- Formation and dehydration of a series of 5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazoles
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Reaction of five (3-oxo-4,4,4-trifluorobutanoyl)heterocycles with hydrazine hydrate under mild conditions gave the corresponding 3-heterocyclyl-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazoles. Thermal elimination of water from the 3-(thien-2-yl), 3-(pyridin-2-yl) and 3-(pyridin-4-yl) compounds readily gave the corresponding pyrazoles but acid catalysis was required to form 3-(benzothiazol-2-yl)-5-trifluoromethylpyrazole and 3-(1-methylbenzimidazol-2-yl)-5-trifluoromethylpyrazole. More forcing conditions were required for the analogous dehydration/aromatisations giving 3,5-bis(trifluoromethyl)-1-(4-nitrophenyl)pyrazole and 3,5-bis(trifluoromethyl)-1-pentafluorophenylpyrazole.
- Singh, Shiv P.,Kumar, Dalip,Jones, Brian G.,Threadgill, Michael D.
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p. 199 - 203
(2007/10/03)
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- 3,5-BIS(TRIFLUOROMETHYL)PYRAZOLE AND SOME N-SUBSTITUTED DERIVATIVES
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The pyrazoles (CF3)2C3HN2R (R = H, COPh, C6F5, C6H4NO2-4 and C6H3(NO2)2-2,4) have been prepared in yields ranging from 27percent (R = C6F5) to 78percent (R = C6H3(NO2)2-2,4) by the reaction between 1,1,1,5,5,5-hexafluoropentane-2,4-dione and the appropriately substituted hydrazine, NH2NHR.
- Claire, Preet P. K.,Coe, Paul L.,Jones, Christopher J.,McCleverty, Jon A.
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p. 283 - 289
(2007/10/02)
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