Enantioselective Friedel-Crafts alkylation of indole with nitroalkenes in the presence of bifunctional squaramide organocatalysts


Creative Commons License

Dündar E. , Tanyeli C.

Tetrahedron Letters, vol.73, pp.1-4, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 73
  • Publication Date: 2021
  • Doi Number: 10.1016/j.tetlet.2021.153153
  • Title of Journal : Tetrahedron Letters
  • Page Numbers: pp.1-4
  • Keywords: Asymmetric synthesis, Organocatalysis, Squaramide organocatalyst, Friedel-Crafts alkylation, Indole, MICHAEL ADDITION, DERIVATIVES, CATALYST

Abstract

© 2021 Elsevier LtdA series of chiral bifunctional quinine and 2-aminoDMAP based squaramide organocatalysts are evaluated in Friedel-Crafts alkylation of indoles with nitroolefins. These 3-substituted indole derivatives are synthesized in the presence of sterically encumbered tert-butyl squaramide/quinine with high enantioselectivity (up to >99% ee) and moderate chemical yields (up to 80%) by representing as chiral precursors for very important biologically active molecules. Besides, this asymmetric transformation provides a very simple, efficient, clean and environmental friendly route. In addition, this process has very mild reaction conditions such as ambient temperature and usage of only 2 mol% catalyst loading compared to previous studies in literature.