Organocatalytic Asymmetric Synthesis of Cyclic Acetals with Spirooxindole Skeleton

Abstract An organocatalytic asymmetric synthesis of cyclic acetal with spirooxindole skeleton has been developed via a domino reaction between isatin and γ ‐hydroxy enones. Bifunctional squaramide catalyst with adamantyl motif was found to be the most effective for the cascade reaction. With 10 mol% of the catalyst, the desired products were obtained in 1.8:1 to 9:1 diastereo‐ and 86% to >99% enantioselectivities from a range of substituted isatins and γ ‐hydroxy enones. magnified image