The NMR spectra and conformations of cyclic compounds—VII: The conformations of β‐pinene, pinocarvone and the cis‐ and trans‐pinocarveols

The proton magnetic resonance spectra of β‐pinene pinocarvone and the cis ‐ and trans ‐pinocarveols have been completely assigned at 220 and 300 MHz. On the basis of the proton‐proton spin‐spin couplings derived, conformations have been deduced for these molecules with greater certainty than has hitherto been possible. Pinocarvone is Y‐shaped, while in all the other compounds the conformation is intermediate between a Y‐shape and a bridged chair, with the C 3 atom bent away from the gem dimethyl groups. These conformations are discussed in terms of the steric interactions in these systems and are compared with related molecules.