臺灣博碩士論文加值系統

中文摘要第一部份 烯醇離子對富烯的連續性Michael加成反應本研究主
要是描述藉由double Michael加成反應的途徑而有效率地合成出
tricyclo[5.3.0.n2,5]alkane ring系統的方法，這類結構是天然物
isobarbatene及rotundenol的基本骨架。本反應是利用烯醇化合物去質子
後產生的雙烯醇陰離子與具有類似Michael受體性質的富烯，藉由一次分
子間及一次分子內的Michael加成反應而獲得三環的骨架。本研究中，最
特別的地方是利用環戊烯酮類進行反應時，一次可以形成兩個鍵及三個立
體中心，而且選擇性非常高。第二部份 2-茂叉-1,3-二氧戊環的合成本
研究是利用環戊二烯及2-氯乙酯氯甲酸以非常高效率的方法來製備2-茂
叉-1,3-二氧戊環。反應最好的條件是將兩當量的環戊二烯鈉與2-氯乙酯
氯甲酸在濃度0.1 M的環境下進行。第三部份 Xestovanin的合成研究本研
究首次完成(-)-rosiridol的全合成以及其結構上的鑑定。另外，並利用
一些鏡像選擇催化劑，以新類型的方法非常高幾何及鏡像選擇性的合
成(-)-rosiridol。另一個重點是合成出xestovanin glycoside。這兩個
化合物都是天然物xestovanin A的部份骨架。

AbstractPart I: Sequential "Double-Michael" Additions of
Dienolates to Fulvene: Rapid Access to the Tricyclo[5.3.0.n2,5
]Alkane SystemsThe double-Michael addition sequence outlined in
this thesis provides a remarkably efficient route to the
tricyclo[5.3.0.n2,5]alkane ring systems, namely the skeletons of
isobarbatene and rotundenol. The dienolates anion formed by the
a-deprotonation of an enone added in a Michael-like fashion to
fulvene and form an anionic intermediate which was then cyclize
through an intramolecular Michael reaction, affording the
tricyclic ketone intermediate upon protonation. The reaction is
particularly attractive in the case of the cyclopentenones as
two bonds and three streocenters are formed in one step with
very high stereoselectivity.Part II: A Simple and Cost Effective
Synthesis of 2-Cyclopenta-dienyliden-1,3-Dioxolane A high
efficient preparation of 2-cyclopentadienyliden-1,3-dioxolane
from cyclopentadiene and 2-chloroethyl chloroformate has been
achieved. Reaction of two equivalents of sodium
cyclopentadienide with 2-chloroethyl chloroformate at 0.1 M
produce the highest yield of this fulvene.Part III: Synthetic
Studies on Xestovanins The first total synthesis of
(-)-rosiridol as well as the conclusion of its strusture
assignment have been achieved. The regio enantioselective
prenylation demonstrated here in this thesis represents a new
class of the catalytic enantioselective reactions. Synthesis of
xestovanin glycoside was also addressed in this thesis.