Synthesis and Evaluation of Novel Carbon-11 Labeled Oxopurine Analogues for Positron Emission Tomography Imaging of Translocator Protein (18 kDa) in Peripheral Organs
To develop a PET ligand for imaging TSPO in peripheral organs, we designed three novel oxopurine analogues [11C]3a–c (LogD: 1.81–2.17) by introducing a pyridine ring in place of a benzene ring in the lead compound [11C]2 (LogD: 3.48). The desmethyl precursors 10 for radiosynthesis were synthesized by reacting glycine 7 with picolylamines 4, followed by hydrolysis and by Curtius rearrangement with diphenylphosphoryl