反应详情

2.37 g (12.2 mmol) of 3-methyl-7-nitro-3H-isobenzofuran-1-one (Example 4) are heated in 5 ml of 30% sodium hydroxide solution (49 mmol) for 1 hour at 90° C. until 2-nitro-6-(1-hydroxyethyl)-benzoic acid can be demonstrated almost quantitatively by TLC (mobile phase: ethyl acetate/hexane 3:1 plus 1 drop of formic acid). 1.2 ml (24.5 mmol) of hydrazine hydrate are then slowly added dropwise and the temperature is maintained for a further 4 hours. The cooled reaction mixture is then adjusted to a pH of 2 and is extracted with ethyl acetate. 1.8 g (90.4%) of crude 7-amino-3-methyl-3H-isobenzofuran-1-one are obtained; 1H-NMR (CDCl3): 7.37 ppm, t, 1H; 6.63 ppm, d, 1H; 6.61 ppm, d, 1H; 5.44 ppm, q, 1H; 5.22 ppm, b, 2H; 1.58 ppm, d, 3H.

1. temperaturethe temperature is maintained for a further 4 hours
2. customThe cooled reaction mixture
3. extractionis extracted with ethyl acetate