Using BrBr, CCC1Cc2c(C)c(OCC(=O)O)c(C)c(C)c2C1=O to produce CCC1(Br)Cc2c(C)c(OCC(=O)O)c(C)c(C)c2C1=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.