反应详情

Concentrated sulphuric acid (6.5 ml) was treated cautiously with stirring at 5°-10° C. with glacial acetic acid (12 ml) and to the resulting solution was added methyl 8-amino-1,4-benzodioxan-5-carboxylate (1.5 g, 0.0072 mole). The mixture was stirred at room temperature for 1 h, then treated portionwise over 45 minutes with potassium nitrate (0.85 g, 0.0084 mole). The mixture was stirred for a further 4 h then poured into water (100 ml) and basified with potassium carbonate. A precipitate was produced and this was filtered off, washed with water and dried to afford methyl 8-amino-7-nitro-1,4-benzodioxan-5-carboxylate as a yellow solid (0.30 g). The filtrate was extracted with ethyl acetate and the extract dried (Na2SO4) and concentrated in vacuo to afford a further 1.1 g of the product as an orange solid. 1H NMR (CDCl3) δ:8.50(s,1 H), 6.0-7.0(v br,2 H), 4.30-4.55(m,4 H), 3.87(s,3 H).

1. stirringThe mixture was stirred for a further 4 h
2. customA precipitate was produced
3. filtrationthis was filtered off
4. washwashed with water
5. customdried