Ruthenium-Catalyzed [2+2+2] Cycloaddition of ,-Diynes and Selenocyanates: An Entry to Selenopyridine Derivatives

A novel synthetic method for the preparation of selenopyridine derivatives, involving a [ 2+ 2+ 2] cycloaddition of.,. -diynes and selenocyanates that is catalyzed by a ruthenium complex is described. This mild and straightforward reaction allows access to a wide range of selenopyridines with high yields and excellent regioselectivities, using dichloromethane or dichloroethane as solvents, at either 50 or 80 degrees C. Post-functionalization of halogenated cycloadducts via cyanation using copper and SNAr reaction provides substituted selenopyridines with good yields.