The Study of Tandem Radical Cyclization of Vinyl Radical with Acylsilanes

• Main Authors: Jen-Yu Hsu, 徐仁佑
• Other Authors: Yeun-Min Tsai
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/01886288224108411631

碩士 === 國立臺灣大學 === 化學研究所 === 96 === According to previous research in our laboratory, cyclizations of acylsilanes with vinyl radicals have been studied. This process involved intramolecular free radical cyclizations of a vinyl radical to the carbonyl group of acylsilane to give a β-silyl alkoxy radical. This radical then undergoes a radical Brook rearrangement to afford an α-silyloxy radical. Due to the presence of the vinyl group, this α-silyloxy radical is also an allylic radical. Finally, hydrogen abstraction occurs at the γ-position of this allylic system to give an enol silyl ether. Generally, 1,5-exo-cyclizations are more efficient than 1,6-exo-cyclizations. In this research we exploited this system further in the context of tandem radical cyclizations. We have constructed two systems in which the intermediate allylic radicals are trapped intramolecularly at the γ-position by radicalphilic groups. Specifically, we have synthesized acylsilanes with vinyl iodide tethered to an alkynyl functional group. The scope and limitations of this type of tandem cyclizations were studied.