Stereoselective One-Pot Sequential Dehydrochlorination/trans-Hydrofluorination Reaction of beta-Chloro alpha-,beta-unsaturated Aldehydes or Ketones: Facile Access to (Z)-beta-Fluoro-beta-arylenals/beta-Fluoro-beta-arylenones

摘要

The monofluoroalkene substructure shows a high potential as a fluorinated synthon in organic synthesis. However, control of the Z/E stereoselectivity of multi-substituted monofluoroalkene products in one-pot reactions still remains a challenge. An unprecedented one-pot approach for the highly regio- and stereoselective preparation of functionalized (Z)-beta-monofluoro tri-substituted alkenes from readily available beta-chloro-alpha,beta-unsaturated aldehydes or ketones has been explored. Mechanistic studies demonstrated that the reaction is initiated by dehydrochlorination of the substrates to give alkynyl aldehydes/ketones, followed by their trans-hydrofluorination. It is worth mentioning that a fluorinating reagent with suitable basicity and nucleophilicity plays a key role in promoting the formation of (Z)-beta-fluoro-beta-aryl tri-substituted monofluoroalkenes.