Design and synthesis of 4-nitroimidazole derivatives with potential antitubercular activity

Objectives. To develop the procedures for synthesis of hybrid molecules with potential anti-tubercular activity containing heterocyclic cores of 4-nitroimidazole and 1,3,4-thiadiazole within the framework of a double-drug strategy and predict bioactivity of target structures and drug-likeness physicochemical parameters.

Methods. Target compounds were prepared by classical organic synthesis methods. The structure of the obtained compounds was characterized by melting points, ¹H and ¹³C nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry. The calculation of the physicochemical parameters of the target compounds and prediction of their biological activity were carried out using publicly available software for cheminformatics and molecular modeling.

Results. Acylation of propargylamine with (2-methyl-4-nitro-1H-imidazol-1-yl)acetic and (4-nitro-1H-imidazol-1-yl)acetic acids provided the corresponding amides, which were cyclized with seven different benzylamines in the presence of zinc triflate. In this way, seven new compounds were obtained at 20–30% yields. Ten arylamines were acylated with chloroacetyl chloride and the resulting chloroacetamides were converted into corresponding thio-oxahydrazides by the Willgerodt–Kindler reaction. Following acylation by (4-nitro-1H-imidazol-1-yl)acetic acid, these compounds were converted into the target hybrid imidazolyl-thiadiazoles at 29–54% yields.

Conclusions. Two series of new heterocyclic compounds with a hybrid structure including a privileged 4-nitroimidazole moiety linked to the second heterocycle, imidazole, or thiadiazole, were obtained. The synthesis and characterization of compounds by physicochemical methods was aimed at searching for anti-tuberculosis activity. The bioactivity potential of target compounds was demonstrated by preliminary calculations performed using public prognostic programs.