Iridium-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Cyanamides

The complex [Ir(cod)Cl](2)/DPPF or racBINAP is an efficient catalyst for the [2+2+2] cycloaddition of alpha,omega-diynes with cyanamides. A wide range of cyanamides derived from secondary amines are good coupling partners for alpha,omega-diynes. The reaction of unsymmetrical alpha,omega-diynes possessing two different internal alkyne moieties with cyanamides is regioselective. A competitive experiment showed that cyanamide is more reactive than nitrile. This higher reactivity of cyanamide than nitrile was analyzed based on density functional theory (DFT) calculations at the B3LYP level.