Profluorescent substrates for the screening of olefin metathesis catalysts

• Raphael Reuter and
• Thomas R. Ward

Beilstein J. Org. Chem. 2015, 11, 1886–1892, doi:10.3762/bjoc.11.203

• ). Allylamine was slowly added to the solution, while stirring. After complete addition, the reaction mixture was allowed to stir overnight. The solvent was removed under vacuum and the residue was purified by flash column chromatography (silica gel, cyclohexane/EtOAc 1:1) to obtain a colourless solid (893 mg

• equiv) and then allylamine (378 µL, 5.05 mmol, 1.10 equiv) was added and the mixture was stirred for 2 h at rt until the TLC showed complete consumption. The solvent was removed under reduced pressure and the residue was purified by flash chromatography (silica gel, cyclohexane/EtOAc 3:1) to obtain 960

• diluted with EtOAc (50 mL), washed with water (2 × 50 mL) and dried over MgSO4. The solvent was removed under vacuum and the residue was purified by flash column chromatography (silica gel, cyclohexane/EtOAc 5:1) to obtain 300 mg of red oil (47%). 1H NMR (400 MHz, CDCl3) δ 8.66 (d, 4JHH = 2.7 Hz, 1H

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• . [28] 134 °C). 6,6'-((1E,1'E)-((1R,2R)-Cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2-(tert-butyl)-4-(dimethylamino)phenol) (7) Prepared by a modified literature procedure [30]. A solution of (1R,2R)-diaminocyclohexane (64 mg, 0.57 mmol) in ethanol (5 mL) was added dropwise to a

• . 5,5'-((1E,1'E)-((1R,2R)-Cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(3-(tert-butyl)-4-hydroxy-N,N,N-trimethylbenzenaminium iodide) (8a) To a solution of 7 (100 mg, 0.192 mmol) in dry acetonitrile (5 mL) was added methyl iodide (271 mg, 1.92 mmol). The solution was stirred at room

• C34H54N4O22+, 275.21; found, 275.21. 5,5'-((1E,1'E)-((1R,2R)-Cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(N-benzyl-3-(tert-butyl)-4-hydroxy-N,N-dimethyl-benzenaminium bromide) (8b) To a solution of 7 (120 mg, 0.231 mmol) in dry acetonitrile (5 mL) was added benzyl bromide (79 mg, 0.46 mmol

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• ]annulene 28, suggesting a higher stacking ability and a larger ring size for 30. Alkyl-substituted TTF[18]annulene 32 was reported to show almost no aggregation behavior in solution [72]. However, the slightly more amphiphilic 31 exhibits self-aggregation in benzene, toluene, and cyclohexane owing to a

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• further oxidation. SCPC oxidations that take place with varying success include toluene to benzaldehyde and benzoic acid [25], cyclohexane to cylohexanone [26], benzylic and allylic alcohols to carbonyl compounds [27] and alkene epoxidations [28]. Conventional syntheses of coumarins, which are important

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• 1,4-diiodobenzene (109) was reacted with the cyclohexane-1,4-dione (114) in the presence of CeCl3/LiCl/n-BuLi to generate the diol 115. Then, the hydroxy groups were protected as MOM groups to generate the key synthone 116. The other building blocks 119a–c were obtained by protection of dialkynes 117a

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

• -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

• , 1:2) to afford bright yellow crystals. X-ray quality crystals were grown by slow evaporation of CDCl3 solution. Yield: 43.2 mg (0.098 mmol, 82%). Mp 198–200 °C; Rf = 0.32 (CH2Cl2/cyclohexane, 1:2); 1H NMR (360 MHz, CDCl3) δ 7.25–7.20 (m, 2H), 6.95–6.91 (m, 2H), 6.79 (s, 2H), 3.83 (s, 3H), 2.43 (s

• chromatography (CH2Cl2/cyclohexane, 1:1) to afford light orange crystals. X-ray quality crystals were grown by slow evaporation of CDCl3/heptane solution. Yield: 53.8 mg (0.105 mmol, 82%); Mp 196–199 °C; Rf = 0.5 (CH2Cl2/cyclohexane, 1:1); 1H NMR (360 MHz, CD2Cl2) δ 7.22–7.17 (m, 2H), 6.81 (s, 2H), 6.76–6.71 (m

Ruthenium-catalyzed C–H activation of thioxanthones

• Danny Wagner and
• Stefan Bräse

Beilstein J. Org. Chem. 2015, 11, 431–436, doi:10.3762/bjoc.11.49

• cyclohexane/ethyl acetate as eluent. Thioxanthone (1a). Route to methoxyarenes 1d, 1f, and 1h. Ru-catalyzed C–H activation of thioxanthones. Conditions: 6 mol % RuH2(CO)(PPh3)3, toluene, 135 °C, 12 h. Synthesis of substituted thioxanthones from thiosalicylic acid.a C–H activation. Supporting Information

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• observed due, apparently, to the addition of the C-radical generated from ketone to benzene [204]. It was shown [209] that the α’-acetoxylation of enones occurs with good selectivity in other solvents, such as cyclohexane and acetonitrile, as well. The acyloxylation of enones and aryl ketones 220 with

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• terminal or lateral positions of the rods. Building blocks with lateral SEGs are called sleeves. In Figure 1 a typical sleeve D (cyan) as well as other typical building blocks of OSK rods are depicted, such as pentaerythritol C (red), cyclohexane-1,4-dione E (green), and piperidine-4-ones B (blue). An OSK

Three-component synthesis of C₂F₅-substituted pyrazoles from C₂F₅CH₂NH₂·HCl, NaNO₂ and electron-deficient alkynes

• Pavel K. Mykhailiuk

Beilstein J. Org. Chem. 2015, 11, 16–24, doi:10.3762/bjoc.11.3

• crystalline product 19b was purified from the liquid starting material by washing with cyclohexane. The yield of 19b was improved to 73% by performing the reaction at 40 °C (Table 3, entry 5). SiMe3-substituted substrates 20, 21 also reacted slowly, but again performing the reaction at 40 °C allowed to obtain

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

• was purchased from Roquette Frères (Lestrem, France) and β-CD-NH2 was synthesized as previously described [31] or purchased from Biocydex (Poitiers, France). Analytical TLC was performed using Silica Gel 60 F254 plates (Merck, Germany). Eluents were mixtures of dichloromethane/methanol or cyclohexane

Microsolvation and sp²-stereoinversion of monomeric α-(2,6-di-tert-butylphenyl)vinyllithium as measured by NMR

• Rudolf Knorr,
• Monika Knittl and
• Eva C. Rossmann

Beilstein J. Org. Chem. 2014, 10, 2521–2530, doi:10.3762/bjoc.10.263

• ), began to change slightly (Tables S8 and S16, [15]) during warm-up in the direction expected [22] for aggregation. The suspicion that n-BuLi might be involved was supported through comparison with a purified sample of 4&TMEDA in Et2O/[D12]cyclohexane (80:14) that contained neither n-BuLi nor MeLi: Now

• solvent [with [D12]cyclohexane (0.060 mL) as the lock substance] with a trace of TMS under argon gas cover was sealed with a soft, solvent-resistant rubber stopper that was finally wrapped with parafilm®. Customary methanol NMR tubes were measured in place of the sample tubes to determine the actual

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• , terminal alcohol silylation, and tertiary alcohol dehydration, affording methylene cyclohexane (−)-20. Treatment of this silyl ether with Jones reagent simultaneously cleaved the silyl group and oxidized the resulting alcohol, furnishing carboxylic acid (−)-12 in 65% yield. With this enantioenriched acid

A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

• Stefanie Wolfram,
• Hendryk Würfel,
• Stefanie H. Habenicht,
• Christine Lembke,
• Phillipp Richter,
• Eckhard Birckner,
• Rainer Beckert and
• Georg Pohnert

Beilstein J. Org. Chem. 2014, 10, 2470–2479, doi:10.3762/bjoc.10.258

• transilluminator whereas BPT (1) offers a very good absorbance at 365 nm, a standard UV excitation wavelength. We then recorded fluorescence spectra of all fluorophores and determined fluorescence quantum yields Φ (Table 1). To characterize BPT (1) in a non-interacting solvent we used cyclohexane resulting in an

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• of a MeOH/H2O mixture (1:1, 150 mL) and the aqueous phase was extracted with CH2Cl2 (4 × 50 mL). The combined organic extracts were dried with MgSO4 and the solvents were removed in vacuo. The crude product was purified by column chromatography on silica gel using cyclohexane/ethyl acetate (10:1) as

• extracted with CH2Cl2 (2 × 50 mL). The combined organic extracts were dried with MgSO4 and the solvents were removed in vacuo. The crude product was purified by column chromatography on silica gel using cyclohexane/ethyl acetate (2:3) as eluent (Rf 0.61). Compound 7 was obtained as colorless solid (3.55 g

• , 89%). Crystals suitable for X-ray analysis have been obtained by slow diffusion of cyclohexane into a Et2O solution of 7. 1H NMR (400 MHz, CD3OD) δ 5.26 (s, 1H, CH2CHCH2), 4.30–4.23 (m, 1H, CH2CHN), 3.83–3.76 (m, 1H, NCH2CH), 3.70–3.63 (m, 1H, NCH2CH), 3.14 (s, 3H, S-CH3), 2.67–2.56 (m, 1H, CHCH2CH

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

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• (59a) (X = NH) [92], the N-methyl-4-hydroxy-6-methylpyridin-2(1H)-one (59b) (X = NMe) [92], N-ethyl-4-hydroxy-6-methylpyridin-2(1H)-one (59c) (X = NEt) [92], 4-hydroxy-6-methyl-2H-pyran-2-one (59d) (X = O) [92], or cyclohexane-1,3-dione (60) [93]. The syntheses of derivatives 61 to 64 represent a

Improving the reactivity of phenylacetylene macrocycles toward topochemical polymerization by side chains modification

• Simon Rondeau-Gagné,
• Jules Roméo Néabo,
• Maxime Daigle,
• Katy Cantin and
• Jean-François Morin

Beilstein J. Org. Chem. 2014, 10, 1613–1619, doi:10.3762/bjoc.10.167

• absence of the influence of the addition of side chains on the gelation properties. In the case of PAM3, however, most of the solvents tested did not lead to gel formation. Thus, only cyclohexane and toluene resulted in a partial gel state. The presence of four amide functions and four 2-hydroxyethoxy

• samples were prepared with PAM1 and PAM2 in cyclohexane at a 10 mg/mL concentration and subjected to differential scanning calorimetry (DSC). The DSC analysis was carried out at temperatures ranging from 298 to 223 K. In both cases, a very sharp exotherm attributable to the crystallization of supercooled

• solvent was observed (see Figure S22 and S23 in Supporting Information File 1). For PAM2, the exotherm at 279 K is closer to the freezing point of cyclohexane (280 K) than for PAM1, which has an exotherm at 267 K. This result suggests that the gel of PAM2 might be less organized than that of PAM1. By

Bis(β-lactosyl)-[60]fullerene as novel class of glycolipids useful for the detection and the decontamination of biological toxins of the Ricinus communis family

• Hirofumi Dohi,
• Takeru Kanazawa,
• Akihiro Saito,
• Keita Sato,
• Hirotaka Uzawa,
• Yasuo Seto and
• Yoshihiro Nishida

Beilstein J. Org. Chem. 2014, 10, 1504–1512, doi:10.3762/bjoc.10.155

• toluene/ethyl acetate, hexane/ethyl acetate, cyclohexane/ethyl acetate, and chloroform/methanol mixtures as eluents. 1H NMR (500 MHz), 13C NMR (125 MHz), and 2D NMR spectra were recorded with a JNM-LA-500s or JNM-ECA-500 spectrometer (JEOL, Japan). Unless otherwise stated, NMR spectra were recorded at 22

• washed with brine, the organic layer was dried over MgSO4, filtered, and concentrated in vacuo. The residue was chromatographed on silica gel by using cyclohexane/ethyl acetate 3:2 to give glycoside 2 as a white solid (2.16 g, 48%): [α]D −11.4 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3) δ 5.35 (dd, J3’,4

Stereoselective synthesis of carbocyclic analogues of the nucleoside Q precursor (PreQ₀)

• Sabin Llona-Minguez and
• Simon P. Mackay

Beilstein J. Org. Chem. 2014, 10, 1333–1338, doi:10.3762/bjoc.10.135

• introduction of diverse aryl groups at the 3-position of the cyclohexane ring using commercially available arylboronic acids as building blocks, and Pd catalysis to form the new C–C bond, followed by a highly diastereoselective ketone-to-amine conversion. Others have reported on similar preparations of 3

Columnar/herringbone dual crystal packing of pyrenylsumanene and its photophysical properties

• Binod Babu Shrestha,
• Shuhei Higashibayashi and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2014, 10, 841–847, doi:10.3762/bjoc.10.80

• reaction was monitored by TLC (100% cyclohexane). The reaction was quenched by saturated aq. Na2S2O3 and the mixture was extracted with CH2Cl2 (50 mL × 3). The combined organic extracts were washed with water, brine, dried over Na2SO4, filtered through Celite, and evaporated. The residue was purified by

• reaction mixture was allowed to stir for 12 h at 40 °C. The completion of reaction was monitored by TLC (100% cyclohexane). The reaction was diluted by CH2Cl2 and the mixture was extracted with CH2Cl2 (50 mL × 3). The combined organic extracts were washed with water, brine, dried over Na2SO4, filtered

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Viktoriia V. Pakalnis,
• Roman O. Iakovenko and
• Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

• chromatography (Scheme 1). To find the optimal reaction conditions a series of experiments was performed with furan-2,3-dione 1a and azirine 2a in different solvents (benzene, toluene, cyclohexane, THF, nitromethane) monitoring the reaction by 1H NMR using 1-methylnaphthalene as internal standard. 1H NMR spectra

Thermodynamically stable [4 + 2] cycloadducts of lanthanum-encapsulated endohedral metallofullerenes

• Yuta Takano,
• Yuki Nagashima,
• M. Ángeles Herranz,
• Nazario Martín and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2014, 10, 714–721, doi:10.3762/bjoc.10.65

• slow or fast to allow their observation in an NMR time scale. The signals from the AB-quartet of 4a coalesce at 290 K (= Tc) indicate a dynamic process, which is attributed to the boat-to-boat interconversion of the cyclohexane ring of the addend similarly to the related carbocyclic analogues of C60

• spectroscopic investigations of 4a reveal temperature-dependent changes related to the conformational changes in the cyclohexane moiety generated upon reaction. The use of sultines for chemical modification of endohedral metallofullerenes has proved to be of general scope, being particularly useful to prepare

Chromatographically separable rotamers of an unhindered amide

• Mario Geffe,
• Lars Andernach,
• Oliver Trapp and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 701–706, doi:10.3762/bjoc.10.63

• relative arrangement of the benzyl substituent. For comparison, the rotational barrier for DMF was calculated using the same functional and basis set (Table 1) and was found to be overestimated by 18–22 kJ/mol based on 82.6 kJ/mol as the value for the experimental barrier in cyclohexane solution [25]. With

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• (22000). Fluorescence (CH2Cl2): λmax: 358 nm. Stokes shift Δ = 3800 cm−1. Quantum yield: Φf = 83% (Ref.: p-terphenyl (Φf = 93% in cyclohexane)). Cyclic voltammetry (CH2Cl2): E1/20/+1 = 1.25 V. Compounds 2d (solid and THF solution) and 2n (solid and THF solution) (from left to right) under daylight (top