Rhodium-Catalyzed Stitching Reaction: Convergent Synthesis of Quinoidal Fused Oligosiloles

Quinoidal fused oligosiloles, a new
family of silicon-bridged π-conjugated
compounds, have been synthesized for the first time based on a new
synthetic strategy, a stitching reaction. Multiple carbon–carbon
bonds can be formed consecutively between two oligo­(silylene-ethynylene)­s
under rhodium catalysis in a stitching manner, and up to five siloles
have been fused in a quinoidal form. Physical properties of these
oligosiloles have also been investigated to find a unique trend in
their LUMO levels, which become higher with longer π-conjugation.