Using Brc1cccc(Br)n1, CCCC[Sn](CCCC)(CCCC)c1cnc(-c2ccc(OC)cc2)s1 to produce COc1ccc(-c2ncc(-c3cccc(Br)n3)s2)cc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.