Phosphorus oxychloride → 5-Chloro-2-methylpyrazolo[1,5-a]pyrido[3,4-e]pyrimidine

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Reaction Steps

200 g. of 2-methylpyrazolo[1,5-a]pyrido[3,4-e]-pyrimidin-5(4H)-one of Example 1c are refluxed with 800 ml. of phosphorus oxychloride overnight. The excess phosphorus oxychloride is removed in vacuo and the oily residue decomposed by pouring on ice. The acidic aqueous solution is made alkaline with sodium hydroxide. The precipitated 5-chloro-2-methylpyrazolo[1,5-a]pyrido[3,4-e]pyrimidine is filtered off, yield: 143 g. (66%); m.p. 169.8° (ethyl acetate).

Provenance & Evidence