Using OO, CC1(C)OC(C)(C)C(=Cc2cc(-c3ccc(Cl)cc3)ccc2Br)C1=O to produce CC1(C)OC(C)(C)C2(OC2c2cc(-c3ccc(Cl)cc3)ccc2Br)C1=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.