Copper-Catalyzed Defluorinative Borylation and Silylation of <i>gem</i>-Difluoroallyl Groups

Stereodefined (<i>Z</i>)-fluoroalkenes are bioisosteres of amides and synthetic precursors to value-added fluorinated compounds, but their stereoselective synthesis remains challenging. Herein, we report a copper-catalyzed formal S_N2' defluorinative borylation of 3-substituted 3,3-difluoropropenes to form 3-fluoroallylboronic esters in high yields with excellent <i>Z</i>/<i>E</i> ratios. The primary 3-fluoroallylboronic esters undergo several synthetic sequences involving S_E2' substitutions, S_N2' substitutions, and sigmatropic rearrangements to provide tertiary allylic fluorides.