Stereodivergent Synthesis of Tetrahydrofuroindoles through Pd-Catalyzed Asymmetric Dearomative Formal [3+2] Cycloaddition
作者:Qiang Cheng、Fang Zhang、Yue Cai、Yin-Long Guo、Shu-Li You
DOI:10.1002/anie.201711873
日期:2018.2.19
palladium‐catalyzed asymmetric dearomative formal [3+2] cycloaddition of nitroindoles with epoxybutenes was developed. The polarity of the solvent was found to play a key role in the diastereoselectivity. In toluene, good to excellent yields (70–99 %), diastereoselectivity (87/13‐>95/5 d.r.), and enantioselectivity (85/15–94/6 e.r.) were obtained, regardless of the properties of the substituents on
通过钯催化的硝基吲哚与环氧丁烯的不对称脱芳香性甲醛[3 + 2]正式加成环加成反应,立体合成了四氢呋喃吲哚。发现溶剂的极性在非对映选择性中起关键作用。在甲苯中,无论取代基的性质如何,均可获得良好至优异的收率(70–99%),非对映选择性(87 / 13-> 95/5 dr)和对映选择性(85 / 15–94 / 6 er)。硝基吲哚。在乙腈中,生产出不同非对映异构体的四氢呋喃吲哚,具有良好至极佳的收率(75–98%)和立体选择性(78 / 22–93 / 7 dr,93 / 7–99 / 1 er)。进行了机理研究以说明非对映性的起源。动力学实验表明,该反应的速率确定步骤在不同的溶剂中是不同的。ESI-MS实验还支持关键的钯络合物中间体的存在和反应的催化循环。