Ruthenium-catalyzed intramolecular [2+2+2] cyclization of allene-yne-enes: construction of fused-tricyclic skeletons.

Three's not a crowd: An intramolecular [2+2+2] cyclization between three different components, allene, alkyne, and alkene, has been realized using a catalytic amount of [Cp*RuCl(cod)] complex (cod = 1,5-cyclooctadiene), and afforded fused-tricyclic compounds in a highly stereoselective manner.