Synthesis of Mono- and Difluoroacetyltrialkylsilanes and the Corresponding Enol Silyl Ethers

A variety of mono- and difluoroacetylsilanes and the corresponding silyl enol ethers were prepared
from trifluoroethanol and chlorotrialkylsilanes in the presence of LDA through retro-Brook
rearrangement. Sterically demanding silyl groups, especially those bound to oxygen, resulted in
higher yields of difluoroacetylsilanes. The yields of difluoroacetylsilanes were also dramatically
affected by the method of the termination of the reaction. Difluorohaloacetylsilanes were prepared
from the corresponding difluoroethenyl silyl ethers with electrophilic halogenating reagents in good
yields. A γ-fluorinated β-diketone 9a was prepared from monofluoroacetyltriisopropylsilane by
nucleophilic acylation with methyl trifluoroacetate.