A novel KI/TBHP-catalyzed 1,3-dipolar cycloaddition/oxidation/aromatization cascade reaction provided a general, efficient and green access to biologically important pyrrolo[2,1-a]isoquinolines.
TBAI/TBHP-catalyzed [3 + 2]cycloaddition/oxidation/aromatization cascade and online ESI-MS mechanistic studies: synthesis of pyrrolo[2,1-<i>a</i>]isoquinolines and indolizino[8,7-<i>b</i>]indoles
作者:Shalini Nekkanti、Niggula Praveen Kumar、Pankaj Sharma、Ahmed Kamal、Fabiane M. Nachtigall、Oscar Forero-Doria、Leonardo S. Santos、Nagula Shankaraiah
DOI:10.1039/c5ra24629f
日期:——
A facile [3 + 2]cycloaddition/oxidation/aromatization cascade reaction for the synthesis of pyrrolo[2,1-a]isoquinolines and indolizino[8,7-b]indoles has been developed. This tandemapproach was accomplished by employing tert-butyl hydroperoxide (TBHP) as the environmentally benign stoichiometric oxidant, with the catalysis of non-toxic tetrabutylammonium iodide (TBAI) and isopropanol as the green solvent
已经开发了一种用于合成吡咯并[2,1- a ]异喹啉和吲哚并[8,7- b ]吲哚的简便的[3 + 2]环加成/氧化/芳构化级联反应。这种串联方法是通过使用叔丁基过氧化氢(TBHP)作为环境友好的化学计量氧化剂,并以无毒碘化四丁基碘化铵(TBAI)和异丙醇作为绿色溶剂的催化作用来实现的。令人欣慰的是,该协议具有高度的通用性,因为多环化合物的构建可以通过容易获得的双极性亲和剂进行定制。只需催化量的TBAI,因为可以就地回收高价亲电子碘(IOH)通过TBHP氧化。此外,首次通过使用ESI-MS / MS在线监测反应来拦截和表征与该级联反应有关的机理方面和推测的中间体。
Iodine-Catalyzed 1,3-Dipolar Cycloaddition/Oxidation/Aromatization Cascade with Hydrogen Peroxide as the Terminal Oxidant: General Route to Pyrrolo[2,1-<i>a</i>]isoquinolines
We report a novel molecular iodine-catalyzed 1,3-dipolar cycloaddition/oxidation/aromatization cascade process with hydrogen peroxide as the terminal oxidant for the construction of pyrrolo[2,1-a]isoquinolines. The product pyrrolo[2,1-a]isoquinolines were obtained from reactions between simple, readily available dipolarophiles and tetrahydroisoquinolines in moderate to excellent yields without the need for a metal catalyst.