Gao, MingzhangWang, MinMeyer, Jill A.Peters, Jonathan S.Zarrinmayeh, HamidehTerrito, Paul R.Hutchins, Gary D.Zheng, Qi-Huang2017-12-292017-12-292017-06Gao, M., Wang, M., Meyer, J. A., Peters, J. S., Zarrinmayeh, H., Territo, P. R., … Zheng, Q.-H. (2017). Synthesis and preliminary biological evaluation of [11C]methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate for the fractalkine receptor (CX3CR1). Bioorganic & Medicinal Chemistry Letters, 27(12), 2727–2730. https://doi.org/10.1016/j.bmcl.2017.04.052https://hdl.handle.net/1805/14932The reference standard methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate (5) and its precursor 2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucine (6) were synthesized from 6-amino-2-mercaptopyrimidin-4-ol and BnBr with overall chemical yield 7% in five steps and 4% in six steps, respectively. The target tracer [11C]methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate ([11C]5) was prepared from the acid precursor with [11C]CH3OTf through O-[11C]methylation and isolated by HPLC combined with SPE in 40–50% radiochemical yield, based on [11C]CO2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the specific activity (SA) at EOB was 370–1110 GBq/μmol with a total synthesis time of ∼40-min from EOB. The radioligand depletion experiment of [11C]5 did not display specific binding to CX3CR1, and the competitive binding assay of ligand 5 found much lower CX3CR1 binding affinity.enPublisher Policy[11C]Methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinatefractalkine receptorradiosynthesisArticle