Generation of benzoimidazo[1,5-a]imidazoles via a copper-catalyzed tandem reaction of carbodiimide and isocyanoacetate

Carbodiimide reacts with isocyanide catalyzed by copper(I) iodide, leading to benzoimidazo[1,5-a]imidazoles in good yields. This reaction is efficient, and proceeds through a formal [3+2] cycloaddition and C-N coupling.