反应详情

Benzyl alcohol (2.60 mL, 25.1 mmol) was added slowly to a stirring solution of 2-fluorobenzoic acid (2.92 g, 20.8 mmol), 4-(dimethylamino)pyridine (251 mg, 2.05 mmol), and 1,3-dicyclohexylcarbodiimide (5.16 g, 25.0 mmol) in anhydrous CH2Cl2 at room temperature under an Ar atmosphere. After 18 h the precipitate was filtered off and washed with CH2Cl2, and the filtrate was concentrated with silica to a powder. Flash chromatographic purification over silica (10% to 20% gradient EtOAc in hexanes) afforded 16 as a clear, colorless liquid (4.20 g, 88%). 1H-NMR (500 MHz, CDCl3) δ 5.39 (s, 2H), 7.14 (ddd, J=1.1, 8.4, 9.5 Hz, 1H), 7.20 (dt, J=1.1, 7.7 Hz, 1H), 7.31-7.36 (m, 1H), 7.37-7.41 (m, 2H), 7.44-7.48 (m, 2H), 7.49-7.55 (m, 1H), 7.96 (dt, J=1.8, 7.3 Hz); 13C-NMR (125 MHz, CDCl3) δ 66.93, 117.0 (d, JC-F=22.1 Hz), 118.7 (d, JC-F=9.6 Hz), 124.0 (d, JC-F=3.8 Hz), 128.1, 128.2, 128.6, 132.2, 134.6 (d, JC-F=9.6 Hz), 135.7, 162.1 (d, JC-F=260 Hz), 164.2 (d, JC-F=3.8 Hz); GC-MS 230 m/z [M]+, C14H11OF2 requires 230.

1. filtrationAfter 18 h the precipitate was filtered off
2. washwashed with CH2Cl2
3. concentrationthe filtrate was concentrated with silica to a powder
4. customFlash chromatographic purification over silica (10% to 20% gradient EtOAc in hexanes)