Facile synthesis of 2-deoxy-2-[18 F]fluorosorbitol using sodium borohydride on aluminum oxide
Koki Hasegawa1, Kazuhiro Koshino2, Takahiro Higuchi3,4,5
1Center for Instrumental Analysis, Kyoto Pharmaceutical University, Kyoto, Japan.
Abstract:
2-Deoxy-2-[18 F]fluorosorbitol (18 F-FDS) has become increasingly useful in functional renal imaging. FDS is synthesized by the one-step reduction of 2-deoxy-2-[18 F]fluoroglucose (18 F-FDG). To develop a more simple and rapid procedure for 18 F-FDS synthesis, we examined reduction reactions with solid-supported NaBH4 . Synthetic yields using BH4 -IRA400 (polymer-based matrix) and NaBH4 -Al2 O3 (clay-based matrix) as solid-supported reagents were compared. NaBH4 -Al2 O3 was found to be far superior to BH4 -IRA400 in the FDG reduction reaction. IRA 400 was not suitable for this reaction because it adsorbs FDG, in addition to glucose, with no FDS synthesized when using BH4 -IRA400. By contrast, NaBH4 -Al2 O3 only required a filtration as workup, affording FDS in 90% yield after a total of 10 min. NaBH4 on alumina was readily consumed in the reaction within 1 min, regardless of the amount used, by simply stirring with a vortex mixer. Complicated procedures, such as microwave irradiation, were not necessary. This simple operation will allow kit formulation and is suitable for radiosynthesis. In conclusion, clay-supported reagents showed low absorption and were time saving, which are highly compatible with 18 F-FDS synthesis.
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