Tetrabutylammonium tosylate as inert phase-transfer catalyst: The key to high efficiency SN2 radiofluorinations.

Here we describe use of the tetrabutylammonium p-toluenesulfonate (TBAOTs) as an inert phase transfer catalyst allowing high efficient aliphatic radiofluorination of labeling precursors for the preparation of common radiotracers using only 0.2-1.2 mg of the substrates. With operational convenience (no need for azeotropic drying) and compatibility with the common types of strong anion-exchange cartridges (QMA), this method has a high potential for routine application in various automated synthesizers and offers significant costs reductions due to less precursors used.