Lewis base-catalyzed perfluoroalkylation of carbonyl compounds and imines with (perfluoroalkyl)trimethylsilane

Lewis base-catalyzed perfluoroalkylation of carbonyl compounds and aldimines with (perfluoroalkyl)trimethylsilanes (TMSCF3, TMSC2F5, and TMSC3F7) is described. The nitrogen- or oxygen-containing anions generated from amides, imides, and carboxylic acids have been found to work as effective Lewis-base catalysts in perfluoroalkylation that proceeds via activation of the carbon-silicon bonds of (perfluoroalkyl)trimethylsilanes. Reactions of carbonyl compounds such as aldehydes, ketones, and esters with TMSCF3 in the presence of a catalytic amount of Lewis bases proceeded smoothly to afford the corresponding adducts in good-to-high yields under mild conditions. Although it was considered difficult, this catalytic perfluoroalkylation of various aldimines with (perfluoroalkyl)trimethylsilane in the presence of Lewis bases such as lithium acetate or benzoate proceeded efficiently to give the corresponding perfluoro-alkylated adducts, because the aldimines here were weak electrophiles toward (perfluoroalkyl)trimethylsilanes. The present reaction is, therefore, the first example of a catalytic perfluoroalkylation of aldimines.