Optical Rotatory Dispersion Studies. 128. Octant Contributions of Methyl Groups in 4-tert-Butylcyclohexanones

Article abstract of DOI:10.1021/ja00528a036

A number of methyl-substituted 4-tert-butylcyclohexanones have been synthesized with high optical purity from naturally occuring chiral molecules of known absolute configuration.The circular dichroism spectra of these compounds were measured at both room temperature and 77 K in polar and nonpolar solvents, and empirical force field calculations were carried out to determine the energy difference between the chair and twist-boat conformations.Of particular interest was the discovery that the trans-3-methyl-4-tert-butylcyclohexanone (+)-4 exists mainly in the twist-boat form.In addition, the apparent antioctant behavior of the β-axial methyl group in compound (-)-5 at low temperature and in polar solvent is interpreted as arising form solvation of the molecule.