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Synthesis and antioxidant assay of new nicotinonitrile analogues clubbed thiazole, pyrazole and/or pyridine ring systems
Author(s) -
Abumelha Hana M.A.
Publication year - 2020
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.3820
Subject(s) - chemistry , phenacyl bromide , thiazole , pyrazole , ethyl acetoacetate , ethyl bromoacetate , malononitrile , knoevenagel condensation , pyridine , chloroacetic acid , hydrazide , medicinal chemistry , organic chemistry , combinatorial chemistry , catalysis
Abstract A series of novel nicotinonitrile derivatives were synthesized by hybridization with thiazole, pyrazole, and pyridine ring systems using 4‐aminobenzohydrazide as link‐bridge. The synthetic strategy of nicotinonitrile‐thiazole analogues involves cyclization of the precursor N ‐phenyl thiosemicarbazide derivative 4 with chloroacetic acid and phenacyl bromide. The reaction of hydrazide 3 with acetylacetone and/or ethyl acetoacetate was applied as a synthetic route for accessing 2‐((4‐(pyrazole‐1‐carbonyl)phenyl)amino)‐nicotinonitrile derivatives 9–10 . The 2‐((4‐(4‐thiazolylidene‐pyrazole‐1‐carbonyl)‐phenyl)amino)nicotinonitriles 14–15 were obtained via a nucleophilic addition of pyrazolone 10 to phenyl isothiocyanate followed by cyclization with chloroacetone, phenacyl chloride, and/or ethyl bromoacetate. The 6‐amino‐4‐aryl‐3,5‐dicyano‐2‐oxo‐1‐(4‐substitutedbenzamido)‐pyridines 19 were synthesized by Knoevenagel condensation N′ ‐(2‐cyanoacetyl)‐benzohydrazide derivative 16 with substituted benzaldehydes followed by heating with malononitrile. All synthesized products were evaluated for their antioxidant potentialities using of 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) radical cation delcolorization assay. The nicotinonitrile‐thiazole hybrid 6b was found the most promising antioxidant agent with inhibition activity 86.27%.