Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• temperature, diluted with water and 50 mL of EtOAc and passed through a pad of celite. The organic layer was washed with H2O (2 × 10 mL) and saturated NaCl (aq) (1 × 10 mL). The organic part was dried over Na2SO4, evaporated and purified by flash chromatography, using ethyl acetate/petroleum ether (2:8) as

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

• Iris Binyamin,
• Shoval Meidan-Shani and
• Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

• not increase the conversion percentage to the desired products significantly. Under these reaction conditions 58–85% yield of 4a–e were observed and the pure products were isolated in 30–80% yield following flash chromatography. The relative amount of the Grignard reagents used was found to be crucial

• high yields (83–97%), leading after work-up and flash chromatography purification to high to moderate (38–95%) isolated yields (Table 2). In general, the relatively higher yields of the phosphine oxides 5a–5e compared to the phosphinate analogs 4a–e can be attributed to the lack of the exocyclic ester

Intermolecular addition reactions of N-alkyl-N-chlorosulfonamides to unsaturated compounds

• Gerold Heuger and
• Richard Göttlich

Beilstein J. Org. Chem. 2015, 11, 1226–1234, doi:10.3762/bjoc.11.136

• radicals. Addition to non-aromatic alkenes proceeds less readily in lower yield and electron-rich alkenes react via a competing polar reaction pathway. Experimental All solvents were purified by distillation and dried, if necessary, prior to use. Products were purified by flash chromatography on silica gel

• and stirred for 48 h at this temperature. The solvent was removed by bulb-to-bulb distillation and the residue was taken up in dichloromethane. Approx. 10 g of silica gel were added and the solvent was removed in vacuo. Purifying by flash chromatography (pentane/ether 10:1 to 1:1) gave the addition

Cathodic hydrodimerization of nitroolefins

• Michael Weßling and
• Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

• washing the solid with petroleum ether/diethyl ether. The products are obtained after purification by flash chromatography as colourless oils, which are mixtures of diastereomers. They crystallize partially or completely after some time and are in general not sensitive against air and light. An exception

• chromatography. The aliphatic nitroalkene 17 could be hydrodimerized in 68% yield to the hydrodimer 31, which is a mixture of diastereomers. Partial separation by flash chromatography and 1H NMR spectroscopy of the fractions indicates four diastereomers in a ratio of about 38:9:14:1. It is possible to substitute

• differ significantly in their MS and IR spectra the compounds had to be characterized by their 1H NMR data. For that purpose the diastereomers were purified as good as possible by flash chromatography and/or HPLC. Single diastereomers are denoted alphanumerically (e.g., 2a, 2b). The same letter means for

Are D-manno-configured Amadori products ligands of the bacterial lectin FimH?

• Tobias-Elias Gloe,
• Insa Stamer,
• Cornelia Hojnik,
• Tanja M. Wrodnigg and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 1096–1104, doi:10.3762/bjoc.11.123

• performed on precoated silica gel plates on aluminum 60 F254 (E. Merck 5554). Detection was effected by UV and/or charring with 10% sulfuric acid in EtOH and/or with ceric ammonium molybdate (100 g ammonium molybdate/8 g ceric sulfate in 1 L 10% H2SO4) followed by heat treatment at ≈180 °C. Flash

• chromatography was performed on silica gel 60 (0.035–0.070 mm, 60 A, Acros Organics 24036) using distilled solvents. For biological testing, black MaxiSorp™ plates were used from Nunc™ (Thermo Scientific™). Bacterial adhesion studies were performed according to the literature [30], using a Tecan infinite® 200

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• aromatic starting material and then purified by flash chromatography on silica gel to afford pure N-arylated MPTTFs. Preparation and characterization of 2-[4,5-bis(propylthio)-1,3-dithiol-2-ylidene]-5-(4-methoxyphenyl)-5H-1,3-dithiolo[4,5-c]pyrrole (4a) and 2-[1,3-dithiol-2-ylidene]-5-(4-methoxyphenyl)-5H

• -dithiolo[4,5-c]pyrrole (4b). Prepared from 7b (0.040 g, 0.119 mmol), CuI (0.023 g, 0.119 mmol), K3PO4 (0.020 g, 0.954 mmol), trans-diaminocyclohexane (22 µL, 0.179 mmol) and 4-bromoanisole (8a, 0.033 g, 0.179 mmol) in 3 mL of dry dioxane. The product was purified by flash chromatography (CH2Cl2/cyclohexane

• 4-bromonitrobenzene (8b, 0.045 g, 0.224 mmol) in 2 mL of dry dioxane. The product was purified by flash chromatography (CH2Cl2) to afford deep red crystals. X-ray quality crystals were grown by slow evaporation of CDCl3/heptane solution. Yield: 59.7 mg (0.116 mmol, 83%). Mp 240–244 °C; Rf = 0.72

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• thin-layer chromatography (TLC). Products were purified by flash chromatography on silica gel (32–63 μm, Macherey & Nagel). Yields refer to chromatographically and spectroscopically (1H NMR) homogeneous materials, unless otherwise stated. NMR spectra were recorded on Bruker (AM 250, AC500, AVIII 700

Synthesis and surface grafting of a β-cyclodextrin dimer facilitating cooperative inclusion of 2,6-ANS

• Lars W. Städe,
• Thorbjørn T. Nielsen,
• Laurent Duroux,
• Reinhard Wimmer,
• Kyoko Shimizu and
• Kim L. Larsen

Beilstein J. Org. Chem. 2015, 11, 514–523, doi:10.3762/bjoc.11.58

• quantitative nature of the CuAAC. The formation of a β-CD trimer was not anticipated to be of major concern because of the unfavorable steric interactions upon grafting of a third β-CD onto the β-CD dimer. This was confirmed during purification by flash chromatography by observation of a major peak with a

• . General procedures: MALDI–TOF mass spectrometry was performed on a Reflex III (Bruker Daltonics, Bremen, Germany) and automated flash chromatography was performed on a Grace Davidson Discovery Science Revelaris system. NMR spectra were recorded at 298.1 K on a Bruker AVIII-600 MHz instrument equipped with

Matsuda–Heck reaction with arenediazonium tosylates in water

• Ksenia V. Kutonova,
• Marina E. Trusova,
• Andrey V. Stankevich,
• Pavel S. Postnikov and
• Victor D. Filimonov

Beilstein J. Org. Chem. 2015, 11, 358–362, doi:10.3762/bjoc.11.41

• a rotary evaporator under reduced pressure and the crude product was purified by flash chromatography. 3-Chloropropyl (E)-3-(4-nitrophenyl)acrylate (3ba): Yield 90%, 0.90 mmol, pale yellow solid, mp 86 °C; 1H NMR (300 MHz, DMSO-d6) δ 8.23 (d, J = 8.7 Hz, 2H), 8.00 (d, J = 8.7 Hz, 2H), 7.77 (d, J

C-5’-Triazolyl-2’-oxa-3’-aza-4’a-carbanucleosides: Synthesis and biological evaluation

• Roberto Romeo,
• Caterina Carnovale,
• Salvatore V. Giofrè,
• Maria A. Chiacchio,
• Adriana Garozzo,
• Emanuele Amata,
• Giovanni Romeo and
• Ugo Chiacchio

Beilstein J. Org. Chem. 2015, 11, 328–334, doi:10.3762/bjoc.11.38

• azides, 11 and 12, epimeric at C-5, in a relative ratio 2:1 with a global yield of 85%. Two azides were separated by flash chromatography (CH2Cl2/MeOH 98:2 as eluent). Compound 12 originates from 11: its formation can be rationalized by considering that the acidic medium of the reaction, linked to the

Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

• Thorbjørn Terndrup Nielsen,
• Catherine Amiel,
• Laurent Duroux,
• Kim Lambertsen Larsen,
• Lars Wagner Städe,
• Reinhard Wimmer and
• Véronique Wintgens

Beilstein J. Org. Chem. 2015, 11, 147–154, doi:10.3762/bjoc.11.14

• conversion of the CPT after 24 hours. The N3CPT was purified by automated flash chromatography and obtained in good yields (>80%) and purity (verified by NMR spectroscopy). From the N3CPT two series of novel CPT-dextrans were synthesized by a copper(I)-catalyzed alkyne azide coupling (CuAAC). The dextrans

• -deoxyβ-CD onto 70 kDa dextran modified by 7-heptynoic acid, in a similar way as described in literature [15]. The polymer contained 58.6% β-CD (w/w). TLC analyses were made with ALUGRAM® SIL G/UV254 TLC plates with 0.2 mm silica gel, and visualized using UV light. Automated flash chromatography was made

• subjected to automated flash chromatography on a 40 g silica column using a linear DCM/methanol gradient (0–8%). The appropriate fractions were combined, the solvent was removed in vacuo and 575 mg (82%) yellow powder was isolated. 1H NMR (CDCl3) δ (ppm) 8.41 (s, 1H), 8.22 (d, 1H), 7.95 (d, 1H), 7.85 (t, 1H

Multicomponent versus domino reactions: One-pot free-radical synthesis of β-amino-ethers and β-amino-alcohols

• Bianca Rossi,
• Nadia Pastori,
• Simona Prosperini and
• Carlo Punta

Beilstein J. Org. Chem. 2015, 11, 66–73, doi:10.3762/bjoc.11.10

• solution was extracted with EtOAc (3 × 50 mL), and the combined organic layers were dried over Na2SO4 and concentrated in vacuum. Purification of the crude residue by flash chromatography afforded aminoalkylated ethers as the last eluting products. Yields of isolated products are based on the starting

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators

• Navneet Goyal,
• Hari P. R. Mangunuru,
• Bargav Parikh,
• Sonu Shrestha and
• Guijun Wang

Beilstein J. Org. Chem. 2014, 10, 3111–3121, doi:10.3762/bjoc.10.328

• corresponding acid chloride was added dropwise to the solution. The mixture was left stirring for 6–10 h, after which the mixture was concentrated by using a rotary evaporator. The crude residue was purified by flash chromatography by means of a hexane/DCM/MeOH gradient solvent system. The amide derivatives 7

• the mixture was concentrated by using a rotary evaporator. If needed, the crude products were purified by flash chromatography on silica gel. A DCM/MeOH gradient solvent system was used for the chromatography separation. Compound characterization data Compound 7: Pentylamide, isolated as a white solid

Synthesis of divalent ligands of β-thio- and β-N-galactopyranosides and related lactosides and their evaluation as substrates and inhibitors of Trypanosoma cruzi trans-sialidase

• María Emilia Cano,
• Rosalía Agusti,
• Alejandro J. Cagnoni,
• María Florencia Tesoriero,
• José Kovensky,
• María Laura Uhrig and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 3073–3086, doi:10.3762/bjoc.10.324

• irradiation during 50 min. The mixture was then poured into a 1:1 H2O/NH4Cl solution (20 mL) and extracted with EtOAc (4 × 15 mL). The organic layer was dried (Na2SO4), filtered, and the solvent was removed under reduced pressure. The residue was purified by flash chromatography, using the solvent system

Synthesis and characterization of a new photoinduced switchable β-cyclodextrin dimer

• Florian Hamon,
• Claire Blaszkiewicz,
• Marie Buchotte,
• Estelle Banaszak-Léonard,
• Hervé Bricout,
• Sébastien Tilloy,
• Eric Monflier,
• Christine Cézard,
• Laurent Bouteiller,
• Christophe Len and
• Florence Djedaini-Pilard

Beilstein J. Org. Chem. 2014, 10, 2874–2885, doi:10.3762/bjoc.10.304

• with a yield of 49% (Scheme 1) [30]. Then, the carboxylic groups were activated by N-hydroxysuccinimide (NHS) and condensed with mono-6-amino-6-deoxy-β-cyclodextrin (β-CD-NH2) [31] in anhydrous DMF at room temperature. Flash chromatography (C18 column, H2O/MeOH 90:10 to 10:90 v/v in 20 min) afforded

• addition of acetone, then dried under reduced pressure. The product 1 was obtained as an orange powder (m = 4.44 g) with a quantitative yield and an HPLC purity over 98%. Then, the product was purified by flash chromatography (20 min, H2O/MeOH from 90:10 to 10:90 (v/v), 40 mL·min−1) to afford compound 1

Galactan synthesis in a single step via oligomerization of monosaccharides

• Marius Dräger and
• Amit Basu

Beilstein J. Org. Chem. 2014, 10, 2658–2663, doi:10.3762/bjoc.10.279

• glycosylation methods, and the rapid access to glycans in a single step is a strength of this approach. All of the oligosaccharides reported here have successfully been separated using routine normal-phase silica gel columns on a commercially available flash chromatography system. The oligomerization described

A new approach for the synthesis of bisindoles through AgOTf as catalyst

• Jorge Beltrá,
• M. Concepción Gimeno and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2014, 10, 2206–2214, doi:10.3762/bjoc.10.228

• these interesting and appealing reaction products, for which there is still a continuous demand. Experimental Purification of reaction products was carried out by flash chromatography using silica gel (0.063–0.200 mm). Analytical thin-layer chromatography was performed on 0.25 mm silical gel 60-F plates

• removed under vacuum. Then, adducts 6 were finally isolated by flash chromatography (SiO2; hexane/EtOAc, 8:2). Yield for each final product is reported in Table 2. Final products should be stored under nitrogen atmosphere and in the fridge. 3,3'-(3-phenylpropane-1,1-diyl)bis(1H-indole) (6ac) Following

Exploration of C–H and N–H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines

• Michael Ghobrial,
• Marko D. Mihovilovic and
• Michael Schnürch

Beilstein J. Org. Chem. 2014, 10, 2186–2199, doi:10.3762/bjoc.10.226

• steric situation. N-Arylation of 4 was initially attempted under the iron-catalyzed N-arylation conditions reported by Bolm [60]. Gratifyingly, the reaction of 4a with iodobenzene afforded product 7a in a good yield of 72% (86% based on re-isolated 4a) after flash chromatography (Table 3, entry 1

Synthesis of 2-substituted tryptophans via a C3- to C2-alkyl migration

• Michele Mari,
• Simone Lucarini,
• Francesca Bartoccini,
• Giovanni Piersanti and
• Gilberto Spadoni

Beilstein J. Org. Chem. 2014, 10, 1991–1998, doi:10.3762/bjoc.10.207

• . The crude product was purified by flash chromatography on silica gel (cyclohexane/ethyl acetate 8:2, or CH2Cl2/methanol 98:2 for 3h, as eluent) and/or crystallization. Friedel–Crafts alkylation of 3-substituted indoles. Optimization of the reaction conditions.a Synthesis of 2-benzyltryptophans 3a–j.a

Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

• Maroš Bella,
• Bohumil Steiner,
• Vratislav Langer and
• Miroslav Koóš

Beilstein J. Org. Chem. 2014, 10, 1942–1950, doi:10.3762/bjoc.10.202

• technique. When reporting assignments of NMR signals, the data for the phenyl moiety are identified by a prime. The EI mass spectra (70 eV) were obtained on a Q-Tof Premier instrument (Waters). Column chromatography was performed as flash chromatography on Silica Gel 60 (E. Merck, 0.063–0.200 mm). The IR

Syntheses of ¹⁵N-labeled pre-queuosine nucleobase derivatives

• Jasmin Levic and
• Ronald Micura

Beilstein J. Org. Chem. 2014, 10, 1914–1918, doi:10.3762/bjoc.10.199

• with hydrazine hydrate. The previously published route [11] recommended N-Boc functionalization of the preQ1 base in the crude reaction mixture to enable flash chromatography on SiO2 followed by cleavage of the auxiliary function, however, although robust in handling, the yields were rather modest. We

Structure/affinity studies in the bicyclo-DNA series: Synthesis and properties of oligonucleotides containing bc^en-T and iso-tricyclo-T nucleosides

• Branislav Dugovic,
• Michael Wagner and
• Christian J. Leumann

Beilstein J. Org. Chem. 2014, 10, 1840–1847, doi:10.3762/bjoc.10.194

• use of compound 6 as nucleobase acceptor improved the yield of nucleosides 7α,β in general and led to an acceptable β:α = 2.5:1 ratio of anomers. Subsequent saponification of 7α,β (unseparable by flash chromatography) proved to be tricky and after testing a series of standard techniques, only

• treatment with Bu4NOH in a mixed organic/aqueous solvent gave nucleosides 8α,β in good yield. It was at this step where the two anomers could be readily separated by flash chromatography. Continuing with 8β the synthesis of 10 was concluded by standard tritylation (→ 9) and phosphitylation. To extend on the

• ,β in a ratio of β:α = 1.2:1. After standard tritylation of 11α,β the anomeric mixture 12α,β became separable by flash chromatography and the corresponding β-nucleoside 12β could be smoothly converted into the phosphoramidite 13 by standard methods. Structural properties of nucleosides To get an

Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum

• Naoya Oku,
• Miyako Matsumoto,
• Kohsuke Yonejima,
• Keijiroh Tansei and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2014, 10, 1808–1816, doi:10.3762/bjoc.10.190

• the availability of genetic resources. Experimental General methods Cosmosil 75C18-PREP (Nacalai Tesque Inc., 75 µm) was used for ODS flash chromatography. NMR spectra were obtained by a Bruker AVANCE 500 spectrometer at 500 MHz for 1H. Residual solvent peaks at δH/δC 7.27/77.0 ppm in CDCl3 were used

One-pot stereoselective synthesis of α,β-differentiated diamino esters via the sequence of aminochlorination, aziridination and intermolecular S_N2 reaction

• Yiwen Xiong,
• Ping Qian,
• Chenhui Cao,
• Haibo Mei,
• Jianlin Han,
• Guigen Li and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 1802–1807, doi:10.3762/bjoc.10.189

• separated, and the aqueous phase was extracted with ethyl acetate (3 × 10 mL). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate, and concentrated to dryness. Purification by flash chromatography (EtOAc/hexane, from 1:20 to 1:3, v/v) provided final products 5. ORTEP

Convergent synthetic methodology for the construction of self-adjuvanting lipopeptide vaccines using a novel carbohydrate scaffold

• Vincent Fagan,
• Istvan Toth and
• Pavla Simerska

Beilstein J. Org. Chem. 2014, 10, 1741–1748, doi:10.3762/bjoc.10.181

• removed during work-up. The residue was alkylated with sodium hydride and propargyl bromide in dry tetrahydrofuran (THF) to give intermediate 7, which was not isolated. The methoxy ester was hydrolyzed in situ by addition of sodium hydroxide. Acid–base extraction and purification by flash chromatography

• . Treatment of commercially available Fmoc-Lys-OH with lauroyl chloride, in the presence of diisopropylethylamine (DIPEA), gave lipidated Fmoc-lysine (8) in 35% yield after flash chromatography (Scheme 3A). The low yield could be attributed to the formation of a significant amount of a dimeric lysine