| Summary: | 碩士 === 國立臺灣大學 === 化學系 === 86 === Aylsilane is an useful functional group which has gained more and
more attention. Recently, we developed a method of radical cyclization of
acylsilanes to form cycloalkyl silyl ether.
In this thesis we describe our study about the synthetic application of
radical cyclizations of acylsilanes in the formation of the basic skeleton of
natural products- slaframine and triquinanes.
Retrosynthetically, slaframine can be prepared through amination of a
silyloxyquinolizidinone. The silyloxyquinolizidinone can be synthesized
via cylization of the corresponding a-acylamino radical. However, we
have some problem on the hydrolysis of a 1,3-dithiane moiety in one of our
synthetic intermediate. A milder hydrolysis condition of 1,3-dithiane
moiety is yet to be found.
With suitable design, radical cyclization of acylsilane with alkyne
moiety underwent tandem cyclization to generate [3.3.0]bicyclo silyl ether
32 which contains the basic stucture of triquinanes. During the tandem
cyclization, the bicyclic products (E)-32, (Z)-32 were formed (29%).
Interestingly unexpected tricyclic products 33, 34 (60%) were also obtained.
When the reaction was performed in the more concentrated, the amount of
bicyclic products increased (63%), and the amount of bicyclic products
were decreased (26%).
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