A new multi-gram synthetic route to labeling precursors for the D2/3 PET agent 18F-fallypride

This Letter describes a new multi-gram synthetic protocol for the preparation of the classic tosylate labeling precursor for the D2/3 PET agent [18F]fallypride. In the course of our studies, we also discovered two novel labeling precusors, the previously undescribed mesylate and chloro congeners of fallypride.