Using Oc1c(Br)cc(Cc2ccc(C3CC3)cc2)c(Cl)c1O, BrCBr to produce Clc1c(Cc2ccc(C3CC3)cc2)cc(Br)c2c1OCO2, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.