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.

Abstract

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.