The reactions of a variety of ester and lactone enolates with methyldiphenylchlorosilane were studied. The Cversus O-silylation, leading to the -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 -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 , -disubstituted esters give only O-silylation, but the a,«-substituted -silyl esters are readily prepared by the alkylation of the appropriate monosubstituted -silylated ester. The reaction of the lithium enolate of ethyl acetate and ierf-butyl acetate with (S)-(-)-l-naphthylphenylmethylchlorosilane showed the reaction to occur with inversion of configuration at silicon. Methylation of fert-butyl (1 -naphthylphenylmethylsilyl)acetate gave a 91:9 mixture of diastereomeric -silyl propionates, which could not be separated. It was found that only the y-lactones gave C-silylation with -valerolactone and e-caprolactone giving O-silylation.The silylation of ester or lactone enolates can occur to produce the silyl ketene acetals or the -silyl esters or lactones, all synthetically useful classes of compounds, as a result of silylation at the Oor C-terminus of the enolate

No abstract

No abstract

The dianions of acetic acid (Ia) and phenyl acetic acid (Ie) are silylated with (II) to give the α‐methyldiphenylsilyl carboxylic acids (IIIa) and (IIIe).

Über die silylierten Ester (III) werden aus den Estern (I) die ‐ gegebenenfalls spezifisch deuterierten ‐ terminalen Olefine (IV) hergestellt.