Water → 1-ethyl-4-chloro-7-carboxy-1H-pyrazolo[3,4-b]quinoline

Reaction equation

[CH2:1]([N:3]1[C:7]([NH:8][C:9]2[C:10](=[CH:14][CH:15]=[C:16]([C:18]([OH:20])=[O:19])[CH:17]=2)[C:11](O)=O)=[CH:6][CH:5]=[N:4]1)[CH3:2].O=P(Cl)(Cl)[Cl:23].O>C(O)(=O)C>[CH2:1]([N:3]1[C:7]2=[N:8][C:9]3[C:10]([C:11]([Cl:23])=[C:6]2[CH:5]=[N:4]1)=[CH:14][CH:15]=[C:16]([C:18]([OH:20])=[O:19])[CH:17]=3)[CH3:2]

Participants

Procedure

A mixture of N-(1-ethylpyrazol-5-yl)-4-carboxyanthranilic acid (2.5 g) and POCl3 (20 ml) is refluxed overnight. The reaction mixture is poured into water, acidified with acetic acid, and the solids which form are collected by filtration. The solid is taken up in 10% NaOH, washed with ether and then the aqueous layer is acidified with concentrated HCl. The mixture is extracted with ether, the ether layer is dried over MgSO4 filtered and evaporated to afford 1 g of 1-ethyl-4-chloro-7-carboxy-1H-pyrazolo[3,4-b]quinoline, as a yellow powder.