An In Situ Directing Group Strategy for Chiral Anion Phase-Transfer Fluorination of Allylic Alcohols

An enantio­selective fluorination of allylic alcohols under chiral anion phase-transfer conditions is reported. The in situ generation of a directing group proved crucial for achieving effective enantio­control. In the presence of such a directing group, a range of acyclic substrates underwent fluorination to afford highly enantio­enriched α-fluoro homoallylic alcohols. Mechanistic studies suggest that this transformation proceeds through a concerted enantio­determining transition state involving both C–F bond formation and C–H bond cleavage.