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An efficient, high specific activity radioiodination of 5‐(1‐hydroxy/methoxy‐2‐iodoethyl)‐2′‐deoxyuridine by isotope exchange labelling in pivalic acid melt
Author(s) -
Iwashina Takashi,
Kumar Rakesh,
Knaus Edward E.,
Wiebe Leonard I.
Publication year - 1990
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580280302
Subject(s) - chemistry , pivalic acid , yield (engineering) , decomposition , radiochemistry , isotope , reagent , specific activity , labelling , nucleoside , deoxyuridine , phosphoric acid , nuclear chemistry , organic chemistry , catalysis , stereochemistry , biochemistry , dna , materials science , physics , quantum mechanics , metallurgy , enzyme
Radioiodinated 5‐(1‐hydroxy‐2‐iodoethyl)‐2′‐deoxyuridine ( 1a ) and 5‐(1‐methoxy‐2‐iodoethyl)‐2′‐deoxyuridine ( 2a ) were prepared from the corresponding unlabelled nucleosides ( 1 and 2 ) by isotope exchange in a pivalic acid melt. Compound 1a was obtained in 71.3% to 26.3% radiochemical yield with a specific activity range of 77 to 2486 GBq/mmol, and 2a 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 radioiodination. Even under optimal conditions (70°C; 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.