Phosphorus oxychloride → 4-Chloro-3-methyl-1-(2-pyridinyl)-1H-pyrazolo[3,4-b]quinoline

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Reaction Steps

A solution of 2-[[3-methyl-1-(2-pyridinyl)-1H-pyrazol-5-yl]amino]benzoic acid (50.2 g, 0.17 mol) in phosphorous oxychloride (120 mL, 1.27 mol) was heated under reflux for 1 hour. The solution was cooled to room temperature and concentrated under reduced pressure, and the residue was poured into iced water. The solution was made basic by the addition of a sodium hydroxide solution, and the organic matter was extracted with chloroform. The extract was washed with saturated brine and water, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue thus obtained was purified by silica gel column chromatography (chloroform:methanol=98:2) to give the title compound (21.5 g, 43% yield).

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