Stepwise radical cation Diels–Alder reaction via multiple pathways

• Ryo Shimizu,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 704–708, doi:10.3762/bjoc.14.59

• adduct 3 as an approximately cis/trans = 1:4 mixture, a significant difference from the synthetic outcome mentioned above (Scheme 3). Notably, no rearrangement was observed without electricity and the vinyl substituent was found to be essential for the transformation since no cyclohexane 6 was obtained

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• preference for larger groups to be in equatorial positions in cyclohexane rings (Scheme 2). The E selectivity is driven by both the high concentrations of reactants and a low dielectric constant of the LAG solvent (or no solvent). To evaluate which might be playing a more critical role in the selectivity

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• % emitter in CBP (35 nm)/TmPyPB (55 nm)/LiF (1 nm)/Al, where 1,1-bis(4-(di-p-tolylamino)phenyl)cyclohexane (TAPC), 4,4'-bis(9H-carbazol-9-yl)biphenyl (CBP), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB) and LiF play the roles of hole transport layer, host material, electron transport layer and electron

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• catalyst particles first dispersed in water using an ultrasonic probe (Jencons Vibra-Cell, 5 min, 130 W). The oils chosen are the aliphatic alkane octane (Sigma, >99%, density 0.699 g/cm3), the cyclic alkane cyclohexane (Fisher Scientific, >99%, density 0.774 g/cm3) and the aromatic oil toluene (VWR

• coalescence as well as their average droplet size depend markedly on particle concentration. As an example, the appearance of cyclohexane-in-water emulsions with time for three selected particle concentrations can be seen in Figure 4. This pattern of behaviour is followed with the other two oils also. For

• higher Sn content, surprisingly no stable emulsion was possible using cyclohexane as oil for particle concentrations in water between 0.01 and 2.0 wt % with complete phase separation occurring within 2 h. For octane, emulsion stability to coalescence increased progressively with particle concentration up

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• was washed with DCM twice to afford a yellow solid (581 mg, 51% yield, purity: 85% calculated based on 1H NMR). [Column chromatography on silica gel (EtOAc/cyclohexane 4:1) yielded pure product as an orange solid with a decreased yield (284 mg, 25% yield)]. 1H NMR (400 MHz, THF-d8) δ 9.26 (br s, 2H

• distilled off from the resulting mixture in vacuo. The residue was purified by column chromatography over SiO2 (ethyl acetate/cyclohexane 1:1) to obtain the product. Time-dependent 1H NMR spectra of the air-exposed complex B. ORTEP drawing (50% probability) of complex B. UV–vis spectrum of complex B was

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• . Among the saturated and unsaturated aliphatic aldehydes, only acetaldehyde gave the expected aldolates (58% yield, ratio 87:13, Table 2, entry 17), while cyclohexane carbaldehyde, acrolein, and crotonaldehyde did not give any aldol products (Table 2, entries 18–20). During the aldol addition, two

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• protocol for the synthesis of multicyclic molecules having a CF2CF2-containing cyclohexadiene or cyclohexane framework in a mesogenic structure. These molecules are promising candidates for vertical alignment (VA)-mode liquid crystal (LC) display devices owing to their large negative dielectric constant

• ; tetrafluorinated cyclohexadiene; tetrafluorinated cyclohexane; Introduction Fluorine-containing organic compounds have attracted much attention in various areas, such as the medicinal, agrochemical, and materials science fields [1][2][3], due to the unique characteristics of the fluorine atom [4][5][6]. It is

• improved methodology enables us to prepare the CF2CF2-containing cyclohexadiene 1a and the corresponding cyclohexane 2c, as selected examples, on the multigram scale. Results and Discussion Improved synthetic design In order to establish an improved synthetic protocol, we initially designed a method for

Preparation and isolation of isobenzofuran

• Morten K. Peters and
• Rainer Herges

Beilstein J. Org. Chem. 2017, 13, 2659–2662, doi:10.3762/bjoc.13.263

• with a yield of 78% relative to the precursor DMIBF (7, Scheme 3). To further purify isobenzofuran (1), the benzene solution was carefully evaporated and the residue was subjected to column chromatography over silica gel (cyclohexane/ethyl acetate). We were able to isolate IBF (1) as a colorless solid

• (cyclohexane/ethyl acetate 8:2, Rf 0.58) A colorless oil was obtained. Yield: 2.13 g (14.2 mmol, 85%); 1H NMR (500 MHz, 300 K, CDCl3) δ 7.41 (d, 3J = 7.3 Hz, 1H), 7.39–7.33 (m, 2H), 7.27 (d, 3J = 7.4 Hz, 1H), 6.19 (d, 4J = 2.2 Hz, 1H), 5.22 (dd, 2J = 12.7 Hz, 4J = 2.2 Hz, 1H), 5.05 (d, 2J = 12.7 Hz, 1H), 3.44

• and then twice with water. The combined organic layers were dried over magnesium sulfate and the solvent was removed under reduced pressure. The crude product was purified by column chromatography on silica gel (cyclohexane/ethyl acetate 8:2, Rf 0.92). The solvent was carefully evaporated at 20 °C. A

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• our synthetic investigations by selecting some cyclohexane β-amino acid esters as model compounds. Thus, diol (±)-8 [23][24][25][26] derived from dihydroxylation of cis-2-aminocyclohex-4-ene carboxylic acid was treated with 1 equiv of Deoxofluor in CH2Cl2. Again, through chemodiscrimination of the

• protocol was applied to commercially available meso-compound 24 having a cyclohexane framework. However, the treatment of 24 with various amounts of Deoxofluor gave only unidentifiable products whereas the reaction in the presence of DBU, afforded ketoester (±)-25 (see also Scheme 6) in 48% yield (Scheme

• -hexane/EtOAc or n-hexane/acetone). X-ray structure of fluorohydrine derivative (±)-5. Fluorination of diol derivative (±)-1. Fluorination of diol derivative (±)-4. Fluorination of diol derivative (±)-6. Fluorination of cyclohexane-derived diol (±)-8. Proposed route for the formation of compounds (±)-10

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• starting fumarate [67]. Differently substituted piperazin-2-ones can be efficiently prepared by reacting dialkyl dicyanofumarates E-1 with alkane or cycloalkane-1,2-diamines. For example, the reaction with trans-cyclohexane-1,2-diamine (72) performed in acetonitrile at room temperature for 30 min gave the

Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

• Alexey Yu. Dubovtsev,
• Maksim V. Dmitriev,
• Аndrey N. Maslivets and
• Michael Rubin

Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218

• the spirocyclization reaction. Our multiple attempts to carry out this transformation with the participation of enolates generated from cyclohexane-1,3-diones 8 (vinylogous carboxylates) in the presence of bases were unsuccessful. This reaction did not proceed in the presence of weak bases (such as

• elusive scaffold. Conclusion In conclusion, we discovered a new mode of cyclocondensations with “inverted” regiochemistry of addition, which involved the acid-catalyzed reaction of 5-alkoxycarbonyl-4-aroyl-1H-pyrrole-2,3-diones with cyclohexane-1,3-diones and lead to the formation of bridged 2,5

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

• Daily Rodríguez-Padrón,
• Alina M. Balu,
• Antonio A. Romero and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1982–1993, doi:10.3762/bjoc.13.194

• basic probe molecules applying a pulse chromatographic titration methodology. The catalyst used (≈0.025 g) was fixed inside a tubular stainless steel microreactor (4 mm internal diameter) by Pyrex glass wool. A cyclohexane solution of titrant (0.989 M in PY and 0.686 M in DMPY, respectively) was

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

• Ken Takaki,
• Makoto Hino,
• Akira Ohno,
• Kimihiro Komeyama,
• Hiroto Yoshida and
• Hiroshi Fukuoka

Beilstein J. Org. Chem. 2017, 13, 1816–1822, doi:10.3762/bjoc.13.176

• (Scheme 3). When the Z-4ai was dissolved in CDCl3 and monitored by NMR, the ratio of E/Z changed slowly to 38:62 after 21 days. In contrast, the original ratio of 40:60 was quickly attained in the presence of the NHC catalyst A. We demonstrated previously the reaction of cyclohexane-1,2-dione (5a) with

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• (bromomethyl)cyclohexane afforded 5e in 56% yield (Table 3, entry 6). The difference in reactivity relative to 5a is probably due to steric hindrance caused by the cyclohexyl ring to the alkynyl anion attack. The basic reaction conditions were responsible for promoting elimination reactions (E2) when secondary

Synthesis of ribavirin 2’-Me-C-nucleoside analogues

• Fanny Cosson,
• Aline Faroux,
• Jean-Pierre Baltaze,
• Jonathan Farjon,
• Régis Guillot,
• Jacques Uziel and
• Nadège Lubin-Germain

Beilstein J. Org. Chem. 2017, 13, 755–761, doi:10.3762/bjoc.13.74

• at 0 °C. Then the mixture was stirred for 12 h at rt and concentrated in vacuum. The residue was purified by flash chromatography (EtOAc/cyclohexane, 3:7 to 1:0) affording the mixture of the corresponding 1-benzyl-4-(2’,3’-O-isopropylidene-2’-C-methyl-β-D-ribofuranosyl)-1,2,3-triazole-5-carboxamide

• for C19H22O5, 330.1467; found, 330.1478. The mixture of carboxamides and palladium chloride (23 mg, 0.13 mmol) in ethanol (10 mL) was hydrogenated with H2 at 4 bar for 48 h. After filtration over Celite and concentration in vacuum, the crude was purified by flash chromatography (cyclohexane/EtOAc 2:8

Fluorinated cyclohexanes: Synthesis of amine building blocks of the all-cis 2,3,5,6-tetrafluorocyclohexylamine motif

• Tetiana Bykova,
• Nawaf Al-Maharik,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2017, 13, 728–733, doi:10.3762/bjoc.13.72

• moieties were then converted to different stereoisomers of the tetrafluorocyclohexyl ring system, and then reductive hydrogenation of the nitrile delivered three amine stereoisomers. It proved necessary to place a methyl group on the cyclohexane ring in order to stabilise the compound against subsequent HF

• elimination. The two all-cis tetrafluorocyclohexyl isomers 5a and 5b constitute facially polarized cyclohexane rings, with fluorines on the electronegative face and hydrogens on the electropositive face. Keywords: all-cis tetrafluorocyclohexane motif; deoxofluorination reactions; fluorinated amines

• ; fluorinated cyclohexanes; Introduction The all-cis-2,3,5,6-tetrafluorocyclohexane 1 ring has been introduced recently as a polarized cyclohexane ring and it has been a focus of our research group to elaborate new building blocks that enable the introduction of this motif into organic discovery programmes

Membrane properties of hydroxycholesterols related to the brain cholesterol metabolism

• Malte Hilsch,
• Ivan Haralampiev,
• Peter Müller,
• Daniel Huster and
• Holger A. Scheidt

Beilstein J. Org. Chem. 2017, 13, 720–727, doi:10.3762/bjoc.13.71

• samples The respective amounts of hydroxycholesterols and phospholipids were dissolved in chloroform at the respective molar ratios. The solvent was evaporated and the samples were re-dissolved in cyclohexane. After overnight lyophilization at high vacuum, the obtained fluffy powder was hydrated with 40

Fast and efficient synthesis of microporous polymer nanomembranes via light-induced click reaction

• Qi An,
• Youssef Hassan,
• Xiaotong Yan,
• Peter Krolla-Sidenstein,
• Tawheed Mohammed,
• Mathias Lang,
• Stefan Bräse and
• Manuel Tsotsalas

Beilstein J. Org. Chem. 2017, 13, 558–563, doi:10.3762/bjoc.13.54

• selectively dissolved using cyclohexane. Afterwards we dissolved the sacrificial substrate to obtain the freestanding CMP membranes. To investigate the freestanding CMP nanomembrane we transferred it to a copper grid and recorded scanning electron microscopy (SEM) images. Figure 4 shows the SEM images of the

• otherwise. Cyclohexane, dichloromethane and dry tetrahydrofuran (THF) were purchased from Merck Millipore; acetone was purchased from VWR Chemicals. Dry THF was degassed three times via freeze-pump-thaw prior to use. PMMA average Mw ≈120.000, PS average Mw ≈170.000, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2

• then obtained by following a procedure described in literature [29]: First PMMA/PS was spin coated as a supporting layer and afterwards rinsed overnight in cyclohexane to remove the PS. Then, the mica was removed by floating in solutions of I2/KI/H2O; KI/H2O and in the last step by immersing the

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• , 1-indanone has been obtained in 80% yield. Interestingly, when aluminum chloride was added to the lactone in benzene, the yield of this reaction decreased (30%) [34]. Irradiation of esters 44 possessing the photoremovable 2,5-dimethylphenacyl group in benzene or cyclohexane solutions led to free

Organofluorine chemistry: Difluoromethylene motifs spaced 1,3 to each other imparts facial polarity to a cyclohexane ring

• Mathew J. Jones,
• Ricardo Callejo,
• Alexandra M. Z. Slawin,
• Michael Bühl and
• David O'Hagan

Beilstein J. Org. Chem. 2016, 12, 2823–2827, doi:10.3762/bjoc.12.281

• example of a facially polarised cyclohexane containing 1,3 related CF2 groups. The dipolar nature of the ring arises from the axial orientation of two of the C–F bonds pointing in the same direction, and set by the chair conformation of the cyclohexane. This electrostatic profile is revealed

• experimentally both in the solid-state (X-ray) packing of the rings and by solution (NMR) in different solvents. A computationally derived electrostatic profile of this compound is consistent with a more electronegative and a more electropositive face of the cyclohexane ring. This placing of CF2 groups 1,3 to

• each other in a cyclohexane ring is introduced as a new design strategy which could be applicable to the preparation of polar hydrophobic cyclohexane motifs. Keywords: aliphatic rings; C–F bond; cyclohexane conformation; difluoromethylene group; organofluorine chemistry; Introduction Selective

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• saturated solution of (S)-3 in cyclohexane (Figure 6, see also CCDC 1521512 for details). To assess the enantiomeric purity of the material, racemization of a small sample of (S)-3 was attempted by treatment with sodium methoxide in methanol at 80 °C for 12 h under rigorous exclusion of moisture, yielding

Synthesis of spiro[isoindole-1,5’-isoxazolidin]-3(2H)-ones as potential inhibitors of the MDM2-p53 interaction

• Salvatore V. Giofrè,
• Santa Cirmi,
• Raffaella Mancuso,
• Francesco Nicolò,
• Giuseppe Lanza,
• Laura Legnani,
• Agata Campisi,
• Maria A. Chiacchio,
• Michele Navarra,
• Bartolo Gabriele and
• Roberto Romeo

Beilstein J. Org. Chem. 2016, 12, 2793–2807, doi:10.3762/bjoc.12.278

• irradiated under microwave conditions at 200 W, 110 °C, for 4 h (CEM Discover Microwave reactor). The removal of the solvent in vacuo afforded a crude material which, after flash chromatography purification by using as eluent a mixture of chloroform/cyclohexane/ethyl acetate 5:3:2, gave compounds 6a and 7a

Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification

• Anna Zaghi,
• Daniele Ragno,
• Graziano Di Carmine,
• Carmela De Risi,
• Olga Bortolini,
• Pier Paolo Giovannini,
• Giancarlo Fantin and
• Alessandro Massi

Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268

• temperature for the stated time, then filtered and concentrated. The resulting residue was analyzed by 1H NMR to determine the conversion. Subsequently, the residue was eluted from a column of silica gel with 20:1 cyclohexane–AcOEt to give isolated 3aa. Procedure for the model Stetter-like reaction under

• resulting residue was analyzed by 1H NMR to determine the conversion. Subsequently, the residue was eluted from a column of silica gel with 13:1 cyclohexane–AcOEt to give isolated 10aa. Trapping experiment (Scheme 2) A mixture of benzil (1a, 210 mg, 1.00 mmol), PS-BEMP 5 (454 mg, 1.00 mmol) and DMF (2 mL

• ) was stirred at 50 °C for 30 min then acetic anhydride (0.94 mL, 10.0 mmol) was added in one portion. The reaction mixture was stirred at 50 °C for 2 h, then cooled to room temperature, filtered, concentrated, and eluted from a column of silica gel with 7:1 cyclohexane–AcOEt to give (Z)-1,2

Facile synthesis of a 3-deazaadenosine phosphoramidite for RNA solid-phase synthesis

• Elisabeth Mairhofer,
• Elisabeth Fuchs and
• Ronald Micura

Beilstein J. Org. Chem. 2016, 12, 2556–2562, doi:10.3762/bjoc.12.250

• diluted with dichloromethane (10 mL) and washed with saturated sodium bicarbonate solution (10 mL). The organic layer was then dried over Na2SO4 and evaporated, and the resulting crude product was purified by flash chromatography (50% ethyl acetate in cyclohexane, size: 19.0 × 1.5 cm, 15 g silica gel

• ). Yield: 73 mg (44%) of compound 8 as white foam. TLC (50% ethyl acetate in cyclohexane): Rf = 0.56; 1H NMR (300 MHz, DMSO-d6) δ 0.74–0.95 (m, 48H, NCHN(CH2CH2CH2CH3)2a,b), Si(CH(CH3)3)3a,b), 1.12–1.23 (m, 24H, N(CH(CH3)2)2a,b), 1.28–1.36 (m, 8H, NCHN(CH2CH2CH2CH3)2a,b), 1.55–1.60 (m, 8H, NCHN