Cis-selective preparation of 2,2-difluorocyclopropyl ketones via non-metal hydride reduction of 2,2-difluorocyclopropenyl ketones

Diastereoselective reduction of gem-difluorocyclopropenyl ketones was accomplished by their Brønsted acid catalyzed reactions with the non-metal based hydride transfer reagent, Hantzsch ester (diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate) (HEH). The high yield reactions produced a significantly cis-enriched product mixture, from which the cis-isomer could be readily separated by column chromatography.

An efficient procedure for cis-selective reduction of gem-difluorocyclopropenyl ketones, using Hantzsch ester as the hydride transfer reagent, is reported.Figure optionsDownload as PowerPoint slideHighlights
► Cis-selective reduction of gem-difluorocyclopropenyl ketones to form 3-substituted-2,2-difluorocyclopropyl ketones.
► Hantzsch ester is a potent hydride donor under acid catalysis.
► Cis-3-substituted-2,2-difluorocyclopropyl ketones are prepared in very good yield.