METHOD OF PRODUCING DIHALOGEN DERIVATIVE OF 1,2,3,4-TETRAHYDROPYRIDO- OR PYRIDO[1,2-]BENZIMIDAZOLE-6,9-DIONE Russian patent published in 2024 - IPC C07D471/04 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a dihalogen derivative of 1,2,3,4-tetrahydropyrido- or pyrido[1,2-a]benzimidazole-6,9-dione, which consists in reduction of 6-nitro-7-R1-8-R2-pyrido[1,2-a]benzimidazole obtained during intramolecular reductive cyclisation of N-(2-nitro-4-R1-phenyl)pyridinium chloride SnCl₂·2H₂O to obtain 7-R1-pyrido[1,2-a]benzimidazole, halogenation of 7-R1-pyrido[1,2-a]benzimidazole with N-bromo- or N-chlorosuccinimide to obtain 7-R1-8-R2-pyrido[1,2-a]benzimidazole and nitration of 7-R1-8-R2-pyrido[1,2-a]benzimidazole with potassium nitrate in H₂SO₄, is carried out under conditions of heterogeneous catalysis in presence of 1% Pd/C catalyst for synthesis of 7-R1-8-R2-pyrido[1,2-a]benzimidazol-6-amine or 10% Pd/C for synthesis of 7-R1-8-R2-1,2,3,4-tetrahydropyrido[1,2-a]benzimidazol-6-amine, subsequent oxidation of the obtained amino derivative is carried out with potassium nitrate in H₂SO₄, wherein R1 is Cl, R2 is Br or Cl.

EFFECT: reduction of total number of steps for synthesis of dihalogen derivatives of 1,2,3,4-tetrahydropyrido- and pyrido[1,2- a]benzimidazole-6,9-dione.

1 cl, 13 ex