Efficient syntheses of [<sup>11</sup>C]zidovudine and its analogs by convenient one-pot palladium(0)-copper(I) co-mediated rapid<i>C</i>-[<sup>11</sup>C]methylation
作者:Zhouen Zhang、Hisashi Doi、Hiroko Koyama、Yasuyoshi Watanabe、Masaaki Suzuki
DOI:10.1002/jlcr.3213
日期:2014.6.30
The nucleosides zidovudine (AZT), stavudine (d4T), and telbivudine (LdT) are approved for use in the treatment of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infections. To promote positron emission tomography (PET) imaging studies on their pharmacokinetics, pharmacodynamics, and applications in cancer diagnosis, a convenient one-pot method for Pd(0)–Cu(I) co-mediated rapid C–C coupling of [11C]methyl iodide with stannyl precursor was successfully established and applied to synthesize the PET tracers [11C]zidovudine, [11C]stavudine, and [11C]telbivudine. After HPLC purification and radiopharmaceutical formulation, the desired PET tracers were obtained with high radioactivity (6.4–7.0 GBq) and specific radioactivity (74–147 GBq/µmol) and with high chemical (>99%) and radiochemical (>99.5%) purities. This one-pot Pd(0)–Cu(I) co-mediated rapid C-[11C]methylation also worked well for syntheses of [methyl-11C]thymidine and [methyl-11C]4′-thiothymidine, resulting twice the radioactivity of those prepared by a previous two-pot method. The mechanism of one-pot Pd(0)–Cu(I) co-mediated rapid C-[11C]methylation was also discussed.
核苷类药物齐多夫定(AZT)、司他夫定(d4T)和替比夫定(LdT)已被批准用于治疗人类免疫缺陷病毒(HIV)和乙型肝炎病毒(HBV)感染。为了促进正电子发射断层扫描(PET)成像技术在其药代动力学、药效学以及癌症诊断中的应用研究,我们成功建立并应用了一种方便的一锅法,通过Pd(0)–Cu(I)协同催化的快速C–C偶联反应,将[11C]甲碘烷与锡前体结合,合成了PET示踪剂[11C]齐多夫定、[11C]司他夫定和[11C]替比夫定。经过HPLC纯化和放射性药物制剂处理后,得到的所需PET示踪剂具有高放射性(6.4–7.0 GBq)和高比活度(74–147 GBq/µmol),以及高化学纯度(>99%)和高放射化学纯度(>99.5%)。这种一锅法Pd(0)–Cu(I)协同催化快速C-[11C]甲基化反应同样适用于合成[甲基-11C]胸苷和[甲基-11C]4′-硫代胸苷,其放射性活度是之前两锅法所制备的两倍。我们还讨论了一锅法Pd(0)–Cu(I)协同催化快速C-[11C]甲基化反应的机制。