Synthesis of a [18F]labeled chelidonine derivative as a possible antitumor agent

{(±)-[5bRS-(5bα,6β,12bα)]-5b,6,7,12b,13,14-hexahydro-13-methyl[1,3]benzodioxolo[5,6-c]-1,3-dioxolo[4,5-I]phenanthridin-6-yl}-4-[18F]fluorobenzoate (6b) an aromatic ester of chelidonine was prepared as a possible PET radiotracer. Compound (6b) was prepared in no-carrier-added (n.c.a) form from the 4-N,N,N-trimethylanilinium triflate derivative (5) in one step. The best results were obtained using Kryptofix2.2.2/[18F] and DMSO as the solvent at 90°C. Column chromatography afforded the desired compound in overall radiochemical yield of 65–70% (EOS) with a specific activity of about 3000 Ci/mmole and radiochemical purity greater than 95% in 15 min.