| Summary: | 碩士 === 國立中正大學 === 化學研究所 === 85 === 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.
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