反应详情

A suspension of (3-nitrophenylacetyl)aminoacetic acid methyl ester (13 g, 0.05 mol) in methanol (40 ml) and toluene (56 ml) was added to a stirred solution of sodium methoxide in methanol (prepared by dissolving sodium (1.5 g, 0,065 mol) in methanol (30 ml)), under nitrogen. The mixture was heated at reflux for 18 h. After this time more sodium methoxide in methanol (prepared by dissolving sodium (0.56 g, 0.024 mol)in methanol (15 ml)) was added and the mixture heated for a further 18 h. The solution was then cooled to ambient temperature and acetic acid added to pH5. The mixture was evaporated in vacuo and azeotroped with toluene (2×20 ml). The residue was chromatographed on silica gel, using 94:6:0.6 dichloromethane:methanol:acetic acid as the eluant, to afford the tetramic acid (2.8 g, 25%) as a yellow solid. mp 245°-247° C. (dec.). 1H NMR (360MHz, D6 -DMSO) δ3.85 (2H, s), 7.31 (1H, brs), 7.57 (1H, dd, J: 8 and 8Hz), 7.93 (1H, dd, J=8 and 1.5Hz), 8.60 (1H, d, J=8Hz), 9.08 (1H, s).

1. temperatureThe mixture was heated
2. temperatureat reflux for 18 h
3. temperaturethe mixture heated for a further 18 h
4. customThe mixture was evaporated in vacuo
5. customazeotroped with toluene (2×20 ml)
6. customThe residue was chromatographed on silica gel