Using O=S(=O)(c1ccc(CBr)cc1)N1CCOCC1, CCC(=O)CC(=O)OC to produce CCC(=O)C(Cc1ccc(S(=O)(=O)N2CCOCC2)cc1)C(=O)OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.