反应详情

A mixture of 9.5 g of 5,8-dihydro-5-ethyl-8-oxofuro-[3,2-b]-1,8-naphthyridine-2,7-dicarboxylic acid (Compound X where R1 =C2H5), 0.8 g of copper powder and 250 ml of diethyl phthalate was heated at 250° to 260° C. for 25 minutes. After cooling, the reaction mixture was separated by partitioning between chloroform and aqueous potassium carbonate solution. The aqueous layer which separated out was acidified with hydrochloric acid and extracted with chloroform. The extract was treated with charcoal, and washed with water, dried and concentrated. The crystals precipitated by adding ethanol were collected by filtration to obtain 4.2 g of 5,8-dihydro-5-ethyl-8-oxofuro[3,2-b]-1,8-naphthyridine-7-carboxylic acid (Compound Ia where R1 =C2H5).

1. temperaturewas heated at 250° to 260° C. for 25 minutes
2. temperatureAfter cooling
3. customthe reaction mixture was separated
4. customby partitioning between chloroform and aqueous potassium carbonate solution
5. customThe aqueous layer which separated out
6. extractionextracted with chloroform
7. additionThe extract was treated with charcoal
8. washwashed with water
9. customdried
10. concentrationconcentrated
11. customThe crystals precipitated
12. additionby adding ethanol
13. filtrationwere collected by filtration