- X-Ray Crystal Structure of the 2-Phenyladamant-2-yl Cation
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The crystal structure of the Sb2F11 salt of the 2-phenyladamant-2-yl cation, 1*Sb2F11, was determined at 183 K (P21/c, R1 = 0.0652, ?(C-C) = 0.02 Angstroem), because earlier published results indicated a charge delocalization from the cationic
- Laube, Thomas,Hollenstein, Sandro
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- Approaches to primary tert-alkyl amines as building blocks
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Primary tert-alkyl amines include analogues of amantadine, a fragment commonly linked to pharmacophoric groups to enhance biological activity. The preparation of primary tert-alkyl amines is considered to be a difficult problem. Four synthetic procedures, some of which have been previously reported for the synthesis of amines with primary (RCH2NH2) or secondary (RR'CHNH2) alkyl and/or aryl groups, were tested for the synthesis of primary tert-alkyl amines (RR′R″CNH2) in aliphatic series including adamantane adducts. These procedures included the formation and reduction of tert-alkyl azides, the Ritter reaction in standard and modified conditions, the addition of organometallic reagents to N-tert-butyl sulfinyl ketimines and one-pot reactions between nitriles and organometallic reagents in the presence of a Lewis acid, Τi(iPrO)4 or CeCl3. These synthetic routes are unexplored for primary tert-alkyl amines. Studies on the synthetic routes for primary tert-alkyl amines are currently lacking. The reaction conditions and substrate limitations were studied for each procedure, with the first procedure being the most general and applicable also for compounds bearing bulky adducts.
- Tzitzoglaki, Christina,Drakopoulos, Antonios,Konstantinidi, Athina,Stylianakis, Ioannis,Stampolaki, Marianna,Kolocouris, Antonios
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supporting information
(2019/07/10)
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- 2-Substituted and 2,2-disubstituted adamantane derivatives as models for studying substituent chemical shifts and C-Hax?Yax cyclohexane contacts - results from experimental and theoretical NMR spectroscopic chemical shifts and DFT structures
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Abstract The complete 1H and 13C NMR chemical shifts assignment for various 2-substituted and 2,2-disubstituted adamantane derivatives 1-38 in CDCl3 solution was realized on the basis of NMR experiments combined with chemical structure information and DFT-GIAO (B3LYP/6-31+G(d,p)-GIAO) calculations of chemical shifts in solution. Substituent-induced 13C NMR chemical shifts (SCS) are discussed. C-Hax?Yax contacts are a textbook prototype of steric hindrance in organic chemistry. The nature of these contacts will be further investigated in this work on basis of new adamantane derivatives, which are substituted at C-2 to provide models for 1,4-C-Hax?Yax and 1,5-C-Hax?Yax contacts. The B3LYP/6-31+G(d,p) calculations predicted the presence of NBO hyperconjugative attractive interactions between C-Hax and Yax groups along C-Hax?Yax contacts. The 1H NMR signal separation, Δδ(γ-CH2), reflects the strength of the H-bonded C-Haxa?Yax contact.
- Kolocouris, Antonios,Koch, Andreas,Kleinpeter, Erich,Stylianakis, Ioannis
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supporting information
p. 2463 - 2481
(2015/03/30)
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- Aminoadamantanes with persistent in vitro efficacy against H1N1 (2009) influenza A
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A series of 2-adamantanamines with alkyl adducts of various lengths were examined for efficacy against strains of influenza A including those having an S31N mutation in M2 proton channel that confer resistance to amantadine and rimantadine. The addition of as little as one CH2 group to the methyl adduct of the amantadine/rimantadine analogue, 2-methyl-2-aminoadamantane, led to activity in vitro against two M2 S31N viruses A/Calif/07/2009 (H1N1) and A/PR/8/34 (H1N1) but not to a third A/WS/33 (H1N1). Solid state NMR of the transmembrane domain (TMD) with a site mutation corresponding to S31N shows evidence of drug binding. But electrophysiology using the full length S31N M2 protein in HEK cells showed no blockade. A wild type strain, A/Hong Kong/1/68 (H3N2) developed resistance to representative drugs within one passage with mutations in M2 TMD, but A/Calif/07/2009 S31N was slow (>8 passages) to develop resistance in vitro, and the resistant virus had no mutations in M2 TMD. The results indicate that 2-alkyl-2-aminoadamantane derivatives with sufficient adducts can persistently block p2009 influenza A in vitro through an alternative mechanism. The observations of an HA1 mutation, N160D, near the sialic acid binding site in both 6-resistant A/Calif/07/2009(H1N1) and the broadly resistant A/WS/33(H1N1) and of an HA1 mutation, I325S, in the 6-resistant virus at a cell-culture stable site suggest that the drugs tested here may block infection by direct binding near these critical sites for virus entry to the host cell.
- Kolocouris, Antonios,Tzitzoglaki, Christina,Johnson, F. Brent,Zell, Roland,Wright, Anna K.,Cross, Timothy A.,Tietjen, Ian,Fedida, David,Busath, David D.
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p. 4629 - 4639
(2014/07/07)
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- 13C NMR spectroscopic comparison of sterically stabilized meta and para-substituted o-tolyldi(adamant-l-yl)methyl cations with conjugatively stabilized benzyl cations
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A series of meta- and para-substituted anti-o-tolyldi(adamant-1-yl)methyl cations has been generated by reaction of anti-o-tolyldi(adamant-1-yl)methanols with trifluoroacetic acid in chloroform. 13C NMR spectroscopy indicates small but significant variations in the chemical shifts of the charged carbon and its nearest neighbours on the adamantyl groups, and departures from additivity of substituent effects on the shifts of the aromatic carbons. Previous work on the closely related di(adamant-1-yl)benzyl cations is discussed. Comparison with data on aryl-substituted carbocations in superacid media reveals marked differences in the aromatic carbon shifts in the two types of carbocation. The dihedral angle between aryl and carbocation planes in aryldi(adamant-1-yl)methyl cations is estimated to be about 60°.
- Lomas, John S.
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p. 2601 - 2609
(2007/10/03)
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- Stereochemistry of 2-Methyl- and 2-Phenyl-2-adamantyl Cations
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When both diastereomers of -2-methyl-2-adamantyl 2,4-dinitrophenolate (18a) and -2-phenyl-2-adamantyl 2,4-dinitrophenolate (18b) were solvolyzed in 40percent aqueous acetone, 1:1 mixtures of (E)- and (Z)--2-R-adamantan-2-ols (19a, b) were obtained.The stereoselectivity of secondary 2-adamantyl cations, attributed to ? participation, is effectively suppressed by charge-stabilizing groups at C-2. - Key Words: Solvolysis / ? Participation / 5-D-2-Adamantyl derivatives
- Herrmann, Roland,Kirmse, Wolfgang
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p. 699 - 702
(2007/10/02)
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- Solvolysis of 2-Aryl-2-chloroadamantanes. A new Y Scale for Benzylic Chlorides
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A series of 2-aryl-2-chloroadamantanes 2, Ar = 4'-methylphenyl, 4'-fluorophenyl, phenyl, 3'-chlorophenyl, 3'-(trifluoromethyl)phenyl, and 4'-(trifluoromethyl)phenyl, were prepared, and the solvolytic rate constants in 23 solvents were measured.Significant
- Liu, Kwang-Ting,Sheu, Hun-Chang
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p. 3021 - 3025
(2007/10/02)
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- A New Oxindole Synthesis
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A quaternary carbon atom can be set up by irradiation of the N-methylaniline enamine 5 of adamantane-2-carbaldehyde giving the indoline 6 in poor yield.This product was converted into the spiro-oxindole 8, but only in very low yield.Quaternary carbon atom
- Fleming, Ian,Moses, Roger C.,Tercel, Moana,Ziv, Joseph
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p. 617 - 626
(2007/10/02)
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- 13C, 1H Spin-Spin Coupling. X - Norbornane: A Reinvestigation of the Karplus Curve for 3J(13C, 1H)
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13C, 1H spin-spin coupling constants over one, two and three bonds were measured from the 100 MHz 13C NMR spectra of deuteriated isotopomers of norbornane-d1 (1) and fenchane-2-d1 (2) and also of a number of monodeuteriated alkyl-substituted adamantanes.The magnitudes of the corresponding J(13C, 1H) values derived from these data by application of the well known relationship J(X, 1H) = 6.5144J(X, 2H) are discussed with respect to the structural data for the hydrocarbons, which were taken from force field calculations with the Allinger MM2 method.In particular, the dihedral angle dependence and the Karplus curve for 3J(13C, 1H) are investigated.Coupling constants calculated by the FP-INDO method are compared with the experimental data, and the effect of substitution by additional CC bonds in α-, β- and γ-positions of the 13C-α-C-β-C-γ-H bond fragment is elucidated.If substituent effects that arise through branching and methyl substitution in 1 and 2 are taken into account for dihedral angles Φ > 90 deg, one derives 3J(13C, 1H) = 4.50 - 0.87 cos Φ + 4.03 cos 2Φ with J(0 deg) = 7.7, J(60 deg) = 2.0 and J(180 deg) = 9.4 Hz.
- Aydin, Rafet,Guenther, Harald
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p. 448 - 457
(2007/10/02)
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- Thermolabile Hydrocarbons, XX. Synthesis, Structure, and Strain of Sym. Tetraalkyl-1,2-diarylethanes
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The syntheses of 18 1,1,2,2-tetraalkyl-1,2-diarylethanes 1 - 4 by dimerisation procedures starting with 10 - 13 are reported.In the absence of p-substituents X and with increasing alkyl side chains the α,p-dimers 6 or their aromatic counter parts 7 are obtained besides or instead of 1.The relationships between strain enthalpy Hs, bond lengths, bond angles, torsional angles, and rotational barrier are discussed on the basis of force field calculations.They are supported by two additional experimental structure determinations by X-ray diffraction.
- Kratt, Guenter,Beckhaus, Hans-Dieter,Lindner, Hans Joerg,Ruechardt, Christoph
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p. 3235 - 3263
(2007/10/02)
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- Adamantane Chemistry. Part 3. Abnormal Hypoiodite Reactions of 2-Substituted Adamantan-2-ols; Synthetic Routes to 4-Oxahomo- and 2-Oxa-adamantanes, and 7-Substituted-bicyclononan-3-ols
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Reaction of 2-methyladamantan-2-ol (1a) with lead tetra-acetate and iodine in boiling benzene did not yield the expected radical fragmentation product (3a), but rather a yellow, crystalline di-iodo-ether which was previously assigned structure (4) on the basis of chemical degradative evidence and on an apparent m/e 418 molecular ion (electron impact).Structure (4) is not supported by the spectroscopic data, and 13C n.m.r. studies on an isotopically enriched sample of the di-iodo-ether indicate the structure to be (5b).Re-investigation of the mass spectrum has revealed that the (fairly intense) molecular ion has m/e 416; previous assignment of the molecular ion to the m/e 418 peak (i.e.M+2) arose largely through the absence at that time of mass-marking facilities and the large interval between M.+ and the highest mass fragment ion.Similar hypoiodite reaction of 2-ethyl- (1b) and of 2-phenyl-adamantan-2-ol (1c) gave, respectively, the products (5a) and (7b), the latter arising from the hydrolysis during isolation of the iodo-ether (6c).Investigation of the chemistry of (5b) and (7b) has revealed useful preparative routes to substituted 4-oxahomo- and 2-oxa-adamantanes as well as 7-substituted-bicyclononan-3-ols.Several unusual reactions have been discovered, and reaction mechanisms are suggested.
- Black, Robin M.,Gill, G. Bryon
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p. 410 - 418
(2007/10/02)
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