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Haloacetylated enol ethers. 11 . Synthesis of 1‐methyl‐ and 1‐phenyl pyrazole‐3(5)‐ethyl esters. A one‐pot procedure
Author(s) -
Martins Marcos A. P.,
Freitag Rogério A.,
Da Rosa Adriano,
Flores Alex F. C.,
Zanatta Nilo,
Bonacorso Helio G.
Publication year - 1999
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.5570360133
Subject(s) - chemistry , pyrazole , enol , enol ether , organic chemistry , medicinal chemistry , catalysis
Abstract A one‐pot synthesis of 1‐methyl‐ and 1‐phenylpyrazole‐3(5)‐ethyl esters 2,3a‐e by the cyclocondensation of β‐alkoxyvinyl trichloromethyl ketones 1a‐e with methyl and phenyl hydrazine hydrochloride under mild conditions, is reported. A study using compounds 1a‐e with different substituents proved that these are versatile building blocks for the synthesis of pyrazole derivatives, having a 3(5)‐ethoxycarbonyl substituent in good yields (60–89%). The hydrazine and β‐alkoxyvinyl trichloromethyl ketone substituent effects on the reaction regiochemistry on the formation of the 1,3‐ and 1,5‐isomer were observed.