Odor of Monocyclic Partial Structures of Patchouli Alcohol and Related Compounds

Numerous substituted trimethylcyclohexanones, trimethylcyclohexenols and trimethylhexanols have been synthesized from either 2,6,6-trimethylcyclohex-2-en-l-one or 3,5,5-trimethylcyclohex-2-en-l-one (isophorone). These compounds were examined as monocyclic partial structures of the tricyclic patchouli alcohol for their odor character and intensity. It was found that the size of the molecule (at least C10), substitution pattern, existence of a hindered tertiary hydroxyl group and the rigidity of structure were similarity determinants of the patchouli aroma character. Even so, the full balanced woody, earthy and camphoraceous character could not be found with any of them. Nevertheless, some of these simple monocyclic analogues possessed a lot of patchouli character. The odor intensity and quality for more than forty monocyclic compounds is described.