4-Toluenesulfonyl chloride → Ethyl alpha-(4-methyl-phenylsulphonyloxymethylene)-phenylacetate

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Reaction Steps

19.2 g (0.1 mol) of ethyl α-hydroxymethylene-phenylacetate are dissolved in 100 ml of acetonitrile, and first 11.2 g (0.1 mol) of potassium tert.-butylate are added, after which 19 g (0.1 mol) of p-toluenesulphonyl chloride are added in portions at 20° to 25° C. The mixture is stirred for 4 hours at room temperature and left to stand overnight. The precipitated salt is filtered off under suction, and the filtrate is evaporated down in vacuo. The residue is dissolved in toluene, and the solution is washed with water, dried over sodium sulphate and evaporated down in vacuo. 23 g (73% of theory) of ethyl α-(4-methyl-phenylsulphonyloxymethylene)-phenylacetate are obtained. The oil is dissolved in 150 ml of ethanol, and then 7.7 g (0.07 mol) of 2-hydrazino-pyrimidine are added. The mixture is stirred for 10 hours at room temperature, and then 13.5 g of concentrated sodium hydroxide solution are added dropwise in the course of 4 hours. After stirring has been continued for a further 5 hours at room temperature, dilute hydrochloric acid is added dropwise until the neutral point is reached, and the mixture is diluted with 750 ml of water. The oily product which separates out is taken up in a small amount of ether, 3.6 g (22% of theory) of 1-pyrimid-2-yl-4-phenylpyrazolin-5-one being precipitated. Melting point 159° to 160° C. (from ethanol).

Provenance & Evidence