Efficient alkali iodide promoted 18F-fluoroethylations with 2-[18F]fluoroethyl tosylate and 1-bromo-2-[18F]fluoroethane

Radiochemical 18F-fluorination yields of several compounds using the secondary labelling precursors 2-[18F]fluoroethyl tosylate ([18F]FETos) and 1-bromo-2-[18F]fluoroethane ([18F]BFE) could be considerably enhanced by the addition of an alkali iodide. The radiochemical yield of [18F]fluoroethyl choline for example could be doubled with [18F]BFE and increased from 13% to ≈80% with [18F]FETos. By addition of alkali iodide to the precursor, the 18F-fluoroethylation yields of established radiopharmaceuticals, especially in the case of automated syntheses, could be significantly increased without major changes of the reaction conditions.