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

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• monitoring and in situ speciation. In addition, phosphine ligands have found various applications as auxiliary ligands in organometallic transition-metal complexes. A great number have exhibited potential application in organic light-emitting devices (OLEDs) [3], medicine [4][5][6] and catalysis [1][7][8

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

• Fei You,
• Xing He,
• Song Gao,
• Hong-Ru Li and
• Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

• IL settled well after the reaction and was absent in the product. Monitoring oligomerization process by 1H NMR (400 MHz, CDCl3). Reusability of the IL catalyst. Reaction conditions: 10 g (30 mmol) ricinoleic acid, 190 °C, 6 h, 50 kPa. 1H NMR (400 MHz, DMSO-d6) spectra of [HSO3-BDBU]H2PO4: a) Fresh

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• collected, i.e., DNA-viscosity measurements [70]. Thus, the monitoring of the DNA viscosity changes when compounds 11 and 12 are present, may be elucidating in regard to their binding mode to DNA. As known, the changes of the relative DNA viscosity (η/ηo)1/3 are proportionally related to changes of the

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• of the initially formed Z-isomers Z-3a and Z-3b, with both processes generally being possible starting from 3b and 3c (Scheme 2). On the one hand, the photometric monitoring as well as the 1H NMR spectroscopic studies of the photoreaction of 3b indicated a preceding E-to-Z isomerization (cf

• base pairs). Spectrophotometric monitoring of the irradiation of styrylquinolizinium derivatives 3a (A), 3b (B), 3c (C), and 3d (D) in acetonitrile [cL = 10 µM (A), cL = 20 µM (B, C, D)]. The arrows indicate the changes of absorption upon irradiation. Absorption of the monomers (c = 20 µM, red) 3b (A

• ) and 3c (B) and their dimers (black) 4b and 4c in H2O after 1.5 h and 4 h, respectively, at ca. 450 nm. Photometric monitoring of the photoreaction of 3b (c = 20 µM) to the dimer 4b by irradiation at ca. 450 nm in H2O (A) and of the photoinduced cycloreversion of 4b (c = 20 µM) to the monomer 3b at 315

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

• María C. Mollo,
• Natalia B. Kilimciler,
• Juan A. Bisceglia and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

• experimental conditions, several novel 2-aryl-1,4,5,6-tetrahydro-1,3-thiazepines were synthesized in good to high yields (Table 2). Due to the different reactivity of each substrate, irradiation times and temperatures were individually adjusted by monitoring the disappearance of substrate (TLC). Derivatives 4f

A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

• Daniel P. Pienaar,
• Kamogelo R. Butsi,
• Amanda L. Rousseau and
• Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

• monitoring. Due to the persistent presence of unreacted starting materials in all examples given, it was decided to dose with second equivalents of base (KOt-Bu) and CH3CN after 1 h of reaction, as seen in most examples in Table 1. Disappointingly, we were unable to further significantly increase product

Preparation of anthracene-based tetraperimidine hexafluorophosphate and selective recognition of chromium(III) ions

• Qing-Xiang Liu,
• Feng Yang,
• Zhi-Xiang Zhao,
• Shao-Cong Yu and
• Yue Ding

Beilstein J. Org. Chem. 2019, 15, 2847–2855, doi:10.3762/bjoc.15.278

• monitoring. In recent years, some fluorescent chemosensors for the detection of chromium(III) have been developed [15][16][17][18][19][20][21][22][23]. Generally, chemosensors with fluorescence enhancement are more efficient than fluorescence turn-off chemosensors [24][25][26][27][28][29] because the

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• (Figure S3, Supporting Information File 1). On repeating this cycle, slow decomposition was observed, estimated at 14% after 3 cycles. Calcium binding by hosts 1E and 1Z was investigated by spectrophotometry, specifically monitoring aromatic ring chromophores which give rise to absorption bands observed

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• solution. Compared to physical radiometry, actinometry is directly transposable to the monitoring of photochemical transformations as it originates from the very same concept and can be performed in the same experimental conditions. It is also adapted to turbid mixtures and can be extended to polychromatic

• green light escapes the photoreactor. Under these conditions the actinometric equation becomes so the flux in photon per second emitted by the source is: where V is the total volume of the DAE solution and the monitoring optical path is 1 cm. Finally, the average upconversion-QY, ΦUC can be estimated by