Using Br[Mg]C1CC1, CC1(C)OC(=O)C(=Cc2cccc(O)c2)C(=O)O1 to produce CC1(C)OC(=O)C(C(c2cccc(O)c2)C2CC2)C(=O)O1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.