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.