Substituted quinolinones. 31. Some new pyrano[3, 2‐c]quinoline‐3‐carboxamides and their antioxidant activity. (10th September 2019)

• Record Type: Journal Article
• Authors: Othman, Elham S.; Hassan, Heba; Abass, Mohamed
• Is Part Of: Journal of heterocyclic chemistry. Volume 56:Number 12(2019)
• Page Start: 3257
• Page End: 3266
• Publication Date: 2019-09-10
• Subjects: Heterocyclic compounds -- Periodicals; 547.59
• DOI: 10.1002/jhet.3721
• Languages: English
• ISSNs: 0022-152X

Abstract

Abstract: 1‐Ethyl‐4‐hydroxy‐2‐oxo‐1, 2‐dihydroquinoline‐3‐carbaldehyde (1 ) was annulated using malonic acid and/or its ethyl ester to furnish pyrano[3, 2‐ c ]quinoline‐3‐carboxylic acid 2 and its ester 3 . Interconversions between acid 2 and ester 3 were successfully carried out. The anticipated pyrano[3, 2‐ c ]quinoline‐3‐carboxamides 5–12 were conveniently attained via condensation of ester 3 with the proper amine. Surprisingly, treatment of ester 3 with dimethylformamide (DMF) in acidic media led to the carboxamide 5 . All attempts to convert ester 3 to its corresponding acid hydrazides by interaction with the proper hydrazine derivative led to formation of pyrazolidinediones 15 and 17 . Ester 3 underwent cyclo‐condensation with malononitrile dimer affording pyrido[3′, 4′:5, 6]pyrano[3, 2‐ c ]quinoline derivative 18 . The new compounds revealed significant antioxidant effect, which suggests that most of them are possible potent antioxidant agents. Abstract :