Sensitive biomolecules cannot withstand the harsh conditions required for direct nucleophilic radiofluorination using [18F]fluoride. Thiol reactive prosthetic groups such as [18F]FBAM, [18F]FBOM, and [18F]FBEM allow the indirect radiolabeling of complex biomolecules such as peptides, proteins, and single stranded oligonucleotides under relatively mild conditions. We wish to report the synthesis of a new thiol reactive bifunctional reagent, FPyAM (5), from a novel radiofluorination precursor 3 .The radiofluorination precursor 3  was synthesized in two steps by the SNAr reaction of DABCO with 2-bromonicotinaldehyde in DCM followed by an exchange of bromide with triflate using trimethylsilyl triflate.1 The oxamine precursor 1  was synthesized according to the reported procedure.2 The radiofluorination of precursor 3  was carried out in DMF at 120 ?C for 10 minutes. The condensation of aldehyde 4  and oxamine 3  was carried out in methanolic HCl at 75 ?C for 15 minutes. The product was purified by C18 Sep-Paks and semi-preparative HPLC on a Phenomenex C18, 10�m X 250 mm column to yield the title compound 5 in 15% radiochemical yield and high radiochemical purity.

2-[<sup>18</sup>F]Fluoropyridine-5-aldehyde-O-[6-(2,5-dioxo-2,5-dihydropyrrol-1-yl)-hexyl]oxime: A new thiol reactive prosthetic group for peptide labeling

248th National Meeting (2014)

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2-[18F]Fluoropyridine-5-aldehyde-O-[6-(2,5-dioxo-2,5-dihydropyrrol-1-yl)-hexyl]oxime: A new thiol reactive prosthetic group for peptide labeling

2-[¹⁸F]Fluoropyridine-5-aldehyde-O-[6-(2,5-dioxo-2,5-dihydropyrrol-1-yl)-hexyl]oxime: A new thiol reactive prosthetic group for peptide labeling