Iridium complex-catalyzed [2+2+2] cycloaddition of α,ω-diynes with monoalkynes: a new and efficient catalyst for cyclotrimerization of alkynes

[Ir(cod)Cl]2 combined with dppe was found to be a new and efficient catalyst for [2+2+2] cycloaddition. Dimethyl dipropargylmalonate reacted with 1-hexyne in the presence of a catalytic amount of [Ir(cod)Cl]2 combined with dppe at room temperature in 20 min to give an indane derivative in 84% yield. Various functionalized monoalkynes can be used for this [2+2+2] cycloaddition.