Using O=C1CCC(=O)N1Br, CC(C)(C)OC(=O)N[C@@H](CCO)C(=O)OC(C)(C)C to produce CC(C)(C)OC(=O)N[C@@H](CCBr)C(=O)OC(C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.