Using CCCC[Sn](CCCC)(CCCC)c1cccnc1, CC(C)(C)OC(=O)N1C(=O)CC2Cc3c(Br)cccc3C21 to produce CC(C)(C)OC(=O)N1C(=O)CC2Cc3c(-c4cccnc4)cccc3C21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.