Using O=C1CCC(=O)N1Br, Cc1csc(C2CCN(C(=O)OC(C)(C)C)CC2)c1 to produce Cc1cc(C2CCN(C(=O)OC(C)(C)C)CC2)sc1Br, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.