Using BrC(Br)(Br)Br, Cc1c(C)c2c(c(C)c1NC(=O)OC(C)(C)C)CC(C)(CCO)O2 to produce Cc1c(C)c2c(c(C)c1NC(=O)OC(C)(C)C)CC(C)(CCBr)O2, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.