Frieda Svensson, T. Kniess, R. Bergmann
Oct 1, 2011
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Journal
Journal of Labelled Compounds and Radiopharmaceuticals
Abstract
The radiosynthesis of N-(5-(((5-(tert-butyl)oxazol-2-yl)methyl)thio)thiazol-2-yl)-4-[18F]fluoro-benzamide [18F]2 as a potential radiotracer for molecular imaging of cyclin-dependent kinase-2 (CDK-2) expression in vivo by positron emission tomography is described. Two different synthesis routes were envisaged. The first approach followed direct radiofluorination of respective nitro- and trimethylammonium substituted benzamides as labeling precursors with no-carrier-added (n.c.a.) [18F]fluoride. A second synthesis route was based on the acylation reaction of 2-aminothiazole derivative with labeling agent [18F]SFB. Direct radiofluorination afforded 18 F-labeled CDK-2 inhibitor in very low yields of 1%–3%, whereas acylation reaction with [18F]SFB gave 18 F-labeled CDK-2 inhibitor [18 F]2 in high yields of up to 85% based upon [18 F]SFB during the optimization experiments. Large scale preparation afforded radiotracer [18 F]2 in isolated radiochemical yields of 37%–44% (n = 3, decay-corrected) after HPLC purification within 75 min based upon [18 F]SFB. This corresponds to a decay-corrected radiochemical yield of 13%–16% based upon [18F]fluoride. The radiochemical purity exceeded 95% and the specific activity was determined to be 20 GBq/µmol. Copyright © 2011 John Wiley & Sons, Ltd.