Structural determination of a zinc reagent from ethyl 3-bromodifluoromethyl-3-benzyloxyacrylate and its reactions with aldehydes

The reactivity of ethyl 3-bromodifluoromethyl-3-benzyloxyacrylate as a novel gem-difluoromethylene synthon was investigated. 19F NMR spectra of its zinc reagent in THF and DMF indicate unambiguously that the active species exists as the γ-carbon metallated form. Moreover, promoted by zinc or TDAE, a complete control of the addition reaction mode (α or γ) of this acrylate with aldehydes can be accomplished.