Syntheses of 2-(trifluoromethyl)-1,3-dicarbonyl compounds through direct trifluoromethylation with CF3I and their application to fluorinated pyrazoles syntheses
Directtrifluoromethylation of 1,3-dicarbonyl compounds with CF3I in the presence of a Fenton reagent in dimethylsulfoxide was investigated. 1,3-Diketones, 3-oxocarboxylates and 3-oxocarboxamides were readily trifluoromethylated at the methylene carbon between two oxo groups. Cycloaddition of hydrazine derivatives to the obtained 2-(trifluoromethyl)-1,3-dicarbonyl compounds provided fluorinated pyrazoles
The trifluoromethylation of enamines of ethyl 3-oxocarboxylates catalyzed by Fenton reagent with CF3I was investigated. Trifluoromethylation followed by acid hydrolysis provided 3-oxo-2-(trifluoromethyl)carboxylates in 64–94% yields, which were greater than those obtained by the trifluoromethylation of 3-oxocarboxylates as reported previously. Enamines trifluoromethylated at the 2-position were isolated