Palladium(II)-catalyzed tandem intramolecular aminopalladation of alkynes and conjugate addition. Synthesis of oxazolidinones, imidazolidinones, and lactams

[reaction: see text]Under the catalysis of a divalent palladium species, oxazolidinones, imidazolidinones, or lactams were conveniently obtained with high chemo- and stereoselectivity from the tandem intramolecular aminopalladation of alkynes, followed by insertion of alkenes, and protonolysis of the newly formed carbon-palladium bond.