Using CC(C)(C)OC(=O)CC(=O)[O-], O=C(CBr)C12CC3CC(CC(C3)C1)C2 to produce CC(C)(C)OC(=O)C(CC(=O)C12CC3CC(CC(C3)C1)C2)C(=O)OC(C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.