Using CCCC[Sn](CCCC)(CCCC)c1nccs1, CC1CC(=O)c2c(O)ccc(Br)c2C1 to produce CC1CC(=O)c2c(O)ccc(-c3nccs3)c2C1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.