Using CN[C@H]1[C@H](O)C[C@H]2[C@@H]3CC=C4C[C@@H](OC(C)=O)CC[C@]4(C)[C@H]3CC[C@@]21C to produce CN[C@H]1[C@H](O)C[C@H]2[C@@H]3CC=C4C[C@@H](O)CC[C@]4(C)[C@H]3CC[C@@]21C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.