FIELD: organic chemistry, heterocyclic compounds. SUBSTANCE: invention relates to novel derivatives of phenyloxazolidinone that have C-C-bond with 4-8-membered heterocyclic rings of the formula (I) 
and their pharmaceutically acceptable salts where X means NR1, S(O)q or O; R1 means H, C1-6-alkyl optionally substituted with one or some CN-groups or halogen atom, -(CH2)h-phenyl, -COR1-1, -COOR1-2, -CO-(CH2)h-COR1-1, -SO2-C1-6-alkyl or -(CO)i-Het; R2 means H, -CO-(CO1-6)-alkyl or fluorine atom; R3 and R4 are similar or different and mean H or halogen atom; R5 means C1-6-alkyl and C3-6-cycloalkyl optionally substituted with one or some halogen atoms; g = 0, 1 or 2; h = 1 or 2; i = 0 or 1; m = 0, 1, 2, 3; n = 0, 1, 2, 3 under condition that m and n taken in common = 1, 2, 3, 4 or 5. EFFECT: improved synthesis of novel derivatives of phenyloxazolidinone with C-C-bond with 4-8-membered heterocyclic rings. 12 cl, 2 tbl
