摘要 Orotidine 5'-monophosphate decarboxylase (ODCase) 催化的orotidine 5'-monophosphate (OMP) 去羧基反應是生物體內合成pyrimidine類核酸化合物重要步驟。針對ODCase酵素及其受質的研究已發現,應用在抗病毒、抗瘧疾及抗癌等疾病上相當有發展的潛力。為了解ODCase催化機制,利用可能成為ODCase受質或抑制劑的化合物與該酵素反應後,觀察結果推測;因此,考慮在uridine鹼基上C6位置作官能基修飾及置換的可能性,設計並準備合成一系列的OMP類似物,其中包含有C-nucleoside及N-nucleoside的類似物。 OMP C-nucleoside的類似物包括有pseudouridine及其衍生物。利用文獻中的合成方法,可由5-bromouracil製備醣具保護的pseudouridine。我們亦嘗試利用合成pseudouridine的方法來製備6-methylpseudouridine,但因進行C-ribosylation時反應的位置是在鹼基環外C6的甲基上,而非預期中的環上C5位置,結果並沒有成功。 設計合成OMP類似物的N-nucleoside方面包含,在鹼基C6位置上的tetrazoles, amide oximes, imidates 及親核性取代基的置換;反應起始物6-cyanouridine的衍生物由文獻合成方法製備而成;6-(tetrazol-5-yl)uridine,從uridine開始製備,經形成6-cyanouridine後與sodium azide進行環化加成反應,經六個合成步驟後可以得到,總產率約29 %。Amide oxime官能基衍生物方面,經由6-cyanouridine的中間產物進行合成,但因醣上保護基移除時所產生的不穩定性,而無法得到。以親核性取代基對6-cyanouridine衍生物上cyano官能基直接進行取代反應也無法順利得到產物。在本篇論文中,我們已成功合成出6-(tetrazol-5-yl)uridine;此化合物是OMP的bioisostere,可用來作為探測ODCase反應機制的受質或抑制劑。
Abstract Orotidine 5'-monophosphate decarboxylase (ODCase) catalyzes the decarboxylation of orotidine 5'-monophosphate (OMP), an essential step in pyrimidine nucleic acid biosynthesis. It has been identified as a potential target for antiviral, antiparasitic and antitumor therapies. In order to develop effective mechanistic probes to disclose the possible mechanisms for ODCase, a series of OMP analogs modified at the C6- position of uridine were designed and prepared to synthesize, including N-nucleoside and C-nucleoside analogs. The C-nucleoside analogs of OMP / UMP included pseudouridine and its derivatives. The sugar protected pseudouridine was prepared based on literature procedures from 5-bromouracil. However, attempts to synthesize 6-methylpseudouridine based on the same approach were unsuccessful. The C-ribosylation occurred at the exocyclic methyl group, instead of the expected pyrimidine ring carbon. The N-nucleoside analogs of OMP designed based on bioisosteric replacement of carboxylate including derivatives with tetrazoles, amide oximes, imidates and nucleophilic substituents on the C6 position of uridine. 6-Cyanouridine derivatives were prepared from uridine by literature procedures as starting materials. 6-(Tetrazol-5-yl)uridine was prepared from uridine through the cycloaddition of 6-cyanouridine intermediate with sodium azide in 6 steps with an over yield of 29 %. Amide oxime functional group was also obtain from the reaction of 6-cyanouridine with hydroxylamine. However, the removal of sugar protecting groups were unsuccessful. Direct substitutions of the cyano group of 6-cyanouridine derivatives with nucleophiles were unsuccessful. In this thesis, we have successfully synthesized 6-(tetrazol-5-yl)uridine. It is a bioisostere of OMP and potential mechanistic probe for ODCase.