Synthesis of trifluoromethylated pyrazoles from trifluoromethylenaminones and monosubstituted hydrazines
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, w
Studies on Organic Fluorine Compounds. XLII. Synthesis and Reactions of Phenyltrifluoromethylacetylenes
Phenyltrifluoromethylacetylene (4a) was synthesized by the pyrolysis of triphenylphosphonium α-(trifluoroacetyl)benzylide (3a), which was easily derived from benzyl halide (1a).This method can be used for the synthesis of 4-substituted-phenyltrifluoromethylacetylenes (4).The 1,3-dipolar reaction of 4 with diazomethane and phenyl azide proceeds readily to give trifluoromethylated pyrazoles and triazoles.Keywords - trifluoromethyl; acetylene; 1,3-dipolar reaction; intramolecular Wittig reaction; trifluoroacetylphosphonium ylide; pyrazole; diazomethane; phenyl azide