Using COc1cc2c(NC(N)=S)cnc(CNC(=O)OC(C)(C)C)c2cc1OC, CCOC(=O)C(=O)CBr to produce CCOC(=O)c1csc(Nc2cnc(CNC(=O)OC(C)(C)C)c3cc(OC)c(OC)cc23)n1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.