Scheme 2. Cu/NFSI Fluorination of Benzylic C–H Bonds.
a1H or 19F NMR yields; CH2Br2 or PhCF3 as internal standard. b35 °C, 0.5 equiv MeB(OH)2. c55 °C, 1 mol% Cu/1.2 mol% BPhen, 4 equiv NFSI, 1 equiv B2pin2 instead of MeB(OH)2. d75 °C 1 mol% Cu/1.2 mol% BPhen, 4 equiv NFSI, 1 equiv B2pin2 instead of MeB(OH)2. eAcetone solvent.