反应详情

A mixture of ethyl 2-amino-4-methylthiophene-3-carboxylate (5 g, 0.03 mol) in methanol (25 ml) and aq. 2M sodium hydroxide (20.24 ml, 0.04 mol) was heated under reflux for 4 h. After cooling the solvents were evaporated, the residue dissolved in water (30 ml) and a 20% solution of phosgene in toluene (24 ml, 0.05 mol) added dropwise with ice cooling. After a further 30 min the solid which had precipitated was filtered, washed with water then ether, and dried to give the title compound 2.93 g (59%). 1H NMR (d6-DMSO) δ 2.31 (3H, s), 6.78 (1H, s), 12.50 (1H, br. s).

1. temperaturewas heated
2. temperatureunder reflux for 4 h
3. temperatureAfter cooling the solvents
4. customwere evaporated
5. dissolutionthe residue dissolved in water (30 ml)
6. customAfter a further 30 min the solid which had precipitated
7. filtrationwas filtered
8. washwashed with water
9. dry with materialether, and dried