Hydrochloric Acid → HCID 178468723, compound

Participants

Reaction Steps

43.6 g. of (3-phenylpropionyl)malonic acid, diethyl ester (0.15 mol.) are added to a stirred mixture of 16.5 g. of 5-amino-1-ethylpyrazole (0.15 mol.) and 220 g. polyphosphoric acid. The mixture is heated to 120° (bath temp.) for 50 minutes. After the mixture has cooled to room temperature, 250 ml. of water are added in portions and stirring is continued for 20 minutes. Then the aqueous phosphoric acid solution is decanted and the undissolved residue is treated with 200 ml. of water and aqueous ammonia (10%) to neutralize the mixture. The mixture is extracted with chloroform, washed twice with water, dried with sodium sulfate and evaporated to yield 39 g. of oily product. The oil is dissolved in about 250 ml. of ether and ethereal hydrochloric acid added to yield 35 g. (62%) of 1-ethyl-4-hydroxy-6-(2-phenylethyl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid, ethyl ester, hydrochloride; m.p. 153°-155° (ethanol/ethyl acetate 1:1).

Provenance & Evidence