A simple loop method for the automated preparation of (11C)raclopride from (11C)methyl triflate.
A simple automated preparation of [11C]raclopride by reaction of [11C]methyl triflate with demethylraclopride triflate is described. The conventional bubbling of [11C]methyl triflate into the precursor solution was compared with two alternative methods which used a commercially available C18 cartridge (on-column method) or an empty PTFE tube (loop method) as support for the precursor solution. The influence of several solvents was assessed for all three methods. The on-column method showed excellent trapping efficiencies of [11C]methyl triflate but gave the lowest radiochemical yields. The loop method proved to be a simplified alternative to the bubbling method, giving comparable radiochemical yields with less precursor and offering an easy way to transfer the reaction mixture into an HPLC column. By the simple-loop method [11C]raclopride could be prepared in over 40% radiochemical yields (decay-corrected and based on [11C]methyl triflate).
Iwata
R
R
Graduate School of Engineering, Tohoku University, Sendai, Japan. ren.iwata@qse.tohoku.ac.jp
Pascali
C
C
Bogni
A
A
Miyake
Y
Y
Yanai
K
K
Ido
T
T
D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D007553:Isotope Labeling / Q000295:instrumentation / Q000379:methods; D008698:Mesylates / Q000737:chemistry; D015394:Molecular Structure; D020891:Raclopride / Q000138:chemical synthesis*; D011874:Radiometry / Q000295:instrumentation / Q000379:methods; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*
D002250:Carbon Radioisotopes; D008698:Mesylates; D019275:Radiopharmaceuticals; C078465:methyl triflate; D020891:Raclopride