Functionalization of Silyldienol Ethers at the γ‑Position via 2‑Silyloxypentadienyl Cations

This report describes Brønsted acid catalyzed <i>de novo</i> synthesis of silyldienol ethers bearing tetrasubstituted double bonds via an intermediacy of 2-silyloxypentadienyl cations. The reactivity of these novel cationic intermediates could be modulated and harnessed toward direct nucleophilic additions regioselectively at the γ-position to produce highly functionalized silyldienol ethers with tunable control of the resulting double bond geometry