[4+2] 陰離子增環反應合成具抗藥性金黃色葡萄球菌活性之線性四環抗生素研究

Studies on Anti-MRSA Linear Tetracyclic Antibiotics via Late-Stage [4+2] Anion Annulation

黃靖凱(Jing-Kai Huang)

指導教授 ： 夏克山 ； 林俊成

國立清華大學/理學院/化學系所/博士(2019年)

摘要

由於抗藥性細菌的快速增長加上新抗生素研發速度減緩，使得全球公共衛生受到嚴重威脅，其中醫院中感染之抗藥性金黃色葡萄球菌因其高致死率，成為惡名昭彰的感染症之一。雖然目前有vancomycin、linezolid、tigecycline和daptomycin可作為臨床治療用，但近年已發現其相應的抗藥性菌株。為了避免在可見的未來出現無藥可用的窘境，開發新種類之抗生素以對抗此多重抗藥性細菌成為急迫的目標。下圖中具gem-二甲基線性四環骨架之抗生素1-9，均具備不同程度抗MRSA之活性成為我們開發新類型抗生素的標的。
本論文的第一章中描述如何以合成後期之陰離子增環反應高度收斂式的完成tetarimycin A (1)、(±)-naphthacemycin A9 (6) 和 (±)-fasamycin A (2) 之全合成，其中利用還原性烯烴偶合反應、Friedel-Crafts醯化反應和Suzuki-Miyaura交叉偶合作為合成中之關鍵步驟，有效率的建立此類線性四環骨架抗生素之合成平台，並合成各種類似物作為初步抗MRSA的SAR研究。
第二章中描述開發vinylogous版本 [4+2] 陰離子增環反應的新方法學，擴展此經典 [4+2] 陰離子增環反應適用至非苯併結構，並同時應用至 (±)-ABX之全合成及benastatin系列骨架之合成。
此外在合成benastatin系列時，意外發現陰離子增環反應所觸發的分子內芳香化Alder-ene反應，由於其位向專一性及相對溫和的反應條件，值得在未來獨立發展成一新的方法學。

關鍵字

抗藥性金黃色葡萄球菌 ； [4+2] 陰離子增環反應 ； 抗生素 ； 全合成 ； 插烯 ； tetarimycin A ； fasamycin A ； benastatin ； naphthacemycin ； ABX ； formicamycin

並列摘要

A rapid increase in multidrug-resistant bacteria and slow development of new antibiotics have posed a great threat to global public health. Notoriously, infection caused by methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most serious problems in hospitals due to its high mortality rate. Though only a few antibiotics are clinically effective against MRSA infections, including vancomycin, linezolid, tigecycline and daptomycin, drug-resistant strains have been observed in recent years. Thus, developing new antibiotics against these multidrug-resistant bacteria is urgently demanded. A class of natural products (compounds 1-9) possess a gem-dimethyl tetracyclic carbon skeleton has been reported to show potent anti-MRSA activities.
The first chapter of this thesis describes a concise total synthesis of tetarimycin A (1), (±)-naphthacemycin A9 (6) and (±)-fasamycin A (2) in a highly convergent manner using an efficient anion annulation in the late stage. With reductive olefin coupling, intramolecular Friedel-Crafts acylation and Suzuki-Miyaura coupling as key operations, these synthetic approaches become economic and general for potential antibiotics possessing a linear tetracyclic carbon skeleton as demonstrated below.
The second chapter of this thesis describes the development of a vinylogous version [4+2] anion annulation for the synthesis of polysubstituted phenols. This novel [4+2] anion annulation enabled the preparation of non-benzophenol in a one-step operation, which allowed us to complete the total synthesis of (±)-ABX and preparation of the benastatin precursors.
In addition, we also discovered a novel aromatized Alder-ene reaction during our efforts toward the total synthesis of benastatin A & B. Due to its stereospecificity and relative mild reaction conditions, the reaction is worth being developed as a new methodology in the future.

並列關鍵字

MRSA ； [4+2] anionic annulation ； antibiotic ； total synthesis ； vinylogous ； tetarimycin A ； fasamycin A ； benastatin ； naphthacemycin ； ABX ； formicamycin

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