The circular dichroism of (–)-(S)-3-methylthian: a study of the electronic transitions and stereochemistry of cyclic sulphur derivatives

Abstract

The u.v. and c.d. spectra of (–)-(S)-3-methylthian and the u.v., l.d., and m.c.d. spectra of thian have been analysed by means of non-empirical MO calculations. While the n→σ* assignment of the transition at ca. 232 nm is confirmed, the absorption at ca. 214 nm is assigned to a σ→σ*(A₁â†�A₁) transition. The stereochemistry of cyclic sulphur derivatives is discussed in the light of a symmetry rule previously proposed.