Iron-Catalyzed Intramolecular Arene C(sp 2 )-H Amidations under Mechanochemical Conditions.

In a ball mill, FeBr 3 -catalyzed intramolecular amidations lead to 3,4-dihydro-2(1H)-quinolinones in good to almost quantitative yields. The reactions do not require a solvent and are easy to perform. No additional ligand is needed for the iron catalyst. Both 4-substituted aryl and β-substituted dioxazolones provide products with high selectivity. Mechanistically, an electrophilic spirocyclization followed by C-C migration explains the formation of rearranged products.