掩飾鄰苯醌與單態氧之化學反應探討與其在有機合成之應用

Photooxygenation of Masked ο-Benzoquinones: Reaction Study and Its Applications in Organic Synthesis

高子喬(Tzu-Chiao Kao)

指導教授 ： 廖俊臣

國立清華大學/理學院/化學系/博士(2009年)

https://doi.org/10.6843/NTHU.2009.00321

摘要

本論文主要討論掩飾鄰苯醌 100 與單態氧(1O2)所進行相關化學反應。單態氧與掩飾鄰苯醌上其中一個電子豐盈性較高的雙鍵作用，依照不同的淬滅方式而形成二種環戊烯酮產物 101 和 102；另外，作為雙烯試劑的掩飾鄰苯醌可與作為親雙烯試劑單態氧進行 [4+2] 環化加成反應而形成 endoperoxide 110。以上兩種反應途徑取決於溶劑效應、取代基效應以及掩飾鄰苯醌 100 之濃度。歸納實驗結果後發現，溶液所提供的分子間氫鍵(例如甲醇)可能有利於形成環戊烯酮產物，反之於無分子間氫鍵的氯仿下以及較高濃度之掩飾鄰苯醌的反應條件較容易生成 endoperoxide；電子豐盈程度較高的掩飾鄰苯醌與單態氧所進行的反應較傾向形成 endoperoxide，例如 R1 或 R3 為甲烷基或甲氧基以及 R2 為甲烷基；反之若 R1 或 R2 為氫原子且 R3 為烷基之電子豐盈程度較相對較低之掩飾鄰苯醌較容易與單態氧反應形成環戊烯酮產物。由於掩飾鄰苯醌與單態氧所形成之環戊烯酮產物相似於一系列天然物衍生物，我們於是應用環戊烯酮產物之合成策略來進行天然物 (±)-Untenone A 的合成，以證明此種方法的有效性。另外，化合物 101 之水解去羧酸反應有助於繼續進行合成類環戊烯酮天然物；化合物 102 藉由加熱或照光所進行之週環反應而得到化合物 136 則提供另一個有效合成 2-pyrone 之策略。

關鍵字

單態氧 ； 光氧化反應 ； 掩飾鄰苯醌

並列摘要

The thesis mainly focuses on the photooxygenation of masked o-benzoquinones 100 (MOBs) and its related applications in organic synthesis. Two reaction pathways are discovered. The first one is that singlet oxygen (1O2) reacts on one of electron-rich double bond of MOBs to generate two types of oxidized cyclopentenones 101 and 102 depending on two quenching methods. Its intermediates and the reaction mechanism have also been discussed as well. The second pathway is that endoperoxides 110 were formed through the reaction of 1O2 and electron-rich MOBs. Based on the experimental results, the reaction tendency is affected by the solvent effect, substituent effect and concentration effect (of MOBs). The internal hydrogen bonding provided by the solvents (such as methanol) promotes the formation of cyclopentenones 101 and 102. On the contrary, solvents having no hydrogen bonding ability like chloroform and a high concentration of MOBs make the generation of endoperoxides 110 dominate, especially in the cases of MOBs with R1, R2 = alkyl or OMe and R3 = alkyl groups. Electron-deficient MOBs with R1, R2 = H, R3 = alkyl groups tend to yield cyclopentenones 101 and 102 which have a lot of potential in organic synthesis. (±)-Untenone A was synthesized to demonstrate the efficiency of this methodology. Moreover, hydrolysis followed by decarboxylation of cyclopentenones 101 are of benefit to synthesis of cyclopenteneone-like natural products; the pericyclic reaction of cyclopentenones 102 caused by heat or irradiation 136 also provide an alternative methodology of synthesis of 2-pyrones derivates.

並列關鍵字

singlet oxygen ； photooxygenation ； Masked o-Benzoquinones

參考文獻

1. Lewis, G. N. Chem. Rev. 1924, 1, 231-248.

S. Rev. Mod. Phys. 1932, 4, 54-56.

3. Greer, A. Acc. Chem. Res. 2006, 39, 797-804.

5. Gollnick, K.; Schenck, G. O. Pure Appl. Chem. 1964, 9, 507-525.

6. Schenck, G. O. Ann. N. Y. Acad. Sci. 1970, 171, 67-78.