Copper-Catalyzed Oxidative Synthesis of 3-Aryl-5-fluoroalkyl-1,3,4-oxadiazol-2(3)-ones Using Perfluorocarboxylic Anhydride as a Reagent.

A copper-catalyzed oxidative annulation of sydnones with perfluorocarboxylic anhydride for the synthesis of 3-aryl-5-fluoroalkyl-1,3,4-oxadiazol-2(3)-ones is developed. A diverse array of 3-aryl-5-fluoroalkyl-1,3,4-oxadiazol-2(3)-ones are prepared with good yields (>73 examples, yields up to 95%). The synthetic utility of the developed protocol was demonstrated by gram-scale synthesis, and the synthetic transformation to 1,2,4-triazol-3-one products.

Synthesis of 2-trifluoromethyl benzimidazoles, benzoxazoles, and benzothiazoles condensation of diamines or amino(thio)phenols with CFCN.

A new and efficient method is developed for the synthesis of 2-trifluoromethyl benzimidazoles, benzoxazoles, and benzothiazoles in good to excellent yields by the condensation of diamines or amino(thio)phenols with generated CFCN. Additionally, the synthetic utility of the 2-trifluoromethyl benzimidazole and benzoxazole products is demonstrated gram scale synthesis. The mechanistic study suggests that the reaction proceeds the nucleophilic addition of trifluoroacetonitrile to the amino group of the diamine derivatives to form an imidamide intermediate, followed by intramolecular cyclization.

Synthesis of 2-trifluoromethyl thiazoles [3 + 2] cycloaddition of pyridinium 1,4-zwitterionic thiolates with CFCN.

2,2,2-Trifluoroacetaldehyde -(aryl)oxime was employed for the [3 + 2] cycloaddition of pyridinium 1,4-zwitterionic thiolates for the synthesis of 2-trifluoromethyl 4,5-disubstituted thiazoles. The reaction works well with various substituted pyridinium 1,4-zwitterionic thiolates in moderate to good yields. The synthetic potential of the obtained 2-trifluoromethyl 4,5-disubstituted thiazoles was demonstrated.