The palladium(0)-promoted cross-coupling of vinylic halides and triflates with alkenes and nucleophiles has been investigated. The use of carbon nucleophiles has never before been published for a three-component coupling reaction of this type. This palladium(0)-catalyzed cross-coupling of vinylic halides or triflates with alkenes and nucleophiles provides a useful new route to products in which two new bonds are formed in a single step. These reactions proceed under mild conditions;The palladium-catalyzed heteroannulation of 1,2-dienes by organic halides can be effected under mild reaction conditions with catalytic amounts of palladium. These synthetic transformations are unique and sufficiently versatile for the synthesis of seven- and eight-membered ring heterocyclic compounds in excellent yields, although regio- and stereoisomeric mixtures often result. The results presented in this dissertation are the first observed examples of the palladium-catalyzed formation of large-membered heterocyclic rings using functionally-substituted organic halides and dienes. The scope and limitations of these reactions are discussed.