Phosphorus oxychloride → 3-Benzenesulphonyl-7-chloro-5-methyl-pyrazolo[1,5-a]pyrimidine

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Reaction Steps

A suspension of 0.91 g (3.14 mmol) of 3-benzenesulphonyl-5-methyl-pyrazolo[1,5-a]pyrimidine in 15 ml of POCl3 was heated at reflux for 1 hr. The reaction solution was cooled to RT and evaporated. The residue was treated with 30 ml of ice-water and the pH value of the solution was adjusted to 8 with sat. NaHCO3 solution. The aqueous phase was extracted three times with 20 ml of CH2Cl2, and the organic phases were dried (MgSO4), filtered and evaporated. Chromatography (SiO2, CH2Cl2/AcOEt 19:1) of the residue yielded 0.84 g (87%) of 3-benzenesulphonyl-7-chloro-5-methyl-pyrazolo[1,5-a]pyrimidine as a beige solid.

Provenance & Evidence