Using COC(=O)C1=Cc2cc(-c3ccc4c(c3)OCO4)ccc2SCC1 to produce O=C(O)C1=Cc2cc(-c3ccc4c(c3)OCO4)ccc2SCC1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.