Water → 7-Chloro-1-hydroxy-3-(4-chlorophenyl)-3,4,5,10-tetrahydropyridazino[4,5-b]quinoline-4,10-dione

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Reaction Steps

To a stirred suspension of dimethyl-7-chloro-4-hydroxyquinoline-2,3-dicarboxylate (2.50 g, 8.45 mM) and 4-chlorophenylhydrazine (10.60 g, 59.20 mM) in ethanol (50 mL) was added triethylamine (9.43 mL) to give a brown solution. This solution was refluxed for 24 hours and then cooled to room temperature. Dilution with water (25 mL) gave a brown precipitate. This suspension was stirred for 16 hours and filtered to remove the solids which were discarded. The filtrate formed another precipitate after standing for seven days. This solid was collected and washed with aqueous methanol (50%) and ether to give the 4-chlorophenylhydrazine salt of the title compound as a brown powder (1.20 g). This material was refluxed in glacial acetic acid (25 mL) for 3 hours and cooled to room temperature. The resulting orange suspension was filtered, and the solids were washed with glacial acetic acid and ether to give the title compound (0.810 g, 25%) as a light orange powder, mp 399-401° C.; MS(CI): 374 (M+H).

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