Beyond Acid Strength in Zeolites: Soft Framework Counteranions for Stabilization of Carbocations on Zeolites and Its Implication in Organic Synthesis
作者:Jose R. Cabrero-Antonino、Antonio Leyva-Pérez、Avelino Corma
DOI:10.1002/anie.201500864
日期:2015.5.4
The generation of a carbocation with an acid depends not only on the acid strength but also on the ability of the counteranion to stabilize the positive charge left behind. Here we report that despite their relatively weak acidity, zeolites are able to generate and stabilize medium‐size (molecular weight ≈300 Da) delocalized carbocations on their surface under mild reaction conditions, as it can be
用酸生成碳正离子不仅取决于酸强度,还取决于抗衡阴离子稳定留下的正电荷的能力。在这里我们报告说,尽管它们的酸度相对较弱,但它们仍可以在温和的反应条件下在其表面上生成并稳定中等尺寸(分子量约300 Da)的离位碳正离子,这可以通过在溶液中加入强Brønsted或路易斯酸来完成。 。沸石因此充当软的大阴离子,充分延长了碳正离子的寿命,从而可以高产率和选择性地与酰胺,硫代酰胺和酚进行多官能化反应。生物学研究表明,此处获得的某些产品对结肠癌细胞具有明显的抑制活性,