Enantioselective Synthesis of Disilacyclohexenes via Nickel-Catalyzed Asymmetric Reductive [4 + 2] Sila-Cycloaddition

So far, numerous asymmetric hydrosilylation
reactions have been
reported, the asymmetric reductive cross-coupling of chlorosilanes
with other electrophiles or alkenes to synthesize chiral organosilicon
compounds has yet to be documented. In this study, we report a nickel-catalyzed
asymmetric [4 + 2] sila-cycloaddition reaction that efficiently produces
disilacyclohexenes with good yields and enantioselectivities of up
to 99% ee. Additionally, we synthesized various achiral cyclic disilanes
and digermanes to demonstrate the reaction’s applicability.
Mechanistic studies, based on Hammett analysis, revealed that the
enantioselectivities are determined by the homolysis and recombination
of the Ni–C bond.