Synthesis of isomeric trifluoromethyl pyrazoles and isoxazoles
作者:Joseph Diab、André Laurent、Isabelle Le Dréan
DOI:10.1016/s0022-1139(97)00056-0
日期:1997.9
Three regioisomeric trifluoromethyl pyrazoles and four regioisomeric trifluoromethylisoxazoles were completely selectively synthesized from three trifluoromethyl enones or acroleins (1, 2 and 3) and phenylhydrazine, azide or hydroxylamine.
Cyclocondensation of monosubstituted hydrazines 2a–c with trifluoromethylenaminones 1a–c afforded 3-CF3 and (or) 5-CF3 pyrazoles 3–6. Addition of N-methylhydrazine to enaminone led to 3-CF3 pyrazole as the major product, whereas phenylhydrazine gave regiospecific formation of 5-CF3 pyrazole.