Rational Design of a Second Generation Catalyst for Preparation of Allylsilanes Using the Silyl-Heck Reaction

Using
rational ligand design, we have developed of a second-generation
ligand, bis­(3,5-di-tert-butylphenyl)­(tert-butyl)­phosphine, for the preparation of allylsilanes using the palladium-catalyzed
silyl-Heck reaction. This new ligand provides nearly complete suppression
of starting material alkene isomerization that was observed with our
first-generation catalyst, providing vastly improved yields of allylsilanes
from simple alkene starting materials. The studies quantifying the
electronic and steric properties of the new ligand are described.
Finally, we report an X-ray crystal structure of a palladium complex
resulting from the oxidative addition of Me3SiI using an
analogous ligand that provides significant insight into the nature
of the catalytic system.