Studies on the directed regio-and stereoselective Ni-catalyzed allylic substitution reactions involving methyl-and phenylmagnesium bromides and various acyclic and cyclic allylic ethers are reported. In the presence of a properly positioned internal Lewis base, C C bonds can be formed catalytically and with excellent levels of selectivity. Internal chelation allows Ni-catalyzed C C bond forming reactions that are otherwise non-selective, ...