Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

• Narcisa Marangoci,
• Rodinel Ardeleanu,
• Laura Ursu,
• Constanta Ibanescu,
• Maricel Danu,
• Mariana Pinteala and
• Bogdan C. Simionescu

Beilstein J. Org. Chem. 2012, 8, 1610–1618, doi:10.3762/bjoc.8.184

• CDCl3, and 1H NMR spectroscopy of PDMS-Im/Br was performed in fully deuterated methanol (CD3OD) with deuterated sulfuric acid (D2SO4) [35]. Appearance of (A) pure PDMS-Im/Br ionic liquid; (B) PDMS-Im/Br ionic liquid containing 1 wt % PRot. Wet-STEM images at 30 kV in bright field mode of: PDMS-Im/Br

meta-Oligoazobiphenyls – synthesis via site-selective Mills reaction and photochemical properties

• Raphael Reuter and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2012, 8, 877–883, doi:10.3762/bjoc.8.99

• concentrated sulfuric acid. Therefore, the reaction sequence was changed to bromination first, followed then by oxidation of the benzylic position. The bromination proceeded slowly, and after three days of stirring at 50 °C, only 53% of 2-nitro-4-tert-butyl-6-bromotoluene (7) was obtained. It turned out that

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• chromatography was performed on TLC plates Si 60 F254 (Merck) in petroleum ether (PE), ethyl acetate (EE) or other solvents as indicated, and compounds were visualized under UV and after spraying with a cerium-molybdate spray reagent (20 g ammonium molybdate, 0.4 g cerium(IV) sulfate in 400 mL 10% sulfuric acid

• ) or vanillin–sulfuric acid spray reagent (1% vanillin in 15% sulfuric acid). Column chromatography was performed on silica gel (63–200 mesh, particle size 60 Å, MP Biomedicals, Eschwege, Germany), Dowex WX8 H+ was from Serva, Heidelberg, Germany. Analytical HPLC was performed on a Jasco HPLC system by

Formation of carbohydrate-functionalised polystyrene and glass slides and their analysis by MALDI-TOF MS

• Martin J. Weissenborn,
• Johannes W. Wehner,
• Christopher J. Gray,
• Robert Šardzík,
• Claire E. Eyers,
• Thisbe K. Lindhorst and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2012, 8, 753–762, doi:10.3762/bjoc.8.86

• -glucopyranoside (6) [27] were prepared according to the literature. Reactions were monitored by thin-layer chromatography using silica gel 60 GF254 on aluminium foil (Merck) with detection by UV light and charring with sulfuric acid in EtOH (10%). Preparative MPLC was performed on a Büchi apparatus using a

2-Allylphenyl glycosides as complementary building blocks for oligosaccharide and glycoconjugate synthesis

• Hemali D. Premathilake and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2012, 8, 597–605, doi:10.3762/bjoc.8.66

• Column chromatography was performed on silica gel 60 (EM Science, 70–230 mesh), reactions were monitored by TLC on Kieselgel 60 F254 (EM Science). The compounds were detected by examination under UV light and by charring with 10% sulfuric acid in methanol. Solvents were removed under reduced pressure at

Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranosides from ManNAc-oxazoline

• Karel Křenek,
• Petr Šimon,
• Lenka Weignerová,
• Barbora Fliedrová,
• Marek Kuzma and
• Vladimír Křen

Beilstein J. Org. Chem. 2012, 8, 428–432, doi:10.3762/bjoc.8.48

• from Sigma-Aldrich, except for 2-acetamido-2-deoxy-D-mannose, which was purchased from BIOSYNTH AG, Staad, CH. The reactions were monitored by TLC with precoated silica gel 60 F254 aluminium sheets from Merck, detected with UV light and/or charred with sulfuric acid (5% in EtOH). The compounds were

Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium

• Michael Dobmeier,
• Josef M. Herrmann,
• Dieter Lenoir and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 330–336, doi:10.3762/bjoc.8.36

• typically proceeds in aqueous solution and requires an excess of HI or strong mineral acids such as phosphoric or sulfuric acid [33][34][35]. We describe a biphasic reaction medium consisting of toluene and aqueous hydriodic acid. The phase separation allows milder reaction conditions compared to the

Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

• Kenichirou Yokota,
• Masayori Hagimori,
• Naoko Mizuyama,
• Yasuhisa Nishimura,
• Hiroshi Fujito,
• Yasuhiro Shigemitsu and
• Yoshinori Tominaga

Beilstein J. Org. Chem. 2012, 8, 266–274, doi:10.3762/bjoc.8.28

• under reflux gave diaminopyrimidine derivatives 3c–e in good yields, i.e., 92%, 51%, and 86%, respectively. The reaction of 1a and 2a under reflux in methanol instead of pyridine gave the methoxy pyrimidine derivative 3f in 55% yield. In the presence of sulfuric acid solution, 2,4-dimethylsulfanyl

Ion-exchange-resin-catalyzed adamantylation of phenol derivatives with adamantanols: Developing a clean process for synthesis of 2-(1-adamantyl)-4-bromophenol, a key intermediate of adapalene

• Nan Wang,
• Ronghua Wang,
• Xia Shi and
• Gang Zou

Beilstein J. Org. Chem. 2012, 8, 227–233, doi:10.3762/bjoc.8.23

• ) Sulfonic acid resins (Amberlite 200 and Amberlite-IR 120, Polysciences Inc.) were regenerated following a procedure reported in the literature [28]: 100 g of resin was stirred with 20% sulfuric acid (500 mL) overnight, then filtered and washed with deionized water until the washings reached a pH value of 5

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• + H+] calcd for C36H43N12, 643.37282; found, 643.37632. 3,3’-Diiododiphenylmethane (5). Based on related procedures [21][32], 3,3’-diaminodiphenylmethane (0.62 g, 3.1 mmol) in concentrated sulfuric acid (10 mL) was stirred at 0 °C. Sodium nitrite (0.62 g, 9.0 mmol) in water (6 mL) was added dropwise

• mL), basified with sodium hydroxide (4.0 g) and heated at reflux for 1 h. Upon cooling the solution was acidified with dilute sulfuric acid and concentrated to 30 mL under reduced pressure which resulted in the precipitation of a white solid. Filtration and subsequent drying in a desiccator overnight

Equilibrium constants and protonation site for N-methylbenzenesulfonamides

• José A. Moreira,
• Ana M. Rosa da Costa,
• Luis García-Río and
• Márcia Pessêgo

Beilstein J. Org. Chem. 2011, 7, 1732–1738, doi:10.3762/bjoc.7.203

• -NO2 (3d), in aqueous sulfuric acid were studied at 25 °C by UV–vis spectroscopy. As expected, the values for the acidity constants are highly dependent on the electron-donor character of the substituent (the pKBH+ values are −3.5 ± 0.2, −4.2 ± 0.2, −5.2 ± 0.3 and −6.0 ± 0.3 for 3a, 3b, 3c and 3d

• composition of the sulfuric acid solution when I = 1 that corresponds to a degree of protonation of 50% can be easily calculated and is namely 65.2, 68.2, 74.0 and 80.6% sulfuric acid (w/w) for compounds 3a, 3b, 3c and 3d, respectively. [H+] and X values for each sulfuric acid concentration were calculated by

• structures, the latter having a greater relevance for the sulfonamides with electron-donor groups (Scheme 3). Conclusion The protonation equilibrium constants (pKBH+) for the para-substituted N-methylbenzenesulfonamides 3a–d in aqueous sulfuric acid were obtained from spectrophotometric measurements

Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

• Elizabeth P. Jones,
• Peter Jones,
• Andrew J. P. White and
• Anthony G. M. Barrett

Beilstein J. Org. Chem. 2011, 7, 1570–1576, doi:10.3762/bjoc.7.185

• aromatic ring, to the same conditions yielded the dipeptide 9 and the desired methyl ester 10 in a 1:1 ratio (Scheme 7). Screening of various acidic hydrolysis reaction conditions in these systems led to the observation that when either 6a or 7c was stirred in neat 6 M sulfuric acid for three days, the

Synthesis and oxidation of some azole-containing thioethers

• Andrei S. Potapov,
• Nina P. Chernova,
• Vladimir D. Ogorodnikov,
• Tatiana V. Petrenko and
• Andrei I. Khlebnikov

Beilstein J. Org. Chem. 2011, 7, 1526–1532, doi:10.3762/bjoc.7.179

• unreactive compound 5. The reactivity of pyrazole-containing thioether 3 in aromatic electrophilic substitution was evaluated by using nitration and iodination reactions as examples. Nitration of compound 3, by 68% nitric acid in concentrated sulfuric acid, results in both substitution in the heterocyclic

Koch–Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor

• Takahide Fukuyama,
• Yu Mukai and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2011, 7, 1288–1293, doi:10.3762/bjoc.7.149

• sulfuric acid, an acid-tolerant system is essential. For this study, we employed a combination of a hastelloy-made micromixer (MiChS, β-150H) having 150 μm reactant inlet holes and 200 μm × 300 μm channels (Figure 1), and a PTFE tube (1.0 mm i.d. × 3 m, inner volume: 2.36 mL) as a residence time unit. To

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• place with an iodoarene that is oxidized at the anode. The radical cation then undergoes a reaction with the other arene to form an intermediate, followed by the loss of a second electron [23]. The solvent system consisted of acetonitrile, sulfuric acid (2 M) and acetic anhydride, which was reported to

• increase the selectivity of the coupling reaction [21]. The sulfuric acid acts both as a counter reaction to the oxidation at the anode, with proton reduction, and simultaneously provides a counter ion for the positively charged iodonium salt. It also acts as an electrolyte in the reaction described above

Gold-catalyzed oxidation of arylallenes: Synthesis of quinoxalines and benzimidazoles

• Dong-Mei Cui,
• Dan-Wen Zhuang,
• Ying Chen and
• Chen Zhang

Beilstein J. Org. Chem. 2011, 7, 860–865, doi:10.3762/bjoc.7.98

• yields of 2a and 3a of 49% and 60%, respectively (Table 1, entries 16–17). Decreasing the amount of the sulfuric acid also resulted in a lower yield, although the addition of a large amount of the acid did not affect the reaction (Table 1, entries 8–9). Different acids were screened (Table 1, entries 1

• , 5–7) and sulfuric acid was found to be the most effective. The use of solvents such as THF, toluene, DCE or ether resulted in a lower conversion (Table 1, entries 10–13). Treatment of 1a in an atmosphere of O2 (1 atm) afforded 2a and 3a in a combined yield of 47% (Table 1, entry 20). When the

• spectrometer (GCT Premier). General procedure Step A (a typical procedure): Sulfuric acid (0.5 mol %) was added to a mixture of 4-butylphenylallene (0.5 mmol), water (10 mmol), (PPh3)AuCl (2 mol %), AgBF4 (8 mol %), and dioxane (1 mL). The mixture was stirred at 60 °C for 24 , the reaction quenched with a

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• reaction was carried out in aqueous dioxane, and hydroxybromoethyl 10 and hydroxychloroethyl 11 derivatives were obtained in 70% and 60% yields, respectively. Subsequent treatment of hydroxyl derivatives 10 and 11 with methanolic sulfuric acid gave the corresponding desired 5-(1-methoxy-2-haloethyl

• , 65%) as diasteroisomeric mixtures. Finally, treatment of hydroxy derivatives 25–27 with methanolic sulfuric acid gave the desired 5-(1-methoxy-2-iodoethyl) nucleosides 28–30 in 81–94% yields. All three compounds were obtained as mixtures of two diastereomers. In order to develop new potential tumor

• reaction was used 14 years earlier by Kumar and co-workers for the synthesis of 5-(1-methoxy-2-haloethyl)uracils 62–64 (Figure 6) [17] by the addition of HOX (X = Br, Cl) or ICl to the 5-vinyluracil (55) and subsequent treatment with methanolic sulfuric acid. In 2002 Ismail and co-workers published an

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• % aqueous sulfuric acid a rearrangement to furnish a mixture of the 3- and 5-nitro derivatives occurs, which unfortunately at this stage, could not be separated by crystallisation. However, when this mixture was subjected to catalytic hydrogenation with Raney nickel a separable mixture of the corresponding

The preparation of 3-substituted-1,5-dibromopentanes as precursors to heteracyclohexanes

• Bryan Ringstrand,
• Martin Oltmanns,
• Jeffrey A. Batt,
• Aleksandra Jankowiak,
• Richard P. Denicola and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2011, 7, 386–393, doi:10.3762/bjoc.7.49

• derivatives [13]. The latter, as well as silacyclohexanes V [14] and phosphorinanes VI [15][16], have been used in conformational and stereochemical studies. The dibromides I or disulfonates II were prepared from 3-substituted 1,5-pentanediols VII. The former were obtained using HBr and concd sulfuric acid [2

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• described the reactions of azoxypyridines in sulfuric acid media. The relative reactivities of the α- and β-isomers 108 and 109 were correlated to stabilization of a developing cationic charge center (Scheme 23). Thus, the α-isomer 108 ionizes in 100% H2SO4 to give the tricationic species 110 and subsequent

Tribenzotriquinacenes bearing three peripheral or bridgehead urea groups stretched into the 3-D space

• Jörg Tellenbröker and
• Dietmar Kuck

Beilstein J. Org. Chem. 2011, 7, 329–337, doi:10.3762/bjoc.7.43

• Discussion As shown earlier, introduction of six amino groups at the periphery of the TBTQ skeleton is achievable by nitration with nitric acid (100%) and sulfuric acid (98%) followed by reduction [20]. However, this holds true only for TBTQ derivatives with alkyl groups at the benzhydrylic bridgehead

SbCl₃-catalyzed one-pot synthesis of 4,4′-diaminotriarylmethanes under solvent-free conditions: Synthesis, characterization, and DFT studies

• Ghasem Rezanejade Bardajee

Beilstein J. Org. Chem. 2011, 7, 135–144, doi:10.3762/bjoc.7.19

• ][30][31][32][33][34]. The reaction of arylaldehydes with N,N-dimethylaniline is one of the most efficient methods for the synthesis of DTMs. This reaction is usually carried out in the presence of Brønsted acids such as sulfuric acid, hydrochloric acid, methanesulfonic acid, or p-TSA, as well as Lewis

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• expected in the future. Experimental Materials 10-undecenoic acid (Sigma–Aldrich, 98%), 1,3-propanediol (Sigma–Aldrich, 99.6%), p-toluenesulfonic acid monohydrate (Sigma–Aldrich, 98.5%), ethyl vinyl ether (Sigma–Aldrich, 99%), sulfuric acid (Fluka, 95–97%), p-benzoquinone (Fluka, 98%), (1,3-bis(2,4,6

• methanol (4 mL) and concentrated sulfuric acid (5 drops) were added to a carousel reaction tube, stirred magnetically, and refluxed at 85 °C for 5 h. At the end of the reaction, the excess of methanol was removed under reduced pressure. The residue was then dissolved in diethyl ether and filtered through a

Synthesis of 3-(quinolin-2-yl)- and 3,6-bis(quinolin-2-yl)-9H-carbazoles

• Yang Li and
• Wentao Gao

Beilstein J. Org. Chem. 2010, 6, 966–972, doi:10.3762/bjoc.6.108

• , the Friedländer quinoline synthesis can be achieved by the use of a variety of Brønsted acid catalysts, such as hydrochloric acid, perchloric acid, sulfuric acid, p-toluene sulfonic acid, sulfamic acid, phosphoric acid, and trifluoroacetic acid [43][44][45]. However, many of these procedures are not

• (OTf)3 [50], Y(OTf)3 [51], silver dodecatungstophosphate (Ag3POW12O40) [52], silica sulfuric acid [53], sulfamic acid [54], neodymium nitrate [55], etc. However, these methods suffer from the serious drawbacks of harsh reaction conditions, use of expensive catalysts, long reaction times, etc. Ionic

En route to photoaffinity labeling of the bacterial lectin FimH

• Thisbe K. Lindhorst,
• Michaela Märten,
• Andreas Fuchs and
• Stefan D. Knight

Beilstein J. Org. Chem. 2010, 6, 810–822, doi:10.3762/bjoc.6.91

• and by charring with 10% sulfuric acid in ethanol or using anisaldehyde and subsequent heating. Flash column chromatography was performed on silica gel 60 (40–63 µm, Merck) and for RP-MPLC a Merck Licroprep RP-18 column (Büchi) was used. Preparative HPLC was accomplished on a Shimadzu LC-8a machine