ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

Mohamed Abass, Mostafa M. Ismail, Wafaa R. Abdel-Monem, and Aisha S. Mayas

Department of Chemistry, Faculty of Education, Ain Shams University, Cairo, Egypt

E-mail: m.abass@chemist.com

Received: 17 July 2009  Revised: 22 August 2009  Accepted: 24 August 2009

Abstract: Reactivity of 2-hydroxy-4-oxo-4H-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.

Keywords: pyridopyrimidinone - enaminones - chalcones - Knoevenagel reaction

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-009-0100-0

Chemical Papers 64 (1) 72–83 (2010)