One-Pot Synthesis of 11 C-Labelled Primary Benzamides via Intermediate [11 C]Aroyl Dimethylaminopyridinium Salts.

Electrophilic 11 C-labelled aroyl dimethylaminopyridinium salts, obtained by carbonylative cross-coupling of aryl halides with [11 C]carbon monoxide, were prepared for the first time and shown to be valuable intermediates in the synthesis of primary [11 C]benzamides. The methodology furnished a set of benzamide model compounds, including the two poly (ADP-ribose) polymerase (PARP) inhibitors niraparib and veliparib, in moderate to excellent radiochemical yields. In addition to providing a convenient and practical route to primary [11 C]benzamides, the current method paves the way for future application of [11 C]aroyl dimethylaminopyridinium halide salts in positron emission tomography (PET) tracer synthesis.