Using COC(=O)CCC(=O)Nc1cnc(Br)cn1, CCCC[Sn](CCCC)(CCCC)c1cccnc1 to produce COC(=O)CCC(=O)Nc1cnc(-c2cccnc2)cn1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.