反应详情

温度

70 °C

To a solution of methyl 5-chloro-2-ethyl-3-nitrobenzoate (6.18 g, 25.36 mmol) in Methanol (250 ml) at room temperature was added ammonium chloride (13.31 g, 253.65 mmol) followed by deionized Water (125 ml). The mixture was heated to 70° C. in air before the addition of iron (8.5 g, 152.19 mmol). The reaction turned to a dark color over the 2.5 hours it was stirred at 70° C. This mixture was allowed to cool to room temperature and was filtered through Kieselgel. The filter pad was washed with MeOH (250 ml) and the filtrate concentrated under reduced pressure. The residue was dissolved in saturated NaHCO3 (aq) (50 ml) and EtOAc (150 ml). The phases were separated and the organic phase was washed with saturated NaHCO3 (aq) (2×50 ml) before being dried over MgSO4, filtered and concentrated under reduced pressure. The residue was purified by FCC (50 g silica, Isolute cartridge, gradient of eluents; 95:5 Heptane:EtOAc to 75:25 Heptane:EtOAc) to give 2.42 g (22%, 7% corrected yields) of methyl 3-amino-5-chloro-2-ethylbenzoate as a yellow oil. The product contains ˜25% ethyl ester and possible ˜15% 4-nitro products. The material was taken through the next step without further purification. LC-MS 31%, 2.00 min (3 minute LC-MS method), m/z=295.0, 1H NMR (500 MHz, Chloroform-d) δ ppm 7.17 (d, J=2.1 Hz, 1H), 6.79 (d, J=2.1 Hz, 1H), 3.87 (s, 3H), 3.86-3.81 (m, 2H), 2.74 (q, J=7.5 Hz, 2H), 1.20 (t, J=7.5 Hz, 3H).

1. customturned to a dark color over the 2.5 hours it
2. temperatureto cool to room temperature
3. filtrationwas filtered through Kieselgel
4. washThe filter pad was washed with MeOH (250 ml)
5. concentrationthe filtrate concentrated under reduced pressure
6. dissolutionThe residue was dissolved in saturated NaHCO3 (aq) (50 ml)
7. customThe phases were separated
8. washthe organic phase was washed with saturated NaHCO3 (aq) (2×50 ml)
9. dry with materialbefore being dried over MgSO4
10. filtrationfiltered
11. concentrationconcentrated under reduced pressure
12. customThe residue was purified by FCC (50 g silica, Isolute cartridge, gradient of eluents; 95:5 Heptane:EtOAc to 75:25 Heptane:EtOAc)