Regioselective Hydronickelation of Allenes and Its Application to the Hydrocyanative Carbocyclization Reaction of Allene–Ynes and Bis-Allenes

The carbocyanative cyclization of allene–ynes and bis-allenes under nickel catalysis is described. The key steps are the regioselective hydronickelation of allenes and subsequent cyclization via carbometalation. The former step determines the reaction pathway, and the latter controls the stereochemistry of substituted olefins. The products are useful carbo- and heterocycles that include a cyano group, functionalized double bonds, and quaternary carbons.