Using OCc1ccccc1, O=C(O)CCC(CSc1ccc2ccccc2c1)C(=O)O to produce O=C(CCC(CSc1ccc2ccccc2c1)C(=O)O)OCc1ccccc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.