Calcium-Catalyzed Formal [5 + 2] Cycloadditions of Alkylidene β-Ketoesters with Olefins: Chemodivergent Synthesis of Highly Functionalized Cyclohepta[<i>b</i>]indole Derivatives
作者:Ariel N. Parker、M. Cynthia Martin、Raynold Shenje、Stefan France
DOI:10.1021/acs.orglett.9b02498
日期:2019.9.20
cycloaddition of indolyl alkylidene β-ketoesters with mono- and disubstituted aryl olefins to form cyclohepta[b]indole derivatives has been established. Unanticipated chemodivergence with phenyl vinyl sulfide/ether revealed a double [5 + 2] cycloaddition cascade providing ethano-bridged cyclohepta[b]indoles. Overall, the method’s highlights include: (1) use of a green, calcium-based catalyst (2.5 mol % loading);
已经建立了吲哚基亚烷基β-酮酸酯与单和二取代的芳基烯烃的钙催化的正式[5 + 2]环加成反应,以形成环庚[ b ]吲哚衍生物。与苯基乙烯基硫醚/醚的意外化学发散表明,双[5 + 2]环加成级联反应提供了乙醇桥联的环庚[ b ]吲哚。总体而言,该方法的亮点包括:(1)使用绿色的钙基催化剂(负载量为2.5摩尔%);(2)反应时间在1小时以下;(3)反应条件温和;(4)底物来源的化学散度;(5)功能组容忍度;(6)衍生化的例子。