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Zum Mechanismus der Carbodesilylierung 4‐ bzw. 5‐substituierter 2‐(Trimethylsilyl)pyridine mit Benzaldehyd
Author(s) -
Effenberger Franz,
Krebs Andreas,
Willrett Peter
Publication year - 1992
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19921250524
Subject(s) - chemistry , benzaldehyde , trimethylsilyl , electrophile , substituent , medicinal chemistry , pyridine , ylide , catalysis , organic chemistry
On the Mechanism of the Carbodesilylation of 4‐ or 5‐Substituted 2‐(Trimethylsilyl)pyridines An “ylide mechanism” is proposed for the carbodesilylation of 2‐(trimethylsilyl)pyridines with benzaldehyde. In contrast, 3‐and 4‐(trimethylsilyl)pyridines, react only in the presence of a base catalyst via pyridyl anions with electrophiles. The rates of the uncatalyzed carbodesilylation reactions of 4‐substituted 2‐(trimethylsilyl)pyridines 2 with benzaldehyde correlate very well with the resonance parameters of the substituents ρ R O , whereas the rates of 5‐substituted 2‐(trimethylsilyl)pyridines 7 correlate with the inductive substituent parameters ρ I in the Taft equation. This is to our knowledge the first direct determination of the resonance parameters ρ R O .