The Study of Synthetic Applications of Free Radical Cyclization of Acylsilanes

• Main Authors: Kuo, Sue-Ling, 郭淑鈴
• Other Authors: Tsai, Y.-M.
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/43450808241909528705

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%).