反应详情

A stirred solution of 8-acetamido-1,4-benzodioxan-5-carboxylic acid (GB 1 571 278) (2.5 g, 0.0105 mole)in methanol (60 ml) was treated with concentrated sulphuric acid (2 ml) and the solution kept at room temperature for 20 hours, then concentrated in vacuo to approxiamately 10 ml volume. The residue was treated with water (30 ml), basified with potassium carbonate and a precipitate was produced. This was filtered off, washed with water and dried to afford methyl 8-amino-1,4-benzodioxan-5-carboxylate as a white solid (1.96 g, 89%). 1H NMR (CDCl3) δ:7.38(d,1 H), 6.28(d,1 H), 4.25-4.43(m,4 H), 4.12(br s,2 H), 3.83(s,3 H).

1. concentrationconcentrated in vacuo to approxiamately 10 ml volume
2. additionThe residue was treated with water (30 ml)
3. customa precipitate was produced
4. filtrationThis was filtered off
5. washwashed with water
6. customdried