反应详情

To a stirring solution of ethyl-N-hydroxyacetimidate (3.79 g, 36.8 mmol) in anhydrous DMF (150 mL) under Ar was added tBuOK (4.09 g, 36.4 mmol) all at once. After 40 min benzyl-4-fluorobenzoate 17 (7.63 g, 17.9 mmol) was added and the reaction was stirred at room temperature. After 4 h the reaction was diluted with H2O (500 mL), extracted with EtOAc (4×100 mL), and the combined organics were washed with H2O (2×100 mL), dried over Na2SO4, filtered, and concentrated. Flash chromatographic purification over silica (5-10% gradient EtOAc in hexanes) afforded 19 as a clear syrup (6.02 g, 58%). 1H-NMR (500 MHz, CDCl3) δ 1.36 (t, J=7.0 Hz, 3H), 2.12 (s, 3H), 4.20 (q, J=7.0 Hz, 2H), 5.34 (s, 2H), 7.15-7.19 (m, 2H), 7.31-7.35 (m, 2H), 7.36-7.41 (m, 2H), 7.42-7.36 (m, 2H), 8.00-8.14 (m, 2H); 13C-NMR (125 MHz, CDCl3) δ 14.3, 14.4, 63.1, 66.4, 113.4, 122.9, 128.1, 128.1, 128.6, 131.5, 136.3, 163.5, 166.3, 166.4; GC-MS 228 m/z [M-85]+, benzyl-4-hydroxybenzoate C14H12O3 requires 228.

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