Studies towards the total synthesis of novel dolabellane-type diterpenoids: construction of the 5,11-fused bicyclic framework

An oxy-Cope protocol has been grafted on to a previously crafted hydroazulenic system to provide a facile entry into the 5,11-fused bicyclic skeleton present in the novel neodolabellane diterpenoids. Formation of a novel tricyclic diterpenoid framework, generated through a transannular cyclization in the 11-membered ring present in the neodolabellane skeleton and embodying a bridged cycloheptatriene moiety, has also been encountered.