Pd-Catalyzed Hydrosilylative Coupling of Alkenes with Alkynes

Significance

This is the first example of a transition metal-catalyzed cyclization-hydrosilylation sequence with trichlorosilane. The process supposedly starts with an alkyne hydropalladation, instead of the usual silylmetallation, so that in the absence of Ph₃P an α-adduct is formed. Addition of Ph₃P leads to a different regioselectivity, and in certain cases only the formation of the β-adduct is observed. The reaction can be performed both in an inter- or intramolecular way and affords useful cyclic or linear polysubstituted silanes.