The 1H NMR spectra of exo‐ and endo‐3‐thiatricylo[4.2.1.02,5]non‐7‐ene 3,3‐dioxide. The shielding effect of the sulfone group

Abstract
The proton spectra of exo‐ and endo‐3‐thiatricyclo[4.2.1.02,5]non‐7‐ene 3,3‐dioxide have been analysed and completely assigned. Considerations of coupling constants indicate that the thietane ring is nonplanar and that the norbornene residue is significantly distorted from the geometry of norbornene itself. The sulfone group induces significant changes in the shielding of the proximate olefinic proton in the endo isomer and the bridge protons in the exo isomer. These shifts appear to be the result of the electrostatic effects and effects associated with the diagmagnetic anisotropy of the sulfone group.