title: Catalytic Electrophilic C-H Silylation of Pyridines Enabled by Temporary Dearomatization.
abstract: A CH silylation of pyridines that seemingly proceeds through electrophilic aromatic substitution (SE Ar) is reported. Reactions of 2- and 3-substituted pyridines with hydrosilanes in the presence of a catalyst that splits the SiH bond into a hydride and a silicon electrophile yield the corresponding 5-silylated pyridines. This formal silylation of an aromatic CH bond is the result of a three-step sequence, consisting of a pyridine hydrosilylation, a dehydrogenative CH silylation of the intermediate enamine, and a 1,4-dihydropyridine retro-hydrosilylation. The key intermediates were detected by (1) H NMR spectroscopy and prepared through the individual steps. This complex interplay of electrophilic silylation, hydride transfer, and proton abstraction is promoted by a single catalyst.
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de.
authors.forename: Simon
authors.initials: S
authors.lastname: Wübbolt
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de. martin.oestreich@tu-berlin.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Oestreich
keywords: CH activation; N-heterocycles; SiH bond activation; electrophilic substitution; hydrosilylation