Phosphorus oxychloride → 1-ethyl-4-chloro-6-(methylthio)-1H-pyrazolo[3,4-b]quinoline

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Reaction Steps

A mixture of N-(1-ethylpyrazol-5-yl)-5-(methylthio) anthranilic acid (4.5 g) and POCl3 (20 ml) is refluxed overnight. The reaction mixture is poured into water, then ice is added. The mixture is extracted with CH2Cl2 and then the CH2Cl2 layer is evaporated. The residue is purified by column chromatography on silica gel eluting with 50% ethyl acetate/hexane to afford 2.4 g of 1-ethyl-4-chloro-6-(methylthio)-1H-pyrazolo[3,4-b]quinoline, m.p. 120°-121° C.

Provenance & Evidence