Using COC(=O)CCCC=CC1C2CCC(C2)C1CO, O=[Cr](=O)([O-])O[Cr](=O)(=O)[O-] to produce COC(=O)CCCC=CC1C2CCC(C2)C1C(=O)O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.