Synthetic Routes Of Cell Cycle-dependent Kinase Inhibitor Palbociclib And Design,Synthesis And Bioactivity Study Of Its Derivatives

Breast cancer(BC)is the first major malignant tumor that threatens the health of women around the world.The annual number of new breast cancer and deaths in China accounted for 12.2%and 9.6%of the world’s total.Although the situation is very serious,its mortality rate decreased year by year.In addition to the improvement of early diagnosis technology,surgical treatment and radiotherapy and chemotherapy,the treatment of new targeted drugs also significantly prolongs the survival of breast cancer patients.In recent years,with cyclin-dependent kinase 4(CDK4)being proved to be an indispensable factor in the development of breast cancer,the CDK4/6 as the target of anti-breast cancer drugs has gradually showing outcrops in the clinical treatment.CDK4/6 can be directly involved in the regulation of cell cycle by phosphorylation of retinoblastoma protein(Rb protein),while CDK4/6 inhibitor can effectively prevent the phosphorylation of Rb protein and reduce the release of transcription factor E2F,so that the cells are arrested in the G1 phase and the cell proliferation is inhibited.Palabociclib is the world’s first approved CDK4/6 inhibitor,which was developed by Pfizer,and it combined with Letrozole or Fulvestrant as the first or second-line treatment of advanced or metastatic breast cancer.Meanwhile,Palbociclib has also been in different stages of clinical trials for the treatment of clonal cell lymphoma,multiple myeloma,leukemia,colorectal cancer,hepatocellular carcinoma,pancreatic ductal adenocarcinoma,germ cell tumor,urothelial carcinoma,endometrial tumor,prostate cancer,non-small cell lung cancer,head and neck squamous cell carcinoma,melanoma,and liposarcoma.In view of the efficacy of Palbociclib in clinical trials,the synthetic routes of Palbociclib were designed and optimized in order to make it more suitable for industrial production.Meanwhile,eight novel Palbociclib organic salts were prepared,and their solubility and in vitro stability were evaluated.Moreover,15 novel Palbociclib derivatives were designed,synthesized and evaluated using Palbocilib as the positive control.The structures of Palbociclib organic salts and derivatives were confirmed by MS,1H-NMR,13C-NMR.In the synthetic route one,the order of addition of the Horner-Wadsworth-Emmons reaction was changed to reduce the reaction time from 60 hours to 12 hours;and in the synthetic rote two,the addition of triphenylphosphine to the palladium acetate-catalyzed Heck reaction not only improved the yield of the reaction but also eliminated the need for column chromatography.Among the Palbociclib organic salts,L-malate(compound 34)and L-pyroglutamic acid salt(compound 31)have good water solubility,and all organic salts have good stability in artificial gastric juice and artificial intestinal fluid.It was found that our Palbociclib derivatives showed inhibitory activities against CDK4/6,and several of theme were superior to the positive control Palbociclib in antiproliferation against breast cancer cells(MCF-7,MDA-MB-231/468),leukemia cells(KG-1,K562),colon cancer cells(HT-29)and non-small cell lung cancer cells(A549).Overall,the target compounds 41d and 41 o had the best antiproliferative activity and KG-1 was the most sensitive cell line to the target compounds.Therefore,the design and synthesis of novel Palbociclib derivatives could lead to the discovery of more potent and selective CDK inhibitors(CKI)and anti-breast cancer drugs.