Long-Distance Chirality Transfer from P‑Ligand to Prochiral Dihydrosilanes via Pd(II) Aryl Iodide Complex in Pd-Catalyzed Silylation of Aryl Iodide: A DFT Study

The mechanism of Pd-catalyzed desymmetric
monoarylation of dihydrosilanes
with aryl iodides in the presence of chiral TADDOL-derived phosphoramidite
ligand toward deeper understanding of the stereoselectivity has been
investigated using hybrid density functional theory (DFT) methodology.
The full catalytic cycle for the favorable reaction pathway, which
is initiated by the oxidative addition of aryl iodide to monoligated
Pd0 leading to the silylation product, was calculated.
The DFT calculation results indicate that the enantio-discriminating
transmetalation between Pd–Ar bond of the Pd­(II) aryl iodide
complex and Si–H bond of the prochiral dihydrosilane was the
enantioselectivity-determining step. On the basis of the structure
of the transition state, the attractive aryl–aryl interactions
between the aryl group of ligand, aryl iodide, and dihydrosilane were
found to play an important role for the chiral transference from the
chiral ligand to asymmetric cleavage of the Si–H bond of the
prochiral dihydrosilane.