A robust protocol for Pd(ii)-catalyzed C-3 arylation of (1H) indazoles and pyrazoles: total synthesis of nigellidine hydrobromide
作者:Mengchun Ye、Andrew J. F. Edmunds、James A. Morris、David Sale、Yejia Zhang、Jin-Quan Yu
DOI:10.1039/c3sc50184a
日期:——
indazole and pyrazoles are privileged structural motifs in agrochemicals and pharmaceuticals. C-3 C-H arylation of (1H) indazole and pyrazole has been a significant challenge due to the poor reactivity of the C-3 position. Herein, we report a practical Pd(II)/Phen catalyst and conditions for direct C-3 arylation of indazole and pyrazole with ArI or ArBr without using Ag additives as halide scavengers. The
C3-芳基吲唑和吡唑是农用化学品和药物中的优先结构基序。由于C-3位置的反应性较差,(1H)吲唑和吡唑的C-3 CH芳基化已成为一项重大挑战。在这里,我们报告了一种实用的Pd(II)/ Phen催化剂,以及吲哚和吡唑与ArI或ArBr进行直接C-3芳基化而不使用Ag添加剂作为卤化物清除剂的条件。发现使用甲苯,氯苯,三氟甲基苯和均三甲苯作为溶剂对于选择性和反应性至关重要。我们通过首次氢溴酸尼古丁的全合成以及与农药和药物分子结构相关的杂环的简便制备,进一步证明了该方案的稳健性。