Synthesis and Mechanistic Investigation of Bipyrazolo[1,5-<i>a</i>]pyridines <i>via</i> Palladium-Catalyzed Cross-Dehydrogenative Coupling of Pyrazolo[1,5-<i>a</i>]pyridines
作者:Pu-Yen Hsiao、Rong Chang、Andrew C.-H. Sue、Jean-Ho Chu、Guan-Wei Liao、Yi-Hsin Lee、Jui-Yang Huang
DOI:10.1021/acs.joc.2c00895
日期:2022.8.5
The synthesis of a range of 3,3′-bipyrazolo[1,5-a]pyridine derivatives via direct cross-dehydrogenative coupling of pyrazolo[1,5-a]pyridine precursors is herein presented. This simple and efficient methodology involving palladium(II)-catalyzed C–H bond activation showed good functional group tolerance and product yield (up to 94%). Through the mechanistic insights gained from both kinetic isotope effect
本文介绍了通过吡唑并[1,5- a ]吡啶前体的直接交叉脱氢偶联合成一系列3,3'-联吡唑并[1,5- a ]吡啶衍生物。这种涉及钯 (II) 催化的 C-H 键活化的简单有效的方法显示出良好的官能团耐受性和产品收率(高达 94%)。通过从动力学同位素效应实验研究和密度泛函理论计算中获得的机理见解,概述了合理的反应机理。此外,生成的 7,7'-diaryl-3,3'-bipyrazolo[1,5- a ]pyridines 的后续衍生化,通过钯介导的邻C-H 键活化,然后是高价碘诱导的氯化,使这一系列化合物具有更多的扩展 π 共轭和扭曲的构象。我们对这些双吡唑并[1,5 - a ]吡啶基发光剂的研究为定制有机发光材料提供了新的机会。