Issue 14, 1976

Chiroptical properties of lactones. Part III. Electronic rotatory strengths of the n→π* transition in αβ-unsaturated γ-lactone systems

Abstract

The chiroptical properties associated with the n→π* transition of dissymmetric αβ-unsaturated γ-lactone systems are calculated and relationships between the chiroptical observables and the stereochemical and electronic structural features of these systems are examined. The calculations are based on the INDO-MO model for the electronic structure of the molecular systems and excited states are constructed in the virtual orbital-configuration interaction approximation. The lowest-energy singlet-singlet transition is calculated to be of the n→π* type for each of the αβ-unsaturated γ-lactone structures examined. The n orbital in this transition is found to be somewhat localized on the carbonyl oxygen atom of the O[double bond, length half m-dash]C–O moiety, whereas the π* orbital is delocalized over the C[double bond, length half m-dash]C and O–C–O fragments. Oscillator strengths, rotatory strengths, and dissymmetry factors are calculated for the n→π* transition in a number of exo-ene and endo-ene αβ-unsaturated γ-lactone systems. The signs and magnitudes of the calculated rotatory strengths are related to specific structural features in these systems.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 2, 1976, 1674-1677

Chiroptical properties of lactones. Part III. Electronic rotatory strengths of the n→π* transition in αβ-unsaturated γ-lactone systems

H. Kreigh and F. S. Richardson, J. Chem. Soc., Perkin Trans. 2, 1976, 1674 DOI: 10.1039/P29760001674

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