Cl[C:2]1[C:7]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[CH:6][N:5]=[C:4]2[CH:13]=[N:14][NH:15][C:3]=12.[CH:16]1[C:21]([NH2:22])=[CH:20][CH:19]=[C:18]([OH:23])[CH:17]=1.C(=O)([O-])[O-].[Na+].[Na+]>C(OCC)(=O)C.C(O)C>[OH:23][C:18]1[CH:19]=[CH:20][C:21]([NH:22][C:2]2[C:7]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[CH:6][N:5]=[C:4]3[CH:13]=[N:14][NH:15][C:3]=23)=[CH:16][CH:17]=1Ethyl 7-chloro-1H pyrazolo[4,3-b]pyridine-6-carboxylate (1.0 g, 0.004 mole) and p-aminophenol (1.0 g, 0.009 mole) were stirred together in ethyl acetate (200 ml) under nitrogen for 48 hours, the temperature being maintained between -10° and -5° C. The ethyl acetate was removed under reduced pressure to give a yellow solid. This solid was dissolved in aqueous ethanol and the pH adjusted to pH8 with 10% sodium carbonate solution. The resulting solid was filtered off washed with water and dried. Recrystallization from methanol/ethyl acetate gave the title compound as a pale yellow solid (650 mg, 50%), m.p. 286°-287° C. (decomposition)
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