Lewis Acid-Catalyzed Ring-Opening Cross-Coupling Reaction of gem-Difluorinated Cyclopropanes Enabled by C–F Bond Activation

Abstract

gem-Difluorinated cyclopropanes have attracted wide research interest in organic synthesis due to their high reactivity. Herein, we report a Lewis acid-catalyzed cross-coupling reaction of mono- and disubstituted gem-difluorinated cyclopropanes with nucleophiles. The formation of a fluoroallyl cation species triggered via the Lewis acid-assisted activation of the C–F bond is proposed in this transformation. The cation species is then trapped by the nucleophiles, including electron-rich arenes and allylsilanes, to deliver a series of fluoroallylic products in good yields. The reaction provides an alternative mode for using gem-difluorinated cyclopropanes as fluoroallyl surrogates.

A fluorolytic sol–gel route to access an amorphous Zr fluoride catalyst: a useful tool for C–F bond activation

“…26 However, recent literature stated that ZrF 4 surfaces are assumed to exhibit lower Lewis acidity and lower catalytic activity compared aluminium-based based counterparts. 26,27 These results are consistent with a theoretical assessment that due to the increased size and different electronic configuration of zirconium compared to aluminium atoms a decreasing Lewis acid strength can be expected. 28 In this work we present the development of an amorphous ZrF 4 heterogeneous catalyst which has been tested in C-F bond activation and was thoroughly characterised.…”

Selectivity in Rh-catalysis with gem-difluorinated cyclopropanes

“…5 Besides, a Lewis acid could activate the gem -DFCPs via C1–F bond activation to produce a fluoroallyl cation species. 8 A ring-opening bifunctionalization of gem -DFCPs with alcohols and alkynes was enabled by dual-functional Cu catalysis, providing diverse fully-substituted and configuration-defined alkyl vinyl ethers, where the Cu catalyst also serves as a Lewis acid to activate the C1–F bond. 9 Other strategies of ring-opening/functionalization of gem -DFCPs such as electroreductive defluorinative carboxylation 10 and Lewis acid-assisted [3+2] cycloaddition of donor–acceptor gem -DFCPs were also realized.…”

CO2 and palladium enabled highly chemoselective hydroxylation of gem-difluorocyclopropanes

“…In this context, we considered gem -difluorocyclopropane electrophiles, 32–34 because these are known to readily react with potent nucleophiles under transition metal palladium catalysis. 35–55 However, selectively producing hydroxylated products without further reactions constitutes a considerable challenge. We thus designed a method for the hydroxylation of gem -difluorocyclopropanes, which is enabled by CO 2 and Pd(0)-catalysis, affording a large series of important fluorinated cinnamyl alcohols 56–69 from water.…”