Reaction Steps
To a solution of 2-(3-chlorophenyl)-2H-chromene (2i) (72.8 mg, 0.3 mmol) and 4-methylmorpholine N-oxide (52.7 mg, 0.45 mmol) in THF (3 mL) and water (0.116 mL) was added a 2.5 wt % solution of osmium tetraoxide in t-BuOH (0.118 mL). The mixture was stirred at 23 C for 16 h and was then quenched with a saturated solution of sodium thiosulfate. The mixture was extracted with EtOAc. The combined organics was washed with brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The crude was purified by flash chromatography using 20% EtOAc/hexanes to afford 9 as an off-white solid (76 mg, 91%). Analytical data for 9: 1H NMR (500 MHz, CDCl3) δ 7.53-7.48 (m, 1H), 7.39 (dd, J=7.6, 1.7 Hz, 1H), 7.37 (d, J=1.4 Hz, 3H), 7.30 (ddd, J=8.6, 7.3, 1.7 Hz, 1H), 7.02 (td, J=7.4, 1.2 Hz, 1H), 6.96 (dd, J=8.2, 1.1 Hz, 1H), 5.05 (d, J=9.5 Hz, 1H), 4.81 (t, J=3.7 Hz, 1H), 4.04 (ddd, J=9.5, 6.6, 3.7 Hz, 1H), 2.57 (d, J=3.7 Hz, 1H), 2.25 (d, J=6.6 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 154.0, 139.9, 134.8, 130.9, 130.7, 130.1, 129.0, 127.8, 125.9, 122.0, 121.7, 117.0, 76.2, 71.1, 66.2; IR (film): 3407, 2919, 2851, 1583, 1485, 1455, 1239, 1036, 1012, 754, 701, 511 cm−1; LRMS (ESI): Mass calculated for [M+H]+ C15H14ClO3: 277.1; found 277.1
