Lactam Synthesis via the Intramolecular Hydroamidation of Alkynes Catalyzed by Palladium Complexes

The palladium complexes catalyzed intramolecular hydroamidation reaction of amidoalkynes gives the corresponding lactams in good to high yields. For example, in the presence of 10 mol % of Pd(PPh3)4 and 20 mol % of PhCOOH, the reaction of the amidoalkyne 3a in 1,4-dioxane at 100 °C proceeded smoothly to give the corresponding lactam 4a in 92% yield.