Force field and multinuclear nmr study of the conformational properties of thiolane-1-oxide and its mono and dimethyl derivatives

Force field calculations and ¹H, ¹³C and ¹⁷O NMR data are reported for thiolane S-oxide and several of its mono and dimethyl derivatives. For comparison carbon-13 and oxygen-17 chemical shifts of the corresponding S-dioxides are also reported. According to force field calculations and NMR data the conformation of S-oxides depends on the number and on the position of ring substituents. Oxygen-17 chemical shifts of thiolane S-oxides are apparently not very sensitive to ring substitution and to the configuration of the sulfinyl group. This is however the result of conformational changes which cannot be easily predicted. For 2-methyl derivatives δ₁₇₀ allows an easy identification of the cis and trans isomers.