112197-32-7Relevant articles and documents
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.
A Two-Step Preparation of α-Alkylidene γ-Lactones from γ-Lactones: A Synthesis of (+/-)-Ancepsenolide
Larson, Gerald L.,Perez, Rosa M. Betancourt de
, p. 5257 - 5260 (2007/10/02)
γ-Butyrolactone, γ-valerolactone, and the cis lactone of 2-hydroxycyclohexaneacetic acid have been C-silylated via their respective lithium enolates with diphenylmethylchlorosilane.The resulting α-silylated γ-lactones can be deprotonated and condensed with aldehydes and ketones to give α-alkylidene γ-lactones in moderate to excellent yield.The enolate of the α-diphenylmethylsilyl cis lactone of 2-hydroxycyclohexaneacetic acid condensed with 1-butanal but not with benzaldehyde or acetaldehyde.
