[(7-Cyano-4,5-dihydro-4-oxo[1,2,4]triazolo[4,3-a]quinoxalin-1-yl)methyl]-phosphonic Acid is derived from Diethylphosphonoacetic Acid (D444745), which is a reagent that is used for enantioselective preparation of α-phosphoryl-α,β-unsatd.-δ-aryl-δ-lactones from nonracemic β-hydroxyaldehydes and their conversion to α-methylene-δ-aryl-δ-lactones.