Using Br[Mg]c1ccccc1, COc1ccc(C(=O)C2Cc3ccccc3C2=O)cc1 to produce COc1ccc(C(=O)C2=C(c3ccccc3)c3ccccc3C2)cc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.