The nucleophilic vinylic substitution reaction of the aliphatic enaminone 3-dimethylamino-2-formyl acrylonitrile 1 with the nucleophiles malononitrile and ethyl cyanoacetate produced the two unusual reaction adducts 3a and 3b in good to moderate yield under milder reaction conditions. Upon reaction with aromatic amines, these adducts yielded enamines 4 and 5, which eventually cyclized in the presence of base to produce the novel pyridin-2(1H)-one derivatives 8 and 9.
A series of pyrazolopyrimidine and pyrazoloquinozoline derivatives has been synthesized in one step by multicomponent reactions using, 5-aminopyrazole, p-substitutedbenzoylacetonitrile/dimedone and triethylorthoesters. pyrazolopyrimidine derivatives were also studied for their absorption and fluorescence maxima.
A convenient route was successfully developed for the synthesis of novel heterocycles such as pyrazolo [3,4-b]pyrrolo [2,3-d]pyridines (PPP) from pyrazolo [3,4-b]pyridines in good yield. The PPP derivatives synthesized were further studied for their photophysical properties, and it was observed that absorption and emission λ max changed, owing to the substituent effect at 4 positions. These compounds were obtained from highly reactive starting materials, 5-aminopyrazoles and α-acetyl γ-butyrolactone.Résumé : On a mis au point une voie réactionnelle qui permet de réaliser la synthèse de nouveaux hétérocycles, telles les pyrazolo[3,4-b]pyrrolo[2,3-d]pyridines (PPP) à partir de pyrazolo[3,4-b]pyridines, avec de bons rendements. On a soumis les dérivés PPP synthétisés à des études de leurs propriétés photophysiques et on a observé que les valeurs des λmax de leurs absorptions et de leurs émissions varient sous l'effet d'un changement dans la nature des substituants en position 4. On a obtenu ces composés à partir de produits de départ très réactifs, soit les 5-aminopyrazoles et l'α-acé-tyl-γ-butyrolactone.
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