Synthesis and biological evaluation of 7-(2-Chlorophenylamino)-5-((2-[ 18F]fluoro-ethyoxy)methyl)pyrazolo[1,5-a]pyrimidine-3-carbonitrile as PET tumor imaging agent

Abstract

An 18F-labeled pyrazolo[1,5-a]pyrimidine derivative, 7-(2-chlorophenylamino)-5-((2-[18F] fluoroethyoxy)methyl)pyrazolo[1, 5-a]pyrimidine-3-carbonitrile ([18F]5), has been designed and prepared as a radio tracer candidate for tumor detection with positron emission tomography (PET). The desired product [18F]5 was synthesized by nucleophilic substitution of the corresponding tosylated precursor with [ 18F]KF=Kryptofix 2.2.2 and potassium carbonate in anhydrous DMF at 100 °C for 20 min followed by purification with HPLC. The radiochemical purity was >98%, and the radio-chemical yield was 25% (decay-uncorrected). Compound [18F]5 was very stable in vitro. The biodistribution study in mice bearing S180 tumors demonstrated that [18F]5 had a rapid and prolonged accumulation in tumors with moderate washout from other tissues.