Deprotonation of perfluoroalkyl- and perfluorophenyl-substituted methyl 2-siloxycyclopropanecarboxylates and subsequent reaction with alkyl halides furnished C-1 alkylated cyclopropanes with high diastereoselectivities. Smooth triethylamine trishydrofluoride mediated desilylation and ring opening afforded the corresponding γ-oxo esters in good to excellent yields. Treatment of methyl 2-siloxycyclopropanecarboxylates with Grignard reagents and subsequent ring opening in the presence of acid provided β,γ-unsaturated ketones with fluorine-containing substituents.
Key words
donor–acceptor cyclopropanes - fluorine - γ-oxo esters - ring opening - defluorination