2566-56-5Relevant academic research and scientific papers
Ring-Inversion Barriers for the 3- and 4-Cyclohexenyl Radicals in Solution
Berson, J. A.,Griller, D.,Owens, K.,Wayner, D. D. M.
, p. 3316 - 3319 (2007/10/02)
Ring-inversion barriers for the 3- and 4-cyclohexenyl radicals were investigated by an electron paramagnetic resonance (EPR) method and were found to be 7.0 +/- 0.9 and 2.4 +/- 0.5 kcal mol-1 in fluid solution.The inversion motions and the magn
Factors Influencing Conformational Preferences in Cyclohexenes
Lambert, Joseph B.,Marko, Dale E.
, p. 7978 - 7982 (2007/10/02)
Conformational preferences have been measured for the first time for 4-substituted cyclohexenes in a solvent of low polarity.Measurements were made for the substituents Cl, Br, I, OH, OSiMe3, and CN and were compared with conformational preferences in cyclohexyl and exo-methylenecyclohex-3-yl.In the nearly nonpolar solvent CF2Cl2, in which intramolecular interactions are maximized, there is a much larger axial population for cyclohexen-4-yl than in cyclohexyl or exo-methylenecyclohex-3-yl.In particular, the dipolar interaction of the endocyclic double bond is reduced from that of the exocyclic double bond.This observation is confirmed by the almost negligible effect of symmetrizing the endocyclic double bond through 1,2-dimethyl substitution, in contrast with the large effect of symmetrizing the exocyclic double bond through 7,7-dimethyl substitution.Polar solvents increase the proportion of the axial conformer to a smaller extent for the endocyclic than for the exocyclic system, again in agreement with a lower dipolar effect in the endocyclic case.These results emphasize the anisotropic nature of the steric effects of double bonds.
Synthetic Applications of Metal Halides.Conversion of Cyclopropylmethanols into Homoallylic Halides.
McCormick, J.P.,Barton, Donald L.
, p. 2566 - 2570 (2007/10/02)
Magnesium and beryllium halides in refluxing diethyl ether effect the transformation of cyclopropylmethanols into homoallylic halides,in contrast to several other metal halides and Lewis acid/nucleophile combinations which were examined.Magnesium bromide and iodide are particularly effective: conditions are mild,yields are high,and little or no byproducts are formed.Tertiary and benzylic alcohols are more reactive than secondary alcohols,while the latter are converted into E homoallylic halides with high stereoselectivity.Cyclopropylmethanol itself fails to react.In the cases of magnesium halide reactions with bicyclo-2-hexanol and bicyclo-2-heptanol,addition of an equimolar amount of zinc halide not only caused substantial rate enhancement but also increased regioselectivity.
