89968-59-2Relevant academic research and scientific papers
Methyldiphenylsilylation of Ester and Lactone Enolates
Larson, Gerald L.,Maldonado, Veronica Cruz de,Fuentes, Lelia M.,Torres, Luz E.
, p. 633 - 639 (2007/10/02)
The reactions of a variety of ester and lactone enolates with methyldiphenylchlorosilane were studied.The C-versus O-silylation, leading to the α-silyl ester or lactone and silyl ketene acetal, respectively, was studied as a function of the structure of the ester or lactone and the reaction conditions.It was found that all simple acetates are C-silylated irrespective of the steric demands of the alcohol portion of the ester.Esters that are monosubstituted in the α-position are cleanly C-silylated with the notable exceptions of ethyl phenylacetate and ethyl phenoxyacetate, both of which give mixtures of C- and O-silylation.The α,α-disubstituted esters give only O-silylation, but the α,α-substituted α-silyl esters are readily prepared by the alkylation of the appropriate monosubstituted α-silylated ester.The reaction of the lithium enolate of ethyl acetate and tert-butyl acetate with (S)-(-)-1-naphthylphenylmethylchlorosilane showed the reaction to occur with inversion of configuration at silicon.Methylation of tert-butyl (1-naphthylphenylmethylsilyl)acetate gave a 91:9 mixture of diastereomeric α-silyl propionates, which could not be separated.It was found that only the γ-lactones gave C-silylation with δ-valerolactone and ε-caprolactone giving O-silylation.
Reaction of α-Silyl Esters with Grignard Reagents: A Synthesis of β-Keto Silanes and Ketones. Preparation of the Douglas Fir Tussock Moth Pheromone
Larson, Gerald L.,Hernandez, David,Lopez-Cepero, Ingrid Montes de,Torres, Luz E.
, p. 5260 - 5267 (2007/10/02)
A variety of α-diphenylmethylsilyl esters have been prepared and reacted with Grignard reagents.The reaction is relatively slow in refluxing THF and can be controlled to allow the addition of 1 equiv of the Grignard reagent, providing the corresponding β-keto silane.Protiodesilylation of the β-keto silane results in the overall conversion of an ester to a ketone.This ester to ketone methodology has been applied to a two-step synthesis of the pheromone of the Douglas fir tussock moth.The β-keto silanes are viable precursors to regioselectively generated enol silyl ethers.The reaction of ethyl 2-methyl-2-(diphenylmethylsilyl)propionate with vinylmagnesium bromide or 2-methyl 1-propenylmagnesium bromide results in the addition of 2 equiv of the Grignard reagent, the second in a Michael fashion.
