Synthesis and Biological Evaluation of Thiosemicarbazide Derivatives Endowed with High Activity toward Mycobacterium Bovis.

Thiosemicarbazides are potent intermediates for the synthesis of pharmaceutical and bioactive materials and thus, they are used extensively in the field of medicinal chemistry. The imine bond (-N=CH-) in this compounds are useful in organic synthesis, in particular for the preparation of heterocycles and non-natural ß-aminoacids. In this paper the synthesis of some new thiosemicarbazide derivatives by condensation reaction of various aldehydes or ketones with 4-phenylthiosemicarbazide or thiosemicarbazide is reported. This synthesis method has the advantages of high yields and good bioactivity. The structures of these compounds were confirmed by IR, mass, 1H NMR, 13C NMR, and single-crystal X-ray diffraction studies. All of these compounds were tested for their in-vitro anti-mycobacterial activity. The influence of the functional group and position of substituent on anti-bacterial activity of compounds is investigated too. The preliminary results indicated that all of the tested compounds showed good activity against the test organism. The compounds 11 and 30 showed the highest anti-tubercular activity (0.39 µg/mL). This synthesis method has the advantages of high yields and good bioactivity.

(E)-1-(2-Nitro-benzyl-idene)-4-phenyl-thio-semicarbazide.

In the title mol-ecule, C(14)H(12)N(4)O(2)S, the conformation about the imine bond is trans. The dihedral angle between the two rings is 88.22 (11)°. An intra-molecular N-H⋯N contact occurs. The crystal structure features N-H⋯S and C-H⋯O hydrogen bonds.