- Molecular Reorientation and Self-Diffusion in Solid Cubane by Deuterium and Proton NMR
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Deuterium and proton NMR line shape and relaxation measurements are reported for the sym-cubane-d2 isotopomer (D3d symmetry) in the temperature range from 200 K to the melting point of the solid.The results confirm the polymorphic phase sequence: solid II solid I liquid, reported earlier by White et al.The deuterium spectrum below 215 K exhibits a Pake doublet corresponding to an axially symmetric quadrupole coupling tensor with a coupling comstant of Qc = 178 kHz.Above this temperature the spectrum develops features characteristic of the onset of dynamic processes leading to a single line at about room temperature.Longitudinal relaxation time measurements show a T1 minimum at 344 K.On transition to solid I there is a discontinuous narrowing of the line and a concomitant increase in T1.These results are quantitatively interpreted in terms of reorientational jumps of the cubane molecules between their various equivalent orientations.The jump rate k in solid II follows an Arrhenius behavior over the range of almost seven decades with an activation energy E = 62 kJ mol-1.Transition to solid I results in a discontinuous increase of k.Proton line width measurements in solid II show two motional narrowing steps.The first, at around 240 K, is due to the cubic jumps while the second, at around 375 K, corresponds to molecular self-diffusion between the lattice sites.The activation energy for this process is Ed = 83 kJ mol-1.On transition to solid I there is also a discontinuous increase in the rate of this process.The proton T1 values are predominantly affected by the reorientation process and are consistent with the deuteron data.At temperatures above 340 K, where the deuterium NMR spectrum is expected to be a single Lorentzian with a width of less than 400 Hz, it actually exhibits, in both phases II and I, a Pake doublet corresponding to an axially symmetric quadrupole coupling tensor with a very small coupling constant Q'c = 0.48 kHz.This indicates that the reaorientation process is not perfectly cubic.Possible reasons for this surprising effect are discussed.
- Detken, A.,Zimmermann, H.,Haeberlen, U.,Poupko, R.,Luz, Z.
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- Decagram Synthesis of Dimethyl 1,4-Cubanedicarboxylate Using Continuous-Flow Photochemistry
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The highly strained cubane system is of great interest as a scaffold and rigid linker in both pharmaceutical and materials chemistry. A straightforward approach is reported for the scale-up of a [2+2] photocycloaddition step using convenient home-made flow photoreactors to access dimethyl 1,4-cubanedicarboxylate on decagram-scale in 33-40% yield over 8 steps. The process is demonstrated on 3.4 g·h -1input with 30 minutes residence time, enabling to reduce the process time and to avoid the use of batch photoreactors. Completion of the characterisation of the photocycloadduct and its hydrates is reported.
- Collin, Diego E.,Jackman, Edward H.,Jouandon, Nicolas,Sun, Wei,Light, Mark E.,Harrowven, David C.,Linclau, Bruno
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p. 1307 - 1314
(2020/11/19)
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- Enantioselective synthesis of (: R)-2-cubylglycine including unprecedented rhodium mediated C-H insertion of cubane
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The first enantioselective synthesis of (R)-2-cubylglycine, an analogue of (R)-2-phenylglycine in which the phenyl ring has been replaced by cubane, is disclosed. The key step was a telescoped Strecker reaction using (S)-2-amino-2-phenylethanol as a chiral auxiliary. Exploration of an alternative synthetic approach resulted in unprecedented cubane C-H insertion.
- Houston, Sevan D.,Chalmers, Benjamin A.,Savage, G. Paul,Williams, Craig M.
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supporting information
p. 1067 - 1070
(2019/02/07)
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- Thermal and Sensitiveness Determination of Cubanes: Towards Cubane-Based Fuels for Infrared Countermeasures
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As infrared seeking technology evolves, threats are better able to distinguish defensive infrared (IR) flares from true targets. Spectrally matched flares, which generally employ carbon-based fuels, are better able to decoy some advanced missiles by more closely mimicking the IR emission of the target. Cubane is a high-energy carbon-based scaffold which may be suitable for use as a fuel in spectrally matched flares. The enthalpy of formation and strain energy of a series of cubanes was predicted in silico, and their thermal and impact stability examined. All were found to undergo highly exothermic decomposition in sealed cell differential scanning calorimetry, and two cubanes subsequently underwent quantitative sensitiveness testing. Despite their F of I values being in the secondary explosive range, cubane-1,4-dicarboxylic acid (F of I=70) and 4-carbamoylcubane-1-carboxylic acid (F of I=90) were identified as potentially useful fuels for pyrotechnic infrared countermeasure flare formulations.
- Dallaston, Madeleine A.,Brusnahan, Jason S.,Wall, Craig,Williams, Craig M.
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supporting information
p. 8344 - 8352
(2019/06/04)
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- Cubane Arrives on the Cucurbituril Scene
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Cubane, an intriguing chemical curiosity first studied in the early 1960s, has become a valuable structural motif and has recently been involved in the structures of a great number of prospective compounds. The first dicationic supramolecular guest 5 is prepared and derived from a 1,4-disubstituted cubane moiety, and its binding behavior toward cucurbit[n]urils (CBn) and cyclodextrins (CD) is studied. The bisimidazolium salt 5 forms 1:1 inclusion complexes with CB7, CB8, and β-CD with the respective association constants (6.7 ± 0.5) × 1011 M-1, (1.5 ± 0.2) × 109 M-1, and 2 M-1 in water. The solid-state structures of the 5@CB7 and 5@CB8 complexes are also reported.
- Jelínková, Kristyna,Surmová, Heda,Matelová, Alena,Rouchal, Michal,Prucková, Zdeňka,Dastychová, Lenka,Ne?as, Marek,Vícha, Robert
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p. 2698 - 2701
(2017/05/24)
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- Synthesis, High-Resolution Infrared Spectroscopy, and Vibrational Structure of Cubane, C8H8
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Carbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family (Pirali, O.; et al. J. Chem. Phys. 2012, 136, 024310). There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp3 hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm-1 region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented.
- Boudon,Lamy,Dugue-Boyé,Pirali,Gruet,D'Accolti,Fusco,Annese,Alikhani
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p. 4418 - 4428
(2016/07/11)
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- Structure-activity relationships of N-substituted 4-(trifluoromethoxy) benzamidines with affinity for GluN2B-containing NMDA receptors
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GluN2B subtype-selective NMDA antagonists represent promising therapeutic targets for the symptomatic treatment of multiple CNS pathologies. A series of N-benzyl substituted benzamidines were synthesised and the benzyl ring was further replaced with various polycyclic moieties. Compounds were evaluated for activity at GluN2B containing NMDA receptors where analogues 9, 12, 16 and 18 were the most potent of the series, replacement of the benzyl ring with polycycles resulted in a complete loss of activity.
- Beinat, Corinne,Banister, Samuel D.,Hoban, Jane,Tsanaktsidis, John,Metaxas, Athanasios,Windhorst, Albert D.,Kassiou, Michael
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p. 828 - 830
(2014/02/14)
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- Cubanes in medicinal chemistry: Synthesis of functionalized building blocks
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A collection of novel, pharmaceutically relevant cubane-containing molecules has been prepared from the commercially available cubane-1,4- dimethylester. A range of synthetic methods have been applied to prepare these cubane building blocks with one or two functional handles to allow easy incorporation into existing medicinal chemistry programs.
- Wlochal, Joanna,Davies, Robert D. M.,Burton, Jonathan
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supporting information
p. 4094 - 4097
(2014/09/29)
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- The first cns-active carborane: A novel p2x7 receptor antagonist with antidepressant activity
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Relative to other polycyclic frameworks (1-3), a carborane cage (4 and Cs·5) exerts a significant biological effect as an inhibitor of the purinergic P2X7 receptor (P2X7R) which allows one to target depression in vivo and thus demonstrate, for the first time, that a carborane has the capacity to modify CNS activity.
- Wilkinson, Shane M.,Gunosewoyo, Hendra,Barron, Melissa L.,Boucher, Aurelie,McDonnell, Michelle,Turner, Peter,Morrison, Daniel E.,Bennett, Maxwell R.,McGregor, Iain S.,Rendina, Louis M.,Kassiou, Michael
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p. 335 - 339
(2014/06/09)
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- Pilot-Scale Production of Dimethyl 1,4-Cubanedicarboxylate
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A scalable process for the preparation of high purity dimethyl 1,4-cubanedicarboxylate (3) is reported. The work described herein builds on previous synthetic work from this and other laboratories, to provide a reliable process that can be used to prepare multigram quantities of 3 in a partially telescoped, 8 step process, with minimal purification of intermediates.
- Falkiner, Michael J.,Littler, Stuart W.,McRae, Kenneth J.,Savage, G. Paul,Tsanaktsidis, John
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p. 1503 - 1509
(2014/01/06)
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- Solvent-induced, selective rearrangement of hydrogen cubane-1,4- dicarboxylate to hydrogen cuneane-2,6-dicarboxylate
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The rearrangement of cubane-1,4-dicarboxylic acid in water to cuneane-2,6-dicarboxylic acid is presented. The reaction is not a transition metal catalyzed, rather a solvent-promoted transformation, and the reaction proceeds via the semi-dissociated form of the cubane diacid, hydrogen cubane-1,4-dicarboxylate. No other, 1,3-disubstituted cuneane isomer is formed. The reaction is significantly accelerated by the addition of 1 equiv of base, suggesting that the hydrogen cubane-1,4-dicarboxylate ion plays a key role in this new type of rearrangement.
- Durkó, Gábor,Jalsovszky, István
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p. 5160 - 5163
(2013/07/05)
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- 7-Azabicyclo[2.2.1]heptane as a scaffold for the development of selective sigma-2 (σ2) receptor ligands
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A series of N-substituted 7-azabicyclo[2.2.1]heptanes (12-17 and 22-25) and similarly substituted pyrrolidines (32-36 and 41-44) were synthesized as sterically-reduced, achiral analogs of adamantane- and trishomocubane-derived σ ligands. In vitro competition binding assays against σ receptors revealed that arylalkyl N-substituents conferred selectivity for the σ2 subtype, while alicyclic or polycarbocyclic substituents imparted high affinity for both subtypes. The σ2 binding and subtype selectivities of N-arylalkyl-7-azanorbornanes was generally greater than the analogously-substituted pyrrolidines, indicating that steric bulk and conformational restriction around the nitrogen atom are likely important for subtype discrimination.
- Banister, Samuel D.,Rendina, Louis M.,Kassiou, Michael
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supporting information; experimental part
p. 4059 - 4063
(2012/07/03)
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- Metal-free efficient, general and facile iododecarboxylation method with biodegradable co-products
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The development of a novel, efficient and robust method for the general conversion of aliphatic and aromatic carboxylic acids to organic iodides without the use of heavy metals or strong oxidizing agents is reported. Commercially available N-iodoamides were used for both initiation and halogen donation under irradiative conditions. Isolation of the product is extremely simple and the major co-product is removed as a water-soluble biodegradable material. Copyright
- Kulbitski, Kseniya,Nisnevich, Gennady,Gandelman, Mark
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supporting information; experimental part
p. 1438 - 1442
(2011/07/30)
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- Thermochemical properties of iodinated cubane derivatives
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Since the initial synthesis of cubane, numerous derivatives have been made with a diverse range of physical, chemical, and biological properties. Some iodinated cubane derivatives have been reported to be thermolytically unstable and/or rearrange in situ. An iodinated cubane-containing, norbornene-based polymer showed rapid thermo-decomposition during TGA studies. Bis-(4-iodocubylmethyl)-dialkoxy disulfide undergoes fragmentation more easily than its non-iodinated counterpart. The synthesis and thermal behaviour of a library of iodinated cubane compounds are herein reported. Most of the iodinated cubane derivatives showed melting/decomposition with no exotherm upon cooling. 4-Iodo-1-vinylcubane was observed to rearrange to 4-vinyl-trans-β-iodostyrene and its cyclooctatetraene intermediate during DSC analysis. TGA studies on 1-iodo-4-(hydroxymethyl)-cubane suggest that this particular iodinated cubane scaffold is mostly prone to rapid thermo-decomposition.
- Griffiths, Justin R.,Tsanaktsidis, John,Savage, G. Paul,Priefer, Ronny
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experimental part
p. 15 - 20
(2010/04/25)
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- Synthesis of a novel chiral cubane-based Schiff base ligand and its application in asymmetric nitro-aldol (Henry) reactions
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The first reported cubane-based chiral Schiff base ligand has been successfully synthesized. This ligand has been evaluated on the nitro-aldol (Henry) reaction. The reactions were performed in the presence of four different copper salts, using eight different solvents, and five different temperatures. The highest enantioselectivity obtained for this novel ligand was ~39% ee.
- Ingalsbe, Michelle L.,St. Denis, Jeffrey D.,Gleason, James L.,Savage, G. Paul,Priefer, Ronny
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experimental part
p. 98 - 102
(2010/05/18)
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- CUBANE NUCLEOSIDE ANALOGS
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Cubane nucleoside analogs useful as anti-viral and anti-cancer agents are provided herein. Methods for preparing cubane nucleoside analogs are also provided. The invention also provides pharmaceutical compositions containing one or more cubane nucleoside analogs and one or more pharmaceutically acceptable carriers, excipients, or diluents. The invention also provides methods for treating cancer and viral infections in mammals. The cubane nucleosides describe herein are compound of the general formula (I) in which B is an optionally substituted purine or pyrimidines nucleoside base and R1, R2, R3, R4, R5, R6, and R7 are defined herein.
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Page/Page column 40
(2010/11/27)
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- Dimethyl cubane-1,4-dicarboxylate: A practical laboratory scale synthesis
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Complete experimental details for the preparation of dimethyl cubane-1,4-dicarboxylate (1) in multigram quantities, from cyclopentanone (2), in an overall yield of c. 23% are presented.
- Bliese, Marianne,Tsanaktsidis, John
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p. 189 - 192
(2007/10/03)
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- Barton decarboxylation of cubane-1,4-dicarboxylic acid: Optimized procedures for cubanecarboxylic acid and cubane
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Cubane-1,4-dicarboxylic acid (3) and its monomethyl ester 2 were converted to cubanecarboxylic acid (4) and cubane (5), respectively, by homolytic decomposition of the corresponding thiohydroxamic esters.
- Eaton,Nodari,Tsanaktsidis,Upadhyaya
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p. 501 - 502
(2007/10/02)
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- Mechanistic Study of Base-Promoted Rearrangement of 1,5-Dibromopentacyclo2,5.03,9.04,8>decane-6,10-dione to 10-Oxa-9-oxopentacyclo2,4.03,6.05,8>decane-3-carboxylic Acid
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The conversion of 1,5-dibromopentacyclo2,5.03,904,8>decane-6,10-dione (1) to 10-oxa-9-oxopentacyclo2,4.03,6.05,8>decane-3-carboxylic acid (6) on treatment with 5percent aqueous potassium hydroxide was shown to proceed through 1, exo-7-dibromo-9-oxotetracyclo2,5.03,8>nonane-endo-4-carboxylic acid (2).Treatment of 1 with the base in heavy water gave rise to 2-d-6 deuterated at the 2-position, but 2 gave the protium analog 6 after the same treatment.These results are discussed in relation to reactions of similar compounds which have been previously described in the literature.
- Hasegawa, Takeshi,Nigo, Tomohiro,Kuwatani, Yoshiyuki,Ueda, Ikuo
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p. 2676 - 2681
(2007/10/02)
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- Synthesis of Alkynylcyclooctatetraenes and Alkynylcubanes
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The coupling of a variety iodocubanes with terminal acetylenes in refluxing NEt3 in the presence of Cu(I) and Pd(0) were examined.The products, isolated in about 50percent yields, were not alkynylcubanes but were instead the first examples of alkynyl-1,3,5,7-cyclooctatetraenes.The first examples of alkynylcubanes (cubylacetylenes) were themselves synthesized in modest yields by Negishi's procedure from alkyl cubyl ketones.Cubylacetylenes were shown to be stable under Heck-like coupling conditions and potentially useful thereby for the introduction of the cubylacetylene moiety into complex systems.
- Eaton, Philip E.,Stoessel, Daniel
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p. 5138 - 5142
(2007/10/02)
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- Oxidation of Primary Amines by Dimethyldioxirane
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Dimethyldioxirane oxidizes primary amines rapidly, and generally in high yield, to the corresponding nitro compounds.The method can also be used to syntesize polynitro compounds.
- Murray, Robert W.,Rajadhyaksha, Shirish N.,Mohan, Lily
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p. 5783 - 5788
(2007/10/02)
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- Decarboxylation of Bridgehead Carboxylic Acids by the Barton Procedure
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Reductive decarboxylation of a series of bicyclic and polycyclic acids in which the carboxyl group is attached to the bridgehead position has been investigated.Conversion of the acids into thiohydroxamic esters occurs via reaction of the derived acid chlorides with N-hydroxypyridine-2-thione.Decomposition of the esters proceeds smoothly in boiling benzene in the presence of 1-butyl mercaptan to give the reduced product in high yield.The procedure appears to be generally applicable, and is unaffected by functional groups such as esters and acetals.
- Della, Ernest W.,Tsanaktsidis, John
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p. 2061 - 2066
(2007/10/02)
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