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Paper | Regular issue | Vol 104, No. 4, 2022, pp.707-722
Published online, 11th January, 2022
DOI: 10.3987/COM-21-14607
Novel Heteroannulated Chromeno[2,3-b]pyridines and Related Compounds Using 6-Methylchromone-3-carbonitrile

Magdy A. Ibrahim* and Al-Shimaa Badran

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11757, Cairo, Egypt

Abstract

6-Methylchromone-3-carbonitrile (1) was utilized as synthetic intermediate for construction of a diversity of annulated chromones. Heteroannulated chromeno[2,3-b]pyridines 2-8 were synthesized from reaction of carbonitrile 1 with some methylene active nitriles and cyclic active methylene ketones. Reaction of carbonitrile 1 with isomeric cyclohexanediones in 2:1 molar ratio gave three isomeric (bischromeno)phenanthrolines. Applying Vilsmeier-Haack formylation on 8-methyl-1,2-dihydro-4H-chromeno[2,3-b]- quinoline-4,6(3H)-dione (11) produced cyclic β-chloroenaldehyde derivative 14 which upon condensation with benzylamine and p-toludine afforded the corresponding Schiff bases. Condensation reactions of β-chloroenaldehyde 14 with hydrazine hydrate and hydroxylamine hydrochloride produced the novel angularchromeno[2,3-b]pyrazolo[3,4-f]quinoline 17 and chromeno[2,3-b]isoxazo-
lo[5,4-f]-quinoline 18, Structures of the new synthesized products were deduced based on their analytical and spectral data.