Using CCCC[Sn](CCCC)(CCCC)c1nc(C)cs1, COC(=O)c1ccnc(Br)c1 to produce COC(=O)c1ccnc(-c2nc(C)cs2)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.