Electronic effect of some epoxides and cyclopropanes. Hyperconjugative electron withdrawal

Charge transfer absorption frequency and carbon nuclear magnetic resonance studies of epoxides and cyclopropane derivatives have given information about the electronic effects of these small rings. The epoxide group is strongly electron-withdrawing from an aromatic ring by hyperconjugative and inductive effects. Dichlorocyclopropane withdraws electrons inductively. The tosylimino group is also electron-withdrawing. These conclusions were drawn from the comparison with open chain analogues.