Palladium- and Nickel-Catalyzed Carbon−Carbon Bond Insertion Reactions with Alkylidenesilacyclopropanes

Palladium and nickel catalysts promoted highly selective carbon−carbon bond insertion reactions with di-tert-butyl-alkylidenesilacyclopropanes. Pd(PPh3)4 was demonstrated to be the optimal catalyst, allowing for a variety of carbon−carbon π-bond insertion reactions. Depending on the nature of the carbon−carbon π bond, the insertion reaction proceeded with either direct insertion into the carbon(sp2)−silicon bond or allylic transposition. Ring-substituted alkylidenesilacyclopropanes required a nickel catalyst to afford insertion products. Using Ni(cod)2 as the carbon−carbon bond insertion catalyst, new double alkyne insertion products and alkene isomerization products were observed.