Using O=[Cr](=O)([O-])Cl, COc1cc(-c2nc3sc4c(c3c(=O)n2Cc2ccccc2)CCCC4)cc(OC)c1OC to produce COc1cc(-c2nc3sc4c(c3c(=O)n2Cc2ccccc2)CCCC4=O)cc(OC)c1OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.