Using Cc1ccc(C2=CCC(C)(C)c3ccc(Br)cc32)cc1, O=C=O to produce Cc1ccc(C2=CCC(C)(C)c3ccc(C(=O)O)cc32)cc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.