Synthesis and Carbon-13 Nuclear Magnetic Resonance Spectroscopy of 5,6-Dihydro-2-methyl-1,4-oxathiin, trans-Tetrahydro-1,4-benzoxathiin, 1,4-Tetrahydro-benzoxathiin, the 4-Oxides, 4,4-Dioxides and Related Acyclic Compounds

Article abstract of DOI:10.1002/mrc.1270160404

The results of a 13C NMR spectral investigation involving 5,6-dihydro-1,4-oxathiins, 1,4-tetrahydro<9,10>benzoxathiin, trans-tetrahydro-1,4-benzoxathiin, and the corresponding sulfoxides and sulfones are reported.An interpretation involving a dipolar structure with (2p -> 2p)? conjugation as opposed to (2p -> 3d)? interactions with the vinyloxy sulfides seems consistent with trends in the 13C NMR shifts.For the sulfoxides and sulfones, the substituent-induced chemical shift (SCS) effects at the β vinylic carbons (βSO and βSO2 effects) are considerably less than those at sp³ carbons.The γSO and γSO2 values at the sp²γ carbons indicate deshielding, in contrast to the shielding at the sp³ carbons.