ISSN:
0170-2041
Keywords:
4-Pyrimidinones, condensed, 2-alkoxy-
;
Annulation of pyrimidines
;
Pyrrolo[2,3-d]pyrimidines
;
Pyrimido[4,5-b]azepines
;
Pyrido[1,2-a]pyrimidines
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Heterocyclic β-Enamino Esters, 52. - New Approaches to Condensed Pyrimidines via IminophosphoranesThe heterocyclic and carbocyclic 2-(triphenylphosphoranyl-ideneamino)-3-carboxylates 1a, b, 4a-d, and 8a, b, d react with isocyanates in a novel type of pyrimidine annulation to give heterocondensed 2-alkoxy-4-pyrimidinones 3a-d, 5a-h, furthermore 14-17 (revised constitutions) as well as 4(3H)-quinazolinones 9a-g, 10a, b. The constitution of model compound 3a has been established by X-ray analysis. - Crossover experiments reveal that partially saturated enamino esters, such as 1a, b, 4a-d, undergo strictly an intramolecular 1,3-shift of the ester alkoxide; a mechanism accounting for this annulation reaction is discussed. Under these conditions, the anthranilates 8 afford a stabilized carbodiimide to which alcohols or amines add before condensation occurs to 4(3H)-quinazolinones 9a-c, 10a, b; however, with the phenyl esters 8b, d the intramolecular 1,3-migration of the phenoxide is clearly favoured to afford 9f,g. - Reaction of the iminophosphoranes 19a,b of the 1,4-dihydropyridines 18a,b with acetylenedicarboxylates results in 1-addition and Aza-Wittig annulation to give the pyrido[1,2-a]pyrimidines 21a-c.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.1990199001166
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