Synthesis of different ring-size heterocycles from the same propargyl alcohol derivative by ligand effect on Pd(0)

The type of ligand on an allenylpalladium complex, which was prepared from propargyl alcohol derivative and Pd(0), plays an important role in determination of the ring size of the cyclized compound. An intermediary palladium complex bearing a monodentate ligand gave a cyclized compound via palladacycle, while that bearing a bidentate ligand gave one-carbon elongated cyclized compound via a η3-propargylpalladium complex.