Using BrBr, CCN1CCOc2cc3c(cc21)CCN(C(=O)OC(C)(C)C)CC3 to produce CCN1CCOc2cc3c(c(Br)c21)CCN(C(=O)OC(C)(C)C)CC3, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.