**2.3. Synthesis of (−)-isocomene and (−)-triquinane by acid catalyzed rearrangement of (−)-modhephene**

Triquinanes have received considerable attention by their unique structure as well as their reported biological activities. (−)-Modhephene **9** of established absolute stereochemistry was subjected to acid catalyzed carbocation rearrangements which led to an interesting synthesis of (−)-isocomene **10** and (−)-triquinane **11**[6]. This study was extended further by preparation of (−)-modhephene **9d** stereospecifically at 14β geminal methyl group. Under same experimental conditions, deuterium labeled (−)-triquinane **11d** a stereospecific 1,2-migration of 7/4β methyl group was observed (**Scheme 4**).
