Synthesis, characterization and<sup>11</sup>C-radiolabeling of aminophenyl benzothiazoles: structural effects on the alkylation of amino group
作者:T. K. Venkatachalam、D. H. R. Stimson、R. Bhalla、G. K. Pierens、D. C. Reutens
DOI:10.1002/jlcr.3216
日期:2014.7
Several aminophenyl benzothiazoles were prepared with a view to using them as amyloid binding agents for imaging β-amyloid in Alzheimer's disease. These precursors were radiolabeled with 11C-positron-emitting radioisotope using an automated synthesizer and selected radiolabeled compounds were further purified by HPLC. Our results demonstrate that changes in structure have a major influence on the radioactive yield and the ease with which the radiolabel can be introduced. Aminophenyl benzothiazoles with an attached isopropyl group resisted dialkylation perhaps due to steric hindrance caused by this group. Straight chain attachment of methyl, ethyl, butyl, and crotyl groups in the structure decreased the radiochemical yield. Notably, the o-aminophenyl benzothiazole derivatives were difficult to alkylate despite stringent experimental conditions. This reactivity difference is attributed to the hydrogen bonding characteristics of the o-amino group with the nitrogen atom of the thiazole ring.
几种氨基苯基苯并噻唑被制备出来,目的是将其用作成像阿尔茨海默病中β-淀粉样蛋白的淀粉样蛋白结合剂。这些前体使用自动合成器用11C正电子发射放射性同位素进行了放射性标记,选定的放射性化合物进一步通过高效液相色谱法(HPLC)纯化。我们的结果表明,结构的变化对放射性产率以及放射性标记引入的难易程度有很大影响。带有异丙基的氨基苯基苯并噻唑由于该基团造成的空间位阻,抵抗了双烷基化。结构中直链的甲基、乙基、丁基和烯丙基的附加降低了放射化学产率。值得注意的是,尽管实验条件严格,o-氨基苯基苯并噻唑衍生物却难以烷基化。这种反应性差异归因于o-氨基基团与噻唑环氮原子的氢键形成特性。