarial and anticancer agents [5][6]. However, electroactive properties of derivatives of this acceptor have been scarcely reported. Quinazoline-based compounds were used as hosts for red phosphorescent OLEDs with an external quantum

A cyclopeptide and three oligomycin-class polyketides produced by an underexplored actinomycete of the genus Pseudosporangium

• Shun Saito,
• Kota Atsumi,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Naoya Oku,
• Md. Rokon Ul Karim,
• Hisayuki Komaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1100–1110, doi:10.3762/bjoc.16.97

• ) was added and then diluted with MeCN/0.2% HCO2H aqueous solution (100 μL, 50:50). The Marfey’s derivatives of the hydrolysate and standards were analyzed by LC–MS using a Cosmosil 5C18-AR-II column eluted with MeCN/0.1% HCO2H aqueous solution at a flow rate of 1.0 mL/min, monitoring at 340 nm with a

Accelerating fragment-based library generation by coupling high-performance photoreactors with benchtop analysis

• Quentin Lefebvre,
• Christophe Salomé and
• Thomas C. Fessard

Beilstein J. Org. Chem. 2020, 16, 982–988, doi:10.3762/bjoc.16.87

• conditions compared to a single vial reactor. Active water cooling protects the LEDs from overheating, while additional air cooling with bespoke fans prevents the vessels to heat over 50 °C. Each vessel is placed at equal distance of a 35 W high power blue LED (Figure 1). Reaction monitoring by TLC–MS

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• . For 3a, further monitoring by absorption spectroscopy revealed that higher Cu2+ concentrations led to an increase of the reaction rate. However, at a spirooxazine concentration of c = 20 µM, slightly more than 2.0 equiv of Cu2+ were required for a complete conversion (Figure S4, Supporting Information

• “adjacent-averaging“ (factor of 10). For the reaction monitoring by absorption spectroscopy, an aliquot of the solutions of Cu(BF4)2, Fe(ClO4)3 or Hg(ClO4)2 was added to a solution of 3a (c = 20 µM) in MeCN to achieve a final concentration of the metal ions of c = 20–60 µM. The solutions were mixed

• vigorously, and absorption spectra were recorded every 5 s. For the reaction monitoring by NMR spectroscopy, six samples were prepared with a fixed concentration of 3a (c = 2.0 mM). In five of the samples, different amounts of Cu(BF4)2 were added to obtain Cu2+ concentrations of c = 0.5, 1.0, 2.0, 3.0 and

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

• Dong Cai,
• ZhiHua Zhang,
• Yufan Meng,
• KaiLi Zhu,
• LiYi Chen,
• ChangXiang Yu,
• ChangWei Yu,
• ZiYi Fu,
• DianShen Yang and
• YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

• , compound 9 did not reacted completely after 48 h (TLC monitoring). The reaction from 2 to 8 proceeded via the intermediate 6, which can be isolated. The intermediate 6 did not react with 1-Boc-piperazine in low boiling point solvents even after an extended reaction time (up to 72 h). Heating the reaction

• , N,N-dimethylformamide (DMF), a solvent with a higher boiling point than acetonitrile, was also tested, yet the reaction led to the formation of unknown compounds (TLC monitoring, Table 2, entry 7). After screening several solvents, the optimal yield was obtained in acetonitrile, though a small

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• suggested that the reaction proceeds via an intermediate six-membered selenocyanate 5, which could be observed at a lower temperature. Indeed, monitoring the reaction by 1H NMR spectroscopy using the same conditions as in the synthesis of the selenocyanate 4, but at 0 °C confirmed this assumption (Scheme 6

• ). The monitoring results are presented in Figure 1 and Table 1. The reaction was studied in the time interval from 0.25 to 6 h. Having assigned the 1H NMR data for compounds 1 and 4, we found signals of an unknown compound, which was easily identified after 0.5 h (at 46% conversion of thiaselenole 1) as

• chemistry. Monitoring the reaction of thiaselenole 1 with KSeCN by 1H NMR spectroscopy (in accordance with the data of Table 1). Reaction conditions: compound 1 (0.5 mmol), KSeCN (0.5 mmol), MeCN (2.5 mL), 0 °C. Possible formation of reaction products starting from 1 via seleniranium 2 or thiiranium cations

Exploring the scope of DBU-promoted amidations of 7-methoxycarbonylpterin

• Anna R. Bockman and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2020, 16, 509–514, doi:10.3762/bjoc.16.46

• the order of several hours. Viewing this reaction as an essential tool for pteridine chemists seeking to rapidly generate diverse pterin structures, we sought to explore the scope of amines which can be easily appended to the pterin core. Trends in reactivity were further probed by monitoring the

• the relative reactivity of the various amines, a pseudo-first order kinetics of the amidation reaction was probed. The reaction was followed by 1H NMR spectroscopy at room temperature, following the disappearance of 7-CMP and appearance of the amide product (Figure 3). By monitoring the reaction