由乙醯葡萄醣胺合成克流感及零流感

Abstract

流行性感冒長期對人類健康傷害，歷史上幾次大流行更造成數千萬人的死亡，為了抵抗流感病毒的侵襲，由Hoffmann La-Roche及GlaxoSmithKline藥廠分別開發出針對唾液酸水解酶(Neuraminidase)的抑制劑—克流感(Tamiflu)及瑞樂沙(Relenza)，讓人類免於流感病毒傷害。然而近幾年許多突變型流感病毒已經有出現對於克流感抗藥性的情況，雖然目前瑞樂沙仍能有效殺死流感病毒，但新型的流感藥物開發刻不容緩，因為誰也無法預料下一次人類流感大流行何時到來，又會有多少生命喪失。 2007年我們實驗室以木醣(D-xylose)為起始物，開發出零流感(Tamiphosphor)化合物，因為磷酸基可以與流感病毒唾液酸水解酶活性中心的三個精胺酸Arg形成較強的靜電作用力(electrostatic interaction)，所以也具有更強的病毒抑制能力，對於克流感抗藥性病毒株能有效抑制，動物實驗也證實服用零流感可增加感染流感病毒的小鼠之存活率。同步進行中，實驗室2008年開發另一個以3-溴-1,2-二羥基環己二烯為起始物的零流感合成途徑，步驟更短產率更高。可惜這兩個合成途徑投入藥廠大量生產時，因為起始物昂貴或者步驟過多等問題，造成生產成本過高，因此希望能開發第三種合成路徑。我們選用便宜的乙醯葡萄醣胺(N-acetyl-glucosamine)為起始物，可以成功合成出文獻中克流感的關鍵中間產物azide 32，經由相似步驟也可得到另一中間產物azide 225，經由phosphoramidite中間產物順利建構3-戊烷氧基，預期可順利得到零流感。

Influenza has endangered human for a long time. Anti-influenza drugs are regarded as the last line of defense against influenza pandemics. Hoffmann La-Roche and GlaxoSmithKline companies have developed two neuraminidase inhibitors – Tamiflu and Relenza against influenza virus. Recently, the emergence of drug-resistant strains of avian influenza has endangered human. The development of new anti-influenza drug is important work to defend the threat of pandemic flu. Tamiphosphor, a phosphonate congener of oseltamivir carboxylate, contains a phosphonate group to exhibit strong electrostatic interactions to bind with the three arginine residues (Arg118, Arg292 and Arg371) in neuraminidase. In our lab, two methods have been explored to synthesize Tamiphosphor from D-xylose and cis-3-bromo-3-cyclohexadiene-1,2-diol, respectively. In order to meet the need of drug development, we further improve the Tamiphosphor synthesis in large scale using D-xylose and D-N-acetylglucosamine, respectively, as the starting materials. We used D-N-acetylglucosamine to prepare the key intermediate azide 32, for a formal synthesis of oseltamivir. Azide 225 and mesylate 230 were also prepared as an approach to the synthesis of Tamiphosphor.