Fluorocyclization of N-Propargyl Carboxamides by λ³-Iodane Catalysts with Coordinating Substituents

Aiming at the enhanced catalytic activity of fluoro-λ³-iodane generated from iodoarene precatalyst with Selectfluor and HF⋅pyridine, this study focused on the λ³-iodanes bearing coordinating substituents. Compared to 4-iodoanisole as a precatalyst of our previous method, N-methyl-2-iodobenzamide or 2-iodobenzamide worked well in the fluorocyclization of N-propargyl carboxamides to oxazoles. Control experiments suggest the equilibrium mixture of iodane-amine complexes and cyclic iodane fluorides would be involved in the present catalysis. (Figure presented.).