Conformational studies of monoterpenes. II–conformational studies of bicyclo[3.1.1]heptane derivatives by 13C NMR

The carbon-13 spectra of seventeen bicyclo[3.1.1]-heptane derivatives have been recorded and assigned. Study of the C-6 and C-7 chemical shifts permits the conformations to be assigned to the bridged chair, Y-shaped, or bridged boat conformations. The spectrum of verbenone is anomalous and is compared to that of umbellulone recorded earlier.