Phosphorus oxychloride → 7-Chloro-5-methyl-2-methylsulphanyl-3-(toluene-4-sulphonyl)-pyrazolo[1,5-a]pyrimidine

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Reaction Steps

A suspension of 3.8 g (10.8 mmol) of 5-methyl-2-methylsulphanyl-3-(toluene-4-sulphonyl)-pyrazolo[1,5-a]pyrimidin-7-ol in 20 l of POCl3 was heated at reflux for 1 hr. The reaction solution was cooled to RT and evaporated. The residue was treated with 100 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 CH2Cl2, and the organic phases were dried (MgSO4), filtered and evaporated. Chromatography (SiO2, CH2Cl2/AcOEt 25:1) of the residue yielded 3.8 g (95%) of 7-chloro-5-methyl-2-methylsulphanyl-3-(toluene-4-sulphonyl)-pyrazolo[1,5-a]pyrimidine as pale yellow crystals, m.p. 197-198°.

Provenance & Evidence