Direct Electrophilic Silylation of Terminal Alkynes
Aleksey A. Andreev, Valeri V. Konshin, Nikolai V. Komarov, Michael Rubin, Chad Brouwer and Vladimir Gevorgyan*
*University of Illinois at Chicago, 845 West Taylor Street, Chicago,
Illinois 60607, Email: vlad
uic.edu
A. A. Andreev, V. V. Konshin, N. V. Komarov, M. Rubin, C. Brouwer, V. Gevorgyan, Org. Lett., 2004, 6, 421-424.
DOI: 10.1021/ol036328p
Abstract
Various alkynylsilanes were efficiently prepared via zinc halides-mediated direct silylation of terminal alkynes with aminosilanes. Base- and nucleophile-sensitive functionalities were tolerated under the reaction conditions. The electrophilic character of this transformation is supported by initial mechanistic studies.
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Details
The document discusses a novel method for the direct electrophilic silylation of terminal alkynes using aminosilanes in the presence of zinc halides. This method efficiently produces various alkynylsilanes, which are important in organic synthesis, without the need for strong bases. Traditional methods involve deprotonation with organolithium or Grignard reagents, followed by trapping with silyl electrophiles. However, these methods are not always practical. The new method described uses zinc halides to mediate the reaction, achieving high yields and tolerating base- and nucleophile-sensitive functionalities. The optimal conditions involve using THF or 1,4-dioxane as solvents, with ZnCl2, ZnBr2, or ZnI2 as the Lewis acids. The reaction mechanism is suggested to be electrophilic rather than nucleophilic, supported by kinetic studies showing that electron-releasing groups facilitate the reaction. This method is scalable and versatile, working well with various aryl and alkyl alkynes. The study provides a straightforward, high-yielding, and scalable approach to synthesizing silylalkynes, complementing existing nucleophilic methods and tolerating a wide range of functional groups. Further research is ongoing to explore the scope and precise mechanism of this silylation reaction.
Key Words
ID: J54-Y2004-040
