反应详情

16.1 g of the Compound VI obtained as above was added to 160 ml of boiling Dowtherm (produced by Dow Chemical Co.) and refluxed for 1 hour. After cooling, the precipitated crystals were collected by filtration to obtain 11.8 g of crude crystals which were then recrystallized from dimethylformamide to yield ethyl 6-ethoxy-4-hydroxy-7-methyl-1,8-naphthyridine-3-carboxylate (Compound VII where R2 =R3 =C2H5), m.p. 279°-282° C. (with decomposition).

1. temperaturerefluxed for 1 hour
2. temperatureAfter cooling
3. filtrationthe precipitated crystals were collected by filtration
4. customto obtain 11.8 g of crude crystals which
5. customwere then recrystallized from dimethylformamide