Using O, COC(=O)c1ccc(CN2C(=O)c3ccccc3C2=O)cc1C(=O)OC to produce COC(=O)c1ccc(CNC(=O)OC(C)(C)C)cc1C(=O)OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.