$-6-$

$5.$ In a recent synthetic effort toward the Dysiherbols A$-$C$,$ synthetic intermediate $4$ was prepared in a series of reactions starting from the four compounds shown in the equation below.

$4$

Outline a synthetic scheme by which you would carry out this synthesis starting from the given compounds and using any other reagents and solvents of synthetic organic chemistry that you may need. In your scheme, give the full structure of any reagents that you propose to use and any side products that form. MECHANISM IS NOT REQUIRED.

$[24]$