Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• chromatographed on silica gel, eluting with hexanes/EtOAc 99:1 to isolate the product 4 after combining the appropriate fractions. Minor fractions of the corresponding compound 3 were isolated in 6% to 17% yield. In addition, we employed acetylacetone (5) as a reagent to obtain an α-thio ketone (Scheme 2

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• pressure (Scheme 4). The product 1 could now be purified by a simple chromatography on silica gel and was obtained in 88% yield. NMR spectroscopic data of the natural product had been published by Wang et al. [2] and by Xiao et al. [7] (Table 1). A comparison of the 13C NMR data of the now synthesized

1,2,3-Triazoles as leaving groups in S_NAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

• Kārlis-Ēriks Kriķis,
• Irina Novosjolova,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

• conversion of starting material 6d was monitored by HPLC, and after completion, product 4d was precipitated from the reaction mixture by hexane. For entries 1 and 3 in Table 2, an extra purification step by silica gel column chromatography was required. For compound 4d, the optimal reaction conditions were 2

• at −20 °C within 10 hours and were then filtered and washed with cold hexane. The product purity, if necessary, was further improved by column chromatography. Some phosphonates, for example, 4b, 4c, and 4f, were reductant to precipitate from hexane and were purified solely by silica gel column

• compounds were monitored by HPLC and TLC analysis using silica gel 60 F254 aluminum plates (Merck). Visualization was accomplished by UV light. Column chromatography was performed on silica gel (60 Å, 40−63 μm, ROCC). The yield of the products refers to chromatographically and spectroscopically homogeneous

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

• Takashi Yamazaki,
• Yoh Nakajima,
• Minato Iida and
• Tomoko Kawasaki-Takasuka

Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14

• oxidation of the other substrates 1 was performed under similar reaction condition, the results of which are summarized in Table 1. We reported the yield as determined by 19F NMR spectroscopy rather than after purification because of the inherent instability of 2 on silica gel, causing partial decomposition

Chemical constituents of Chaenomeles sinensis twigs and their biological activity

• Joon Min Cha,
• Dong Hyun Kim,
• Lalita Subedi,
• Zahra Khan,
• Sang Un Choi,
• Sun Yeou Kim and
• Chung Sub Kim

Beilstein J. Org. Chem. 2020, 16, 3078–3085, doi:10.3762/bjoc.16.257

• -preparative HPLC system equipped with a Gilson 306 pump (Middleton, WI, USA), a Shodex refractive index detector (New York, NY, USA), a Luna C18 10 µm column (250 mm length × 10 mm i.d.; Phenomenex, Torrance, CA, USA), and an Apollo Silica 5 μm column (250 mm length × 10 mm i.d.; Apollo, Manchester, UK) at a

• flow rate of 2 mL/min. Low pressure liquid chromatography (LPLC) was performed with a LiChroprep Lobar-A Si 60 column (Merck, Darmstadt, Germany) and an FMI QSY-0 pump. Open columns packed with silica gel 60 (70–230 and 230–400 mesh; Merck), RP-18 silica gel (230–400 mesh; Merck, Darmstadt, Germany

• ), or Diaion® HP-20 resin (Sigma, St. Louis, MO) were implemented for crude fractionation and separation. Precoated silica gel F254 plates and RP-18 F254s plates (Merck, Darmstadt, Germany) were utilized for thin-layer chromatography (TLC) and the spots were detected under UV light or by heating after

Deoxyfluorination of acyl fluorides to trifluoromethyl compounds by FLUOLEAD^®/Olah’s reagent under solvent-free conditions

• Yumeng Liang,
• Akihito Taya,
• Zhengyu Zhao,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2020, 16, 3052–3058, doi:10.3762/bjoc.16.254

• mL), and the combined organic layer was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The yield was determined by 19F NMR analysis of the crude mixture by using C6H5OCF3 (40.0 μL, 0.3 mmol, 1.0 equiv) as an internal standard. The residue was purified by silica gel

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• -(amino)cyanocyclopropane derivatives not contaminated by intermediates or ring-opening byproducts [21], whereas the asymmetric Strecker synthesis induced by chiral amines was successfully conducted by sonication in the presence of silica gel [22]. Pursuing our interest in developing environmentally

UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

• Tim Holtum,
• Vikas Kumar,
• Daniel Sebena,
• Jens Voskuhl and
• Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

• –vis spectrometer (Perkin-Elmer Lambda 650) where liquid samples were kept in 2 mm fused silica cuvettes (Hellma). DFT calculations were performed with the Gaussian 16 program package [25]. The molecule was calculated in the gas phase in its protonated form with one positive net charge. The resulting

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

• Dmitrii A. Aksenov,
• Nikolai A. Arutiunov,
• Vladimir V. Maliuga,
• Alexander V. Aksenov and
• Michael Rubin

Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239

• hydrazide was filtered off and rinsed several times with cold ethanol. The combined filtrates were concentrated under reduced pressure to provide the crude amine, which was purified by flash column chromatography on silica gel, eluting with a mixture of dichloromethane/ethanol/triethylamine, gradient 80:10

• mL). The combined organic extracts were concentrated, the residue dried in vacuum, and then purified by preparative column chromatography on silica gel, eluting with a mixture of petroleum ether and ethyl acetate. The titled compound was obtained as yellow solid (lit. [53] yellow crystals), yield 77

Incorporation of a metal-mediated base pair into an ATP aptamer – using silver(I) ions to modulate aptamer function

• Marius H. Heddinga and
• Jens Müller

Beilstein J. Org. Chem. 2020, 16, 2870–2879, doi:10.3762/bjoc.16.236

• , and Merck. Dry pyridine was purchased from Acros Organics. Dichloromethane was distilled and dried over molecular sieves. Milli-Q water was used to prepare solutions and buffers. The silica gel used for product purification (Geduran® Si60, 40–63 µm) was purchased from Merck. The DMT- and

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

• ), 40 wt % PW on silica (Table 1, entry 9), a 30 wt % PW loading on montmorillonite K30 clay (Table 1, entry 11), and a 40 wt % PW loading on alumina (Table 1, entry 12). The study on the optimal reaction conditions shed a light on the acidity and the physical characteristics required for the reaction

• was dried overnight at 110 °C and ultimately calcined at 250 °C in a furnace under air for 4 h to obtain a white powder (1 g), which was stored in a calcium chloride/silica-filled desiccator. General method The general method involved the addition of 1 equiv of the aldehyde (5 mmol), 2 equiv ethyl

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• additive that decides on preferential 2’-O-silylation. The salt has been suggested to influence reaction kinetics in the way that the silylation reagent TBDMS chloride is changed to the nitrate, which subsequently is consumed faster by nucleophilic attack of the 2’-OH group onto the silica atom as compared

On the mass spectrometric fragmentations of the bacterial sesterterpenes sestermobaraenes A–C

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2020, 16, 2807–2819, doi:10.3762/bjoc.16.231

• , Wilmington, USA). The gas chromatographic separation was done using a HP5-MS fused silica capillary column (30 m, 0.25 mm i.d., 0.25 μm film, Agilent). The GC settings were 1) inlet pressure: 77.1 kPa, He 23.3 mL min−1; 2) injector temperature: 250 °C; 3) injection volume: 2 μL; 4) injector operation mode

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• , the mixture was filtered through a short pad of silica, the silica washed with CH2Cl2, and the organic solution was carefully evaporated to give the crude products. If necessary, the products were purified by column chromatography. General procedure under argon atmosphere (B) Anhydrous dichloromethane

• was degassed before reaction. To the oxaenediyne (1 equiv) in CH2Cl2 was added the Grubbs or Hoveyda–Grubbs catalyst (0.05 equiv) in CH2Cl2 and the mixture was stirred under an argon atmosphere at 25 °C for 24 h. Afterwards, the mixture was filtered through a short pad of silica, the silica washed

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• silica gel column using a mixture solvent of CHCl3/MeOH (1:0, 20:1, 10:1, 4:1, 2:1, 1:1, and 0:1, v/v). Fraction 3 (10:1) was concentrated to yield 0.38 g of a brown oil, which was further fractionated by ODS column chromatography with a stepwise gradient of a MeCN/0.1% HCO2H aqueous solution (2:8, 3:7

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• bis(carbazolyl)urea-derived receptor allowed the sensitive detection of diphosphate in water by surface plasmon resonance (SPR) [29]. Silica nanoparticles containing a dye coordinated to a bis(zinc(II)–DPA) receptor released the dye upon diphosphate binding [30], and thus producing an optical signal

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

• silica gel column chromatography the desired nucleoside was obtained in 52% yield. The rather long reaction time of the phosphorolysis and the Ara-1P-base coupling is mainly connected with the low quantity of the employed UP and PNP in both transformations. Indeed, it is noteworthy that in the work of

• evaporated, and the residue treated with EtOH (20 mL). The non-dissolved fine powder was filtered off and the filtrate evaporated and co-evaporated with EtOH (2 × 20 mL). The obtained residue was dissolved in MeOH (10 mL), mixed with silica gel (2 mL), evaporated and the residue was put on the top of a

• silica gel column (1.5 × 23 cm) prepared in EtOAc. The fractions containing the nucleoside were combined, evaporated and dried to afford the powdered product (25 mg; 66%) of 95.5% purity (HPLC), that was crystallized from MeCN to give nelarabine (19 mg; 53%; 99.0% purity by HPLC). For NMR data, see

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• every 3 cycles to limit agglomeration of the powder. The resulting powder was purified by flash chromatography on silica gel using acetonitrile/water 9:1 to 8:2 (v/v) as mobile phase. Isolated yield 21% (364 mg). All runs were performed at least twice in order to ensure reproducibility. X-ray powder

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• pressure and water (25 mL) was added to the mixture, which was extracted with ethyl acetate (3 × 15 mL). The combined organic layers were dried over anhydrous magnesium sulfate and concentrated to dryness. The crude residue obtained was purified by silica gel column chromatography (petroleum ether/ethyl

A new method for the synthesis of diamantane by hydroisomerization of binor-S on treatment with sulfuric acid

• Rishat I. Aminov and
• Ravil I. Khusnutdinov

Beilstein J. Org. Chem. 2020, 16, 2534–2539, doi:10.3762/bjoc.16.205

• the whole amount of H2SO4 has been added, the reaction mixture was stirred at 20 °С for 15 h. After completion of the reaction, 10% NaOH was added to the reaction mixture, the organic phase was separated, and filtered through a silica gel layer (with petroleum ether as the eluent). The solvent was

• reaction mixture was stirred at 20 °С for 7 h. After completion of the reaction, 10% NaOH was added to the reaction mixture, the organic part was separated, and filtered through a silica gel layer (with petroleum ether as the eluent). The solvent was distilled off and the residue was recrystallized from a

• stirred at 40 °С for 8 h. Then the reactor was cooled to room temperature, the reaction mixture extracted with petroleum ether, and filtered through a silica gel layer (with petroleum ether as the eluent). Hexacyclo[8.4.0.02,7.03,14.04,8.09,13]tetradec-5-ene (4а) and hexacyclo

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• 2 (3 mmol) and ferric nitrate (0.5 mmol). The reaction mixture was stirred magnetically at reflux for 6 h. After completion of the reaction (monitored by TLC), the product was diluted with water, extracted with ethyl acetate (15 mL) and purified by column chromatography (100–200 mesh silica gel

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

• Ken-ichi Nakashima,
• Junko Tomida,
• Tomoe Tsuboi,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 2100–2107, doi:10.3762/bjoc.16.177

• Technologies). DNA sequencing was performed using an Applied Biosystems 3130 genetic analyzer. Silica gel AP-300 (Toyota Kako) was employed for column chromatography (CC). Silica gel 60 F254 and RP-18 F254S (both Merck) were used for TLC. Fungal material and identification Muyocopron laterale ECN279 was

• fraction was then separated by silica gel CC using CHCl3/acetone (stepwise gradient, 1:0, 25:1, 10:1, and 0:1 v/v) as the eluent. The fractions were combined according to TLC analysis to yield five fractions. Fraction 2 was recrystallized in MeOH to yield 3 (96.9 mg), while fraction 3 was subjected to

• silica gel CC with n-hexane/ethyl acetate (stepwise gradient, 3:1, 2:1, and 1:1 v/v) to obtain compound 4 (37.3 mg). Fraction 5 was also subjected to silica gel CC with n-hexane/ethyl acetate (stepwise gradient, 4:1, 3:1, 2:1, and 1:1 v/v) to obtain compounds 2 (263.2 mg) and 1 (241.6 mg) eluted at

Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

• Maximillian Heidrich and
• Herbert Plenio

Beilstein J. Org. Chem. 2020, 16, 2080–2086, doi:10.3762/bjoc.16.175

• using silica gel 60 F254 (0.2 mm) on alumina plates. For preparative chromatography silica gel 60 (70–200 µm) was used. Measurements of the high resolution mass spectra (HRMS) were performed on a Bruker Daltonics Autoflex Speed TOF. Gas chromatographic data was obtained on a Clarus 500 gas

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• ), calf thymus (ct)-DNA, and poly(dG-dC)2 were obtained from Sigma–Aldrich. The starting compound 1 was prepared according to the literature [31]. Column chromatography was performed on silica gel (MerckSilica 60, particle size 0.04–0.063 mm). Semipreparative HPLC was performed on a Jai system (LC-9105

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• Organ and co-workers, who have developed silica-immobilized Pd–PEPPSI–IPr–SiO2 [31] and Pd–PEPPSI–IPent–SiO2 [32] catalysts. They observed a gradual catalyst deactivation due to the slow release of palladium over time. However, the high level of catalyst activity, especially for Pd–PEPPSI–IPent–SiO2