Using CC(C)(C)OC(=O)N1CCOC[C@H]1C=O, BrC(Br)(Br)Br to produce CC(C)(C)OC(=O)N1CCOC[C@H]1C=C(Br)Br, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.