Using CC(C)(C)OC(=O)n1ccc2c(-c3nc(CO)co3)cccc21, BrC(Br)(Br)Br to produce CC(C)(C)OC(=O)n1ccc2c(-c3nc(CBr)co3)cccc21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.