As an effort to improve 18F-radiolabeling of biomolecules in method robustness and versatility, we report the synthesis and radiolabeling of a new azido precursor potentially useful for the so-called “click reaction,” in particular the ligand-free version of the copper(I)-catalyzed alkyne-azide cycloaddition. The new azido precursor may help to overcome problems sometimes exhibited by most of the currently used analogues, as it is safe to handle and it displays long-term chemical stability, thus facilitating the development of new radiolabeling procedures. Moreover, the formed 18F-labeled 1,2,3-triazole is potentially metabolically stable and could enhance the in vivo circulation time. The above azido precursor was successfully radiolabeled with 18F, with 51% radiochemical yield (nondecay-corrected). As a proof of concept, the 18F-labeled azide was then tested with a suitable alkyne functionalized aminoacid (l-propargylglycine), showing 94% of conversion, and a final radiochemical yield of 27% (>99% radiochemical purity), nondecay-corrected, with a total preparation time of 104 minutes.
为了提高18F标记
生物分子在方法稳健性和多样性方面的表现,我们报告了一种新型
叠氮前体的合成及其放射性标记,该前体可能适用于所谓的“点击反应”,特别是无
配体版的
铜(I)催化的
炔烃-
叠氮环加成反应。这种新型
叠氮前体有助于克服当前使用的大多数类似物有时展现的问题,因为它易于处理且具有长期的
化学稳定性,从而有助于开发新的放射性标记程序。此外,形成的18F标记的
1,2,3-三唑潜在地具有代谢稳定性,并可能增强体内循环时间。上述
叠氮前体成功通过18F进行了放射性标记,放射
化学产率为51%(未校正衰变)。作为概念验证,随后测试了18F标记的
叠氮与适当的炔基功能化
氨基酸(L-
丙炔甘
氨酸),显示出94%的转化率,最终放射
化学产率为27%(>99%放射
化学纯度),未校正衰变,总制备时间为104分钟。