Using C1OCOCO1, CNC(=O)Nc1nc2c(s1)C(C)(C)CC(C)(C)C2 to produce CN1COCN(c2nc3c(s2)C(C)(C)CC(C)(C)C3)C1=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.