Optimizing Novel Ouinazoline Inhibitors For Hepatitis Virus And Diversity Oriented Synthesis Of Azachromone

Topic for this thesis is "Optimizing Novel Quinazolines Inhibitors for Hepatitis Virus and Diversity Oriented Synthesis of Azachromone." It's separated into two parts,first part is research and development of quinazoline type HCV inhibitors and the optimization of its synthetic route,while the second part is optimization of selective synthesis of diverse Azachromones.Chronic hepatitis C virus(HCV)infection poses a major threat to human health around the world.There are currently a few inhibitors approved for use on the market while most are undergoing clinical trials.HCV is a positive single stranded RNA virus belonging to the Flavivirus family.In depth research have been made toHCV viral cycle in which a few targets were identified for inhibition.Current HCV DAAs(Direct-Acting Antivirals)are separated into three categories:NS3/4A,NS5A,and NS5B.Althought there are currently many HCV inhibitors out on the market,the virus have a strong ability to adapt and become resistant to drugs.It's necessary to develop novel inhibitor with new mechanism of action to allow for greater ability to fight against this troublesome virus.Through continued effort to combat HCV we have discovered that a novel quinazoline compound P-2 which has a simpler structure and is easier to synthesize and modify.Prior research indicated that the current quinazoline derivative to have ability to inhibit HCV replicons with EC50 up to 0.47pM.P-2 has shown to have good HCV inhibition,however upon further investigation it was found to be cytotoxic to cells.We suspect that the cytotoxicity was due to the unsubstituted amines at the 2 and 4 position of P-2.Modification of the 2 and 4 position was proposed.Building upon prior research into HCV quinazoline inhibitors done by Chao B.et al,we plan to modify and further investigate the SAR and attempt to identify compounds with better efficiency,lower toxicity,and superior ADMET properties than the reported compound.We synthesized 23 compounds to determine the SAR of the 2 and 4 position of the 2,4-dichloro-5-(3-methoxyphenoxy)quinazoline(S-6)intermediate.During the synthetic process of S-6,many changes were made to the synthetic route.The first major optimization was the synthesis of S-3 intermediate to avoid byproduct S-3b.Optimal reaction conditions was found to be 15 hours and at 40? which prevented the overation.Second major optimization was for the synthesis of S-5.Use of CDI is safer,convenient,and easier to handle than triphosgene.Lowering the temperature at the start of the reaction avoided formation of byproduct S-5c.Synthesis of S-5 showed that reactions using CDI afforded consistantly higher yield than triphosgene.Third major optimization was performed for the synthesis of S-6 intermediate.S-6 is generated through reaction with POCl3 allowing for the chlorination of the carbonyl groups on S-5.In this reaction a byproduct was commonly seen which may invovle side raction on Methoxyphenyl ring.We found that the optimal reaction time was 1 to 2 hours.With successful synthesis of key intermediate S-6,2,4-disubstituted quinazoline analogues can be readily synthesized.During the optimization of synthesizing S-6 intermediate,careful evaluation of the quinazoline backbone was proposed and it was found that hydrogen replacement on the 4 position had good effect in inhibiting HCV virus with an inhibition of 90%at 1?M(Shang Jia et.al).However,further investigation revealed that this compound was cytotoxic.In an attempt to address this problem,a series of analogues were synthesized with the hydrogen fixed at the 4 position and changes on the substituent of the 5 position.A series of 8 compounds were synthesized and evaluated.It was found that only one compound S-22 exhibited HCV inhibition.The rest of the compounds lacked HCV inhibition.However,indepth study on S-22 has revealed that it also has high level of cytotoxicity,therefore study on this series have been discontinued.To deal with the toxicity problem that may be caused by the unsubstituted amine,further modification at both the 2 and 4 position of the quinazoline with diverse amines including primary,secondary,alkyl,and aromatic amine were carried out.A total of 13 compounds were synthesized and evaluated.Among them there are 2 compounds that display good efficacy and safety.The first compound(S-30)has pyrrolidines substituted at both the 2 and 4 position.It showed remarkable IC50 and CC50 values of 0.56?M and 15.37pM respectively.This compound has demonstrated efficacy that is comparable to P-2.It shows that pyrrolidine group might play an important role in HCV inhibiton.The second compound(S-33)has pyrrolidine substituted at the 4 position and a p-tert-butylphenylamine substituted at the 2 position.It has revealed an IC50 of only 1.3pM,however,the CC50 had a suprising value of 20.03?M.Compounds S-30 and S-33 have helped establish a foundation for further modification of quinazoline type HCV inhibitors.The second part of my research is the development of a one-pot three component synthesis of azachromones through cascade Carbonylation-Sonogashira-Cyclization reaction.Azachromone is a chromone like structures that appears in a variety of natural and synthetic bioactive compounds.6-aza chromones have shown many biological activities such as anti-allergic,anti-microbial,and p-lactamase inhibitors.Currently there are only a few approaches for preparation of 6-aza chromones,which is mainly done through condensation of 3-acetyl-quinolinone with di-ethyl oxalate(or benzaldehyde or vilsmeier reagent),which limits the diversification and development of these compounds.Our goal is to develop a new method for generating diversified natural-product-like scaffolds of azachromone to create a database of compounds that can be used to test antiviral activity of azachromones.Synthesis of azachromone 3-iodo-4-hydroxylpyridine via cascade CO insertion,Sonogashira coupling,and cyclization.Through carefully controlling the reaction conditions,both T series and T2 series of azachromone can be selectively synthesized in good to moderate yield.In conclusion,exploration of 2,4 disubstituted quinazoline,a total of 23 compounds were synthesized and evaluated on their efficacy and toxicity.Investigation into quinazoline type HCV inhibitors have shown that some analogs bearing a hydrogen at the 4 position and an unsubstituted amine at the 2 position has good HCV inhibition,however they are found to be cytotoxic.Modification was done to the 5 position,but was unsuccessful.This prompted further investigation and exploration of the SAR at the 2 and 4 position.From this we were able to discover two compounds S-30 and S-33 that have efficacy comparable to P-2,with improvement on the toxicity.In the second part I have applied and optimized a Sonogashira coupling cascade reaction for the selective synthesis of azachromone compounds.