研究生: |
許仁祥 |
---|---|
論文名稱: |
金鋼烷衍生物與格里納試劑反應之立體化學探討 |
指導教授: | 姚清發 |
學位類別: |
碩士 Master |
系所名稱: |
化學系 Department of Chemistry |
畢業學年度: | 85 |
語文別: | 中文 |
論文頁數: | 112 |
中文關鍵詞: | 格里納試劑 、金鋼烷衍生物 、立體障礙效應 |
英文關鍵詞: | RMgX |
論文種類: | 學術論文 |
相關次數: | 點閱:119 下載:0 |
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電子效應:
當金鋼烷衍生物的五號碳上的取代基為拉電子基時,格里鈉試劑(RMgX)大部分由順式(zu face)方向攻打金鋼烷衍生物的2號碳,進而得到E form為主要產物,當金鋼烷衍生物的5號碳上取代基為推電子基時,得到Z form為主要產物,原因在於反應過程中,在過渡狀態時有超共軛(hyperconjugation)現象出現,所以可以穩定過渡狀態(transition-State)時的能量,由此,我們可以發現明顯的電子效應。
立體障礙效應:
在立體障礙方面,當格里鈉(MgX)的R基為甲基(CH3-)、汴基(PhCH2-)時,得到加成產物,當R基為乙基(CH3CH2-)、異丙基時((CH3)2CH-)時,得到加成及還原產物,當R基為新丁基((CH3)3c-),只有還原產物,這是由於金鋼烷上的4號、8號、9號、10號碳上氫與格里鈉試劑(RMgX)存在立體障礙效應。
2,5-Disubstituted adamantane have been proved to be useful in reasearch aimed at understanding the electronic factors in the face selection. The advantage of this compound is that the presence of two virtually isosteric. The absence of conformation is not certified and the possible of forming just has two geometrically isomeric products.
We have used different kinds of 5-substituted groups (X=Br, Ph, F, Si(CH3)3) to prove electron-effect can affect the ratio of the E and Z form product. When X is electron-withdrawing group, the nucleophiles of the Grignard reagents will attack preferably at zu face. If X is electrondonoring group, nucleophiles will attack preferably at en face to generate E form product All these results can be interpreted in term of transitionstate hyperconjugate stabilization.
In addition to these above effect, there also exist steric effect between the 2,5-disubtituted adamantane and Grignard reagents. The generation of the addition or reduction product can be explain by this effect.