Efficient syntheses of phosphonylated isochromenes by regioselective 6-endo-dig addition to carbon-carbon triple bond catalyzed by Pd(OAc)2.

Palladium(II)-catalyzed cycloisomerization of [(2-alkynylphenyl)hydroxymethyl]phosphonates 6 provides an efficient route to phosphonylated isochromenes 7 in THF at room temperature and the reaction proceeded in a regioselective manner leading to the 6-endo-dig products 7 in moderate to excellent yields.