Design synthesis characterization and biological activity of novel nitrogen containing heterocyclic compounds

Abstract

Background newlineNitrogen-containing heterocyclic compounds possess a variety of pharmacological activities, newlineamong them, 1, 3, 4-oxadiazole derivatives are associated with diverse biological activities, newlineSuch as antibacterial, antimalarial, anti-inflammatory, and antifungal. many investigations newlinehave also revealed the anticonvulsant, antidepressant, and antimicrobial potential of 1,3,4- oxadiazole, benzimidazole, and quinoline analogs. newlineAims newlineTo synthesize new compounds with improved pharmacological potential containing 1,3,4- oxadiazole, benzimidazole and quinoline newlineMethods newline2-Phenylquinoline-4-carbohydrazide (1c) was prepared by using isatin and newlineacetophenone via 2-Phenylquinoline-4-carboxylic acid (1a) and ethyl-2-phenyl-1,2- dihydroquinoline-4-carboxylate (1b) in part A of scheme I. The title compounds 4-[5- Substituted-[1,3,4]oxadiazole-2-yl]-2-phenylquinoline (1-15) were synthesized from newlinecompound 1c. In the part B of scheme I, title compounds (22E)-N-Substituted benzylidene- 5-((1, 2-dihydro-2-phenylquinolin-4-yl)methyl)-1,3,4-oxadiazol-2-amine (16-25) were newlineprepared from compound 1b via 2-(2-phenyl-1, 2-dihydroquinoline-4-carbonyl)hydrazine- 1-carboxamide (1d) and 5-[(2-phenyl-1, 2-dihydroquinolin-4-yl)methyl]-1,3,4-oxadiazol-2- amine (1e). In the next scheme II, 2-Chloroquinoline-3-carbaldehyde (2a) was synthesized newlinevia Vilsmeier Haack method using acetanilide.3-(1H-benzimidazole-2-yl)-2- chloroquinoline (2b), ethyl-[2-(2-chloroquinoline-3-yl)-1H-benzimidazole-1-yl)acetate (2c) newlineand 2-[2-(2-Chloroquinolin-3-yl)-1H-benzimidazole-1-yl]-acetohydrazide (2d) were newlineprepared from compound 2a. In the next step, synthesis of 2-chloro-3-(1-(5-substituted- 1,3,4-oxadiazaol-2-yl)methyl)-1H-benzo[d]-imidazole-2-yl)quinoline (26-40) was done newlinefrom compound 2d. In scheme-III, 2-(3-formyl-2-oxoquinolin-1(2H)-yl)acetohydrazide newline(3c) was prepared from compound 2c via the synthesis of 2-oxo-1, 2-dihydroquinoline-3- carbaldehyde (3a) and ethyl-2-(3-formyl-2-oxoquinolin-1(2H)-yl)acetate (3b), which on newlinereaction with different reagents gave 1,2-d