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 B2pin2 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.