Preferred Conformations of cis-2-Substituted 5, 8-dimethyl-4-chromanols

Abstract

The OH stretching absorptions of cis-2-substituted 5, 8-dimethyl-4--chromanols have been measured in dilute carbon tetrachloride solution. cis-2-Methyl[6] and cis-2-phenyl-5, 8dimethy1-4-chromanols [7]∼[10] take diequatorial conformation having 4-quasi-equatorial OH and 2-equatorial methyl or phenyl groups preferably. On the other hand, cis-2ethoxycarbony1-5, 8-dimethyl-4-chromanol [11] prefers the quasi-axial OH conformation. In order to confirm the conformational equilibrium, temperature dependence of the OH absorption intensities for[6]∼[10] and ¹H-NMR of all the compounds were examined.