Using [Cl-], CC(=O)c1ccc(C2CC(C)(C)CC(C)(C)C2)cc1 to produce CC(=O)c1ccc(C2CC(C)(C)CC(C)(C)C2)c(Cl)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.