Palladium-Catalyzed Stereoselective Defluoroborylation of gem -Difluoroalkenes with Unsymmetrical Diboron: Access to Tetrasubstituted Monofluorinated Vinyl-B(dan) Derivatives.

The stereoselective C-F bond borylation of tetrasubstituted β,β-difluoroacrylates has been achieved. In contrast to the previously used B 2 pin 2 reagent, which only led to dimerization products, this work employs the unsymmetrical diboron reagent (pin)B-B(dan) under the palladium(0)-catalyzed conditions to access novel boronamides containing the monofluorinated vinyl-B(dan) functionality. These compounds can cross-couple directly with gem -difluoroalkenes without reactivation in Suzuki-Miyaura reactions to afford vincinal difluoro 1,3-dienes with modular control of the substituents.