Bulky organosilicon compounds based on sulfanyltetrazoles: their synthesis and in vitro antibacterial evaluation

The study introduces different organosilicon derivatives incorporating sulfanyltetrazole ring for biological applications. Initially, the sulfanyltetrazole derivatives and halo-analogues (Br, I) were synthesized. Later, selective reaction of tris(trimethylsilyl)methyllithium (TsiLi) in the presence (?46 and 0 °C) and absence (room temperature) of CS₂ with halo-sulfanyltetrazole derivatives yielded new multifunctional sulfanyltetrazole regioisomers with SH, C = S, ethynylthio and SiMe₃ groups, respectively. All the synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR spectra and elemental analysis data. The compounds were screened for their antibacterial activities against clinically important gram-positive and gram-negative bacteria using the spectrophotometric microdilution method. The preliminary screening indicated that the organosilicon derivatives incorporating SH and C = S (mercapto-silyl-thiones) and silyl-thioalkynes have antibacterial activities, whereas no antibacterial activity was observed on compounds containing (Me₃Si)₃C groups. Of the synthesized compounds, compound 5d showed the best activity against all the tested organisms (3.91–31.25 µg/mL).