C-13 chemical shifts of the carbonyl group—VI: Transannular interactions in mesocyclic compounds

The utility of C-13 NMR in detecting transannular interactions of a carbonyl group with ? O? , ? S? and ? N? in eight-membered ring compounds has been studied. The C-13 carbonyl chemical shifts were determined in two solvents, employing frequency-sweep and pulse/Fourier transform techniques. The results confirm earlier conclusions based upon other physical methods and indicate that C-13 NMR should prove useful in studies of such interactions.