A modified approach to a carbon-14-labeled pyridine ring system was developed based on the electrocyclic ring-closure of 1,4,4-trisubstituted butadiene. The new method was applied to prepare 2-(3,4-difluorophenoxy)-5-fluoro-[2-14C] nicotinic acid and other halogen-substituted analogs. The targeted compound was isolated with a radiochemical purity of >98% and a specific activity of 53 mCi/mmol from four radiochemical steps, starting from ethyl [1-14C] cyanoacetate in an overall radiochemical yield of 39%. Copyright © 2011 John Wiley & Sons, Ltd.
基于1,4,4-三取代
丁二烯的电环合闭环反应,开发了一种改良的碳-14标记
吡啶环系方法。该新方法应用于制备2-(3,4-二
氟苯氧基)-5-
氟-[2-14C]尼古
丁酸及其他卤素取代的类似物。从乙基[1-14C]
氰基
乙酸酯出发,经过四步放射
化学步骤,总放射
化学产率为39%,分离得到了目标化合物,其放射
化学纯度>98%,比活度为53 mCi/mmol。版权所有 © 2011 John Wiley & Sons, Ltd。