Ring-expansion reaction for the synthesis of 2-(trifluoromethyl)oxazoles and 3-(trifluoromethyl)-1,2,4-triazines

A ring-expansion reaction of 2H-azirine with trifluoroacetic anhydride for the synthesis of 2-(trifluoromethyl)oxazoles is disclosed. The reaction features readily available reactants, relatively mild conditions, and high yields of products. The generated 2-(trifluoromethyl)oxazole core could be easily converted into 3-(trifluoromethyl)-1,2,4-triazines through hydrazinolysis reaction.