55076-31-8Relevant academic research and scientific papers
Heterocyclic β-Enamino Esters, 52. - New Approaches to Condensed Pyrimidines via Iminophosphoranes
Wamhoff, Heinrich,Wintersohl, Heinrich,Stoelben, Stephan,Paasch, Joachim,Nai-jue, Zhu,Fang, Guo
, p. 901 - 911 (2007/10/02)
The heterocyclic and carbocyclic 2-(triphenylphosphoranylideneamino)-3-carboxylates 1a,b, 4a-d, and 8a,b,d react with isocyanates in a novel type of pyrimidine annulation to give heterocondesed 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 strictyl an intramolecular 1,3-shift of the ester alkoxide; a mechanism accounting 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 pyridopyrimidines 21a-c.
