Employing commercially available 1,5-cyclooctadiene 5 as the starting material, the first total synthesis of the tricyclic sesquiterpene hydrocarbon kelsoene 3 has been accomplished, which also reaffirms its assigned structure. The basic strategy delineated here for the construction of the tricyclo[6.2.0.0(2,6)]decane framework is eminently suitable for the synthesis of other members of this class. (C) 1999 Elsevier Science Ltd. All rights reserved.