Nickel-Catalyzed Mono- and Dihydrosilylation of Aliphatic Alkynes in Aqueous and Aerobic Conditions

1,1-Disilanes are synthetically versatile building blocks,
owing
to their low toxicity, high stability, and unique structures. However,
the practical synthesis of 1,1-disilanes is still a challenge. Despite
the available Fe-, Co-, La-, and B-catalyzed protocols, the use of
highly reactive reductants, such as EtMgBr, NaBHEt3, or
KHMDS, inevitably requires air- and moisture-free conditions. Herein,
we report the homogeneous Ni-catalyzed mono- and dihydrosilylation
of aliphatic terminal alkynes under either air and water conditions
or neat conditions, affording β-(E)-vinylsilanes
and 1,1-disilanes in high yields with complete regioselectivity and
stereoselectivity. Importantly, our method is gram-scalable and the
sole example of Ni-catalyzed dihydrosilylation of alkynes. We demonstrated
the introduction of different silyl groups through the stepwise addition
of each silane source in a reaction vessel. Furthermore, the reaction
intermediates were characterized with spectroscopic/spectrometric
tools, and density functional theory calculations were performed to
understand the reaction mechanism and the origins of the regioselectivity
for β-(E)-vinylsilanes and 1,1-disilanes.