The general procedure for the synthesis of 7-nitro-3,4-dihydro-2H-1,4-benzisoxazin-3-one from 7-nitro-2H-1,4-benzisoxazin-3-one was as follows: 7-nitro-4H-benzo[1,4]oxazin-3-one (2.00 g, 10.3 mmol) was dissolved in tetrahydrofuran (THF, 10 mL), and borane-THF complex was added subsequently ( 1.0 M solution of THF, 35 mL). The reaction mixture was heated to reflux for 30 min, then cooled to 0 °C and the reaction was quenched with 1 N hydrochloric acid (20 mL). After continued stirring for 30 min, the reaction solution was concentrated to 1/10 of the original volume. the orange solid product was collected by filtration, washed with water and dried under vacuum to afford 7-nitro-3,4-dihydro-2H-1,4-benzisoxazine (1.66 g, 89% yield). The mass spectrum (electrospray positive ion mode) showed m/z 181.1 ([M+H]+) and the mass spectrum (electrospray negative ion mode) showed m/z 179.2 ([M-H]-).1H NMR (400 MHz, DMSO-d6) data were as follows: δ 7.68 (dd, 1H, J = 8.8, 2.6 Hz), 7.53 (s, 1H), 7.47 (d , 1H, J = 2.6 Hz), 6.63 (d, 1H, J = 9.2 Hz), 4.15 (t, 2H, J = 4.4 Hz), 3.44-3.40 (m, 2H).
