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

This report describes
Brønsted acid catalyzed de novo 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.