On treatment with a Grubb's catalyst, compound A and styrene combined to give a single...

On treatment with a Grubb's catalyst, compound A and styrene combined to give a single product having the formula C13H20O2 in 95% yield. This product was converted to baconipyrone C, a metabolite that was isolated from a mollusk. What is the substituent labeled "R" in the product? ("L" in the catalyst refers to the ligands that were used in this modified version of the original Grublrs catalyst.)