We have reported a direct and stereoselective synthesis of functionalized dienoic carboxylates from the simple bicyclic lactone 1. The use of oxygen- or nitrogen-based nucleophiles in a domino allylic alkylation/4π-electrocyclic ring opening affords reliable access to dienes with interesting functionalities. Alternatively, halide substitution offers synthesis of other classes of functionalized dienoic acids. Herein, we demonstrate the utility of such dienoic products as key building blocks in various transformations as well as natural product synthesis.