Organopalladium approaches to oxygen heterocycles

Several groups of oxygen heterocycles have been prepared utilizing organopalladium chemistry. The first group synthesized were butenolides. The strategy employed for their synthesis involved the palladium(II)-assisted intramolecular cyclization of organomercurials containing acyclic olefin and ester functionality. A variety of substitution patterns were examined. The second group of oxygen heterocycles obtained were bicyclic lactones and bicyclic acetals. The method used for the preparation of the bicyclic lactones involved the palladium(II)-assisted intramolecular cyclization of organomercurials containing cyclic olefin and ester functionality. Several substituted bicyclic lactones were obtained. Bicyclic acetals were generated via a novel oxypalladation reaction from cyclic allylic alcohols and vinyl ethers. The scope and limitations of this oxypalladation reaction were examined. Benzofurans were prepared utilizing two methods. The first approach involved the palladium(II)-assisted cyclization of allylic aryl ethers containing mercury functionality. The second approach examined the palladium(0)-catalyzed intramolecular cyclization of allylic aryl ethers containing iodide functionality. Several substituted benzofurans were subsequently synthesized