Catalytic Electrophilic CH Silylation of Pyridines Enabled by Temporary Dearomatization |
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Authors: | Simon Wübbolt Prof. Dr. Martin Oestreich |
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Affiliation: | Institut für Chemie, Technische Universit?t Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu‐berlin.de |
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Abstract: | A C? H 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 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 1H 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. |
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Keywords: | C H activation electrophilic substitution hydrosilylation N‐heterocycles Si H bond activation |
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