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