Sila-spirocyclization involving unstrained C(sp(3))−Si bond cleavage

C − Si Bond cleavage is one of the key elemental steps for a wide variety of silicon-based transformations. However, the cleavage of unstrained Si−C(sp(3)) bonds catalyzed by transition metal are still in their infancy. They generally involve the insertion of a M − C(sp(2)) species into the C − Si bond and consequent intramolecular C(sp(2))‒Si coupling to exclusively produce siloles. Here we report the Pd-catalyzed sila-spirocyclization, in which the Si−C(sp(3)) bond is activated by the insertion of a M − C(sp(3)) species and followed by the formation of a new C(sp(3))‒Si bond, allowing the construction of diverse spirosilacycles. This reactivity mode, which is strongly supported by DFT calculations may open an avenue for the Si−C(sp(3)) bond cleavage and silacycle synthesis.