38256-01-8Relevant articles and documents
Structural effects on the thermochemical properties of carbonyl compounds. II. Enthalpies of combustion, vapour pressures and enthalpies of sublimation, and standard enthalpies of formation in the gaseous phase, of 1-adamantyl methyl ketone and of 1,1'-diadamantyl ketone
Abboud, J.-L. M.,Jimenez, P.,Roux, M. V.,Turrion, C.,Lopez-Mardomingo, C.,Sanz, G.
, p. 217 - 223 (1992)
The energies of combustion of 1-adamantyl methyl ketone, and 1,1'-diadamantyl ketone have been determined using a static bomb calorimeter.The vapour pressures have been measured over a temperature range of about 17 K by the Knudsen-effusion technique.From the experimental results the following quantities for the two compounds, at T = 298.15 K, have been derived: table.Structural effects on ΔfHmdeg(g) for these and other ketones have been discussed.
Hydrogen bonding and solvent effects in heteroaryldi(1-adamantyl)methanols: An NMR and IR spectroscopic study
Lomas, John S.,Adenier, Alain,Cordier, Christine,Lacroix, Jean-Christophe
, p. 2647 - 2652 (1998)
Reaction ot the organolithium derivatives of certain heteroaromatics [2-furanyl, 2-thienyl, 2-thiazolyl, 2-pyridyl and 2-(3-methylpyndyl)] with di(1-adamantyl) ketone gives potentially rotameric tertiary alcohols With 2-pyndyl- and 2-(3-methylpyridyl)lithium only the syn isomer is obtained. The syn isomer makes up 85-100% of (2-furanyl)diadamantylmethanol and 80-90% of the 2-thienyl derivative, depending on the NMR solvent. In chloroform or benzene the 2-thiazolyl derivative is a 2:1 mixture, the isomer with the sulfur atom syn to the OH group predominating; in DMSO or in the solid state this is the sole species. The IR absorption frequency for OH stretching correlates with the corresponding proton NMR shift in chloroform and with its temperature dependence Δδ/ΔT. In pyridine Δδ/ΔT is either large (-20 ppb/°C) or small (-1 to -2 ppb/°C) for intermolecular and intramolecular hydrogen-bonded species, respectively. Semi-empirical calculations (AM1 and PM3) suggest that the anti alcohols should be the more stable in the gas phase, but solvent effects and hydrogen bonding in the case of the pyridyl derivatives, appear to reverse this situation, making the isomer with OH syn to the heteroatom the principal, and sometimes the only, species observed in solution.
Deoxygenation of dithiirane 1-oxides with Lawesson's reagent leading to the corresponding dithiiranes
Ishii, Akihiko,Yamashita, Remi,Saito, Masashi,Nakayama, Juzo
, p. 1555 - 1558 (2003)
3,3-Disubstituted dithiirane 1-oxides were efficiently reduced with Lawesson's reagent (LR) to give the corresponding dithiiranes. X-ray diffraction analysis of 3,3-di(1-adamantyl)dithiirane is reported. Reaction of 34S-labeled 3,3-di(1-adamant
Exhaustive One-Step Bridgehead Methylation of Adamantane Derivatives with Tetramethylsilane
Bonsir, Maxime,Davila, Christian,Geerts, Yves,Kennedy, Alan R.
, p. 5227 - 5237 (2021/10/19)
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.
Trifluoroacetylation and ionic hydrogenation of [2-(3-alkoxy-thienyl)]di(1-adamantyl)methanols
Lomas, John S.,Vauthier, Edouard,Vaissermann, Jacqueline
, p. 1399 - 1408 (2007/10/03)
Lithiation of 3-alkoxythiophenes followed by reaction with di(1-adamantyl) ketone leads to anti-[2-(3-alkoxy-thienyl)]di(1-adamantyl)methanols where the C-OH proton is intramolecularly hydrogen-bonded to the alkoxy group. The structure of the 3-methoxy derivative was confirmed by a single crystal X-ray diffraction study. Reaction of this alcohol with trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) in dichloromethane gives a trifluoroacetate, the initially formed carbocation undergoing an intramolecular 1,5-hydride shift to give a carboxonium ion. However, in the absence of anhydride, trifluoroacetate is formed to the extent of about 15% only. Ionic hydrogenation with TFA and an organosilane in dichloromethane gives syn- and anti-[2-(3-methoxythienyl)]-diadamantylmethanes by reduction of the carbocation, with a preference for the isomer with the Ad2CH hydrogen close to methoxy. The corresponding 3-ethoxy compound behaves quite differently: in TFA-dichloromethane a trifluoroacetate is formed which then eliminates acetaldehyde to give anti-[2-(3-hydroxythienyl)]diadamantylmethane. In the presence of an organosilane syn- and anti-[2-(3-ethoxythienyl)]diadamantylmethanes are formed together with the 3-hydroxy derivative. Isotope labelling experiments show that the anti deoxygenation product is obtained by reduction of both the carbocation and the carboxonium ion. The 3-isopropoxy derivative reacts sluggishly with TFA and, with an organosilane, tends to give preferentially the less stable, syn deoxygenation product. The activation energies for syn to anti rotation in the [2-(3-alkoxythienyl)]diadamantylmethanes indicate significant differences in the steric effects of the alkoxy groups.
Heteroaromatic organolithium addition to a congested ketone: Conformational isomerism in (N-alkylpyrrol-2-yl)di(1-adamantyl)-methanols
Lomas, John S.,Vaissermann, Jacqueline
, p. 1777 - 1781 (2007/10/03)
Tertiary alcohols have been prepared by reaction of 2-lithio-N-methylpyrrole and 2-lithio-N-ethylpyrrole with di(1-adamantyl)ketone. The conformations of the N-methyl derivatives have been determined by single crystal X-ray diffraction studies. The N-alkylpyrrol-2-yl derivatives are synthesized as the anti isomers which upon heating undergo rotation about the sp2-sp3 C-C bond to give the more stable, syn isomers with activation energies in benzene of 31.0 (Me) and 30.7 (Et) kcal mol-1. Semi-empirical (AM1) and ab initio (3-21G*//AM1) calculations indicate that the energy difference between the two rotamers is of the order of 5 kcal mol-1. Ionic hydrogenation of anti-(N-methylpyrrol-2-yl)diadamantylmethanol in dichloromethane-TFA-triethylsilane gives the anti isomer of (N-methylpyrrol-2-yl)diadamantylmethane, accompanied by substantial amounts of diadamantylketone. The barrier to anti→syn rotation in the deoxygenation product is about 4 kcal mol-1 higher than for the corresponding alcohol.
Tri(1-adamantyl)methane and its Thermolysis
Lomas, John S.
, p. 1531 - 1532 (2007/10/02)
The synthesis of the title compound, a new tri(tert-alkyl)methane, and the kinetics and products of its thermolysis are described.
An EPR Study of 1-Adamantylmethyl Radicals
Davies, Alwyn G.,Neville, Anthony G.
, p. 2021 - 2024 (2007/10/02)
The 1-adamantylmethyl, di(1-adamantyl)methyl, and tri(1-adamantyl)methyl radicals have been prepared by photolysis of hexabutylditin in the presence of the corresponding bromide, the 1-adamantylhydroxymethyl radical by photolysis of di-tert-butyl peroxide in the presence of 1-adamantylmethanol, and the di-1-adamantylketyl radical anion by photolysis of di-1-adamantyl ketone in the presence of sodium-potassium alloy.The EPR 1H and 13C hyperfine coupling constants which are observed in these radicals and in the tetra-1-adamantylcyclobutadiene radical cation are discussed in terms of the structures of the radicals.The di-1-adamantylmethyl radical decays in cyclopentane at 310 K and in toluene at 180-240 K by clean pseudo first-order kinetics.The reaction is much faster in the latter solvent, implying that it involves abstraction of benzylic hydrogen.At 190 K in pentane, the decay shows second-order kinetics.The decay of the tri-1-adamantylmethyl radical shows more complicated behaviour.
Reactions of Thermally Generated tert-Butyl and Di(tert-alkyl)ketyl Radicals in Toluene: Cage Effects and Hydrogen Transfer
Lomas, John S.,Briand, Sylvette,Fain, Dominique
, p. 166 - 175 (2007/10/02)
Thermolysis of di(1-adamantyl)-tert-butylmethanol (2a) in toluene at 145-185 deg C gives mainly bibenzyl, di(1-adamantyl) ketone, di(1-adamantyl)methanol, and the cross-product, 1,1-di(1-adamantyl)-2-phenylethanol.In the presence of benzophenone (BP) or benzenethiols as hydrogen-accepting and hydrogen-donating radical scavengers, respectively, the di(1-adamantyl)methanol/di(1-adamantyl) ketone ratio tends to steady values as the scavenger/2a ratio is increased, while the cross-product disappears.At 165 deg C the secondary alcohol minimum is 8percent (BP) and the ketone minimum 11percent (thiol).These represent the contributions of geminate hydrogen atom transfer reactions to the overall yields, i.e., the cage effects.With BP the major cross-product is 1,1,2-tri-phenylethanol.Products from the self- and cross-reactions of benzyl and thiyl radicals are found when thiol is present, the diaryl disulfide predominating at high thiol concentration.In both cases, cross-products resulting from reaction of the tert-butyl radical with the scavenger-derived radical are detected in small amounts, being of greater importance in deuteriated toluene.The tert-butyl radical is considered, therefore, to be less reactive in hydrogen atom abstraction than the 1-adamantyl radical.Cage effects for other di(tert-alkyl)-tert-butylmethanols that thermolyze with exclusive t-Bu-C bond fission have also been measured and the product composition of the scavenger-free reaction interpreted by kinetic simulation based on the steady state approximation.Rate constants for hydrogen abstraction by the tert-butyl radical from toluene are not accurately determined by this procedure but seem, nevertheless, to indicate that the literature value (14.4 M-1s-1 at 48 deg C) is an overestimate. Solvent hydrogen abstraction by the ketyl radical shows a small but well-defined steric effect.
Reactions of Thermally Generated 1-Adamantyl and Di(1-adamantyl)ketyl Radicals in Toluene
Lomas, John S.,Fain, Dominique,Briand, Sylvette
, p. 1052 - 1058 (2007/10/02)
Thermolysis of tri(1-adamantyl)methanol in toluene at 145-185 deg C gives bibenzyl, di(1-adamantyl)ketone, di(1-adamantyl)methanol and a cross-product, 1,1-di(1-adamantyl)-2-phenylethanol, in yields which depend on the temperature and the isotopic composition of the solvent.In the presence of benzophenone the intermediate di(1-adamantyl)ketyl radical transfers hydrogen, giving ketone and the hydroxybenzhydryl radical, the cross-product then being 1,1,2-triphenylethanol.The cage effect (0.38-0.415) has been determined by studying thermolysis in deuterium labeled toluene.In normal toluene almost all the secondary alcohol is formed from Ad2C*OH by hydrogen abstraction from the solvent, whereas in deuterated toluene 22-32percent results from self-disproportionation of ketyl radicals, showing that there is a substantial kinetic isotope effect on hydrogen abstraction.Kinetic modeling of the reaction by means of a rapid, iterative procedure based on the steady-state approximation suggests values in the range 6.0-7.4, decreasing as the temperature rises.
