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Transformations of phenylhydrazones of dialkyl 2‐oxo‐propane‐1,3‐dicarboxylate and of ethyl acetoacetate in concentrated sulfuric acid
Author(s) -
Bevk David,
Svete Jurij,
Stanovnik Branko
Publication year - 2005
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570420724
Subject(s) - chemistry , ethyl acetoacetate , phenylhydrazine , sulfuric acid , hydrazone , alkyl , medicinal chemistry , acetoacetic ester synthesis , organic chemistry , pyrazole , alkoxy group , propane , catalysis
Abstract 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‐2‐yl)acetates ( 5a,b ), and ethyl (5‐ethoxy‐1‐phenyl‐1 H ‐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‐1 H ‐pyrazole ( 12 ), and 3‐methyl‐1‐phenyl‐1 H ‐pyrazol‐5‐one ( 13 ).