Lory, Pedro M.J.; Jones, Raymond C.F.; Iley, James N.; Coles, Simon J. and Hursthouse, Michael B.
(2006).
Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles.
Organic and Biomolecular Chemistry, 4
pp. 3155–3165.
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.
| Item Type: |
Journal Article
|
| ISSN: |
1477-0520 |
| Extra Information: |
Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract. |
| Keywords: |
intramolecular; 1,3-dipolar cycloaddition; dihydroimidazolium ylides; imidazoline ylides; |
| Academic Unit/Department: |
Science > Life, Health and Chemical Sciences |
| Item ID: |
5954 |
| Depositing User: |
James Iley
|
| Date Deposited: |
29 Nov 2006 |
| Last Modified: |
02 Dec 2010 19:55 |
| URI: |
http://oro.open.ac.uk/id/eprint/5954 |
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