Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• Information File 1). It should be noted that attempts of chromatographic separation of triflates 4a–c into individual E- and Z-isomers on silica gel led to a decrease of their yields and a change in E/Z-ratio. That reveals instability of these compounds on silica gel. In the same reaction in H2SO4 (Scheme 4

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• solvent was removed under reduced pressure and the resulting crude biaryl carbonyls were purified using silica gel column chromatography (using EtOAc/hexane mixtures as eluent). Experimental details for the preparation of compounds 13a–f can be found in Supporting Information File 1. Oxime ester formation

• saturated NaHCO3 solution (10 mL) and brine (10 mL). The solution was dried over MgSO4 and the solvent was evaporated under reduced pressure. The resulting crude oxime esters were purified by silica gel column chromatography (using EtOAc/hexane mixtures as eluent). Experimental details for the preparation

• (450 W medium pressure Hg lamp, through a quartz filter) for 3 h. The crude residue was purified by silica gel column chromatography (using EtOAc/hexane mixtures as eluent). Experimental details for the preparation of compounds 15a–d and 16a–f as well as compounds 23 and 24 can be found in Supporting

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• SYNAPT G2 mass spectrometer and semipreparative HPLC was conducted using a Gilson 306 pump with a Shodex refractive index detector and a Phenomenex Luna 10 μm column (250 × 10 mm). Silica gel 60 (Merck, Darmstadt, 70–230 mesh, and 230–400 mesh) and RP-C18 silica gel (Merck, 230–400 mesh) were used for

• column chromatography. Low-pressure liquid chromatography was performed over Merck LiChroprep Lobar-A Si gel 60 (240 × 10 mm) with an FMI QSY-0 pump (ISCO). Merck precoated silica gel F254 plates and RP-18 F254s plates were used for TLC. Spots were detected on TLC under UV light or by heating after

• –C6). Fraction C1 (2.0 g) was subjected to RP-C18 silica gel chromatography, eluting with gradient solvent system (30 → 100% aq. MeOH) to yield four subfractions (C2A–C2D). Fraction C2C (210 mg) was purified by semipreparative HPLC (2 mL/min, 50% aq. MeOH) to yield compounds 17 (5 mg) and 19 (6 mg

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• chromatography (TLC) was performed on Marchery-Nagel Polygram SIL G/UV254 plates. Column chromatography was done on silica gel 60 (70–230 mesh). 1H, and 13C NMR spectra were recorded on Bruker DRX 300 MHz, Bruker Avance 4 Neo 400 MHz, and Bruker Avance 4 Neo 700 MHz instruments. Chemical shifts (δ) are reported

• . Compound 3 [29][30][31] (200 mg, 0.720 mmol) was added and the mixture was heated to 110 °C in a pressure tube for 24 h. After neutralization with glacial acetic acid the volatiles were removed in vacuo. The crude product was dry-loaded onto silica gel and purified via flash column chromatography (5–20

• combined organic layers were washed with brine and dried over magnesium sulfate. The solvents were removed and the remaining crude product was purified by flash column chromatography on silica gel (10–30% ethyl acetate in cyclohexane) to give 1.00 g of compound 4 (79%) as a white foam. TLC: 40% ethyl

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• and were characterized by IR and GC–MS. All novel pruducts were characterized by IR, 1H NMR, 13C NMR, elemental analysis and GC–MS. The reactions were monitored by TLC using silica gel plates and the products were purified by flash column chromatography on silica gel (Merck; 230–400 mesh), eluting

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

• medium, and the whole culture broth was extracted with 1-butanol. The extract was subjected to silica gel and ODS column chromatography, and the final purification was achieved by reversed-phase HPLC to yield two new spirotetronate polyketides, nomimicins B (1) and C (2), along with a known compound

• from the aqueous layer containing the mycelium. Evaporation of the solvent gave 3.8 g of extract from 2 L of A16 culture. The extract was subjected to silica gel column chromatography with a step gradient of CHCl3/MeOH (1:0, 20:1, 10:1, 4:1, 2:1, 1:1, and 0:1, v/v). Fraction 4 (4:1) was concentrated to

• silica gel column chromatography with a gradient of CHCl3/MeOH (1:0, 20:1, 10:1, 4:1, 2:1, 1:1, and 0:1, v/v). Fraction 7 (0:1) was concentrated to give 0.37 g of brown oil, which was then fractionated by ODS column chromatography with a gradient of MeCN + 0.1% HCO2H solution (2:8, 3:7, 4:6, 5:5, 6:4, 7

Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF₃·OEt₂ catalysis

• Karthikeyan Soundararajan,
• Helen Ratna Monica Jeyarajan,
• Raju Subimol Kamarajapurathu and
• Karthik Krishna Kumar Ayyanoth

Beilstein J. Org. Chem. 2021, 17, 2186–2193, doi:10.3762/bjoc.17.140

• filtration, the solvent was removed under reduced pressure and the crude product was purified on silica gel (using hexane/EtOAc) to afford the desired product 6a as a white solid (81%). Methyl 1H-indene-2-carboxylate (6a): Yield: 160 mg (81%); white solid; mp 85–87 °C; IR (cm−1): 3062, 2953, 2884, 1947, 1735

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

• on the elemental analysis, the authors provided the formula representation C10H6(I2)0.4 for PAZ-I2 and C10H4.9(Br2)0.72 for PAZ-Br2. The gel permeation chromatography (GPC) analysis of the tetrahydrofuran (THF)-soluble fraction of PAZ-Br2 indicated the presence of oligomeric species (average degree

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)

• Tania Xavier,
• Sylvie Condon,
• Christophe Pichon,
• Erwan Le Gall and
• Marc Presset

Beilstein J. Org. Chem. 2021, 17, 2085–2094, doi:10.3762/bjoc.17.135

• . Another advantage inherent to this class of reagents is their easy purification by a classical acid/base work-up thanks to the presence of the carboxylic acid moiety, even if they could also be purified by standard chromatography on silica gel. They have thus been used in a variety of reactions, the most

• DCC and 5 mol % of DMAP in CH2Cl2, Table 4, entry 1), the desired product was isolated in an encouraging yield of 22% after chromatography on silica gel. By adding a solution of DCC in CH2Cl2 to a solution of the other reagents in CH3CN (Table 4, entry 2), the yield was increased to 46%. The

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• convenient synthesis of triarylmethanes and 9,10-diarylanthracenes from reactions of arenes and aromatic aldehydes by using acetyl bromide in the presence of silica gel-supported zinc bromide [43]. The methodology developed by these authors involved using excess of one of the reagents. When the authors

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves

• Christin Walther,
• Pamela Baumann,
• Katrin Luck,
• Beate Rothe,
• Peter H. W. Biedermann,
• Jonathan Gershenzon,
• Tobias G. Köllner and
• Sybille B. Unsicker

Beilstein J. Org. Chem. 2021, 17, 1698–1711, doi:10.3762/bjoc.17.118

• : initiation and activation of polymerase (95 °C/5 min); followed by 35 cycles of denaturation (95 °C/30 s), annealing (65 °C/30 s) and elongation (72 °C/90 s) and a single, final elongation step (72 °C/10 min). For gel electrophoresis, 4 µL PCR product was mixed with one drop loading dye (0.3 mL 30% glycerol

• and 2.5 mg bromphenol blue/mL) and applied to an 1% agarose gel (1 g agarose/100 mL 0.5% TBE; 5 µL Midori Green). A 1 kb DNA ladder (Gene Ruler, Thermo Fisher Scientific) was applied to determine the fragment size of the products. Electrophoresis was performed in 0.5% TBE buffer (Thermo Fisher

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• from MZ-Gel SD plus, 500 A and 100 A, linear 5 µ; UV detector (SPD-20A) and RI detector (RID-20A)) using THF as eluent. Poly(styrene) standards in the range of 350 to 17800 g/mol purchased from Polymer Standard Service were used for calibration. Computational details All calculations were run with the

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• recent studies show that J can be further optimized. Chen and co-workers reported that substitution of oxygen-4 of J with sulfur improved the Hoogsteen binding properties of 4-thiopseudoisocytosine (L, Figure 6) [98]. UV thermal melting and gel electrophoresis studies showed that L formed more stable L•G

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• by thin-layer chromatography (TLC) using commercial silica-gel plate 60 coated with a fluorescence indicator and the visualization was performed by UV (254 nm). Organic compounds were purified using Merck Silica gel 60 (0.043–0.06 mm). Solvents for work-up and column chromatography were distilled

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• determined by 1H NMR spectroscopy. Chromatographic separation was carried out on silica gel 60H (200–300 mesh) manufactured by Qingdao Haiyang Chemical Group Co. (China). High-resolution mass spectrometry (HRMS) was measured on a Thermo-DFS mass spectrometer. NMR spectra were recorded on a JEOL 600 NMR

• ® pad, the reaction mixture was extracted with EtOAc (3 × 20 mL). The combined organic phase was washed with brine (20 mL) and dried over Na2SO4. Then, Et3N (0.5 mL) and silica gel (0.8 g) were added, and the combined solvent was removed under reduced pressure. The residue solid sample was purified by

• column chromatography on silica gel (petroleum/EtOAc 5:1 to 2:1, with 1% Et3N), yielding the desired product 3. (Z)-3-Benzylidene-2-(methyl[pyridin-2-yl]amino)isoindolin-1-one (3aa) The general procedure was followed using hydrazide 1a (68.2 mg, 0.30 mmol) and alkyne 2a (91.9 mg, 0.90 mmol). Purification

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• chromatography was carried out on silica gel (grade 60, mesh size 230–400, Scharlau). Visualization techniques for TLC plates include using ultraviolet light (254 nm) and KMnO4. NMR spectra were collected at room temperature on Bruker-500, or Bruker-700 spectrometers and calibrated to the appropriate solvent

• silica-gel chromatography (100% hexane), to furnish (±)-4 as a yellow solid (6.70 g, 26.5 mmol, 55%), (±)-5 as a yellow crystalline solid (1.68 g, 6.24 mmol, 13%), and 6 as light yellow crystals (2.61 g, 9.15 mmol, 19%). 4-Nitro[2.2]paracyclophane (4) 1H NMR (500 MHz, CDCl3) δ (ppm) 7.22 (d, J = 1.2 Hz

• (5.00 g, 17.5 mmol, 1.00 equiv) in CH3OH (0.20 M, 87.6 mL) was added TFA (1.00 M, 17.5 mL) and stirred at rt for 24 h. The solution was concentrated under reduced pressure yielding a light orange solid, which was purified by flash silica-gel chromatography (gradient of 0% to 60% EtOAc, hexane over 1 h

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• conducted in air. Products were purified by standard column chromatography (CC) on silica gel (230–400 mesh; deactivated prior to use with 2% Et3N in petroleum ether) by using freshly distilled solvents as eluents (petroleum ether, CH2Cl2, AcOEt) or recrystallized from hot CHCl3. THF was dried over sodium

• until the starting material 1 was fully consumed (based on TLC monitoring, petroleum ether/dichloromethane 1:1). After the resulting precipitate and unconsumed carbonate were filtered off, the solvent was removed under reduced pressure. The crude mixtures were purified by CC using silica gel as the

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• thin-layer chromatography (TLC) was carried out on silica gel plates (silica gel 60 F254 aluminum supported plates), and the spots were visualized with a UV lamp (254 nm and 365 nm) or using chemical staining with Brady’s reagent, KMnO4, ninhydrin, iodine, and bromocresol. Column chromatography was

• performed using silica gel (100–200 mesh or 230–400 mesh) and neutral alumina (175 mesh). DMF, DCM, DMA, toluene, and acetonitrile were dried using CaH2 and distilled over flame-dried 4 Å molecular sieves. THF and Et2O were dried over Na/benzophenone and stored over flame-dried 4 Å molecular sieves under an

Organocatalytic asymmetric Michael/acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones

• Chandrakanta Parida and
• Subhas Chandra Pan

Beilstein J. Org. Chem. 2021, 17, 1447–1452, doi:10.3762/bjoc.17.100

• 2 (0.1 mmol), 10 mol % VII in 0.6 mL 1,2-dichloroethane were reacted at 25 °C for 12 hours. Yields correspond to isolated yields after silica gel column chromatography and ees were determined by chiral HPLC. Catalyst screening and optimization of the reaction conditions. Scope of α-nitroketones 2 in

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

• Birthe Sandargo,
• Leon Kaysan,
• Rémy B. Teponno,
• Christian Richter,
• Benjarong Thongbai,
• Frank Surup and
• Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

• Spin® Gel and PCR Clean-up kit (Macherey-Nagel, Düren, Germany). Sequencing of the PCR products was carried out at the Department of Genome Analytics of the Helmholtz Centre for Infection Research, Braunschweig, Germany. Fermentation and isolation of metabolites 1–6 Cultures of Marasmius sp. strain

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• . Pyrrole was used after distillation. Analytical thin-layer chromatography (TLC) was performed on aluminium plates coated with silica gel by using a suitable mixture of EtOAc and petroleum ether for development. Column chromatography was performed by using silica gel (100–200 mesh) with an appropriate

• crude product was extracted with ethyl acetate. The combined organic layer was washed with water (100 mL × 2) and dried over Na2SO4. After evaporation of the solvents, the residue was passed through silica gel to give the final product as a white powder (7.5 g, 95%). The 1H NMR spectrum was perfectly

• ) was degassed with nitrogen for 15 min. After adding the Grubbs’ catalyst (15 mol %), the stirring was continued for 12 h at the same temperature. Next, the solvent was removed under reduced pressure followed by silica gel column chromatography (5% EtOAc/petroleum ether) provided the required product 6

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• ultrafiltration with reassembly buffer using a 100 kDa Amicon centrifuge filter (0.5 mL, Millipore) at 8,000g for 15 min, and the step was repeated at least three times. VLPs assembly products were analyzed by gel electrophoresis mobility shift assay (EMSA) in native agarose gel at 1%. The electrophoresis was run

• in a horizontal agarose gel system (FBSB710 Fisher Scientific) for 4 h at 50 volts (virus buffer), 4 °C and then, the gel was stained with ethidium bromide. The image was captured using a documentation system (MS Major Science). Transmission electron microscopy analysis of VLPs. 6 µL of VLP-dsRNAvp28

• difficult. The correlation of the TEM and EMSA results suggests that the band in the agarose gel migrated slightly less than the wild type CCMV corresponds to, in multiple icosahedral capsids and short tubes with dsRNA. Similar results have been obtained with long ssRNA [42]. In contrast, the band that is

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• (Scheme 3a). The 2,2-unsymmetrically substituted sulfoxides 2d–g were obtained as mixtures of geometric isomers that were separated by column chromatography on silica gel. FBW rearrangement of magnesium alkylidene carbenoids Based on the results of DFT calculations, the degree of the vinylidene character

• air- or water-sensitive compounds were conducted under an argon atmosphere. Argon gas was dried by passage through P2O5. Anhydrous THF and toluene were purchased and used as supplied. Silica gel 60N containing 0.5% fluorescence reagent 254 and a quartz column were used for column chromatography, and

• water (50 mL), dried over Na2SO4, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (hexane/EtOAc 1:1) to give the alcohol [6.90 g, 16.7 mmol, 83%, Rf = 0.45 (hexane/EtOAc 1:1)] as a single diastereomer; yellow solid; mp 102.5–104.0 °C; IR (ATR