Yu.V. Shabalina - Ph.D. (Pharm.), Associate Professor,Department of Pharmaceutical Chemistry Courses with Analytical and Toxicological Chemistry, Bashkir State Medical University, Ufa
F.A. Khaliullin - Dr.Sc. (Pharm.), Professor, Head of Department of Pharmaceutical Chemistry Courses with Analytical and Toxicological Chemistry,Bashkir State Medical University, Ufa
R.M. Sharafutdinov - Post-graduate Student, Department of Pharmaceutical Chemistry Courses with Analytical and Toxicological Chemistry,Bashkir State Medical University, Ufa
A.K.Bulgakov - Dr.Sc. (Pharm.), Professor, Department Mikobiologii, Bashkir State Medical University, Ufa

Xanthine derivatives have a variety biological activities. It is known that the heterocyclic ylidenhydrazines exhibit antimicrobial and anti-tuberculosis activity. A new 8-arylylidenhydrazino-substituted 7-(thietanyl-3)-, 7-(1-oxothietanyl-3)- and 7-(1,1-dioxothietanyl-3)-1-n-butyl-3-methylxanthines were obtained with 52-89% yield by condensation of 1-n-butyl-8-hydrazino-3-methylxanthines containing thietane ring with aromatic carbonyl compounds. The structures of the synthesized compounds were confirmed by UV, IR, 1H NMR spectroscopy. The geometrical isomerism of thietane containing 8-arylylidenhydrazino-1-n-butyl-3-methylxanthines was described. It was found the presence of sterically more stable E-isomer. The synthesized compounds exhibit weak antimicrobial activity.