A carbon-13 and proton nuclear magnetic resonance study of 5,6-dihydro-2-methyl-1,4-oxathiin derivatives

Proton and carbon-13 n.m.r. spectral data for a series of 5,6-dihydro-2-methyl-1,4-oxathiins and the corresponding 4-oxide and 4,4-dioxide derivatives are reported. Results show that while the oxathiins and the 4,4-dioxide derivatives are conformationally mobile, the 4-oxide derivatives preferentially adopt the conformer which possesses an axial oxide.