Radiosynthesis of dimethyl-2-[18F]-(fluoromethyl)-6-methyl-4-(2- nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate for L-type calcium channel imaging

Abstract

Dimethyl 2-(fluoromethyl)-6-methyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3, 5-dicarboxylate 4a, a fluorinated nifedipine analog, has been shown to elicit significant calcium channel blocker activity using a guinea pig ileal longitudinal smooth muscle model. In order to perform biological studies for detection of L-type calcium channel distribution, we decided to prepare the [18F]-labeled compound. The latter compound was prepared in no-carrier-added (n.c.a.) form from dimethyl 2-(bromomethyl)-6-methyl-4-(2- nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate 2 in one step at 80°C in Kryptofix[222]/K[18F]F and acetonitrile as a solvent in 15 min. Column chromatography afforded the radiochemically pure compound in 20 min. Radiochemical purity of the 18F-nifedipine was determined by RTLC and HPLC (> 98%) and specific activity of 21-48 GBq/μmol (EOB). © by Oldenbourg Wissenschaftsverlag.