Two-step radiosynthesis of [18F]N-succinimidyl-4-fluorobenzoate ([18F]SFB)

The acylation reagent (F-18]N-succinimidyl-4-fluorobenzoate (F-18-SFB) has been prepared using a new two-step approach. The starting material p-[F-18]fluorobenzaldehyde (F-18-FBA) was obtained by an improved radiosynthesis with a decay-corrected radiochemical yield of 66 +/- 6 % (n=3). Reaction of F-18-FBA with (diacetoxyiodine)benzene and N-hydroxysuccinimide and preparative HPLC purification furnished 18F-SFB in an r.c.y. of 49 +/- 6 % (n=3), based on the starting radioactivity of F-18-FBA. The radiochemical purity of 18F-SFB was >99%. Alternatively, purification by solid phase extraction gave 18F-SFB with an r.c.y. of 77 +/- 9% (n=4) and a radiochemical purity of 89 +/- 5% (n=4). This radiochemical synthesis only used non-aqueous solvents, which simplifies the method and facilitates subsequent applications of F-18-SFB.