Preparation and reactions of ethyl 4-bromo-2,3-dioxobutyrate 2-arylhydrazones and 4-bromo-2,3-dioxo-1-phenylbutanal 2-arylhydrazones

Abstract

Ethyl 2,3-dioxobutyrate 2-arylhydrazones and 2,3-dioxo-1-ph enylbutanal 2-arylhydrazones react with bromine in ether to give the corresponding 4-bromo-derivatives. Some ethyl 1-aryl-4-hydroxypyrazole-3-carboxylates and 1-aryl-3-benzoyl-4-hydroxypyrazoles have been synthesised by refluxing these 4-bromo-compounds in ethanol containing sodium acetate. 1-Aryl-3-benzoyl-4-hydroxypyrazoles react with toluene-p-diazonium salts to give 1-aryl-3-benzoyl-5-(p-tolylhydrazono)-2-pyrazolin-4-ones.