13C NMR of organosulfur compounds the 13C chemical shifts of monocyclic γ- and δ-sultones

The ¹³C NMR spectra of several monocyclic γ-sultones(1,2-oxathiolane 2,2-dioxides) and δ-sultones(1,2-oxathiane 2,2-dioxides) have been determined and are presented herein. The chemical shifts of the ring carbons of these compounds are compared in terms of conformational, electronic and anisotropic differences. Electric field effects may be responsible for the chemical shifts of the C-α carbon, but do not appear to be important for C-α. Anisotropic deshielding also appears to be important for the chemical shifts of C-α, but the effects on C-α appear to be small. Dipole changes at C-α and C-α, induced by back donation of electron density from the ring oxygen to sulfur, may explain the chemical shifts at C-α. Substituent effects are readily explained in terms of well-known effects. In general, the carbons closest to the sulfonate group are found to be the most affected, and the carbons of the δ-sultones proximate to the sulfonate group are found to be more deshielded than those of the γ-sultones.