Radiochemical synthesis of [18F]fluororaclopride

The radiochemical synthesis of [18F]Fluororaclopride (S-3,5-dichloro-6-methoxy-N-(1-(2-[18F]fluoroethyl)-2-pyrrolidinylmet hyl) salicylamide) is accomplished via a two step synthesis. [18F]Fluoroethyltriflate is prepared by [18F]fluoride displacement on the bis triflate of ethylene glycol. [18F]Fluoroethyl triflate is then allowed to alkylate a secondary amine precursor to yield [18F]fluororaclopride. Purification of the radiopharmaceutical involves use of a short silica BONDELUT column and subsequent reverse-phase HPLC. The final product is obtained with a radiochemical yield of approximately 15% (corrected for decay) in a synthesis time of approximately 50 min. Fluororaclopride displays a 3- to 4-fold lower affinity for the D2 receptor than does raclopride.