反应详情

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).

1. temperatureThe mixture is heated to 120° (bath temp.) for 50 minutes
2. customThen the aqueous phosphoric acid solution is decanted
3. additionthe undissolved residue is treated with 200 ml
4. extractionThe mixture is extracted with chloroform
5. washwashed twice with water
6. dry with materialdried with sodium sulfate
7. customevaporated
8. customto yield 39 g
9. dissolutionThe oil is dissolved in about 250 ml
10. customto yield 35 g