Using CCOC(=O)c1ccc([Se]c2cc3c(cc2OCOCCOC)C(C)(C)CCC3(C)C)nc1 to produce CCOC(=O)c1ccc([Se]c2cc3c(cc2O)C(C)(C)CCC3(C)C)nc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.