Using O=C(O)CCI, CC(=O)O[C@@H]1[C@H](OC(C)=O)[C@H](C)O[C@H](S)[C@H]1OC(C)=O to produce CC(=O)O[C@@H]1[C@H](OC(C)=O)[C@H](C)O[C@H](SCCC(=O)O)[C@H]1OC(C)=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.