Triethyl 5-ethyl-3-hydroxy-8-oxo-2,3,5,8-tetrahydrofuro[3,2-b]-1,8-naphthyridine-2,2,7-tricarboxylate → 5,8-Dihydro-5-ethyl-8-oxofuro-[3,2-b]-1,8-naphthyridine-2,7-dicarboxylic acid

HRID 847777Notes

Reaction equation

[CH2:1]([N:3]1[C:12]2[N:11]=[C:10]3[CH:13](O)[C:14](C(OCC)=O)([C:16]([O:18]CC)=[O:17])[O:15][C:9]3=[CH:8][C:7]=2[C:6](=[O:27])[C:5]([C:28]([O:30]CC)=[O:29])=[CH:4]1)[CH3:2]>S(=O)(=O)(O)O>[CH2:1]([N:3]1[C:12]2[N:11]=[C:10]3[CH:13]=[C:14]([C:16]([OH:18])=[O:17])[O:15][C:9]3=[CH:8][C:7]=2[C:6](=[O:27])[C:5]([C:28]([OH:30])=[O:29])=[CH:4]1)[CH3:2]

Participants

Conditions

Temperature: 100 °C

Procedure

5.0 g of triethyl 5-ethyl-3-hydroxy-8-oxo-2,3,5,8-tetrahydrofuro[3,2-b]-1,8-naphthyridine-2,2,7-tricarboxylate was added to 80 ml of 20% sulfuric acid and stirred at 100° C. for 2 hours. After allowing it to cool, the reaction solution was poured into ice water. The precipitated crystals were collected by filtration and recrystallized from dimethylformamide to obtain 2.61 g of 5,8-dihydro-5-ethyl-8-oxofuro-[3,2-b]-1,8-naphthyridine-2,7-dicarboxylic acid (Compound X where R1 =C2H5), m.p. >300° C.

Workup

temperatureto cool
filtrationThe precipitated crystals were collected by filtration
customrecrystallized from dimethylformamide

Sources & evidence

ORD record: ord-647396cd7e934d2281eb4a89b0556c2f
Source dataset: uspto-grants-1981_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04293695

Reaction notes

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