Synthesis, characterization, and antibacterial activities of some novel N,N'-disubstituted thiourea, 2-amino thiazole, and imidazole-2-thione derivatives

In the search of bioactive molecules, a series of novel N-substituted thiourea derivatives 3(a-d) are prepared by reaction of the alpha-amino pyridyl ketone hydrochloride (2a) with the corresponding aryl isothiocyanates. The synthesis of some new 2-amino thiazoles 4(a-d) and imidazole-2-thiones 6(a-d) were attempted by intramolecular cyclization reaction of the N,N'-disubstituted thioureas 3(a-d) and their intermediate ketals 5(a-d) in diluted aqueous acidic and strong acidic mediums. The structure of all newly synthesized compounds was established by analytical and spectral data. The antibacterial studies to all of the synthesized compounds against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis bacteria with Gram-positive and negative strains, as MIC values are reported. Some of these compounds such as 3a,b,d and 4b,d exhibited a good to significant antibacterial activity. Also, all of new synthesized compounds 3,4,6(a-d) were active against Gram-positive S. aureus bacterium. Thus, some of these compounds can emerge as a promising tool for further research work.