Using COC(=O)c1sc2c(sc3ccccc32)c1O, CC(C)(C)OC(=O)CBr to produce COC(=O)c1sc2c(sc3ccccc32)c1OCC(=O)OC(C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.