Synthesis of [18F]-labeled EF3 [2-(2-nitroimidazol-1-yl)-N-(3,3,3-trifluoropropyl)-acetamide], a marker for PET detection of hypoxia

[F-18]-2-(2-Nitroimidazol-1-yl)-N-(3,3,3-trifluoropropyl)-acetamide ([F-18]-EF3) has been prepared, in 65% chemical yield and 5% radiochemical yield, by coupling 2,3,5,6-tetrafluorophenyl 2-(2-nitroimidazol-1-yl) acetate 1 with [F-18]-3,3,3-trifluoropropylamine 7. This original radiolabelled key-synthon was obtained in 40% overall chemical yield by oxidative [F-18]-fluorodesulfurization of ethyl N-phthalimido-3-aminopropane dithioate 4, followed by deprotection with hydrazine of the resulting [F-18]-N-phthalimido-3,3,3-trifluoropropylamine 5. All the process was performed within 90 min, from the [F-18]-HF production in the cyclotron to the purification of the final target. (C) 2001 Elsevier Science Ltd. All rights reserved.