FIELD: organic chemistry. SUBSTANCE: invention relates to new 2-bromo- and 2-nitroxy-derivatives of 3,3- -dibromo-4-oxoazethidines of the general formula (I) 
where R1 and R2 mean bromine atom; R2 means the group 
where R4 means hydrogen atom, methyl, benzyl; X means bromine atom or nitroxy-group. 2-Bromo- and 2-nitroxy-derivatives of 3,3-dibromo-4-oxoazethidines are synthesized by reaction of penicillanic acid 1,1-dioxide derivatives of the formula (II) 
where R1 and R2 mean bromine atom and R4 means methyl or benzyl with DBN reagent (1,5-diazabicyclo-[3.4.0] -none-5-ene) and obtained sulfinic acid DBN salt or isolated sulfinic acid is subjected for reaction with thionyl chloride. Thionyl chloride is removed by evaporation, obtained residue is passed through column with silica gel and eluted with methylene chloride or any other solvent or obtained residue is dissolved in tetrahydrofurane or in any other suitable solvent followed by reaction with tetrabutylammonium bromide and isolation of a derivative of the formula (I) where R1 and R2 are bromine atom; R3 means the group 
where R4 means hydrogen atom, methyl or benzyl and X means bromine atom. Isolated compound can be subjected for interaction with silver nitrate in isopropanol followed by isolation of derivatives of 2-nitroxy- -3,3-dibromo-4-oxoazethidine. Synthesized compounds are suitable intermediate substances for synthesis of 1-oxapenems and show antitumor activity. Also, invention proposes a method of growth SUPPRESSION of human uterus cervix tumor cells (HeLa) but without effect on human fibroblasts. Invention relates to also new 2-chloro-derivatives of 3,3-dibromo-4-oxoazethidines of the formula (I) where R1 and R2 mean bromine atom; R3 means the group 
where R4 means hydrogen atom or benzyl and X means chloride atom. EFFECT: improved method of synthesis and enhanced tumor cell growth inhibition. 12 cl, 8 ex
