Metal‐Free Defluoroborylation of 3,3‐Difluoropropenes

Abstract The defluorinative functionalization of allylic fluorides represents an attractive approach for the preparation of molecules containing a monofluoroalkene core. In that sense, introducing a “boryl nucleophile” is a powerful strategy to obtain polyvalent borylated intermediates as versatile synthetic precursors. To perform this reaction without the use of transition metals, the nucleophilic character of a diborane/fluoride system was exploited in a S N 2′ type‐substitution reaction of gem ‐difluoropropenes to install a pinacolborane group. The use of HMDS as a silylated additive is necessary to improve the reactivity. A direct oxidation of the intermediate boronates allowed the isolation of the corresponding β‐fluoroallyl alcohols in low to good yields (9–81 %). Other synthetic transformations of a (2‐fluoroallyl)boronate are also illustrated.