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

• case, the subsequent elimination step leading to an aromatized product cannot take place. All products of the type 9 are colored, typically pale yellow, both in the solid state and in solution. The UV–vis spectroscopic analysis of the naphthoquinone-derived series (compounds 9a–h) revealed less intense

• stationary phase and either petroleum ether (or hexanes)/dichloromethane or petroleum ether/AcOEt mixtures as eluent to give analytically pure products 9a–h and 10c. 1-Phenyl-3-(trifluoromethyl)-1H-benzo[f]indazole-4,9-dione (9a) Reaction time 2 d; CC (SiO2, petroleum ether/CH2Cl2 2:1); 320 mg (93%); yellow

• -dihydro-1H-indazole-4,7-dione (10c) Reaction time 2 d; CC (SiO2, petroleum ether/AcOEt 20:1); 193 mg (53%); yellow oil; 1H NMR (CDCl3, 600 MHz) δ 1.39 (s, 3H, Me), 1.52 (qbr, J = 0.5 Hz, 3H, Me), 2.05–2.07 (m, 6H, 2 Me), 2.32 (s, 3H, Me), 6.95–6.97, 7.10–7.12 (2 m, 2H each, Tol); 13C NMR (CDCl3, 151 MHz

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• products were light yellow solids with the same melting point of 115–116 °C and both had the same measured mass when analyzed by HRMS. The differences were that the specific optical rotation was measured to be +67.0° for compound 8 and +91.4° for compound 9 and their 1H NMR spectra differed for the signals

• reductive amination employing sodium triacetoxyborohydride as the reducing agent. The desired product precursor 27 was successfully recovered as a yellow oil in a yield of 95%. HRMS showed the desired mass whilst NMR spectroscopy showing a single set of signals for each half of the structure, confirmed the

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

• are provided in Supporting Information File 1. Fulvoferruginin B (2): faint yellow solid; [α]D20 +14 (c 1, MeOH); UV (MeOH) λmax (log ε) 200 (3.7), 249 (3.5) nm; 1H NMR and 13C NMR data (1H 700 MHz, 13C 175 MHz) in CD3OD: see Table 1; HRMS–ESI (m/z): [M + H]+ calcd for C15H21O3+, 249.1477; found

• –ESI (m/z): [M + H]+ calcd for C15H18O4+, 263.1283; found, 263.1276. Fulvoferruginin D (4): light yellow solid; [α]D20 +19 (c 1, MeOH); UV (MeOH) λmax (log ε) 201 (4.4), 249 (4.2) nm; 1H (700 MHz) and 13C NMR (175 MHz) data in CD3OD are collected in Table 1 and copies of spectra are collected in

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

• chromatography to deliver the required compound 8 as yellow solid (4.15 g, 99%); Rf = 0.52 (10% EtOAc/petroleum ether); 1H NMR (300 MHz, CDCl3) δ 8.53 (d, J = 8.7 Hz, 3H), 8.37 (d, J = 9 Hz, 6H), 2.99–2.90 (m, 6H), 2.21–2.23 (m, 6H), 0.99–0.82 (m, 12H), 0.58-0.52 (m, 30H); 13C NMR (75 MHz, CDCl3) δ 154.86

• with CH2Cl2, acetone, and finally with ethyl acetate to give 11 (3.13 g, 92%) as a yellow solid. Synthesis of 2,7,12-tribromo-5,5,10,10,15,15-hexabutyl-10,15-dihydro-5H-diindeno[1,2-a:1',2'-c]fluorene (5): Compound 11 (1.5 g, 2.59 mmol), dimethyl sulfoxide (20 mL), and potassium tert-butoxide (2.61 g

• , 59%) as a yellow solid; Rf = 0.60 (8% MeOH/petroleum ether); 1H NMR (400 MHz, CDCl3) δ 8.39 (d, J = 8 Hz, 3H), 7.96 (s, 3H), 7.40 (d, J = 12 Hz, 9H), 7.22 (s, 3H), 2.94–2.88 (m, 6H), 2.10–2.05 (m, 6H), 0.92–0.83 (m, 12H), 0.43–0.40 (t, J = 8 Hz, 30H); 13C NMR (101 MHz, CDCl3) δ 155.71, 145.45, 139.12

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

• 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

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• the recognition of thymol (3) [5]. The nature of the color depends on the number of phenolic hydroxy groups and the substituents. With thymol (3) and charvacrol, the color is red-violet and with resorcinol blue-violet, in both cases turning to yellow upon acidification. Compared to other color

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• yellow powder was ultrasonicated in water to obtain a g-CN aqueous colloidal dispersion. The freshly prepared CM/water colloidal dispersion was mixed with water-soluble monomer (N,N-dimethylacrylamide, DMA) and crosslinker (N,N’-methylenebisacrylamide, MBA) followed by the addition of the redox couple

• oven at 550 °C for 4 hours, with a heating rate of 2.3 °C /min. The resulting yellow powder is labeled as g-CN (CM). Synthesis of g-CN nanosheets embedded hydrogel (HGCM): 150 mg as-prepared CM was dispersed in 30 mL distilled water and sonicated 3 times for 30 minutes to exfoliate g-CN nanosheets (CM

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• carbon and filtered. Then, toluene and other potential volatiles were removed, the residue crystallized from a toluene and heptane solvent mixture to afford 36.0 g (97%) of the desired thioamide 2e as yellow crystalline solid. With the proof that ethylene glycol can efficiently decompose compound A and

• temperature. After filtration, the yellow-colored toluene solution was concentrated and the residue recrystallized from 75% EtOH/water to afford 26.1 g (84%) of the desired product 4 as yellow crystalline solid. Because of a relative lower solubility and the higher molecular weight of diamide substrate 5, a

• longer time for the reaction with LR was essential for the completion of the reaction according to TLC monitoring. Following the similar workup procedure as described for compound 4, the resulting crude product was recrystallized from toluene to afford the product as bright-yellow crystalline solid in 91

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• haloalkanes, the highest yield was given. Since a marked yellow color appeared immediately upon mixing substrates, the existence of an EDA complex could be confirmed by UV–vis spectroscopy. Conclusion In this review, reactions and mechanisms of EDA complexes were discussed from the aspects of cyclization

DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies

• Yongdong Su,
• Maitsetseg Bayarjargal,
• Tracy K. Hale and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2021, 17, 749–761, doi:10.3762/bjoc.17.65

• section are shown: nuclear DNA (blue), 4Ts-FAM/ON (magenta), cell membrane (yellow). Scale bar: 20 μm. The synthesis of ONs with Ts and N+ modification using the Staudinger reaction during the solid-phase DNA synthesis. Conditions: (i) 0.5 M TsN3, MeCN, 37 °C, 30 min for Ts modification; 0.7 M 4

Simulating the enzymes of ganglioside biosynthesis with Glycologue

• Andrew G. McDonald and
• Gavin P. Davey

Beilstein J. Org. Chem. 2021, 17, 739–748, doi:10.3762/bjoc.17.64

• reaction network predicted by the Glycologue enzyme simulator. Starting from ceramide, which is the root (leftmost) node, 41 carbohydrate structures are predicted using 10 enzymes. The edges of the graph represent enzyme reactions, colored according to the type of sugar transferred: yellow

• reactions are shown as lines colored according to the type of sugar transferred: yellow (galactosyltransferases); blue (glucosyltransferases); brown (N-acetylgalactosaminyltransferases). Single-letter codes used and their IUPAC equivalents. Enzymes of ganglioside biosynthesis and Glycologue reaction

Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases

• Naohiro Horie,
• Takao Yamaguchi,
• Shinji Kumagai and
• Satoshi Obika

Beilstein J. Org. Chem. 2021, 17, 622–629, doi:10.3762/bjoc.17.54

• (698 mg, 72%) as a yellow solid substance. 2a: −26.4 (c 1.0, CHCl3); IR (KBr): 2999, 2952, 2837, 1696, 1606, 1509, 1451, 1410, 1297, 1251, 1177, 1155, 1074, 1035 cm−1; 1H NMR (CDCl3) δ 2.00 (s, 3H), 2.80 (s, 3H), 3.48, 3.57 (AB, J = 10.7 Hz, 2H), 3.67 (s, 2H), 3.74 (s, 3H), 3.74 (s, 3H), 4.37 (s, 1H

• . NaHCO3, after which sat. aq. NH4Cl was added. Following filtration, the product was extracted with ethyl acetate, washed with water and brine, dried (using Na2SO4), and concentrated. The product was purified using column chromatography to yield 2b (1.56 g, 65%) as a yellow solid substance. 2b: −15.2 (c

• product was extracted with dichloromethane. The organic phase was washed with water and brine, dried (using Na2SO4), and concentrated. The product was purified using column chromatography to yield 3a (1.62 g, 87%) as a yellow solid substance. 3a: 31P NMR (CDCl3) δ 149.15, 149.31; HRMS–MALDI (m/z): [M + Na

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

• Marek Kõllo,
• Marje Kasari,
• Villu Kasari,
• Tõnis Pehk,
• Ivar Järving,
• Margus Lopp,
• Arvi Jõers and
• Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

• . The residue was chromatographed on silica gel with gradient 10% to 40% acetone in petroleum ether to give acetate 3 (213.2 mg, 93%) as pale yellow oil. [α]D20 +180.0 (c 0.58, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 5.68 (d, J = 1.4 Hz, 1H), 5.47 (q, J = 3.1 Hz, 1H), 2.57–2.21 (m, 6H), 2.20–2.05 (m, 4H

Breakdown of 3-(allylsulfonio)propanoates in bacteria from the Roseobacter group yields garlic oil constituents

• Anuj Kumar Chhalodia and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 569–580, doi:10.3762/bjoc.17.51

• , 7.56 mmol, 30%) as pale yellow oil. TLC Rf 0.44 (cyclohexane/EtOAc 10:3); IR (diamond-ATR) ν̃: 2998 (w), 2952 (w), 2845 (w), 2256 (w), 1730 (m), 1436 (w), 1354 (w), 1240 (w), 1215(w), 1195 (w), 1171 (w), 1139 (w), 1046 (w), 1017 (w), 979 (w), 907 (w), 822 (w), 726 (m), 648 (w), 435 (w) cm−1; 1H NMR

• minutes, 30% hydrogen peroxide solution (0.52 mL, 0.57 g, 5.0 mmol, 2.0 equiv) was added dropwise. The color of the reaction mixture changed from colorless to yellow. The reaction mixture was stirred for 30 minutes at room temperature. After completion of the reaction, EtOAc (10 mL) was added, causing

Identification of volatiles from six marine Celeribacter strains

• Anuj Kumar Chhalodia,
• Jan Rinkel,
• Dorota Konvalinkova,
• Jörn Petersen and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

• chromatography (cyclohexane/ethyl acetate 99:1) gave a mixture of stereoisomers (Z)-42 and (E)-42 as pale yellow oil (96 mg, 0.65 mmol, 92%, dr 94:6 by 1H NMR). The product mixture was separated by preparative HPLC to give pure (Z)-42 (73 mg, 0.50 mmol, 70%) and (E)-42 (6 mg, 0.04 mmol, 6%). (Z)-42. Rf 0.74

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• (toluene/MeCN; gradient 50% → 75%) gave product 5a as a slightly yellow amorphous solid, Rf = 0.17 (toluene/MeCN 1:1). Yield 103 mg, 87%. HPLC: tR = 6.33 min, purity 98%; IR (KBr) ν (cm−1): 3400, 2955, 2925, 2855, 2205, 2170, 1590, 1460, 1430, 1410, 1350, 1235, 1040; 1H NMR (300 MHz, CD3OD + D2O) δ 9.05 (s

Helicene synthesis by Brønsted acid-catalyzed cycloaromatization in HFIP [(CF₃)₂CHOH]

• Takeshi Fujita,
• Noriaki Shoji,
• Nao Yoshikawa and
• Junji Ichikawa

Beilstein J. Org. Chem. 2021, 17, 396–403, doi:10.3762/bjoc.17.35

• ) to give 1b (60 mg, 92%) as a yellow solid. 1H NMR (500 MHz, CDCl3) δ 6.66 (dd, J = 8.5, 7.4 Hz, 2H), 7.19 (dd, J = 7.9, 7.4 Hz, 2H), 7.58 (d, J = 8.5 Hz, 2H), 7.80 (d, J = 7.9 Hz, 2H), 7.89 (s, 4H), 7.93 (d, J = 8.1 Hz, 2H), 7.96 (d, J = 8.1 Hz, 2H); 13C NMR (126 MHz, CDCl3) δ 124.0, 124.6, 125.5

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• quaternization proceeded regioselectively using the t-BuOH/HClO4 system [25]. Further, the salts 7 were treated with sodium hydroxide in the biphasic system water/chloroform giving aminides 8, which were extracted from the reaction mixtures by chloroform. The obtained aminides 8 are yellow solids and soluble in

• various organic solvents, such as alcohols, chloroform, dichloromethane, hexane, acetonitrile, toluene, and THF. They are also soluble in water. Remarkably, the solutions in organic solutions are yellow colored, whereas aqueous solutions are colorless. The UV–vis spectra of 8a were found to show

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• then diluted with aq acetic acid (20 mL, H2O/AcOH 3:1 (v/v)), concentrated, and extracted with ethyl acetate (3 × 100 mL). The combined organic extracts were washed sequentially with water (40 mL) and brine (10 mL), then dried (Na2SO4) and concentrated to afford a pale yellow solid which could be used

• of water with toluene (2 × 50 mL). The residue was purified by column chromatography (toluene/ethyl acetate/acetone 3:2:0–12:8:5) to afford the title compound as a yellow amorphous solid (345 mg, 56% corrected for the presence of ≈10 wt % toluene). The data are consistent with literature values [22

• . The residue was purified by column chromatography (toluene/ethyl acetate/acetone 3:2:0–0:1:1) to afford the title compound as a yellow glass (34.7 mg, 37%). The data are consistent with literature values [22]. Rf 0.40 (acetone/ethyl acetate/toluene 2:1:1); mp 49 °C [lit. mp not given]; IR νmax 3234br

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• ether from 0 to 50%) afforded the pure ferulates 1a, 1b, 3–9, and 12. 5-Bromo-4-chloro-3-indolyl 5-O-trans-feruloyl-α-ʟ-arabinofuranoside (1a, 107 mg, 0.19 mmol, 73%). Green-yellow foam. The NMR data (CD3OD) were consistent with those previously reported [15]. 4-Nitrophenyl 5-O-trans-feruloyl-α-ʟ

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

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

• of above 50 μM. This screening was performed by measuring the cell viability using an MTT assay, where the viability is assessed based upon the reduction of the yellow tetrazolium MTT [3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide] by metabolically active and hence viable cells. The

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• the F4Az-based assemblies did not show fluorescence behaviour, the following discussion focuses on the assemblies NO2-C9∙∙∙F4St as representative example. The fluorescence of NO2-C9 appears yellow-green, while F4St is non-fluorescent. Upon formation of the halogen-bonded liquid crystal, green

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• column chromatography to afford the products 2. 2-Bromo-2-chloro-1,1-difluoroethyl phenyl ether (2a): The title product 2a was purified by column chromatography and preparative TLC (hexane only) and obtained in 74% yield (199.6 mg). Pale yellow oil; 1H NMR (400 MHz, CDCl3) δ 5.91 (t, J = 5.2 Hz, 1H

• diastereoisomers (syn/anti 2:1) in 21% yield (36.9 mg). Yellow oil; 1H NMR (400 MHz, CDCl3) δ 3.48 (ddd, J = 18.7, 5.2, 1.4 Hz, anti-isomer), 3.73 (ddd, J = 18.7, 7.0, 1.2 Hz, anti-isomer, 2H), 3.57–3.71 (m, syn-isomer, 2H), 4.04–4.18 (m, anti-isomer, 1H), 4.29–4.37 (m, syn-isomer, 1H), 4.66 (ddd, J = 7.0, 6.0