A new method for the stereoselective synthesis of substituted tetrahydrofurans and pyrrolidines via Pd-catalyzed reactions of gamma-hydroxy or gamma-amino alkenes with aryl or vinyl halides will be described. These reactions form both a carbon-carbon and a carbon-heteroatom bond in a single transformation, generating up to two stereocenters in one step with diastereoselectivities of up to >20:1. Mechanistic studies suggest the reactions proceed via the intramolecular syn-insertion of an olefin into an intermediate Pd(Ar)(OR) or Pd(Ar)(NRR') complex. The structure of the Pd-catalyst has a dramatic influence on the relative rates of several competing mechanistic pathways, which allows for the selective synthesis of several structurally different heterocyclic products from identical precursors by changing the catalyst. The scope and limitations of this methodology will be discussed, along with other applications such as the use of these reactions in tandem processes and for the synthesis of biologically active molecules.