Synthetic Studies on the Marine-Derived Sesquiterpene (+)-Viridianol: Divergent Behaviour of Two Structurally Related, Ring-Fused Cyclopropanes under the Same Hydrogenolytic Conditions

Hydrogenolytic cleavage of the ring-fused cyclopropane 11 using hydrogen in the presence of platinum oxide afforded the gem-dimethylated cyclohexane 12 in 99 % yield. In contrast, analogous treatment of congener 13 afforded only trace amounts of the targeted and gem-dimethylated sesquiterpene (+)-viridianol (1), the major products of reaction now being the vic-dimethylated compound 14 and the 2-fold ring-cleavage product 15.