反应详情

A solution of bromine (7.0 mL, 137.3 mmol) in dichloromethane is added dropwise to a cold (−10° C.) solution of ethyl 4-aminobenzoate (22.0 g, 133.3 mmol) in dichloromethane. The reaction mixture is allowed to come to room temperature, stirred for 18 h and diluted with water. The organic phase is separated, washed twice with brine, dried over MgSO4 and concentrated in vacuo. The resultant residue is purified by flash chromatography (SiO2, 8/1 hexanes/EtOAc as eluent) to afford the title compound as a white solid, 28.6 g (88% yield), identified by HNMR and mass spectral analyses. MS m/e 242 (M−H)+; 1H NMR (400 MHz, DMSO-d6) δ 1.28 (t, J=7.01 Hz, 3H), 4.22 (q, J=7.16 Hz, 2H), 6.18 (brs, 2H), 6.81 (d, J=7.91 Hz, 1H), 7.65 (dd, J=8.54, 1.98 Hz 1H), 7.89 (d, J=1.83 Hz, 1H).

1. customto come to room temperature
2. customThe organic phase is separated
3. washwashed twice with brine
4. dry with materialdried over MgSO4
5. concentrationconcentrated in vacuo
6. customThe resultant residue is purified by flash chromatography (SiO2, 8/1 hexanes/EtOAc as eluent)