Reaction Steps
Prepared according to the general procedure using (Z)-4-benzylidene-2-(2,5-difluorophenyl)-1H-imidazol-5(4H)-one and (E)-hex-2-enal. The unpurified residue was purified by flash chromatography using 15% EtOAc/hexanes to afford 17 as an off-white solid (103 mg, 90%). Analytical data for 17: 1H NMR (500 MHz, CDCl3) δ 9.54 (d, J=8.5 Hz, 1H), 7.88 (ddd, J=9.2, 6.1, 3.2 Hz, 1H), 7.35-7.27 (m, 2H), 7.12-7.03 (m, 3H), 7.01-6.93 (m, 1H), 4.29 (d, J=6.8 Hz, 1H), 3.18-3.08 (m, 1H), 1.86-1.73 (m, 1H), 1.46-1.36 (m, 2H), 1.36-1.15 (m, 4H), 0.86 (t, J=7.3 Hz, 3H); 13C NMR (CDCl3, 126 MHz) δ 169.2, 159.1 (d, JCF=243.5 Hz), 155.4 (d, JCF=240.4 Hz), 149.2, 137.2, 136.3, 129.2, 128.1, 127.7, 118.5 (dd, JCF=12.8, 9.0 Hz), 117.1 (dd, JCF=25.6, 8.8 Hz), 116.5 (dd, JCF=24.7, 9.4 Hz), 114.5 (dd, JCF=27.1, 3.8 Hz), 110.6 (d, JCF=3.8 Hz), 46.0, 39.3, 29.3, 26.7, 22.4, 13.9; IR (film) cm−1 3084, 3030, 2957, 1773, 1619, 1528, 1482, 1464, 1238, 1174, 1138, 1118, 1094, 1068, 874, 812, 766, 699; LRMS (ESI): Mass calcd for [M+H]+ C22H21F2N2O2: 383.2. found 383.4; Enantiomeric ratio was measured by chiral phase HPLC (Chiralcel OD-H; 0-30 min: isocratic 12% IPA/hexanes; 30-45 min: 20% IPA/hexanes 1.0 mL/min, 280 nm), Rt1 (major)=16.8, Rt2 (minor)=37.6 min; er=>99:1.
