Enantioselective Friedel-Crafts alkylation of indole with nitroalkenes in the presence of bifunctional squaramide organocatalysts. (8th June 2021)

• Record Type: Journal Article
• Authors: Dündar, Esra; Tanyeli, Cihangir
• Is Part Of: Tetrahedron letters. Volume 73(2021)
• Publication Date: 2021-06-08
• Subjects: Asymmetric synthesis -- Organocatalysis -- Squaramide organocatalyst -- Friedel-Crafts alkylation -- Indole; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2021.153153
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Abstract: A 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.