We describe a general method for the synthesis of 5-(trifluoromethyl)isoxazoles by denitrogenative cyclization of vinyl azides with trifluoroacetic anhydride in the presence of NEt₃. The scope of this protocol was further extended to the synthesis of perfluoroalkylated isoxazoles. This reaction allows facile synthesis of structurally diverse 5-(perfluoroalkyl)isoxazole derivatives with various vinyl azides.

A novel synthesis approach for the construction of 2-trifluoroethyl-substituted benzofurans under copper-catalyzed conditions has been developed. The reaction of salicylaldehyde p-tosylhydrazones with 2-bromo-3,3,3-trifluoropropene proceeded through a sequential process to afford products in moderate to excellent yields (up to 93%). This method is also applicable to the formation of 2-trifluoroethylated indoles.

A base promoted annulation of pyridinium ylides with trifluoroacetyl diazoester has been reported. Highly functionalized 4-trifluoromethyl pyridazines were synthesized in good yields without the use of any heavy metal catalysts. The developed methodology was compatible with a variety of important functional groups. Mechanistic studies revealed that trifluoroacetylated hydrazone was an active intermediate of this three-component annulation. Synthetic versatility of the method via aminolysis and condensation toward amide- and pyridazino[4,5-c]pyridazine-derivatives has been showcased.

We herein describe a general approach to 5-trifluoromethyl 1,2,4-triazoles via the [3 + 2]-cycloaddition of nitrile imines generated in situ from hydrazonyl chloride with CF₃CN, utilizing 2,2,2-trifluoroacetaldehyde O-(aryl)oxime as the precursor of trifluoroacetonitrile. Various functional groups, including alkyl-substituted hydrazonyl chloride, were tolerated during cycloaddition. Furthermore, the gram-scale synthesis and common downstream transformations proved the potential synthetic relevance of this developed methodology.

A Knoevenagel-type reaction of 1,3-diketone substrates with trifluoroacetic anhydride is described. The electrophilic species of trifluoroacetaldehyde is easily generated in situ by the reaction of trifluoroacetic anhydride/difluoroacetic anhydride with triethylamine. By this efficient and simple approach, a library of 2-(2,2,2-trifluoroethylidene)-1,3-dicarbonyl compounds that contain a wide range of functional groups were synthesized in good yields. Moreover, the reaction with difluoroacetic anhydride affords the corresponding (2,2-difluoroethyl)-1,3-dicarbonyls. Some of these compounds exhibited promising fungicidal activities.