In our continuing studies on Pauson-Khand reaction (PKR) of exo-cyclic enynes,1 we examined synthesis of [5.n.1.01,5] tricyclic compounds (n = 2-4) by intramolecular PKR of various 3-alkynyl-1-alkylidenecyclic compounds. We applied the present reaction to formal total synthesis of α- and β-cedrenes.