Synthesis and Biological Evaluation of Some Heterocyclic Compounds from Salicylic Acid Hydrazide

Abstract

Different heterocyclic compounds were prepared starting from 2‐hydroxy benzohydrazide; for example, cyclization of hydrazide hydrazone 3 derived from 2‐hydroxybenzohydrazide 2 with acetic anhydride or concentrated sulfuric acid gave 1,3,4‐oxadiazole derivatives 4–5. On the other hand, direct cyclization of 2‐hydroxy benzohydrazide 2 with one carbon cyclizing agent gave a new derivative of 1,3,4‐oxadiazole 7, 8, 9, 10, 11. Heating of hydrazide hydrazone 3 with thioglycolic acid in pyridine gave thiazolidinone 12. When 2‐hydroxy benzohydrazide 2 reacted with aliphatic carboxylic acids such as formic acid or acetic acid, it gave the corresponding N‐formyl or N‐acetyl derivatives 6. Subsequent cyclization of 6 using phosphorous pentasulphide in pyridine gave 1,3,4‐thiadiazoles 13. Cyclization of 2‐hydroxy benzohydrazide with ethyl acetoacetate gives pyrazolone derivative 14. Finally, when an ethanolic solution of acid hydrazide 2 was treated with ammonium thiocyanate in 35% HCl, it gave the thiosemicarbazide 15. Subsequent treatment of 15 with concentrated sulfuric acid or 10% sodium hydroxide gave 5‐amino‐1,3,4‐thiadiazole 16 and 1,2,4‐triazole 17, respectively. The structures of all newly isolated compounds were confirmed using 1H NMR, IR spectra, and elemental analyses. The antimicrobial activities for all isolated compounds were examined against different microorganisms.

Synthesis of Thiazolium-Labeled 1,3,4-Oxadiazole Thioethers as Prospective Antimicrobials: In Vitro and in Vivo Bioactivity and Mechanism of Action

“…Meanwhile, 1,3,4-oxadiazole skeleton that acts as another versatile building block has been extensively studied and developed for its dramatic behavior in reforming the bioactivity. − It can serve as a desirable surrogate for carboxylic acids, esters, and amides, which are always accompanied by augmented biological silhouettes. − A certain amount of designed frameworks owning 1,3,4-oxadiazole moieties are in the commercialization stage or have been launched into the market. For example, zibotentan (anticancer agent) and furamizole (antibiotic agent) are in the late stage of clinical trials, whereas raltegravir and fenadiazole that serve as antiretroviral and hypnotic drugs, respectively, have been successfully exploited to manage human immunodeficiency virus infection and insomnia. In our previous works, we demonstrated that 1,3,4-oxadiazole thioether/sulfoxide/sulfone derivatives possess superior bioactivities against plant bacterial diseases; two sulfone candidates (5-(4-fluorophenyl or 2,4-dichlorophenyl)-2-(methylsulfonyl)-1,3,4-oxadiazole) are in the novel pesticide registration stage. , Such diverse range of applications motivate us to explore and develop 1,3,4-oxadiazole-labeled derivatives as prospective antimicrobial surrogates.…”

Synthesis of a new series of 2-hydroxy-5-iodo-N’-(1-arylethylidene)benzohydrazides using a deep eutectic solvent as solvent/catalyst under sonication

“…Additionally, hydrazides are also essential precursors in the synthesis of hydrazones and heterocyclic compounds [30, 31]. As a result, several synthesis approaches have been developed for the construction of these hydrazides [32]. However, the problem of using the excess organic solvent or catalyst and the high temperature for the transformation remains to be solved.…”

Crystal structure of (E)-N'-[1-(4-aminophenyl)ethylidene]-2-hydroxy-5-iodobenzohydrazide methanol monosolvate

“…N-substituted hydrazides have been attracted much attention for their structures, coordination ability, biological activities and transformations to heterocyclic compounds (Majumdar et al, 2014;Asif & Husain, 2013;Khan et al, 2017). Derivatives of salicylic acid act as antibacterial (Kumar et al, 2012;Cui et al, 2014;Sarshira et al, 2016), antifungal (Wodnicka et al, 2017;Abbas et al, 2017) and antitumor (Murty et al, 2014) agents. In addition, some salicylhydrazones exhibit significant antitrypanosomal activity with IC 50 ranging from 1 to 34 mM.…”