Using O=C1OC(=O)[C@@H]2CC=CC[C@H]12, COc1ccc([Mg]Br)cc1OC to produce COc1ccc(C(=O)C2CC=CCC2C(=O)O)cc1OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.