Abstract
In order to address the limitations associated with the present range of PET radiotracers used for imaging protein synthesis in vivo we have synthesized a candidate PET radiotracer based on Puromycin (3, PURO), a protein synthesis inhibitor. The desmethylPURO 9 precursor for radiolabeling with carbon-11 radioisotope was synthesized in two steps employing EDC/HOBt amide coupling in overall 76% yield. Optimal conditions for radiolabeling were then established via methylation/deprotection sequence. Under these conditions as determined by NMR analysis 9 showed partial stability (ca. 80%) under acidic conditions. Limited evidence of stereochemical stability of 3 was also found. The radiolabeling of intermediate [(11)C]12 was accomplished with up to 57% conversion from [(11)C]iodomethane. An automated method was then developed for high radioactivity radiosynthesis to produce [(11)C]3 ([(11)C]PURO) in 16 ± 6% (n = 3) decay corrected radiochemical yields.