Catalytic Reductive (Double) [4+1] Sila-cycloaddition of 1,3-Dienes with Di-, Tri-, and Tetrachlorosilane(s) Enabled by the Pyridine–Diimine–Nickel Complex

Herein, we report a catalytic reductive [4+1] sila-cycloaddition between functionalized 1,3-dienes and chemical feedstock di-, tri-, and tetrachlorosilane(s), enabled by a cost-effective pyridine–diimine–nickel complex, providing a practical method to prepare diverse silacyclopent-3-enes in up to 92% yield, including bridged and spiro silacarbocycles. This reaction demonstrates a broad substrate compatibility, including 1,3-dienes with different substitution patterns and a more accessible E/Z isomeric mixture. Notably, trichlorosilanes undergo tandem [4+1] sila-cycloadditions/nucleophilic substitutions, while tetrachlorosilane successfully performs double [4+1] sila-cycloadditions with 2 equiv of 1,3-dienes to directly construct spiro silacarbocycles.