Scientific Publications by FDA Staff

J Labelled Compd Rad 1994 Mar;34(3):247-54

Synthesis of 17O (and 18O) labelled isophosphoramide mustard

Han SY, Shulman-Roskes EM, Misiura K, Anderson LW, Szymajda E, Gamcsik MP, Chang YH, Ludeman SM

The ifosfamide metabolite isophosphoramide mustard (IPM) was synthesized with isotopic enrichment at oxygen. Labelled benzaldehyde was made by exchange with isotopically enriched water (13.4 atom % 170, 25.5 atom % 180) and this was then reduced with sodium borohydride to give labelled benzyl alcohol (72% yield). Triethylamine and labelled benzyl alcohol were added to POCl3/CHCl3 at ¿23°C. Subsequent addition of 2-chloroethylamine hydrochloride (2 equiv) and then triethylamine (4.4 equiv) (¿15°C) provided 170/180 enriched N,N¿-bs-(2-chloroethyl)phosphorodiamidic acid phenylmethyl ester [61%, BzOP(O)(NHCH2CH2Cl)2]. Catalytic (10% Pd/C) hydrogenation of this ester at atmospheric pressure gave IPM (22%). GC/MS was used to determine mole percent enrichments of 9.3% 170 and 17.9% 180 for IPM (single labelling within one molecule).