Synthesis and reactivity of boron-substituted silyllithium as a nucleophilic Si-B unit

Boron-substituted silyllithium was synthesized via Sn-Li exchange between the corresponding (boryl)silylstannane and n-BuLi and reacted with chlorosilanes to afford a series of Si-B-containing di-, tri-, and tetrasilanes. The tri- and tetrasilane derivatives were examined by UV-vis spectroscopy and density functional theory calculations to assess the electronic consequences of boron incorporation into σ-conjugated silane frameworks. In addition, the diaminoboryl moiety bound to boron can be selectively transformed into a pinacolatoboryl group without Si-B bond cleavage. Overall, this work provides a chemically intuitive entry to Si-B-containing oligosilanes and enables systematic investigation of boron incorporation into σ-conjugated silane frameworks.