Using O=C(c1cc(Br)cc(Br)c1)c1cc(Br)cc(Br)c1, Brc1ccccc1-c1ccccc1 to produce Brc1cc(Br)cc(C2(c3cc(Br)cc(Br)c3)c3ccccc3-c3ccccc32)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.