Phosphorus oxychloride → 4-chloro-1,3-dimethyl-6-phenyl-1H-pyrazolo[3,4-b]pyridine

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Reaction Steps

73 gms. of 1,3-dimethyl-4-hydroxy-6-phenyl-1H-pyrazolo[3,4-b]pyridine (0.31 mol.) are refluxed in 800 ml. of phosphorus oxychloride for 6 hours. The excess phosphorus oxychloride is removed in vacuo and the oily residue is treated with ice-water by which operation the compound becomes solid. The compound is extracted with ether, washed with an aqueous sodium carbonate solution (10%) and again with water. Evaporation of the dried (Na2SO4) and charcoal treated ethereal extract provides 4-chloro-1,3 -dimethyl-6-phenyl-1H-pyrazolo[3,4-b]-pyridine which is washed with absolute ethanol, yield: 55.6 gms. (69.8%) of white product melting at 89°-90° C.

Provenance & Evidence