The ¹⁸F syntheses of tracers for positron emission tomography (PET) typically require several steps, including extraction of [¹⁸F]fluoride from H₂[¹⁸O]O, elution, and drying, prior to nucleophilic substitution reaction, being a laborious and time-consuming process. The elution of [¹⁸F]fluoride is commonly achieved by phase transfer catalysts (PTC) in aqueous solution, which makes azeotropic drying indispensable. The ideal PTC is characterized by a slightly basic nature, its capacity to elute [¹⁸F]fluoride with anhydrous solvents, and its efficient complex formation with [¹⁸F]fluoride during subsequent labeling. Herein, we developed tri-(tert-butanol)-methylammonium iodide (TBMA-I), a quaternary ammonium salt serving as the PTC for ¹⁸F-fluorination reactions. The favorable elution efficiency of [¹⁸F]fluoride using TBMA-I was demonstrated with aprotic and protic solvents, maintaining high ¹⁸F-recoveries of 96–99%. ¹⁸F-labeling reactions using TBMA-I as PTC were studied with aliphatic 1,3-ditosylpropane and aryl pinacol boronate esters as precursors, providing ¹⁸F-labeled products in moderate-to-high radiochemical yields. TBMA-I revealed adequate properties for application to ¹⁸F-fluorination reactions and could be used for elution of [¹⁸F]fluoride with MeOH, omitting an additional base and azeotropic drying prior to ¹⁸F-labeling. We speculate that the tert-alcohol functionality of TBMA-I promotes intermolecular hydrogen bonding, which enhances the elution efficiency and stability of [¹⁸F]fluoride during nucleophilic ¹⁸F-fluorination.

中文翻译：

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使用三叔丁醇碘化铵作为相转移催化剂的 18F-氟化：另一种极简主义方法

用于正电子发射断层扫描 (PET) 示踪剂的¹⁸ F 合成通常需要几个步骤，包括在亲核取代反应之前从 H ₂ [ ¹⁸ O]O 中提取 [ ¹⁸ F] 氟化物、洗脱和干燥，这是一个费力且费力的步骤。耗时的过程。[ ¹⁸ F]氟化物的洗脱通常通过水溶液中的相转移催化剂（PTC）实现，这使得共沸干燥必不可少。理想的 PTC 的特点是具有微碱性，能够用无水溶剂洗脱 [ ¹⁸ F] 氟化物，并且在随后的标记过程中与 [ ¹⁸ F] 氟化物有效形成复合物。在这里，我们开发了三（叔-丁醇)-甲基碘化铵 (TBMA-I)，一种季铵盐，用作¹⁸ F-氟化反应的 PTC 。使用 TBMA-I的 [ ¹⁸ F] 氟化物的良好洗脱效率在非质子和质子溶剂中得到了证明，保持了 96-99% 的高¹⁸ F 回收率。以脂肪族 1,3-二甲苯基丙烷和芳基频哪醇硼酸酯为前体，研究了使用 TBMA-I 作为 PTC 的¹⁸ F 标记反应，以中等至高放射化学产率提供¹⁸ F 标记产物。TBMA-I 显示出适用于¹⁸ F-氟化反应的足够特性，可用于洗脱 [ ¹⁸F]氟化物与 MeOH，在¹⁸ F 标记之前省略额外的碱和共沸干燥。我们推测TBMA-I的叔醇官能团促进了分子间氢键，这增强了 [ ¹⁸ F] 氟化物在亲核¹⁸ F-氟化过程中的洗脱效率和稳定性。