Using CCOC(=O)c1cc2c(CC)nc(CC)cc2[nH]c1=O, CO to produce CCOC(=O)c1c(O)c2c(CC)nc(CC)cc2[nH]c1=O, please predict the solvent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.