Jump to main content
Jump to site search

Issue 16, 2006
Previous Article Next Article

Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles

Author affiliations

Abstract

N-Alkylation of 4,5-dihydroimidazoles with alkene-containing bromomethyl ketones and treatment of the so-formed 4,5-dihydroimidazolium ions with DBU gives rise to an intramolecular 1,3-dipolar cycloaddition reaction that affords (via a reaction cascade involving eliminative ring-opening, recyclisation and prototropic tautomerism) unexpected hexahydropyrrolo[1,2,3-de]quinoxaline products. Steric bulk in both the dihydroimidazole and the dipolarophile allows isolation of an imidazo[1,2-a]indole, the initial product of cycloaddition. When the bromomethyl ketone contains no other functionality, or when cycloaddition is inhibited due to steric constraints, the dihydroimidazolium ion undergoes ring-opening hydrolysis followed by recyclization of the exposed amino ketone to afford either 3-alkyl-1-formylpiperazine-2-ones or 3-aryl-1-formyl-1,4,5,6-tetrahydropyrazines.

Graphical abstract: Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles

Back to tab navigation

Supplementary files

Publication details

The article was received on 18 Apr 2006, accepted on 28 Jun 2006 and first published on 18 Jul 2006


Article type: Paper
DOI: 10.1039/B605458G
Org. Biomol. Chem., 2006,4, 3155-3165

  •   Request permissions

    Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles

    P. M. J. Lory, R. C. F. Jones, J. N. Iley, S. J. Coles and M. B. Hursthouse, Org. Biomol. Chem., 2006, 4, 3155
    DOI: 10.1039/B605458G

Search articles by author

Spotlight

Advertisements