Enantioselective organocatalytic Friedel-Crafts alkylation reaction of indoles with 5-hydroxyfuran-2(5H)-one: access to chiral γ-lactones and γ-lactams via a Ugi 4-center 3-component reaction

J Org Chem. 2011 Oct 21;76(20):8143-50. doi: 10.1021/jo201184p. Epub 2011 Jul 12.

Abstract

5-Hydroxyfuran-2(5H)-one 1, a readily available renewable resource, was used as an electrophile in the Friedel-Crafts alkylation of indoles catalyzed by a diphenylprolinol silyl ether. Moderate catalyst loading was achieved because of the high reactivity of 5-hydroxyfuran-2(5H)-one 1 in this process. Reduction of the Friedel-Crafts adduct (FC adduct) afforded indoyl lactones in high yield and enantioselectivity. Moreover, the FC adduct was used as a chiral synthon in a diversity-oriented synthesis, as illustrated by its successful engagement in a 4-center 3-component Ugi reaction (U-4C-3CR) to afford chiral five-membered lactams in high yield and enantioselectivity.

MeSH terms

  • Alkylation
  • Catalysis
  • Chemistry, Pharmaceutical / methods*
  • Chromatography, Thin Layer
  • Drug Discovery*
  • Ethers / chemistry
  • Furans / chemistry*
  • Indoles / chemistry*
  • Lactams / chemical synthesis*
  • Lactones / chemical synthesis*
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Proline / analogs & derivatives
  • Proline / chemistry
  • Stereoisomerism

Substances

  • Ethers
  • Furans
  • Indoles
  • Lactams
  • Lactones
  • diphenylprolinol silyl ether
  • Proline