Using OCCBr, Oc1ccc(-c2nc(-c3ccccc3)nc(-c3ccccc3)n2)c(O)c1 to produce OCCOc1ccc(-c2nc(-c3ccccc3)nc(-c3ccccc3)n2)c(O)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.