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Pyrimidine annelated heterocycles - synthesis and cycloaddition of the first pyrimido[1,4]diazepine n-oxides

Heaney, Frances
; 
Burke, Cathriona
; 
Cunningham, Desmond
; 
McArdle, Patrick
Repository DOI
Publication Date
2001-01-01
Keywords
intramolecular 1,3-dipolar cycloaddition, potentially useful intermediate, azepine-ring formation, ene reactions, 1,3-azaprotio cyclotransfer, acid derivatives, zh systems, periphery, nitrones, oximes
Type
Article
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Citation
Heaney, Frances; Burke, Cathriona; Cunningham, Desmond; McArdle, Patrick (2001). Pyrimidine annelated heterocycles - synthesis and cycloaddition of the first pyrimido[1,4]diazepine n-oxides. Journal of the Chemical Society, Perkin Transactions 1 (6), 622-632
Abstract
5-Formyl- and 5-acetyl-4-(alkenylamino)pyrimidines 5 have been prepared as precursors to novel pyrimido[1,4]diazepine N-oxides 3. In addition to cyclisation to the targeted dipoles the substrates 5 have also been observed to form imidazopyrimidines 12 and 39 via an intramolecular Michael addition; additionally 5b has been observed to form the pyrimidoazepinone 42. Aldonitrone 3a cycloadded readily to olefinic dipolarophiles; ketodipole 3b did not share this reactivity. Both dipoles reacted with acetylenic dipolarophiles but the ensuing cycloadducts 37 were unstable; facile ring contraction of their isoxazolopyrimidodiazepine skeletons to the pteridine nucleus is noted. The structure of 37c has been determined by X-ray crystallography.
Funder
Publisher
Royal Society of Chemistry (RSC)
Publisher DOI
10.1039/b007163n
Rights
Attribution-NonCommercial-NoDerivs 3.0 Ireland
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Externally hosted open access publications with University of Galway authors (1)