反应详情

To a solution of 2-methyl-5-bromopyridine (40 g, 0.23 mol) in dichloromethane (500 ml) was added m-CPBA (64 g, 0.25 mol) in batches at 0° C. After stirring for 16 h at room temperature, the mixture was washed with sat. aq. NaHCO3, aq. NaHSO3 and brine successively. The organic layer was dried over MgSO4 and then concentrated to give 35 g, (79.2%) of 2-acetoxymethyl-5-bromopyridine as a yellow solid. A mixture of 35 g (0.19 mol) 2-acetoxymethyl-5-bromopyridine and Ac2O (160 ml) was heated to reflux for 1 hour. To this mixture was cautiously added 150 mL EtOH (until the excess Ac2O was converted to EtOAc and AcOH). After concentration, the residue was neutralized with aq. KHCO3 and extracted with CH2Cl2. The extract was dried over MgSO4 and purified by silica gel chromatography to give 2-(acetoxymethyl)-5-bromopyridine. 1H-NMR (400 MHz, CDCl3) δ 8.65 (d, J=2.4 Hz, 1H), 7.82 (q, J1=8.4 Hz, J2=2.4 Hz, 1H), 7.25 (q, J1=7.8 Hz, J2=0.6 Hz, 1H), 5.17 (s, 2H), 2.16 (s, 3H) m/z: 231.15 (M+1)

1. washthe mixture was washed with sat. aq. NaHCO3, aq. NaHSO3 and brine successively
2. dry with materialThe organic layer was dried over MgSO4
3. concentrationconcentrated