Seyferth–Gilbert Homologation as a Route to 18F‐Labeled Building Blocks: Preparation of Radiofluor­inated Phenylacetylenes and Their Application in PET Chemistry

Abstract A convenient method for the preparation of hitherto unknown ([ 18 F]fluorophenyl)acetylenes ([ 18 F]FPAs) using the Seyferth–Gilbert homologation is reported. The novel building blocks were efficiently prepared from easily accessible [ 18 F]fluorobenzaldehydes by using the Bestmann–Ohira reagent. High radiochemical yields and excellent radiochemical purities were achieved within only 20 min of reaction time; 2‐ and 4‐[ 18 F]FPAs were applied to prepare radiofluorinated heterocycles by using different cycloaddition and cross‐coupling reactions. Additionally, these building blocks were used to prepare three novel PET tracers. Thus, an artificial radiofluorinated protected amino acid [ 18 F] 10 , a COX‐2‐specific ligand [ 18 F] 14 , and a PSMA‐selective inhibitor [ 18 F] 16 were obtained in high radiochemical yields.