Efficient O- and N-(beta-fluoroethylation)s with NCA [~(18)F]beta-fluoroethyl tosylate under microwave-enhanced conditions

摘要

Reactions of no-carrier-added (NCA) [~(18)F]beta-fruoroethyl tosylate with amine, phenol or carboxylic acid to form the corresponding [~(18)F]N-(beta-fluoroethyl)amine, [~(18)F]beta-fruoroethyl ether or [~(18)F]beta-fiuoroethyl ester, were found to be rapid (2-10 min) and efficient (51-89% conversion) under microwave-enhanced conditions. These conditions allow reactants to be heated rapidly to 150(deg)C in a low boiling point solvent, such as acetonitrile, and avoid the need to use high boiling point solvents, such as DMSO and DMF, to promote reaction. The microwave-enhanced reactions gave about 20% greater radiochemical yields than thermal reactions performed at similar temperatures and over similar reaction times. With a bi-functional molecule, such as DL-pipecolinic acid, [~(18)F]beta-fluoroethyl tosylate reacts exclusively with the amino group.