Using CC(C)(C)OC(=O)C(=O)OCC1Cc2c(sc(N)c2C(=O)OC(C)(C)C)CO1 to produce COC(=O)C(=O)OCC1Cc2c(sc(N)c2C(=O)OC(C)(C)C)CO1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.