A highly efficient strategy has been developed for the rapid asymmetric synthesis of gem- dimethyl and spirocyclopropyl norbornyl carboxylic acids. The key transformation involved the unprecedented asymmetric Diels-Alder reaction of highly reactive β, β-cyclopropyl-α, β- unstaturated N-acyloxazolidinones with cyclopentadiene affording the adducts in high yield and de.
