Using C=Cc1cc(Cl)c(-c2nc3ccnc(Cl)c3s2)c(Cl)c1, CO to produce O=Cc1cc(Cl)c(-c2nc3ccnc(Cl)c3s2)c(Cl)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.