Water → HCID 136398824, compound

Participants

Reaction Steps

351 g of 4-[2-(2-cyano-3-ethoxy-3-oxo-1-propenyl)hydrazino]-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid, ethyl ester are heated in 2 liters of acetic acid containing 50 g of zinc chloride for 24 hours. After this time, the solution is cooled and 2 liters of cold water are added. The precipitated 8-ethyl-5,8-dihydro-5-oxo-4H-pyrazolo[1,5-a]pyrazolo[4',3':5,6]pyrido[3,4-e]pyrimidine-3-carboxylic acid, ethyl ester is filtered off and purified by dissolving in the theoretical amount of sodium hydroxide in water and precipitating the compound with acetic acid, yield 256 g (83%); m.p. 263°-265°.

Provenance & Evidence