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 30.0 g of 9,10-dimethoxy-3,4,6,7-tetrahydro-2H-pyrimido(6,1-a)isoquinolin-2,4-dione and 300 ml of phosphorus oxychloride is heated on a steam bath for 4 hours. The excess of phosphorus oxychloride is distilled under reduced pressure. The residue is poured into a cold solution of sodium hydroxide. A yellow solid precipitates which is collected by filtration. The product is purified by passage through a silica gel column using chloroform as eluent. Yield 28.0 g, m.p. 235°-236° C.

Provenance & Evidence