Stereospecific benzylic dehydroxyfluorination reactions using Bio’s TMS-amine additive approach with challenging substrates

Reactions involving the conversion of a benzylic alcohol into a benzylic fluoride using RSF3 reagents are notoriously difficult to achieve with high stereochemical inversion (SN2 reaction) due to competing dissociative SN1 reaction processes. This Letter develops the methodology of Bio et al., and reports that the addition of a preformed 1:TMS-amine 1:RSF3 (fluorination reagent) complex as the reagent in these reactions significantly suppresses the SN1 process and promotes a highly stereospecific reaction generating benzylic fluorination products of high %ee.