Using Br[Mg]C1CC1, C[C@@H]1CCc2ncnc(N3CC4(CCN(C(=O)OC(C)(C)C)CC4)c4cc(Br)ccc43)c21 to produce C[C@@H]1CCc2ncnc(N3CC4(CCN(C(=O)OC(C)(C)C)CC4)c4cc(C5CC5)ccc43)c21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.