Synthesis of functionalized hydrosilanes via titanium-catalyzed hydroboration and hydrogenation of C(sp3)–Si bonds in silacyclobutanes

The design and synthesis of molecules featuring both boron and silicon moieties hold significant promise for delivering unique reactivity patterns and material properties. Herein, a titanium-catalyzed selective hydroboration of the C(sp3)–Si bonds in silacyclobutanes for the synthesis of boryl-functionalized hydrosilanes is developed. Our protocol accommodates a broad range of structurally distinct silacyclobutanes, affording a diverse library of boryl-functionalized hydrosilanes (R2B~link~Si–H). The free Si–H and boryl functional groups allow for their seamless integration into synthetic chemistry and many other research areas. The facile synthesis of sila-substituted drug molecules via our strategy is also demonstrated. Furthermore, our methodology is successfully extended to the hydrogenation of the C(sp3)–Si bond using H2 gas, offering a general route to synthesize a broad spectrum of heteroleptic-substituted hydrosilanes, including their deuterated derivatives. Mechanistic investigations, complemented by DFT calculations, reveal an unusual two-electron process at the titanium metal center. The essence of the selective activation of C(sp3)–Si bonds over C(sp2)–Si in silacyclobutanes by titanium catalyst is elucidated. The design and synthesis of molecules featuring both boron and silicon moieties hold significant promise for delivering unique reactivity patterns and material properties. Herein, the authors report a titaniumcatalyzed selective hydroboration of the C(sp3)–Si bonds in silacyclobutanes for the synthesis of boryl-functionalized hydrosilanes.