Refined model of optical activity of cis-dihydrodiol metabolites: role of 1,3-diene conformation in the electronic circular dichroism spectra

The effect of the secondary structural feature, that is, nonplanarity of carbon-carbon double bonds, on the rotatory strength of the long-wavelength π-π* electronic transition has been investigated for the series of monocyclic cis-dihydrodiol arene metabolites and model compounds. The contribution from nonplanar C=C bonds to the overall rotatory strength of the π-π* electronic transition is more significant than the contribution from twisted 1,3-diene chromophore. The effect of the substitution pattern in the cyclohexadiene skeleton may be decisive for the sign of the long-wavelength π-π* Cotton effect.