An efficient, high specific activity radioiodination of 5‐(1‐hydroxy/methoxy‐2‐iodoethyl)‐2′‐deoxyuridine by isotope exchange labelling in pivalic acid melt

Abstract

Radioiodinated 5-(l-hydroxy-2-iodoethyl)-2'-deoxyuridine (la) and 5 -( l-methoxy-2-iodoethyl)-2'-deoxyuridine (a) were prepared from the corresponding unlabelled nucleosides (1 and 2) by isotope exchange in a pivalic acid melt.Compound la was obtained in 71.3% to 26.3% radiochemical yield with a specific activity range of 77 to 2486 GBq/mmol, and was prepared in 70.3% radiochemical yield at a specific activity of 100.6 GBq/mmol. Low temperatures and the mild reaction conditions encountered in the pivalic acid melt method, which reduce the extent of nucleoside decomposition, were essential for successful exchange radi oi odi nati on.Even under optimal conditions (7OoC; 100 min), the order in which the reagents were mixed was critical to obtain high radiochemical yields and to minimize chemical decomposition of the nucleosides.

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

“…4) [15] which was obtained by radio-iodination of 5-(1-methoxy-2-iodoethyl)-2'-deoxyuridine ( 28 ) via isotope exchange by the pivalic acid melt method.…”

“…In order to develop new potential tumor localization agents, Iwashina and co-workers investigated the radiolabelled 5-(1-methoxy-2-iodoethyl) nucleoside 31 ( Fig. 4 ) [ 15 ] which was obtained by radio-iodination of 5-(1-methoxy-2-iodoethyl)-2'-deoxyuridine ( 28 ) via isotope exchange by the pivalic acid melt method.…”