Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• , Scheme S2) [26]. When rac-TBPP was mixed with DGG at molar ratios from 1:100 to 1:16 (rac-TBPP/DGG), transparent yellow co-gels were successfully formed by being heated to dissolve in chloroform, and then cooled to ambient temperature (Supporting Information File 1, Figure S6). Owing to the AIE effect of

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• yellow solid (the longest λmax 414 nm, CH2Cl2) [42]. All azine-fused analogs of 12 are yellow-orange. The annelation of the pyridine or pyrazine ring to the skeleton of 12 only slightly changed the wavelength of the absorption maximum (the longest λmax 411 and 418 nm, respectively), whereas the

• ]helicenes 10 only weak fluorescence in the solution under UV irradiation was observed (Table 7, see also Supporting Information File 1, Figures S42–S45). Helicenes 10b and 10c exhibited blue emission with emission peaks at 481 and 440 nm, respectively. Quinoxaline-fused helicene 10a demonstrated a yellow

Semiautomated glycoproteomics data analysis workflow for maximized glycopeptide identification and reliable quantification

• Steffen Lippold,
• Arnoud H. de Ru,
• Jan Nouta,
• Peter A. van Veelen,
• Magnus Palmblad,
• Manfred Wuhrer and
• Noortje de Haan

Beilstein J. Org. Chem. 2020, 16, 3038–3051, doi:10.3762/bjoc.16.253

• pattern check of the raw data). The assignment of the compositions is based on information from all replicates. Lines between compositions indicate the mass difference for Hex (yellow), HexNAc (blue), HexHexNAc (green), Fuc (red), and NeuAc (purple). * Indicates potential deconvolution errors and

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• ). Fluorescence resonance energy transfer (FRET) relies on the distance-dependent transfer of energy from a donor fluorophore to an acceptor fluorophore. Genetically encoded fluorophores, such as green fluorescent protein (GFP) and related blue, cyan, yellow and red fluorescent proteins have provided the ability

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• characterized by nuclear magnetic resonance spectroscopy (NMR, Supporting Information File 1, Figures S1–S24) as well as exact electrospray mass spectrometry (EM–ESIMS, Supporting Information File 1, Figures S25–S30) and appear as white to faint yellow solids. Only the dimethylamino-substituted product shows a

• bright yellow color. The detailed procedures, additional structural and spectroscopic data can be found in Supporting Information File 1. To get a deeper understanding at the molecular level, a crystalline sample suitable for an X-ray diffractometric analysis was obtained for Me by slow evaporation of a

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

• 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

• bath preheated to 160 °C, and stirred for 2 h. Upon reaction completion, the aqueous work-up, isolation, and purification of the product was performed in the same way as described in the typical procedure 1. The titled compound was obtained as yellow solid (lit. [54] yellow crystals), yield 66% (96 mg

• completion, the aqueous work-up, isolation, and purification of the product were performed in the same way as described in the typical procedure 1. The titled compound was obtained as yellow solid (lit. [36] yellow solid), yield 76% (147 mg, 0.76 mmol). Alternatively, the same compound was obtained via the

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

• ): 1af (red), 1bf (yellow), 1cf (green), and 1df (blue) (n = 3). Conditions: 1 μM oligonucleotide, 300 mM NaClO4, 5 mM Mg(ClO4)2, and 20 mM MOPS buffer (pH 7.4). Elution of the aptamers from the ATP-agarose gel in the presence of 1 equiv of Ag(I): 1af (red), 1bf (yellow), 1cf (green), and 1df (blue) (n

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

• change from colorless to yellow, which darkened or brightened to orange or yellow and thickened with the occurrence of crystals on the sides of the flask. Once the spot or the peak corresponding to the benzaldehyde disappeared on the TLC plate or in the gas chromatogram, the time was taken as the

Synthesis and investigation of quadruplex-DNA-binding, 9-O-substituted berberine derivatives

• Jonas Becher,
• Daria V. Berdnikova,
• Heiko Ihmels and
• Christopher Stremmel

Beilstein J. Org. Chem. 2020, 16, 2795–2806, doi:10.3762/bjoc.16.230

• DMSO (15 mL). The DMSO fractions were combined and the solvent was removed in vacuum. The remaining yellow solid was suspended in MeCN (500 mL) and filtered through a short pad of celite. The solvent was evaporated under reduced pressure and the crude product was purified by column chromatography (SiO2

• , CH2Cl2/MeOH 5→10%). After crystallization of the major fraction from MeOH/Et2O 7:3 the desired product was obtained as yellow solid. 9-O-{β-{4'-[(9''-Adenyl)methyl]-1H-1',2',3'-triazol-1'-yl}ethyl}berberine bromide (4a) According to the GP, a solution of 3a (150 mg, 292 µmol), 2 (60.6 mg, 350 µmol

• µmol) was stirred at reflux in THF/H2O/MeCN 2:2:1 (25 mL). After purification by column chromatography (Rf = 0.12, 10% MeOH) and crystallization the product 4b was obtained as yellow, amorphous solid (42.3 mg, 64.0 µmol, 26%); mp 189–192 °C (dec.); 1H NMR (600 MHz, DMSO-d6) δ 2.41 (tt, 3J = 7 Hz, 3J

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• removed under reduced pressure to give 1.5 g of a slightly yellow solid. This was redissolved in 20 mL of 1:1 mixture of dichloromethane/hexane and kept at −15 °C. A yellow precipitate (0.1 g) was filtered off, and the solvent was removed to leave 1.2 g of the crude product (mp 86–88 °C), which was found

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

• ). Nocarimidazole C (1) was obtained as a pale yellow amorphous solid. The molecular formula was determined as C12H21N3O based on a protonated molecular ion [M + H]+ at m/z 224.1763 (Δ = +0.6 mmu). The four degrees of unsaturation, calculated from the molecular formula, and the UV absorption band around 296 nm

• -enantiomer (Figure 4b). Additionally, the same chiral analysis with bulbimidazole A (5) obtained in this study proved the enantiomeric ratio as R/S = 1.4:98.6 (Figure 4c). Nocarimidazole D (2) was isolated as a pale yellow amorphous solid. The molecular formula of 2 was deduced as C13H23N3O, 14 amu

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

• heated under a nitrogen atmosphere at 70 °C for 12 h. The mixture was then cooled to room temperature and the suspension was filtered, and washed with acetonitrile. The resulting filtrate was evaporated under vacuum to afford the crude product as yellow solid. Further recrystallization from

• dichloromethane/ethanol provided the pure product as pale-yellow solid (1.06 g, 1.71 mmol, 31%). Mp 197.3–197.4 °C; 1H NMR (400 MHz, CDCl3) δ 7.09 (s, 6H, HAr), 4.72 (dd, J = 3.7 Hz, J = 2.4 Hz, 12H, OCH2), 4.32 (s, 3H, Ar2CH), 2.53 (t, J = 2.3 Hz, 6H, C≡CH), 1.68 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) 147.87

• were dried on a slide glass. C60 was tested in powder form on a slide glass. Molecular model of the complex TBTQ-(OG)6 C60 in water, as generated by DFT calculations. (a) Side-view; (b) top-view; (c) hydrophobic surface diagram. In part, H atoms were omitted for clarity (yellow: C, red: O, blue: N

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• NPs. A one-pot synthesis method was used to both deposit Pd salts and reduce them into NPs onto the support material. First, PdCl2 was mixed for 15 min with either ChNC or ChsNC in an acidic aqueous medium to form a dark yellow mixture. This step facilitated coordination of Pd salts onto the support

• parameters were performed on PdCl2 and either ChNC or ChsNC, but with no H2 reductant. In this case, the solution color remained yellow, indicating that using either ChNC or ChsNC alone cannot fully reduce PdCl2. The resulting hybrid materials are noted PdNP@ChNC and PdNP@ChsNC, respectively. Dihydrogen was

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• 5a at the lactone carbonyl group, and the product 4a, when o-aminothiophenol’s NH2 group attacked compound 5a at the lactone carbonyl group. The in situ formation of 5-phenylfuran-2,3-dione (5a) was indicated by the appearance of bright yellow color (characteristic for the 5-arylfuran-2,3-diones 5 [6

• ]) after mixing the suspension of acid 2a with a carbodiimide. In addition, after mixing the suspension of acid 2a in acetonitrile with DIC, the formation of the yellow precipitate of 5-phenylfuran-2,3-dione (5a) was observed, and compound 5a could be isolated by simple filtration. Moreover, after mixing

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

• Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

• ]. Photoreaction of 7a and 7b Irradiation of a degassed solution of 7a,b in benzene at 254 nm for 3–4 h yielded a pale yellow solid of ketene 10a,b (Scheme 5, Table 2) through regioselective photoinduced 1,5-phenyl migration and we did not obtain any 1,2-AS or any other photoproduct. The same ketenes were isolated

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• changes. As shown in Figure 6, the color of the free dye 12 dissolved in DMSO was light yellow. The addition of 15 equiv of TBAOH to the solution led to a change of the colorless solution to blue under UV light, whereas no color change was observed in ambient light. The observed color change under UV

• light indicated that the dye was deprotonated. Indeed, the addition of only 5 equiv of TFA regenerated the light yellow color of the solution indicative for the reversed protonation of 12. All dyes, except 8, showed this reversibility. Furthermore, the limits of detection (LOD) and quantification (LOQ

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

• ) was added and the yellow precipitate was filtered, and washed with ether. The crude product was further purified by column chromatography (1% methanol in chloroform). Yield 50%. 1H NMR (300 MHz, DMSO-d6, Figure S28, Supporting Information File 1) δ 8.59 (br. s, 4H, NDI), 8.04 (br. s, 2H, NH), 7.87

• atmosphere. Then, water (100 mL) was added and the yellow precipitate was filtered, and washed with ether. After Boc and Fmoc deprotection by using TFA and piperidine, respectively, crude compound 4 was obtained. The crude product was further purified by column chromatography (1% methanol in chloroform

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

• catalytic efficiency of persulfate. The reaction was found occurring most efficiently with 1 equiv of 1i, 3 equiv of potassium thiocyanate 2, and 0.5 equiv of potassium persulfate with a yield of 97% of 3i. The yellow solid obtained after filtration of the reaction mixture afforded pure product 3i without

• TLC), the solid that separated was filtered, washed with water and acetonitrile and recrystallized with cold diethyl ether to obtain pure yellow product 3. General procedure for the preparation of 4: To a solution of azidochalcone 1 (1 mmol) in dry acetonitrile (2 mL) were added potassium thiocyanate

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

• muyocopronones A (1) and B (2) were isolated from the ethyl acetate layer together with eugenitin (3) [17], and 6-methoxymethyleugenin (4) [18]. The structures of compounds 3 and 4 were identified on the basis of their 1H and 13C NMR data (Figure 1). Muyocopronone A (1) was isolated as yellow amorphous solid

• configuration of muyocopronone A (1) was established as the (2′R,3′R,4′S,7S,10R,11R) stereoisomer. Muyocopronone B (2) was also obtained as yellow amorphous solid, and its ESIMS was consistent with the molecular formula C25H32O7, thereby suggesting the addition of two hydrogen atoms relative to 1. A comparison

• solvent mixture ratio of 2:1 and 1:1, respectively. Muyocopronone A (1) Yellow amorphous solid; [α]D22 +41 (c 0.1, MeOH); UV (MeOH) λmax (log ε) 221 (4.34), 329 (4.25) nm; ECD (0.02 mg/mL, MeOH) λext (Δε) 219 (−2.48), 236 (−4.29), 255 (+1.10), 276 (−1.37), 326 (+2.05), 358 (+2.25) nm; IR (KBr) νmax: 3468

Isolation and structure determination of a tetrameric sulfonyl dilithio methandiide in solution based on crystal structure analysis and ⁶Li/¹³C NMR spectroscopic data

• Jürgen Vollhardt,
• Hans Jörg Lindner and
• Hans-Joachim Gais

Beilstein J. Org. Chem. 2020, 16, 2057–2063, doi:10.3762/bjoc.16.172

• leading to an exchange of the dianionic C atoms. It stands in THF in equilibrium with a second aggregate, which is only stable at low temperatures. Functionalized dilithio methandiides (FG = functional group). Structure of (2a)4·(THF)6 in the crystal. Color code: black, C; green, Si; yellow, S; red, O

• Symmetric carbon–lithium chain of 2a-I in THF, showing the carbon–lithium connectivities, multiplicities of the NMR signals (left), and magnitudes of 1J(6Li,13C) couplings in Hz (right) [15]. the structure of (2a)6·Li2O·(THF)6 in the crystal [15]. Color code: black, C; green, Si; yellow, S; red, O; pink, Li

Automated high-content imaging for cellular uptake, from the Schmuck cation to the latest cyclic oligochalcogenides

• Rémi Martinent,
• Javier López-Andarias,
• Dimitri Moreau,
• Yangyang Cheng,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2020, 16, 2007–2016, doi:10.3762/bjoc.16.167

• protein were used to segment whole cells and mitochondria, respectively (blue and yellow areas, Figure 7a). The structural characteristics of the cells were extracted from both masks. Possible damaged cells with early signs of apoptosis or abnormal mitochondrial networks were excluded (Figure 7a, right

• constant number of selected cells based on the above criteria, with an increasing concentration, revealed that complex 25 is not toxic up to 20 µM (Figure 9a, black). The effective concentration of 25 obtained with the mitochondria mask was CP50 = 7.3 ± 0.5 μM (Figure 9a and Figure 9b, yellow). With the

• underexpression of the fusion protein, and undesired localization out of the selected organelle. To explore how automated HC imaging can handle these problems, a whole-cell body mask was applied first (Figure 10a, cyan, including yellow). With this mask, the fluorescence of GFP and 26 correlated with r2 = 0.626

Synthesis, docking study and biological evaluation of ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones as potential inhibitors of the mycobacterial galactan synthesis targeting the galactofuranosyltransferase GlfT2

• Marek Baráth,
• Jana Jakubčinová,
• Zuzana Konyariková,
• Stanislav Kozmon,
• Katarína Mikušová and
• Maroš Bella

Beilstein J. Org. Chem. 2020, 16, 1853–1862, doi:10.3762/bjoc.16.152

• –GlfT2 interactions are depicted as dashed lines (yellow – hydrogen bonds, magenta – salt bridge, green – cation/π interaction). The Mg2+ ion is shown as a purple sphere. TLC analysis of the effects of the target compounds at 500 μM on the production of lower lipid-linked galactan precursors. CON

One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes

• Haruyasu Asahara,
• Minami Hiraishi and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2020, 16, 1830–1836, doi:10.3762/bjoc.16.150

• water (100 mL), the pH value was adjusted to 7 with a 2 M aqueous sodium hydroxide solution. This was extracted with ethyl acetate (50 mL × 3), and the organic layer was washed with brine (100 mL × 1), dried over magnesium sulfate, and concentrated to afford crude product (2.66 g) as yellow solid. The

• solid was recrystalized with a mixed solvent (hexane/dichloromethane 10:1) to afford nitrostyrene 1a [24] (1.99 g, 12.2 mmol, 76%) as yellow needles. The other nitroalkenes 1b–f [25][26][27][28][29] were prepared in the same way. One-pot Diels–Alder reaction of nitrostyrene 1a and Danishefsky’s diene (2

• sealed tube. After the removal of the solvent under reduced pressure, the residue was treated by column chromatography using silica gel (hexane/ethyl acetate 9:1) to afford the major isomer of cyclohexanone 4a (205 mg, 0.32 mmol, 78%) as yellow solid and the minor isomer of cyclohexanone 4a (26.3 mg

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• , 0.20 g (86%) as yellow solid. General experimental procedure for the synthesis of β-carboline C-1-substituted benzothiophenone derivatives (2aA, 2bA, 2dA, and 2hA) as exemplified for compound 2bA. A 10 mL round-bottomed flask was charged with 2-nitrochalcone 1bA (0.20 g, 0.482 mmol), Et3N (0.336 mL

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

• achieved as a pure pale yellow solid directly from the reaction medium with the best yields (Table 1, entry 7). In tetrahydrofuran (THF), in ethyl acetate (EtOAc), and in alcohols such as methanol, ethanol, isopropanol (MeOH, EtOH, iPrOH) the reaction furnishes a complicate profile, where the desired 2a is

• )-9,10-dimethoxy-5,6,8,13-tetrahydro-[1,3]dioxolo[4,5-g]isoquinolino[3,2-a]isoquinolin-7-ium bromide (2a): 2a was isolated by precipitation in the reaction medium (DCM) in 66% yield (428 mg). Pale yellow amorphous solid; mp: 123–124 °C; 1H NMR (400 MHz, DMSO-d6, 25 °C) δ 1.45 (s, 9H, C(CH3)3), 2.54–2.60