Using COc1c(-c2cccs2)c(=O)c2ccc(Cl)cc2[nH]c1=O to produce O=c1[nH]c2cc(Cl)ccc2c(=O)c(-c2cccs2)c1O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.