endo-Dicyclopentadiene Synthesis of (±)-Sesquifenchene and (±)-epi-β-Santalene

Abstract The observation by Brown2 that P-2 nickel boride catalyst3 allows a simple, convenient, highly selective hydrogenation of norbornene double bonds in the presence of other double bonds (e.g. 1 → 2) suggested the possibility of utilizing endo-dicyclopentadiene (1) as a starting point for the synthesis of sesquiterpenes possessing the bicyclo[2.2.1]heptane nucleus. Specifically our objective was the development of a route from endo-dicyclo-pentadiene to sesquifenchene(3). We wish to report the details of an alternate synthesis of sesquifenchene4 as well as the conversion of a synthetic intermediate along the pathway to 3 into epi-β-santalene(4).