Transformations of phenylhydrazones of dialkyl 2-oxo-propane-1,3-dicarboxylate and of ethyl acetoacetate in concentrated sulfuric acid

✍ Scribed by David Bevk; Jurij Svete; Branko Stanovnik

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2005
• Tongue: English
• Weight: 63 KB
• Volume: 42
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570420724

✦ Synopsis

The hydrazones 3a,b, prepared from phenylhydrazine (1) and dialkyl 2-oxopropane-1,3-dicarboxylate (2a,b) were converted in concentrated sulfuric acid at -5 °C into a mixture of alkyl (3-carboxyindol-2yl)acetates (5a,b), and ethyl (5-ethoxy-1-phenyl-1H-pyrazol-3-yl)acetate 6. The hydrazone 8, prepared from 1 and ethyl acetoacetate (7) was transformed under the same conditions into a mixture of five compounds: ethyl 2-methylindol-3-carboxylate (9), 2-methylindol-3-carboxylic acid (10), 2-methylindol (11), 5-ethoxy-3-methyl-1-phenyl-1H-pyrazole (12), and 3-methyl-1-phenyl-1H-pyrazol-5-one (13).