 Trimethylsilyl chloride

Trimethylsilyl chloride is $\mathrm{M}{\mathrm{e}}_3\mathrm{SiCl}$. Reaction of an oxygen nucleophile at silicon can replace chloride and form a trimethylsilyl ether.

Trapping an enolate on oxygen forms a silyl enol ether. This preserves an enol-derived carbon-carbon double bond while changing the species' charge and handling properties.