The Study of Tandem Radical Cyclization of Vinyl Radical with Acylsilanes
Date Issued
2008
Date
2008
Author(s)
Hsu, Jen-Yu
Abstract
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.n 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.
Subjects
radical
cyclization
acylsilane
vinyl radical
Type
thesis
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