Silyl enol ether

A silyl enol ether has the connectivity $\mathrm{C}=\mathrm{C}-\mathrm{O}-\mathrm{Si}{\mathrm{R}}_3$. Nucleophilic attack at silicon can cleave the Si–O bond and generate an enolate without adding to the original carbonyl carbon.

An O-silylated ester enolate, with two oxygen substituents on one carbon of the enol double bond.