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