Phosphorus oxychloride → 3-Benzenesulphonyl-7-chloro-5-methoxymethyl-2-methylsulphanyl-pyrazolo[1,5-a]pyrimidine

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Reaction Steps

A suspension of 2.5 g (6.8 mmol) of 3-benzenesulphonyl-5-methoxymethyl-2-methylsulphanyl-pyrazolo[1,5-a]pyrimidin-7-ol in 40 ml of POCl3 and 20 ml of diethylaniline 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 100 ml of CH2Cl2,and the organic phases were dried (MgSO4), filtered and evaporated. Chromatography (SiO2, CH2Cl2/MeOH 20:1) yielded 2.1 g (79%) of 3-benzenesulphonyl-7-chloro-5-methoxymethyl-2-methylsulphanyl-pyrazolo[1,5-a]pyrimidine as a pale yellow powder, m.p. 194-197°.

Provenance & Evidence