NMR spectra and conformation of cembrene in solution

Using dimeric NMR spectroscopy, a complete interpretation of the¹H and¹³C NMR spectra of the diterpene hydrocarbon cembrene has been made. The experimental values of the SSCs for the¹H atoms in the PMR spectra of cembrene agree well with those calculated for the lowest-energy (“crystal”) conformation. In the light of the observation of intramolecular NOEs and of the low-temperature¹³C NMR spectra, it has been concluded that the cembrene molecule retains the “crystal” conformation in solution.