title: High molar activity of [11C]TCH346 via [11C]methyl triflate using the "wet" [11C]CO2 reduction method.
abstract: [(11)C]TCH346, a compound acting on the glycolytic enzyme, glycerol-aldehyde-3-phosphate dehydrogenase, was produced under optimised conditions by methylation of the desmethyl compound with no-carrier added (n.c.a.) [(11)C]methyl triflate. An i.v. injectable solution of n.c.a. [(11)C]TCH346 containing 4040+/-1550 MBq (n=6) containing a molar activity between 40 and 5700 GBq/micromol and a radiochemical purity of >99% was obtained within 30 min (after EOB) by irradiation of nitrogen gas containing 0.5% oxygen with 16.5 MeV protons at 45 microA for 30 min. The alkylation reagent [(11)C]methyl triflate was prepared via on-line conversion of [(11)C]methyl iodide. For the formation of [(11)C]methyl iodide, [(11)C]carbon dioxide from the target chamber was reduced by a lithium aluminium hydride solution, and the methanol obtained on-line was converted using triphenylphosphine diiodide. The molar activity of [(11)C]TCH346 could be improved from 40 up to nearly 5700GB q/micromol during the optimisation of the synthesis using the same stock solution of lithium aluminium hydride solution in tetrahydrofuran.
authors.affiliation: Institut für Neurowissenschaften und Biophysik: Nuklearchemie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany. j.ermert@fz-juelich.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Ermert
authors.forename: Stefan
authors.initials: S
authors.lastname: Stüsgen
authors.forename: Markus
authors.initials: M
authors.lastname: Lang
authors.forename: Werner
authors.initials: W
authors.lastname: Roden
authors.forename: Heinz H
authors.initials: HH
authors.lastname: Coenen