Isopropanol → 2-(2-Methylpyrazolo[1,5-a]pyridin-3-yl)-4-(2-nitrophenyl)-1,3-thiazole-5-carboxylic acid

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Reaction Conditions

Reaction Steps

A mixture of 2-methylpyrazolo[1,5-a]pyridine-3-carbothioamide hydrochloride (1.2 g, 5.2 mmol) obtained in Example 11-B(v), ethyl 2-chloro-3-(2-nitrophenyl)-3-oxopropanoate (1.7 g, 8.4 mmol) obtained above and 2-propanol (20 mL) was stirred at 80° C. for 4 h. To the reaction mixture were added saturated aqueous solution of sodium bicarbonate, EtOAc and THF. Insoluble materials were removed by filtration and the filtrate was extracted with a 1:1 mixture of EtOAc and THF. The organic layer was washed with brine and dried over anhydrous magnesium sulfate. Insoluble materials were removed by filtration and the filtrate was concentrated under reduced pressure. To the residue were added MeOH (10 mL), THF (25 mL) and 8N aqueous sodium hydroxide solution (2.5 mL), and the mixture was stirred at 70° C. for 1 h. The reaction mixture was allowed to cool to 0° C., 6N hydrochloric acid was added to adjust the solution to about pH 3.0. The resulting precipitate was collected by filtration, washed with diisopropyl ether, and dried to give the title compound (620 mg, 31%) as a yellow solid.

Provenance & Evidence