Ammonium Chloride → 6-amino-4-(3-methoxy-propyl)-2,2-dimethyl-4H-benzo[1,4]oxazin-3-one

Participants

Reaction Conditions

Reaction Steps

At room temperature, an ethanolic solution (80 ml) of 4-(3-methoxy-propyl)-2,2-dimethyl-6-nitro-4H-benzo[1,4]oxazin-3-one (9.76 g, 33.2 mmol) is treated with H2O (80 ml), NH4Cl (3.58 g, 66.9 mmol), and powdered Zn (10.97 g, 0.17 mol), heated to 80° C., stirred for 2 h under reflux, cooled to room temperature, and filtered via celite pad. After washing the cake with CH2Cl2 for several times, the both layers of the combined filtrate are separated. The aq. layer is treated with 5N NaOH (6.0 ml) to adjust its pH 9˜10, and extracted with CH2Cl2 (3×100 ml). The combined org. layer is washed with sat. aqueous solution of NaHCO3 (100 ml) and brine (50 ml), dried (Na2SO4), and evaporated. A SiO2 flash chromatography (250 g, CH2Cl2/acetone 3:1) gives 6-amino-4-(3-methoxy-propyl)-2,2-dimethyl-4H-benzo[1,4]oxazin-3-one (9.23 g, 99%) as brown oil. Rf(CH2Cl2/EtOAc 2:1) 0.34. 1H-NMR (400 MHz, CDCl3) 1.39 (s), 1.80-1.91 (m, 2 H), 3.28 (s), 3.35 (t, J=8.0), 3.44 (br. s), 3.88 (t, J=9.0), 6.23 (dd, J=9.0, 0.4), 6.33 (d, J=0.4), 6.68 (d, J=9.0).

Provenance & Evidence