 Solution

A suitable sequence is selective alpha-bromination, then enol O-methylation. Use one equivalent of Br${}_2$ under controlled acidic enolization conditions to introduce bromine at the enolizable alpha carbon that becomes the brominated vinyl carbon. The other alpha site is a constrained bridgehead and cannot form the required ordinary enol double bond. Then O-alkylate the ketone with trimethyloxonium tetrafluoroborate and remove the brominated alpha proton with a nonnucleophilic base such as triethylamine. Collapse of the O-methylated carbonyl oxonium gives the alpha-bromo methyl enol ether E.

The methyl group belongs on oxygen, not on the alpha carbon. Simply writing methyl iodide with an unspecified enolate would not guarantee this outcome because competitive C-alkylation is possible. Use conditions designed for carbonyl O-alkylation followed by deprotonation, and limit bromine to avoid overbromination or damage to the protecting group.