143635-16-9Relevant academic research and scientific papers
Trimethylsilyl Cyanide - A Reagent for Umpolung, XX. - On the Regioselectivity of the Addition of Carbonyl Compounds to α,β-Unsaturated Aldehydes after Umpolung
Huenig, Siegfried,Schaefer, Matthias
, p. 177 - 190 (2007/10/02)
By addition of tBuMe2SiCN to α,β-unsaturated aldehydes 5 the silylated cyanohydrins 6 are produced.Deprotonation of 6 provides allylic anions which can be attached to aldehydes and ketones in α-position (kinetic control) (-> 8) or γ-position (thermodynamic control) (-> 9).In contrast to the Me3Si group which has been applied so far the tBuMe2Si group is stable under the reaction conditions.Therefore, the ratio of α/γ adducts can be tuned from > 95:5 to 5:95 depending on the substitution pattern of 6, the aldehydes and ketones, the reaction time and temperature, and even by some additives.The γ adducts 9 are easily transformed into γ-butyrolactones 27 by acidic hydrolysis. Key Words: Umpolung / Regioselectivity / Substituent effects / Acylation, nucleophilic / Aldehydes, α,β-unsaturated / Trimethylsilyl cyanide
