反应详情

To a stirring solution of ethyl-N-hydroxyacetimidate (2.06 g, 20.0 mmol) in anhydrous DMF (60 mL) under Ar was added tBuOK (2.21 g, 19.7 mmol) all at once. After 30 min benzyl-2-fluorobenzoate 16 (4.13 g, 17.9 mmol) was added as a solution in DMF (20 mL) and the reaction was stirred at room temperature. After 3 h the reaction was diluted with H2O (400 mL), extracted with EtOAc (3×100 mL), and the combined organics were washed with H2O (3×50 mL) and brine (50 mL), dried over Na2SO4, filtered, and concentrated. Flash chromatographic purification over silica (5-10% gradient EtOAc in hexanes) afforded 18 as a clear syrup (3.61 g, 64%). 1H-NMR (500 MHz, CDCl3) δ 1.34 (t, J=7.0 Hz, 3H), 2.00 (s, 3H), 4.18 (q, J=7.0 Hz, 2H), 5.34 (s, 2H), 6.96 (dt, J=1.1, 7.7 Hz, 1H), 7.30-7.35 (m, 1H), 7.35-7.39 (m, 2H), 7.42-7.48 (m, 3H), 7.55 (dd, J=1.1, 8.4 Hz, 1H), 7.90 (dd, J=1.8, 7.7 Hz, 1H); 13C-NMR (125 MHz, CDCl3) δ 14.4, 14.5, 63.1, 66.6, 114.5, 117.0, 120.4, 128.2, 128.4, 128.5, 131.7, 133.8, 136.1, 159.5, 165.8, 166.7; GC-MS 313 m/z[M]+, C18H19NO4 requires 313, 228 m/z [M-85]+, benzyl-2-hydroxybenzoate C14H12O3 requires 228.

1. extractionextracted with EtOAc (3×100 mL)
2. washthe combined organics were washed with H2O (3×50 mL) and brine (50 mL)
3. dry with materialdried over Na2SO4
4. filtrationfiltered
5. concentrationconcentrated
6. customFlash chromatographic purification over silica (5-10% gradient EtOAc in hexanes)