- Exhaustive One-Step Bridgehead Methylation of Adamantane Derivatives with Tetramethylsilane
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A methylation protocol of adamantane derivatives was investigated and optimized using AlCl3 and tetramethylsilane as the methylation agent. Substrates underwent exhaustive methylation of all available bridgehead positions with yields ranging from 62 to 86 %, and up to six methyl groups introduced in one step. Scaling-up of the reaction was demonstrated by performing the >40 gram-scale synthesis of 1,3,5,7-tetramethyladamantane with 62 % yield. For several substrates, rearrangements were observed, as well as cleavage of functional groups or Csp3?Csp2 bonds or even cyclohexyl-adamantyl bonds. Based on mechanistic studies, it is suggested that a reactive methylation complex is formed from tetramethylsilane and AlCl3. X-ray diffraction structures of hexamethylated bis-adamantyls reveal elongation or widening of sp3 carbon bonds between adamantyl moieties to 1.585(3) ? and 125.26(9)° due to repulsive H???H contacts.
- Bonsir, Maxime,Davila, Christian,Geerts, Yves,Kennedy, Alan R.
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supporting information
p. 5227 - 5237
(2021/10/19)
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- Binding study on 1-adamantylalkyl(benz)imidazolium salts to cyclodextrins and cucurbit[n]urils
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Multitopic guests are used as key components of molecular triggers, switchers, sensors, or reactors in recent supramolecular chemistry studies. The increasing complexity of these compounds correlates with the need for versatile, synthetically available binding motifs (building blocks) with tuneable supramolecular properties. The utilisation of a favoured 1-adamantylmethyl moiety in ammonium, imidazolium and pyridinium salts is sometimes restricted by synthetic difficulties most likely related to the adamantane cage bulkiness. Therefore, we prepared a series of new adamantylated (benz)imidazolium salts with longer flexible linkers between the adamantane cage and cationic moiety. We tested the supramolecular properties of these binding motifs towards the natural cyclodextrins α-CD, β-CD and γ-CD and cucurbit[n]urils (n= 7, 8) using NMR, mass spectrometry and titration calorimetry. All tested guests formed 1:1 complexes with the abovementioned hosts, retaining binding strengths, selectivity, and complex geometries in comparison to the parent methylene-linked homologues. We did not confirm our original concern that longer linkers would negatively affect the binding strength towards CBns due to the reduction in the ion-dipole interaction contribution. Therefore, we believe that adamantylalkyl imidazolium binding motifs can be used for multitopic supramolecular guest construction.
- Jelínková, Kristyna,Kova?evi?, Jelica,Wrzecionková, Eva,Prucková, Zdeňka,Rouchal, Michal,Dastychová, Lenka,Vícha, Robert
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supporting information
p. 7071 - 7079
(2020/05/16)
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- Synthesis and Photodimerization of 2- And 2,3-Disubstituted Anthracenes: Influence of Steric Interactions and London Dispersion on Diastereoselectivity
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There is increased evidence that the effect of bulky groups in organic, organometallic, and inorganic chemistry is not only repulsive but can be attractive because of London dispersion interactions. The influence of the size of primary alkyl substituents in 2- and 2,3-positions of anthracenes on the diastereoselectivity (anti vs syn dimer) of the [π4s + π4s] photoinduced dimerization is investigated. The synthesis of the anthracene derivatives was achieved by Suzuki-Miyaura reaction of 2,3-dibromoanthracene with alkylboronic acids as well as by reduction of anthraquinones that were obtained from 2,3-disubstituted 1,3-butadienes and naphthoquinone followed by dehydrogenation. The mixtures of dianthracene isomers were analyzed with respect to the anti/syn-ratio of the products by X-ray crystallography and nuclear Overhauser effect spectroscopy. While for the 2,3-dimethylanthracene the anti and syn isomers were formed in equal amounts, the anti dimers are the major products in all other cases. A linear correlation (R2 = 0.98) between the steric size (Charton parameter) and the isomeric ratio suggests that the selectivity is dominated by classical repulsive steric effects. An exception is the iso-butyl substituent that produces an increased amount of the syn isomer. It is suggested that this is due to an exalted effect of London dispersion interactions.
- Geiger, Thomas,Haupt, Anne,Maichle-M?ssmer, C?cilia,Schrenk, Claudio,Schnepf, Andreas,Bettinger, Holger F.
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p. 10120 - 10135
(2019/08/26)
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- Synthesis and Transformations of Aryl-Substituted Alkenes of the Adamantane Series
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Aryl-substituted alkenes of the adamantane series, 1-[(Z,E)-3-phenylprop-2-en-1-yl]adamantane and 1-[(Z)-3-phenylprop-1-en-1-yl]adamantane, have been synthesized by the Wittig reaction. Their allylic bromination involves two concurrent reactions, radical substitution and raical addition. The different chemical behaviors of the aryl-substituted alkenes have been demonstrated in the Ritter reaction. Depending on the alkene structure and acid catalyst nature, the products are secondary amides, sulfonic acid derivatives, and homoadamantane γ-sultone.
- Savel’eva,Leonova,Baimuratov,Klimochkin, Yu. N.
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p. 996 - 1002
(2018/09/12)
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- Metallocene compounds, including the catalyst, the catalyst used in the process of olefin polymers, olefin homopolymers and copolymers and
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PROBLEM TO BE SOLVED: To solve shortcomings of metallocene compounds of the present technology standard and to provide metallocenes that increase desirable characteristics such as high melting point, high molar mass homopolymers and high molar mass copolymers, and do so at higher productivities when used as components of supported catalysts under industrially relevant polymerization conditions at temperatures of from 50 to 100°C.SOLUTION: Certain metallocene compounds are provided that, when used as a component in a supported polymerization catalyst under industrially relevant polymerization conditions, afford high molar mass homo polymers or copolymers like polypropylene or propylene/ethylene copolymers without the need for any α-branched substituent in either of the two available 2-positions of the indenyl ligands.
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Paragraph 0198
(2017/11/01)
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- Transmembrane anion transport mediated by adamantyl-functionalised imidazolium salts
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We present the design, synthesis and transmembrane anion transport properties of a new class of mobile organic transporters, possessing a central imidazolium cation and two external adamantyl units. We demonstrate herein that the imidazolium cation can be incorporated in the structure of active mobile anion transporters. Depending on the nature of the counter-anion of the salt, as well as the extravesicular anions, different anion selectivities were obtained. We show the importance of the H2 proton of the imidazolium cation in order to obtain a higher binding constant of the chloride anion. Furthermore, we demonstrate the importance of the flexibility of the spacers between the adamantyl groups and the imidazolium cation in the transport process.
- Gravel, Julien,Schmitzer, Andreea R.
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p. 364 - 371
(2015/08/18)
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- Preparative synthesis of vinyl diamondoids
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We describe a convenient four-step preparation of 1-vinyl adamantane, 1-vinyl diamantane, and 4,9-divinyl diamantane from the respective diamondoid acetic acids in 50-80% isolated yields involving esterification, reduction, and hydrobromination/dehydrobromination. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Fokin, Andrey A.,Butova, Ekaterina D.,Barabash, Anastasiya V.,Huu, Nhan N.,Tkachenko, Boryslav A.,Fokina, Natalie A.,Schreiner, Peter R.
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p. 1772 - 1777
(2013/05/21)
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- METALLOCENE COMPOUNDS, CATALYSTS COMPRISING THEM, PROCESS FOR PRODUCING AN OLEFIN POLYMER BY USE OF THE CATALYSTS, AND OLEFIN HOMO-AND COPOLYMERS
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Certain metallocene compounds are provided that, when used as a component in a supported polymerization catalyst under industrially relevant polymerization conditions, afford high molar mass homo polymers or copolymers like polypropylene or propylene/ethylene copolymers without the need for any α-branched substituent in either of the two available 2-positions of the indenyl ligands. The substituent in the 2-position of one indenyl ligand can be any radical comprising hydrogen, methyl, or any other C2-C40 hydrocarbon which is not branched in the α-position, and the substituent in the 2-position of the other indenyl ligand can be any C4-C40 hydrocarbon radical with the proviso that this hydrocarbon radical is branched in the β-position. This metallocene topology affords high melting point, very high molar mass homo polypropylene and very high molar mass propylene-based copolymers. The activity/productivity levels of catalysts including the metallocenes of the present invention are exceptionally high.
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- Immobilization of rhodium complexes at thiolate monolayers on gold surfaces: Catalytic and structural studies
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Chiral rhodium-diphosphine complexes have been incorporated into self-assembled thiolate monolayers (SAMs) on gold colloids. Catalysts of this type are of interest because they combine properties of homogeneous and heterogeneous systems. In addition, it s
- Belser, Thomas,Stoehr, Meike,Pfaltz, Andreas
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p. 8720 - 8731
(2007/10/03)
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- INHIBITORS OF PRENYL-PROTEIN TRANSFERASE
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The present invention comprises piperazine/piperazinone-containing compounds having multicyclic ring system substituents on one of the piperazine/piperazinone nitrogens, which inhibit prenyl-protein transferases, including farnesyl-protein transferase and geranylgeranyl-protein transferase type I. Such therapeutic compounds are useful in the treatment of cancer
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Page column 65
(2010/01/21)
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- Cosalane Analogues with Enhanced Potencies as Inhibitors of HIV-1 Protease and Integrase
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Several new analogues of the novel anti-HIV agent cosalane have been synthesized and evaluated as inhibitors of HIV-1 integrase and protease, HIV-1 replication, HIV-1 and HIV-2 cytopathicity, HIV-1- and HIV-2-mediated syncytium formation, and cytopathicit
- Cushman, Mark,Golebiewski, W. Marek,Pommier, Yves,Mazumder, Abhijit,Reymen, Diane,et al.
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p. 443 - 452
(2007/10/02)
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- ARYL THIOPYRANO[2,3,4-C,D]INDOLES AS INHIBITORS OF LEUKOTRIENE BIOSYNTHESIS
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Compounds having the formula I: are inhibitors of 5-lipoxygenase and inhibitors of leukotriene biosynthesis. These compounds are useful as anti-asthmatic, anti-allergic, anti-inflammatory, and cyto-protective agents. They are also useful in treating angina, cerebral spasm, glomerular nephritis, hepatitis, endotoxemia, psoriasis, uveitis, and allograft rejection and in preventing the formation of atherosclerotic plaques.
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- Thiopyrano[2,3,4-c,d]indoles as inhibitors of leukotriene biosynthesis
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Compounds having the formula I: STR1 are inhibitors of leukotriene biosynthesis. These compounds are useful as anti-asthmatic, anti-allergic, anti-inflammatory, and cytoprotective agents. They are also useful in treating angina, cerebral spasm, glomerular nephritis, hepatitis, endotoxemia, psoriasis, uveitis and allograft rejection and in preventing the formation of atherosclerotic plaques.
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- Imidazole derivatives and salts thereof and pharmaceutical formulations useful in thrombo-embolic disorders
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Imidazoles of formula (I) STR1 wherein A is a chemical bond or a straight or branched, saturated or unsaturated, aliphatic residue having from 1 to 6 carbon atoms wherein 1, 2 or 3 of such carbon atoms may be replaced by a corresponding number of heteroatoms selected from oxygen, sulphur and nitrogen providing (in the case of 2 or 3 heteroatoms) that any such heteroatom is not located adjacent to a further such heteroatoms or heteroatoms R is a fused, saturated or unsaturated, non-aromatic carbocyclic, polycyclic ring system; a saturated or unsaturated, carbocyclic spirocyclic ring system, optionally containing one or more ring heteroatoms selected from oxygen, sulphur and nitrogen; or a saturated or unsaturated, carbocyclic bridged-polycyclic ring system, optionally containing one or more ring heteroatoms selected from oxygen, sulphur and nitrogen and having one or more bridges; or AR together represent a straight or branched, saturated or unsaturated, aliphatic residue having 3 to 6 carbon atoms, wherein 1, 2 or 3 of such carbon atoms may be replaced by a corresponding number of heteroatoms selected from oxygen, sulphur and nitrogen providing (in the case of 2 or 3 heteroatoms) that any such heteroatom is not located adjacent to a further such heteroatom or heteroatoms; which aliphatic residue is substituted by at least two groups, which may be the same or different, selected from the groups specified for R above. and acid addition salts and pharmaceutically acceptable bioprecursors thereof. Methods of preparing the imidazoles are disclosed. The imidazoles and their acid addition salts and bioprecursors are useful in the treatment or prophylaxis of thrombo-embolic conditions.
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