Using CC(=O)OC[C@H]1CC(=O)C[C@@H]2CC[C@H]3[C@@H]4CC[C@H](OC(C)=O)[C@@]4(C)CC[C@@H]3[C@]21C to produce CC(=O)OCC1=CC(=O)C=C2CC[C@@H]3[C@H](CC[C@]4(C)C(=O)CC[C@@H]34)[C@]21C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.