Synthesis and Antibacterial Evaluation of Hydrazone Derivatives Bearing 6-Chlorothieno[3,2-c]pyridine Moiety

Abstract

The present investigation describes the overall preparation of 6-chlorothieno[3,2-c]pyridine-2-carbohydrazide-hydrazone subsidiaries (7a-r) from industrially accessible ethyl-4,6-dichloronicotinate as starting material. The synthesis of these derivatives involve some prominent reactions such as (i) NaBH4 reduction of ethyl ester group (ii) MnO2 oxidation of 1º alcohol (iii) cyclization of aldehyde with ethylmercapto acetate leading to thieno[3,2-c]pyridine ring (iv) hydrazinolysis of the ethyl group (v) condensation of selected aldehydes with 6-chlorothieno[3,2-c]pyridine-2-carbohydrazide leading to the desired 6-chlorothieno[3,2-c]pyridine-2-carbohydrazide-hydrazone derivatives (7a-r). The structure of the derivatives was characterized by elemental analysis, NMR, infrared and mass spectroscopic analysis. These compounds were screened for their antibacterial property towards Gram positive and Gram negative bacterial strains using agar diffusion method with reference to norfloxacin as reference antibiotic.