Facile synthesis of 2‐deoxy‐2‐[18F]fluorosorbitol using sodium borohydride on aluminum oxide

2‐Deoxy‐2‐¹⁸F]fluorosorbitol (¹⁸F‐FDS) has become increasingly useful in functional renal imaging. FDS is synthesized by the one‐step reduction of 2‐deoxy‐2‐¹⁸F]fluoroglucose (¹⁸F‐FDG). To develop a more simple and rapid procedure for ¹⁸F‐FDS synthesis, we examined reduction reactions with solid‐supported NaBH₄. Synthetic yields using BH₄–IRA400 (polymer‐based matrix) and NaBH₄–Al₂O₃ (clay‐based matrix) as solid‐supported reagents were compared. NaBH₄–Al₂O₃ 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–Al₂O₃ 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 ¹⁸F‐FDS synthesis.