Iridium- and Rhodium-Catalyzed [2+2+2] Cycloadditions of Diynes with Maleimide: A New Synthetic Route to Highly Substituted Phthalimides

The [2+2+2] cycloaddition of maleimide with α,ω-diynes in the presence of [IrCl(cod)] 2 or [RhCl(cod)] 2 and DPPE gives cyclohexadiene derivatives which are readily aromatized with DDQ or MnO 2 . This two-step procedure gives access to highly substituted phthalimides in good yields.