Using O=C1CCC(=O)N1Br, CSc1ncnc2sc(-c3c(-c4ccccc4)ncn3C)nc12 to produce CSc1ncnc2sc(-c3c(-c4ccccc4)nc(Br)n3C)nc12, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.