We report here a series of studies that explore solid-phase methodologies for the synthesis of various cyanine dyes. The scope of the previously reported catch-and-release method using sulfonyl chloride resin(1) has now been extended to include pentamethine and water-soluble cyanine dyes. We also report a new and chemically distinct synthetic strategy, employing the stepwise attack of heterocyclic carbon nucleophiles on immobilized polyene-chain precursors, allowing the clean synthesis of hydrophobic and hydrophilic trimethine and pentamethine dyes from more easily obtained starting materials. Overall, both approaches appear to be robust and versatile strategies to delivering a wide range of cyanine-based dyes in high purity.

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Fluorine-18 labelled fluoropyridines have found increasing application in the medical imaging technique of Positron Emission Tomography. The fluorine-18 has largely been restricted to the 2-and 6-position where its introduction may be readily achieved, from a range of appropriate precursors, by nucleophilic aromatic substitution using [ 18 F]fluoride. However, fluorine at this position may be labile in vivo limiting the potential of the radiotracer. To date the more stable 3-fluoro and 5-fluoropyridines have not been exploited due to unsuitable methods of preparation. Pyridyliodonium salts provide a convenient way to overcome this restriction and allow the introduction of fluorine-18, as fluoride, into the 3-or 5-position.

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