Using CC1C(=O)CC(C(=O)O)N1C(=O)OC(C)(C)C, O=C([O-])[O-] to produce COC(=O)C1CC(=O)C(C)N1C(=O)OC(C)(C)C, please predict the solvent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.