METHOD FOR PREPARING SUBSTITUTED PYRIDO[1,2-A][1,3]-BENZIMIDAZOLES Russian patent published in 2004 - IPC

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention describes a method for preparing substituted pyrido[1,2-a][1,3]-benzimidazoles of the general formula:

wherein (1): R is NO₂; R1 is hydrogen atom (H); (2): R is CF₃; R1 is hydrogen atom (H); (3): R is CN; R1 is hydrogen atom (H); (4): R = R1 is CN that can be used as intermediate compounds in synthesis of fluorescent and biologically active substances. Method involves interaction of 2-nitro-4-R-5R1-halogenbenzene with pyridine and reducing the prepared salt of N-(2-nitro-4-R-5-R1-phenyl)pyridinium wherein interaction of 2-nitro-4-R-5-R1-halogenbenzens with pyridine is carried out at temperature 20⁰C and in the mole ratio 2-nitro-4-R-5-R1-halogenbenzene : pyridine = 1:7 and salt alcoholic solution is subjected for reduction with SnCl₂ x 2 HO solution in 3% HCl in the mole ratio N-(2-nitro-4-R-5-R1-phenyl)-pyridinium salt : SnCl₂ x 2 H₂O = 1:3 at temperature 20⁰C for 0.12 h. Method provides preparing the end product with high yield and purity from available raw at room temperature and for short time interval.

EFFECT: improved preparing method.

2 cl, 2 tbl, 8 ex