Design,Synthesis And Preliminary Activity Evaluation Of A New Type BTK Inhibitor

In many B-cell malignant tumors,B-cell receptor（BCR）signaling pathway plays a key role in the proliferation and survival of cancer cells.BTK is a key component of B cell receptor signaling pathway and an important regulator of B cell malignant tumor cell proliferation and survival.Therefore,BCR pathway components will be an attractive target for cancer treatment,and tyrosine kinase（BTK）,a non-receptor protein kinase of TEC family,is an important target.Ibrutinib,a listed BTK inhibitor,is a small molecule drug that can irreversibly covalently bind to BTK and has been proved to be a drug for the treatment of various B-cell malignant tumors.However,it has miss-target activity to other kinases,which is related to clinical side effects,and there have been reports of ibrutinib resistance,which limits its clinical application.The development of highly selective second-generation BTK inhibitors has become a hotspot in new drug research.Although great progress has been made in the development of more selective and less side effects second-generation BTK inhibitors,we still need to continue to strive for more efficient BTK inhibitors.Based on the analysis of BTK inhibitors,we found that most of the BTK inhibitors are composed of four parts: the first part is the hinge region binding fragment,which is the core region of the inhibitors,forming receptor and hydrogen bonding with ATP binding sites in kinase;the second part is aromatic structure,which occupies the hydrophobic pocket of BTK;the third part is the N-containing fatty ring,which improves the binding.Part IV is Michael adduct receptor,which covalently bonds with cysteine in the ATP-binding pocket of kinase to enhance the affinity of the compound and prolong the action time of the drug.Hinge region binding fragment is the mother nucleus of BTK inhibitors,which is crucial for the structural novelty and selectivity of BTK inhibitors.At present,aminopyrimidine or pyrazine fragments are mostly used in the hinged region of BTK inhibitors,so it is urgent to develop novel hinged region binding fragments.A novel hinged binding fragment 1-amino-1H-imidazole-5-formamide was obtained by skeleton transition of acalabrutinib（ACP-196）,a second-generation BTK inhibitor,in which the amino hydrogen of the imidazole ring and the carbonyl oxygen energy of the ortho-formamide formed intramolecular hydrogen bonds to simulate the structure of pyrazine in the pronucleus.In this paper,48 target compounds were designed and synthesized using 1-amino-1H-imidazole-5-formamide as a novel hinged binding fragment.48 compounds were synthesized and their structures were confirmed by 1H-NMR and MS.Literature review confirms that all the compounds synthesized are innovative compounds,which have never been reported in the literature.At the same time,the activity test showed that the half inhibitory concentration(IC₅₀)of several compounds reached the nanomolar level and was lower than that of ACP-196,a positive control drug.The IC₅₀ of compound 28 and compound 36 reached 12.5nM and 13.5nM respectively through screening of their preliminary activities,which indicated that the novel kinase hinge binding fragments we designed were successful and laid a foundation for further development of BTK inhibitors.