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Annulation of dihydroimidazoles: a 1,3-dipolar cycloaddition route to pyrrolo[1,2-a]imidazoles, pyrrolidines and pyrroles

1998; Issue: 13 Linguagem: Inglês

10.1039/a802048e

2050-8255

Raymond C. F. Jones, K. J. HOWARD, John R. Nichols, J. S. Snaith,

Fluorine in Organic Chemistry

4,5-Dihydroimidazolium ylides, formed by N-alkylation of 4,5-dihydroimidazoles, undergo diastereoselective endo 1,3-dipolar cycloaddition with electron-deficient alkene dipolarophiles to afford hexahydropyrrolo[1,2-a]imidazoles; reduction of the aminal functionality in the cycloadducts leads to substituted pyrrolidines. Cycloaddition using 2-chloropropenonitrile, followed by base treatment, affords pyrroles.