Using CC(=O)O[C@]1(C(C)=O)CC[C@H]2[C@@H]3[C@@H]4O[C@@H]4C4=CC(=O)OC(O)[C@]4(C)[C@H]3CC[C@@]21C, Cl to produce CC(=O)O[C@]1(C(C)=O)CC[C@H]2[C@@H]3[C@H](O)[C@@H](Cl)C4=CC(=O)OC(O)[C@]4(C)[C@H]3CC[C@@]21C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.