Application of Carbon-13 Nuclear Magnetic Resonance to Conformational Analysis of Trimethylene Sulfites

Carbon-13 n.m.r. chemical shifts are reported for trimethylene sulfite, 10 alkyl derivatives, and a related 1,3,2-dioxathiane. Data are discussed in terms of possible chair and twist conformations and in some cases the data permit definitive conformational assignments. Results are compared with previous conclusions based on proton n.m.r. and dipole moment measurements. The orientation of the S=O group is shown to have a very pronounced influence on the C-4 and -6 ring carbon shieldings.