Using COC(OC)OC, CCOC(=O)C1C(=O)C(C(=O)OCC)C2CC(=O)CC12 to produce CCOC(=O)C1C(=O)C(C(=O)OCC)C2CC(OC)(OC)CC12, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.