Two potent glucocorticoid receptor agonists were prepared labeled with carbon-14 and with stable isotopes to perform drug metabolism, pharmacokinetics, and bioanalytical studies. Carbon-14 labeled (1) was obtained from an enantiopure alkyne (5) via a Sonogashira coupling to a previously reported 5-amino-4-iodo-[2-14C]pyrimidine [14C]-(6), followed by a base-mediated cyclization (1) in 72% overall radiochemical yield. Carbon-14 labeled (2) was prepared in five steps employing a key benzoic acid intermediate [14C]-(13), which was synthesized in one pot from enolization of trifluoromethylketone (12), followed by bromine–magnesium exchange and then electrophile trapping reaction with [14C]-carbon dioxide. A chiral auxiliary (S)-1-(4-methoxyphenyl)ethylamine was then coupled to this acid to give [14C]-(15). Propargylation and separation of diastereoisomers by crystallizations gave the desired diastereomer [14C]-(17) in 34% yield. Sonogashira coupling to iodopyridine (10) followed by cyclization to the azaindole [14C]-(18) and finally removal of the chiral auxiliary gave [14C]-(2) in 7% overall yield. For stable isotope syntheses, [13C6]-(1) was obtained in three steps using [13C4]-(6) and trimethylsilylacetylene-[13C2] in 26% yield, while [2H5]-(2) was obtained by first preparing the iodopyridine [2H5]-(10) in five steps. Then, Sonogashira coupling to chiral alkyne (24) and cyclization gave [2H5]-(2) in 42% overall yield.
两种强效的糖皮质激素受体激动剂被制备并标记为碳-14以及稳定同位素,以进行药物代谢、药代动力学和
生物分析研究。碳-14标记的(1)是通过Sonogashira偶联反应从一种对映体纯的
炔烃(5)得到的,该
炔烃与先前报道的5-
氨基-4-
碘-[2-14C]
嘧啶[14C]-(6)反应,随后经过碱介导的环化反应(1),总体放射
化学产率为72%。碳-14标记的(2)经过五个步骤制备,采用了一个关键的
苯甲酸中间体[14C]-(13),该中间体通过三
氟甲基酮(12)的烯醇化反应在一个反应锅中合成,随后进行
溴-
镁交换反应,并与[14C]
二氧化碳进行亲电试剂捕获反应。接着,将一个手性助剂(S)-
1-(4-甲氧基苯基)乙胺与该酸偶联,得到[14C]-(15)。再经炔基化及通过结晶分离二
氟异构体,得到所需的二
氟异构体[14C]-(17),产率为34%。随后对
碘吡啶(10)进行Sonogashira偶联反应,再进行环化反应得到氮杂
吲哚[14C]-(18),最后去除手性助剂,得到[14C]-(2),总体产率为7%。在稳定同位素合成方面, [13C6]-(1)通过三步反应从[13C4]-(6)和三甲基
硅基
乙炔-[13C2]得到,产率为26%;而[2H5]-(2)的合成首先通过五个步骤制备
碘吡啶[2H5]-(10)。然后,与手性
炔烃(24)进行Sonogashira偶联反应并环化,得到[2H5]-(2),总体产率为42%。