Technology Research For Synthesis Of Pyrazolopyridine Compounds

Pyrazolopyridine compounds widely exist in natural products and drug molecules with biological activity,is an important pharmaceutical intermediate,its synthesis has attracted attention.Pyrazolopyridine compounds have herbicidal and fungicidal activity of certain insecticides,so the synthesis of pyrazole and pyridine compounds,has very high application value.This paper mainly focuses on the following aspects:The synthesis and biological activities of pyrazole[3,4-b]pyridine pyridine derivatives are mainly introduced.2-chloro-3-cyanopyridine was synthesized from3-pyridine-formamide,focusing on the synthesis of pyrazolpyridines on the basis of2-chloro-3-cyanopyridine.The target compounds were synthesized by condensation,diazotization and deamination with DMF,ethanol and n-butanol as solvents.The optimum ratio of 3-pyridine-formamide to hydrogen peroxide was 1:1.8（mol/mol）and the mass ratio of N-oxo-3-pyridylformamide to POCl₃:PCl₅ was 1.0:3.0:2.6.The n-butanol was selected as the solvent to optimize the synthesis process.In the process of denitrification,excessive H₂SO₄ was used and NaNO₂ was added.Then we remove amino from NaH₂PO₃ to get the product.The yield of the target product was increased to 88.8%,and the purity of the product was increased to 98.9%.The reaction route was to maximize the use of low cost raw materials,easy control of reaction conditions,and high selectivity,less by-products,product postprocessing is relatively simple to obtain the ideal products,suitable for large-scale industrialized production.