反应详情

A mixture of ethyl 6-ethoxy-4-hydroxy-7-methyl-1,8-naphthyridine-3-carboxylate (2.8 g), glyoxylic acid monohydrate (1.5 g) acetic acid (20 ml) and trifluoroacetic acid (10 ml) was heated at 90°-95° C. for 2 hours, with stirring. The mixture was evaporated down under reduced pressure. The residue was triturated with hot ethanol and filtered to give 3-(3-ethoxy-6-ethoxycarbonyl-5-hydroxy-1,8-naphthyridin-2-yl)acrylic acid, m.p.>280° C.

1. temperaturewas heated at 90°-95° C. for 2 hours
2. customThe mixture was evaporated down under reduced pressure
3. customThe residue was triturated with hot ethanol
4. filtrationfiltered