Design, Synthesis And Antitumor Activity Of 5-alkoxy Substituted Pyrazolo[1,5-a]pyridine Compound

Cancer is one of the major diseases that threaten human life and health.The primary clinical treatment for cancer is surgery in combination with chemotherapy.Currently,there are many anti-tumor drugs available for clinical treatment,but there are widespread problems such as drug resistance and toxic side effects,so there is an urgent need to develop new anti-cancer drugs for clinical use.In the past few decades,perovskites have emerged as an important class of nitrogen-containing heterocyclic compounds due to their specific physiological activity and structural similarity to indoles and azindoles.C-terminal tyrosine kinase（CSK）is a potential anti-tumor target.Pyrazole[1,5-a]pyridine compounds have been reported to inhibit CSK.Studies have shown that many compounds containing this structure have made good progress in anti-tumor,anti-virus,anti-inflammatory,anti-tuberculosis and anti-bacterial applications.Compound 11 has been reported as a potential CSK inhibitor with good antitumor activity,but its metabolism is not stable in animals and it is difficult to prepare as a drug.In this study,compound 11 was used as the lead compound.On the basis of retaining key groups,the side chain was optimized,and the alkoxy base segments were introduced into the pyrazole[1,5-a]pyridine ring using the splicing principle to improve the antitumor activity and metabolic activity of this compound.Through reverse synthesis analysis,38 novel 5-alkoxy-substituted pyrazolo[1,5-a]pyridine compounds were designed and synthesized from 4-mycoprotein or 4-nitropyridine-N-oxide by cyclization,hydrolysis,reduction,substitution,and condensation.The structure of the target compound was characterized and confirmed by ¹H NMR,¹³C NMR and HRMS.Using MTT assay,human breast cancer cells（MCF-7）,human colon cancer cells（HCT-116）and human lung cancer cells（A549）were used as test cell lines,and paclitaxel and 5-fluorouracil（5-FU）were used as positive controls.The results showed that most of the target compounds had good inhibitory activity against the three cells.Compound C7 showed the best anti-proliferation effect on MCF-7 and HCT-116 cells,with IC₅₀ values of 8.28μM and 31.18μM,respectively.Preliminary structure-activity relations indicate that the substituents of the 5-alkoxy group are better active in the long chain than in the short chain.The activity of benzodiazepines without substituents is better than that with substituents.The N-methylpiperazine substitution was found to be more beneficial in enhancing the inhibition rate of the target compound.This study can serve as a foundation for the study of CSK inhibitors.