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Heterocyclische β‐Enaminoester, 52. Neue Wege zu kondensierten Pyrimidinen über Iminophosphorane
Author(s) -
Wamhoff Heinrich,
Wintersohl Heinrich,
Stölben Stephan,
Paasch Joachim,
NaiJue Zhu,
Fang Guo
Publication year - 1990
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1990199001166
Subject(s) - chemistry , annulation , pyrimidinones , medicinal chemistry , carbodiimide , stereochemistry , organic chemistry , catalysis
Heterocyclic β‐Enamino Esters, 52. — New Approaches to Condensed Pyrimidines via Iminophosphoranes The 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(3 H )‐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 intra molecular 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(3 H )‐quinazolinones 9a – c , 10a , b ; however, with the phenyl esters 8b , d the intra molecular 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 .