Using COC(=O)CC(=O)OC, CC(C)(C)OC(=O)c1ccc(Br)cc1 to produce COC(=O)C(C(=O)OC)c1ccc(C(=O)OC(C)(C)C)cc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.