Phosphorus oxychloride → 3-Chloro-6-(propan-2-yl)pyridazine

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Reaction Steps

6-Isopropyl-3(2H)-pyridazinone (3.30 g) and phosphorus oxychloride (15.0 ml) were heated for 1 hour under reflux. After an excess of phosphorus oxychloride was distilled away, ice-water (200 ml) was added to the residues which were then adjusted to pH 6 with 20% aqueous sodium hydroxide solution. The reaction solution was extracted 3 times with ethyl acetate, and the extracts were combined, dried over anhydrous magnesium sulfate and concentrated. The residues were purified by silica gel column chromatography (ethyl acetate:chloroform=1:2) to give the title compound as pale red crystals. The yield was 1.60 g (40.8% based on 5-methyl-4-oxohexanoic acid).

Provenance & Evidence