Regiospecific Synthesis of 5-Trichloromethyl-1H-Pyrazole and 1HPyrazole-5-Carboxylic Ester Derivatives

Author(s): Alex F.C. Flores, Sidnei Moura, Favero R. Paula, Ernani Pinto, Pablo Machado, Marcos A.P. Martins

Journal Name: Letters in Organic Chemistry

Volume 5 , Issue 2 , 2008

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Reaction of 1,1,1-trichloro-4-methoxy-3-penten-2-one (1) with hydrazines (2a-h) (NH2NHR, R = H, Me, t-Bu, Ph, 4-NO2-C6H4, C6F5, CO2Me, CONH2) under differing conditions regiospecifically affords different pyrazole derivatives, 3-methyl-5-trichloromethyl-5-hydroxy-4,5-dihydropyrazoles (3a, d-h), 3-methyl-5-trichloromethyl-1H-pyrazoles (4a,b,d-g) and 5-carboxyethyl-3-methyl-1H-pyrazoles (5a-e). The structural assignments were based on the analysis of their 1H/13C NMR and ESI-MS data.

Keywords: Pyrazoles, trichloromethyl-1H-pyrazoles, 1, 1, 1-trichloro-4-alkoxy-3-alken-2-ones, cyclocondensation [CCC +NN]

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Article Details

Year: 2008
Page: [91 - 97]
Pages: 7
DOI: 10.2174/157017808783743984
Price: $65

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