Catalytic Electrophilic CH Silylation of Pyridines Enabled by Temporary Dearomatization

A CH silylation of pyridines that seemingly proceeds through electrophilic aromatic substitution (SEAr) is reported. Reactions of 2- and 3-substituted pyridines with hydrosilanes in the presence of a catalyst that splits the SiH bond into a hydride and a silicon electrophile yield the corresponding...

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Published inAngewandte Chemie International Edition Vol. 54; no. 52; p. 15876
Main Authors Wubbolt, Simon, Oestreich, Martin
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 21.12.2015
EditionInternational ed. in English
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Summary:A CH silylation of pyridines that seemingly proceeds through electrophilic aromatic substitution (SEAr) is reported. Reactions of 2- and 3-substituted pyridines with hydrosilanes in the presence of a catalyst that splits the SiH bond into a hydride and a silicon electrophile yield the corresponding 5-silylated pyridines. This formal silylation of an aromatic CH bond is the result of a three-step sequence, consisting of a pyridine hydrosilylation, a dehydrogenative CH silylation of the intermediate enamine, and a 1,4-dihydropyridine retro-hydrosilylation. The key intermediates were detected by 1HNMR spectroscopy and prepared through the individual steps. This complex interplay of electrophilic silylation, hydride transfer, and proton abstraction is promoted by a single catalyst.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201508181