Using C[C@@H]1C[C@@H](C(=O)O)N(C(=O)OC(C)(C)C)C1=O, O to produce C[C@H](C[C@H](NC(=O)OC(C)(C)C)C(=O)O)C(=O)O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.