Phthalic anhydride를 출발물질로 halogenation, phosphorylation하여 diethyl phthalimidoalkylphosphonate를 합성하였다. 이 화합물을 chlorination하여 O-ethyl phthalimidoalkylphosphonochloridate를 만든후 diphenylmethyl 7-β-amino-3-acetoxymethyl-3-cephem-4-carboxylate와 coupling하여 지금까지 알려져 있지 않은 화합물 diphenylmethyl-7-β-[O-ethylphthalimidoethylphosphonyl]-3-acetoxymethyl-3-cephem-4-carboxylate와 diphenylmethyl-7-β-[O-ethyl phthalimidomethylphosphonyl]-3-acetoxymethyl-3-cephem-4-carboxylate를 각각 19%, 43%의 수율로 합성하였다.

7-Aminocephalosporanic acid(7-ACA) was reacted with diphenyldiazomethane(DPM) to get diphenylmethyl 7-(β-amino-3-acetoxymethyl-3-cephem-4-carboxylate. Diethyl phthalimidoalkylphosphonate was chloridated with a slight excess of phosphorus pentachloride to the O-ethyl phthalimidoalkylphosphonochloridate. Previously unreported two compounds, diphenylmethyl 7-β-[O-ethyl phthalimidomethylphosphonyl]-3-acetoxymethyl-3-cephem-4-carboxylate and diphenylmethyl 7-β-[O-ethyl phthalimidoethylphosphonyl]-3-acetoxyethyl-3-cephem-4-carboxylate were synthesized by coupling reaction of DPM 7-ACA and O-ethyl phthalimidoalkylphosphonochloridate. All of the compounds including starting materials and reaction intermediates were characterized by ¹H NMR and FT-IR spectroscopy.