Phosphorus oxychloride → 2-Chloro-6,7-dihydro-9,10-dimethoxy-4H-pyrimido[6,1-a]isoquinolin-4-one

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Reaction Steps

A mixture of 1-(3,4-dimethoxyphenylethyl)barbituric acid (20.2 g) and phosphorus oxychloride (100 ml) is refluxed for 2.5 hours at 100°-110° C. The excess of phosphorus oxychloride is distilled. The residue is poured onto crushed ice and made basic with a cold solution of 30% aqueous sodium hydroxide. A yellow gummy precipitate is separated and extracted with chloroform. The extract is washed with water, dried over sodium sulfate and concentrated to dryness under reduced pressure. The residue is purified by passage over a silica gel column using chloroform as eluent to give the desired compound.

Provenance & Evidence