Substituted pyridopyrimidinones. Part 5. Behavior of 2-hydroxy-4-oxo-4H-pyrido[1,2-α]pyrimidine-3-carbaldehyde in nucleophilic condensation reactions

• Published in: Chemical papers 2010-02, Vol.64 (1), p.72-83
• Main Authors: Abass, Mohamed, Ismail, Mostafa M., Abdel-Monem, Wafaa R., Mayas, Aisha S.
• Format: Article
• Language: English
• Subjects: Biochemistry; Biotechnology; chalcones; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; enaminones; Industrial Chemistry/Chemical Engineering; Knoevenagel reaction; Materials Science; Medicinal Chemistry; Original Paper; pyridopyrimidinone
• ISSN: 0366-6352; 1336-9075; 1336-9075
• DOI: 10.2478/s11696-009-0100-0

Reactivity of 2-hydroxy-4-oxo-4 H -pyrido[1,2- a ]pyrimidine-3-carbaldehyde ( I ) towards N - and C -nucleophiles was described. A series of new enaminones II–III , Schiff’s base IV , and hydrazinomethylenediketones V–VIII and X were prepared in good yields. Cyclization of compounds X was achieved by an action of acetic acid to give pyrazolo[3,4- d ]pyrido[1,2- a ]pyrimidines XI . Base catalyzed Knoevenagel condensation of aldehyde I with some active methyl and methylene compounds led to a series of chalcone-like derivatives XII, XV, XVII, XX, XXIII, XXV, XXVII, XXIX, XXXI, XXXII , and XXXV , in fair yields. Cyclization of enones XII , XV , and XX with hydrazine gave novel heterocyclyl substituted pyrazoles XIII, XVII , and XXI , respectively. Pyrano[2,3- d ]pyrido[1,2- a ]pyrimidine-2,5-diones XXXIII, XXXIV , and XXXVI derivatives were obtained via cyclization of their respective enone derivatives.