Hydrochloric Acid → 2-Cyano-3-(1,4-dihydro-1-phenyl-indeno[1,2-c]pyrazol-3-yl)-3-oxo-propanoic acid, ethyl ester

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Reaction Steps

Ethyl cyanoacetate (1.4 g) is treated with 50% sodium hydride (0.58 g) in anhydrous dioxane (20 ml) under stirring at room temperature until the effervescence subsides. To this solution 1,4-dihydro-1-phenyl-indeno [1,2-c]pyrazole-3-carbonyl chloride (3 g), prepared according to Example 5, dissolved in anhydrous dioxane (50 ml) is added under stirring at room temperature. The reaction mixture is allowed to react for 20 hours, then it is dilusted with ice water and acidified to pH 3 with 37% HCl. The precipitate is extracted with ethyl acetate and the organic solution washed with water and then evaporated to dryness in vacuo. The residue is purified over a SiO2 column, using hexane-ethyl acetate 80:20 as eluent, to give 2-cyano-3-(1,4-dihydro-1-phenyl-indeno[1,2-c]pyrazol-3-yl) -3-oxo-propanoic acid, ethyl ester (2.2 g), which is reacted with aniline (3.4 g) in xylene (100 ml) at the reflux temperature for 48 hours. After cooling the precipitate is filtered and washed with xylene, then crystallized from dichloro-methane/methanol to give 1.2 g of 2-cyano-3-(1,4-dihydro-1-phenyl-indeno [1,2-c]pyrazol-3-yl)-3-oxo-N-phenyl-propanamide, m.p. 273°-277° C.

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