Using BrC(Br)(Br)Br, CCCCCC(C=O)c1ccc2c(c1)C(C)(C)CCC2(C)C to produce CCCCCC(C=C(Br)Br)c1ccc2c(c1)C(C)(C)CCC2(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.