cis-(3-Methyloxiranyl)phosphonic Acid Bis(phenylmethyl) Ester is an intermediate in the synthesis of[2-[2-Amino-3-hydroxy-2-(hydroxymethyl)propoxy]-1-hydroxypropyl]phosphonic Acid (A611565), which is a Fosfomycin (F727500) impurity. Fosfomycin is an antibiotic that exerts a broad spectrum of antibacterial activity.