Ross Tobias L, Ermert Johannes, Hocke Carsten, Coenen Heinz H
Institut für Nuklearchemie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
J Am Chem Soc. 2007 Jun 27;129(25):8018-25. doi: 10.1021/ja066850h. Epub 2007 May 31.
Diaryliodonium salts containing the 2-thienyl group as an example of an electron-rich heteroaromatic moiety proved to be very potent precursors for the nucleophilic, regioselective no-carrier-added (nca) radiofluorination of various arenes. It even allowed the nucleophilic introduction of nca [18F]fluoride into electron-rich arene compounds in one step. The influences of the substitution pattern, of counteranions, and of different reaction conditions were studied. Effects of counterions could be explained by the influence of solvent on ion pair separation of precursor salts. Different aryl(2-thienyl)iodonium salts were used as precursors, where the homoaromatic group systematically varied from bearing electron-deficient to electron-rich substituents. Relative rates of exchange kinetics correlated linearly with Hammett constants of the appropriate substituents confirming a nucleophilic aromatic substitution reaction of high reactivity and low selectivity.
含有2-噻吩基作为富电子杂芳族部分示例的二芳基碘鎓盐被证明是用于各种芳烃的亲核、区域选择性无载体添加（nca）放射性氟化的非常有效的前体。它甚至允许一步将nca [18F]氟化物亲核引入富电子芳烃化合物中。研究了取代模式、抗衡阴离子和不同反应条件的影响。抗衡离子的影响可以通过溶剂对前体盐离子对分离的影响来解释。使用不同的芳基（2-噻吩基）碘鎓盐作为前体，其中同芳族基团系统地从带有缺电子取代基变化到富电子取代基。交换动力学的相对速率与适当取代基的哈米特常数线性相关，证实了高反应性和低选择性的亲核芳香取代反应。
