Stereoselective Synthesis of Difluorinated 1,3-Dienes via Palladium-Catalyzed C-F Bond Activation of Tetrasubstituted gem-Difluoroalkenes.

A highly diastereoselective Pd(0)-catalyzed synthesis of difluorinated 1,3-dienes is described. Symmetrical 1,3-dienes containing a vicinal difluoro moiety can be obtained as single diastereomers from tetrasubstituted gem-difluoroalkenes. The reaction presumably proceeds through a stereoselective twofold Pd-catalyzed Miyaura borylation/Suzuki-Miyaura cross-coupling of the C-F bond. Moreover, modular synthesis of unsymmetrical difluorinated 1,3-dienes is also achievable by the coupling between gem-difluoroalkenes and borylated monofluoroalkenes.