Synthesis of fluorine‐18‐labelled 5‐ and 6‐fluoro‐2‐pyridinamine

Abstract

A one-pot radiosynthesis method to prepare the new fluorine-18-labelled fluoropyridine derivatives 5-[

Chemistry with [18F]Fluoride Ion

“…For the introduction of [ 18 F]fluoride ion into a pyridinyl 3‐position, activation by an electron‐withdrawing group is needed 83. A cyano or amido group is sufficient.…”

Radiochemistry

“…Fluorine-18 has been introduced to benzene rings in a similar way in the preparation of intermediates in the labelling of an epibatidine based antagonist 133 for nicotinic acetylcholine receptors, of fluorobenzene-and pyridine-carbohydrazide-folates, 134 of fluoro-o-conotoxin GVIA 135 and of 5-and 6-fluoro-2-pyridinamine. 136 Other recently labelled compounds using nucleophilic aromatic substitution have included O-(2-fluoroethyl)-L-tyrosine, 137,138 and N-(3-fluoro-4-nitronaphthyl)-cis-5-norbornene-endo-2,3-dicarboxylic imide. 139 Derivatives of many different amine bases that participate in biochemical processes have also been labelled with fluorine-18, such thymidine, 140,141 guanine, 142 adenosine 143 and pyrimidine.…”

Diaryliodonium salts: a solution to 3‐[18F]fluoropyridine

“…An example of this approach (Scheme 2) is in the formation of LBM-415. 5 In this case a carbonyl group is employed para to the bromine leaving group allowing conventional S N Ar chemistry to occur and the introduction of the fluorine-18. Subsequent post-radiolabel transformations convert the [ 18 F]fluoropyridine into the final target.…”