The Design, Synthesis And SAR Studies Of Two Types Of FXR Antagonists And The Exploring Of The Reactivity Of Aryne In Several Reactions

This dissertation mainly focuses on two parts. The first is the medicinal chemistry research, two HTS （high-throughput screening） hits of FXR antagonists were selected for SAR studies and nearly150derivatives were designed, synthesized and evaluated with biological activity. The second part is the methodological research, several heterocyclic backbones were constructed via multicomponent reaction or cascade reaction involving arynes and nitrogen containing nucleophilic compounds.FXR （Farnesoid X receptor） is a ligand-acitivated transcriptional factor which is a number of the nuclear receptor superfamilay. FXR is involved in the regulation of bile acid and cholesterol homeostasis, lipoprotein and glucose metabolism as a bile acid sensor. FXR has been thought to be involved in the formation of metabolic syndrome which including obesity, dyslipidemia, diabetes and so on. FXR antagonists lower the contents of triglyceride and cholesterol and increase the high-density lipoprotein （HDL） in HepG2cells and in high-fat diet C57BL/6mice. Despite the promising perspective of FXR antagonists in the regulation of numerous biological processes and related diseases development, the FXR antagonists reported in the literature are limited in low potency and difficulty in obtaining. Two moderate FXR antagonists AA7and DCW229obtained via HTS were selected for further modification and the results are shown as follows.To exploring the structure-activity relationship of AA7,33analogs were designed, synthesized and evaluated with FXR antagonist activities. The most potent derivative AA7-2was almost30-fold more potent than the hit AA7and more than80-fold stronger than the positive control FXR antagonist GS. To our great disappointment, further evaluation of AA7-2in hepatic cell shown no positive effect on inhibition of FXR.As for another FXR antagonist DCW229, more than100analogs were designed, synthesized and test with its FXR antagonist activities. The analog FXR-21was found to inhibit the CDCA induced coactivator recruitment of FXR and its downstream target genes in hepatic cells with moderate potency. Besides that, FXR-21also exhibited a high selectivity over other nuclear receptors. Further evaluation in high-fat diet mice found it could efficiently reduced the total level of cholesterol, which implied its promising prospective in the treatment of metabolism disorders. To further improve its potency, several rounds of design, synthesis and evaluation were carried out and more potent FXR antagonist FXR-99was discovered with IC₅₀=0.3μM. FXR-99also showed potent inhibition of FXR and its downstream target genes and high selectivity over other nuclear receptors in hepatic cells. However, FXR-99showed no positive effect on the regulation of total cholesterol in high-fat diet mice. Considering the high Log P value and low water solubility of FXR-99, we supposed the failure in the high-fat diet mice might be attributed to its low solubility and poor physicochemical property.After the discovery of the potent FXR antagonist FXR-99, our cooperators successfully cultivated the cocrystal complex of FXR-99with FXR and elucidated its structure, which is the first cocrystal complex of FXR with FXR antagonist. Based on the binding pocket of the complex crystal, several new FXR-99analogs with improved physicochemical property were designed, synthesized and evaluated with its FXR antagonist activity. However, these analogs turned out to show reduced antagonist activity.During the SAR studies of DCW229, we serepiditiouly found that aromatic aldehydes could react with acylidenemalononitriles via Stetter-cyclization process to form2-amino furan derivatives. The reaction conditions and substrates scope were investigated and found that aromatic aldehydes with electron-deficient substitution afford the desired product in good yields while electron-donating substituted aromatic aldehydes give moderate yields.The second part of this dissertation explored the reactivity of aryne in the multicomponent and cascade reaction with nitrogen containing nucleophilic compounds. Arynes are very reactive intermediates, which had been studied more than60years. However, aryne had not been widely used in constructing biological moleculars or natural products which mainly due to harsh conditions required to generate arynes. Most recently, the using of o-silyl aryl triflates as aryne precursors reported by Kobayashi has attracted great attention for the stability of these compounds and mild condition required to generate arynes.In segement2chapter2, we described the multicomponent reaction involving arynes, N-heteroaromatic compounds and aldehydes or ketones to give benzo-annulated1,3-oxazine derivatives in moderate to high yields. The reaction conditions and substrates scope were investigated thoroughly and a possible mechanism was also proposed to illustrate the regioselectivity and distereoselectivity when3-OMe benzyne was used in this reaction. It worth to be mentioned that aldehydes or ketones with a hydrogen reacted smoothly in our conditions to generate the desired products while Cheng et. al. had reported in their conditions to give1,2-disubstituted N-aromatic compounds.During the optimization of the multicomponent reaction, we found dichloromethane could efficiently react with arynes and N-hetaroaromatic compounds to form the 1,2-disubstituted pyridine, quinoline or isoquinoline derivatives. Trichloromethane and dibromomethane could also participate in this reaction to afford the corresponding products.Segement2chapter3investigated the cascade reaction of aza-Morita-Baylis-Hillman adducts with arynes to generate the3-methylene-2,3-dihydroquinolin-4（1H）-one derivatives with TMAF as the fluride sources. Initial efforts were focused on the direct reaction of Morita-Baylis-Hillman adducts with aryne. However, no desried product was obtained which probably due to the low nucleophilic of hydroxyl group with aryne. n-Butylamine derivate178a reacted with benzyne smoothly to afford the desired product in low yield, with the N-Ph derivative as main byproduct. The low yield of desried product might be attributed to the stable configuration of the intermediate in which Phenyl anion is prone to attack proton rather than carbonyl group. To overcome this problem, a-Phenyl derivative180a was used in this reaction and the yield of the desried product was improved to moderate.