We have developed a synthetic strategy for Et 3 N-promoted [5 + 3] cycloaddition reactions between acetoxypyranones and azomethine imines to access functionalized azabicyclo[3.3.1]alkenones with three tertiary stereocenters (31 examples, 36% to 87% yield, 5.5:1 to > 20:1 dr). The method was scalable, and the products could be transformed to various eight-membered-ring bridged heterocyclic molecules.