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In Situ Generation of Silyl Anion Species through Si−B Bond Activation for the Concerted Nucleophilic Aromatic Substitution of Fluoroarenes
Author(s) -
Kojima Kumiko,
Nagashima Yuki,
Wang Chao,
Uchiyama Masanobu
Publication year - 2019
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201900069
Subject(s) - chemistry , silylation , nucleophile , nucleophilic substitution , bond cleavage , photochemistry , substitution reaction , medicinal chemistry , electrophilic aromatic substitution , organic chemistry , catalysis
In situ generated silyl anion species enable the concerted nucleophilic aromatic substitution of fluoroarenes. Model DFT calculations indicated that addition of a base to a silylborane would thermodynamically form a silyl borate complex and then kinetically release a silyl anion species through Si−B bond cleavage, and that the in situ generated silyl anion equivalent would further react with a fluoroarene through a concerted nucleophilic aromatic substitution pathway with an activation barrier of ca. 20 kcal/mol to afford the silylated product with a large energy gain. Experiments confirmed that the defluorosilylation reaction took place smoothly at room temperature simply upon mixing fluoroarenes with commercially available silylborane and NaO t Bu. Radical scavenger and radical clock reaction experiments provide further evidence for the in situ generation of the silyl anion.